Initial check in dumb 0.9.2 - has a few usages of floating point that should

be rewritten to fixed point. seems to compile cleanly for iriver.


git-svn-id: svn://svn.rockbox.org/rockbox/trunk@6197 a1c6a512-1295-4272-9138-f99709370657

7 files changed, 3467 insertions, 0 deletions

diff --git a/apps/codecs/dumb/docs/deprec.txt b/apps/codecs/dumb/docs/deprec.txt
new file mode 100644
index 0000000000..88ca2e9fda
--- /dev/null
+++ b/apps/codecs/dumb/docs/deprec.txt
@@ -0,0 +1,281 @@
+/*  _______         ____    __         ___    ___
+ * \    _  \       \    /  \  /       \   \  /   /       '   '  '
+ *  |  | \  \       |  |    ||         |   \/   |         .      .
+ *  |  |  |  |      |  |    ||         ||\  /|  |
+ *  |  |  |  |      |  |    ||         || \/ |  |         '  '  '
+ *  |  |  |  |      |  |    ||         ||    |  |         .      .
+ *  |  |_/  /        \  \__//          ||    |  |
+ * /_______/ynamic    \____/niversal  /__\  /____\usic   /|  .  . ibliotheque
+ *                                                      /  \
+ *                                                     / .  \
+ * deprec.txt - Deprecated functions, why they        / / \  \
+ *              were deprecated, and what to do      | <  /   \_
+ *              instead.                             |  \/ /\   /
+ *                                                    \_  /  > /
+ *                                                      | \ / /
+ *                                                      |  ' /
+ *                                                       \__/
+ */
+
+
+**********************************************
+*** How the functions have been deprecated ***
+**********************************************
+
+
+   GCC 3.1 and later provide a very useful attribute. The following:
+
+      __attribute__((__deprecated__))
+
+   when written alongside a function prototype, variable declaration or type
+   definition, will result in a warning from GCC if any such part of the API
+   is used. The warning will even tell you where the declaration is, and I
+   have inserted comments by all the deprecated declarations, telling you
+   what to do.
+
+   Unfortunately, GCC 2.x and 3.0.x and MSVC do not have any means to
+   deprecate things. The approach I have taken with these compilers is to
+   avoid prototyping the declared functions. This means you will get
+   warnings and errors, and they won't be very helpful. If your program
+   compiles, you may get strange crashes when you run it, since the compiler
+   needs the declarations in order to make sure function calls are carried
+   out correctly.
+
+   If you would like the deprecated parts of the API to be declared, you can
+   compile with the -DDUMB_DECLARE_DEPRECATED switch for GCC, or the
+   -D"DUMB_DECLARE_DEPRECATED" switch for MSVC. This will be accepted by
+   GCC 3.x but is unnecessary. Use this switch with other people's projects
+   if necessary, but please make the effort to update your own projects to
+   use the new API, as the deprecated parts may be removed in the future.
+
+   The rest of this file explains why some parts of the API were deprecated,
+   and how to adapt your code.
+
+
+**************************************
+*** What happened to DUH_RENDERER? ***
+**************************************
+
+
+   The DUH_RENDERER struct was designed for rendering audio to an end-user
+   format - 8-bit or 16-bit, signed or unsigned, with stereo samples
+   interleaved. In order for it to do this, it was built on top of the
+   hitherto undocumented DUH_SIGRENDERER struct, which rendered audio in
+   DUMB's internal 32-bit signed format with channels (left/right) stored
+   separately. The DUH_RENDERER struct contained a pointer to a
+   DUH_SIGRENDERER struct, along with some other data like the position and
+   number of channels.
+
+   There were then some developments in the API. The DUH_SIGRENDERER struct
+   also stored the position and the number of channels, so I decided to write
+   functions for returning these. Suddenly there was no need to store them in
+   the DUH_RENDERER struct. Before long, the DUH_RENDERER struct contained
+   nothing but a pointer to a DUH_SIGRENDERER.
+
+   I decided it would be a good idea to unify the structs. After all, there
+   really is no difference between the data stored in each, and it would be
+   easy to make duh_render(DUH_RENDERER *dr, ...) and
+   duh_render_signal(DUH_SIGRENDERER *sr, ...) work on the same type of
+   struct. (Note that duh_render_signal() is now deprecated too; see the next
+   section.) It took some deliberation, but I decided I didn't want functions
+   to be #defined (it prevents you from using these names for member
+   functions in C++ classes), and that meant they had to be defined
+   somewhere. Defining redundant functions is a source of bloat, inefficiency
+   and general inelegance. After weighing things up, I decided it was better
+   to deprecate the redundant functions and have people begin to use the more
+   efficient versions, and eventually the redundant functions will be able to
+   be removed.
+
+   So why did I choose to keep the more complicated name, DUH_SIGRENDERER?
+   The reason has to do with what DUMB will become in the future. Signals are
+   an inherent part of the DUH struct and how .duh files will be constructed.
+   It will be possible to have multiple signals in a single DUH struct, and
+   you will be able to choose which one you want to play (this is the 'sig'
+   parameter passed to duh_start_sigrenderer()). But don't hold your breath;
+   we still have a long way to go before .duh files will start to appear...
+
+
+typedef DUH_SIGRENDERER DUH_RENDERER;
+
+   Wherever you are using DUH_RENDERER in your program, simply replace it
+   with DUH_SIGRENDERER. An automated (case-sensitive!) search and replace
+   operation should get this done.
+
+
+DUH_RENDERER *duh_start_renderer(DUH *duh, int n_channels, long pos);
+
+   Use duh_start_sigrenderer() instead. It takes an extra parameter, 'sig',
+   which comes after 'duh' and before 'n_channels'; pass 0 for this. So an
+   example would be, replace:
+
+      sr = duh_start_renderer(duh, 2, 0);
+
+   with:
+
+      sr = duh_start_sigrenderer(duh, 0, 2, 0);
+
+
+int duh_renderer_get_n_channels(DUH_RENDERER *dr);
+long duh_renderer_get_position(DUH_RENDERER *dr);
+void duh_end_renderer(DUH_RENDERER *dr);
+
+   These are easy enough to fix; all you have to do is replace 'renderer'
+   with 'sigrenderer'. So the new functions are:
+
+      int duh_sigrenderer_get_n_channels(DUH_SIGRENDERER *sigrenderer);
+      long duh_sigrenderer_get_position(DUH_SIGRENDERER *sigrenderer);
+      void duh_end_sigrenderer(DUH_SIGRENDERER *sigrenderer);
+
+
+Note that duh_render() has NOT been deprecated. It now uses DUH_SIGRENDERER
+instead of DUH_RENDERER, but its functionality is unchanged. You do not have
+to change calls to this function in any way.
+
+
+DUH_RENDERER *duh_renderer_encapsulate_sigrenderer(DUH_SIGRENDERER *sr);
+DUH_SIGRENDERER *duh_renderer_get_sigrenderer(DUH_RENDERER *dr);
+DUH_SIGRENDERER *duh_renderer_decompose_to_sigrenderer(DUH_RENDERER *dr);
+
+   These functions did not exist in the last release of DUMB, so you are
+   probably not using them, but they are included here for completeness. All
+   you have to do here is unwrap the function, since the structs have been
+   unified. So, for instance, replace:
+
+      duh_renderer_encapsulate_sigrenderer(my_sigrenderer)
+
+   with:
+
+      my_sigrenderer
+
+   Simple!
+
+
+AL_DUH_PLAYER *al_duh_encapsulate_renderer(DUH_RENDERER *dr,
+                                       float volume, long bufsize, int freq);
+DUH_RENDERER *al_duh_get_renderer(AL_DUH_PLAYER *dp);
+DUH_RENDERER *al_duh_decompose_to_renderer(AL_DUH_PLAYER *dp);
+
+   Again, these functions were not in the last release, so you probably
+   aren't using them. Nevertheless, the fix is simple as always: simply
+   replace 'renderer' with 'sigrenderer'. So the new functions are:
+
+      AL_DUH_PLAYER *al_duh_encapsulate_sigrenderer(DUH_SIGRENDERER *sr,
+                                       float volume, long bufsize, int freq);
+      DUH_SIGRENDERER *al_duh_get_sigrenderer(AL_DUH_PLAYER *dp);
+      DUH_SIGRENDERER *al_duh_decompose_to_sigrenderer(AL_DUH_PLAYER *dp);
+
+
+*********************
+*** Miscellaneous ***
+*********************
+
+
+long duh_render_signal(DUH_SIGRENDERER *sigrenderer,
+                       float volume, float delta,
+                       long size, sample_t **samples);
+
+   This function used to return samples in DUMB's internal format. This
+   format consisted of 32-bit integers whose 'normal range' was -0x8000 to
+   0x7FFF (any samples outside this range would have to be clipped when sent
+   to the sound card).
+
+   DUMB's internal format has changed. DUMB still uses 32-bit integers, but
+   now the normal range is -0x800000 to 0x7FFFFF. The lowest eight bits are
+   discarded at the final stage by duh_render() when you ask for 16-bit
+   output. A new function, duh_sigrenderer_get_samples(), will return samples
+   in DUMB's new internal format. It takes exactly the same parameters, so
+   all you have to do to the call itself is change the name; however, you
+   will most likely have to change your code to account for the new
+   normalised range.
+
+   duh_render_signal() will still be able to give you the samples in DUMB's
+   old internal format, but it is inefficient. You should change your code as
+   soon as possible.
+
+
+typedef void (*DUH_SIGRENDERER_CALLBACK)(void *data, sample_t **samples,
+                                         int n_channels, long length);
+
+void duh_sigrenderer_set_callback(DUH_SIGRENDERER *sigrenderer,
+                              DUH_SIGRENDERER_CALLBACK callback, void *data);
+
+   This callback was intended to allow you to analyse the output. It was by
+   no means intended to let you modify the output. For this reason, the names
+   have been changed to DUH_SIGRENDERER_ANALYSER_CALLBACK and
+   duh_sigrenderer_set_analyser_callback, and the 'samples' parameter to your
+   callback should now be specified as follows:
+
+      const sample_t *const *samples
+
+   The first 'const' indicates that you must not modify the samples. The
+   second indicates that you must not modify the pointers to each channel.
+
+   There is a second reason why this change was necessary, and it is the one
+   described further up for duh_render_signal()'s entry: the format in which
+   the samples themselves are stored has changed. They are 256 times as
+   large, with a normal range from -0x800000 to 0x7FFFFF. You will most
+   likely need to change your code to account for this.
+
+   If you try to call the old function, it will print a message to stderr
+   directing you to this file, and it will not install the callback. You
+   shouldn't be able to get this far without a compiler warning (or, if you
+   don't have GCC 3.1 or later, some compiler errors).
+
+   If you wanted to use this callback to apply a DSP effect, don't worry;
+   there is a better way of doing this. It is undocumented, so contact me
+   and I shall try to help. Contact details are at the bottom of this file.
+
+   For reference, here are the new definitions:
+
+   typedef void (*DUH_SIGRENDERER_ANALYSER_CALLBACK)(void *data,
+                const sample_t *const *samples, int n_channels, long length);
+
+   void duh_sigrenderer_set_analyser_callback(DUH_SIGRENDERER *sigrenderer,
+                     DUH_SIGRENDERER_ANALYSER_CALLBACK callback, void *data);
+
+
+int dumb_resampling_quality;
+
+   This variable has changed meaning. It used to hold a value from 0 to 4,
+   whose meaning was as follows:
+
+        0   - aliasing
+       1,2  - linear interpolation
+        3   - quadratic interpolation
+        4   - cubic interpolation
+
+       0,1  - always use a straightforward interpolation algorithm
+      2,3,4 - when decimating (increasing the pitch), use a linear average
+              algorithm designed to reduce frequencies that would otherwise
+              reflect off the Nyquist
+
+   Now the variable only holds values from 0 to 2, and these values have
+   preprocessor constants associated with them. The somewhat inappropriate
+   quadratic interpolation has been removed. The linear average algorithm has
+   also been removed, and may or may not come back; there are probably more
+   efficient ways of achieving the same effect, which I shall be
+   investigating in the future.
+
+   This change will have hardly any noticeable effect on existing programs.
+   Levels 2, 3 and 4 used considerably more processor time because of the
+   linear average algorithm. Likewise, Level 2 in the new scheme (cubic) uses
+   considerably more processor time than Levels 1 and 0, and Levels 3 and 4
+   will behave identically to Level 2.
+
+
+******************
+*** Conclusion ***
+******************
+
+
+"I conclude that... DUMB is the bestest music player in the world because...
+Complete this sentence in fifteen words or fewer... D'OH!"
+
+The preceding conclusion formerly appeared in dumb.txt, and is deprecated
+because it's lame.
+
+
+Ben Davis
+entheh@users.sf.net
+IRC EFnet #dumb
+See readme.txt for details on using IRC.
diff --git a/apps/codecs/dumb/docs/dumb.txt b/apps/codecs/dumb/docs/dumb.txt
new file mode 100644
index 0000000000..86b2cc3374
--- /dev/null
+++ b/apps/codecs/dumb/docs/dumb.txt
@@ -0,0 +1,1699 @@
+/*  _______         ____    __         ___    ___
+ * \    _  \       \    /  \  /       \   \  /   /       '   '  '
+ *  |  | \  \       |  |    ||         |   \/   |         .      .
+ *  |  |  |  |      |  |    ||         ||\  /|  |
+ *  |  |  |  |      |  |    ||         || \/ |  |         '  '  '
+ *  |  |  |  |      |  |    ||         ||    |  |         .      .
+ *  |  |_/  /        \  \__//          ||    |  |
+ * /_______/ynamic    \____/niversal  /__\  /____\usic   /|  .  . ibliotheque
+ *                                                      /  \
+ *                                                     / .  \
+ * dumb.txt - DUMB library reference.                 / / \  \
+ *                                                   | <  /   \_
+ * See readme.txt for general information on         |  \/ /\   /
+ * DUMB and how to set it up.                         \_  /  > /
+ *                                                      | \ / /
+ * If you are new to DUMB, see howto.txt.               |  ' /
+ *                                                       \__/
+ */
+
+
+***********************************
+*** Include Files and Libraries ***
+***********************************
+
+
+dumb.h
+
+   Include this if you only want the core DUMB library functions. You will
+   be able to load music files and render them into memory buffers at your
+   own pace. The core library is completely portable, and as such does not
+   access hardware; you must relay the sound data to the sound card yourself.
+   A stdio file input module is available, but you must actively register it
+   if you wish to use it (see dumb_register_stdfiles()); if you do not
+   register it, it will not be linked into your executable. You must register
+   it, or a DUMBFILE module of your own, in order to load stand-alone music
+   files.
+
+   Optimised: -ldumb   or  /link dumb.lib
+   Debugging: -ldumbd  or  /link dumbd.lib
+
+
+aldumb.h
+
+   Include this if you wish to use DUMB with Allegro. This will provide you
+   with functions to play DUHs back through Allegro's audio streams and embed
+   music files in Allegro datafiles. A file input module using Allegro's
+   packfiles is provided; you have a choice between this and the stdio
+   module (or provide one of your own). You will be able to load datafiles
+   containing music files no matter which file input module you register, or
+   even if you register no file input module. However, you must register a
+   file input module in order to load stand-alone files.
+
+   Optimised: -laldmb -ldumb -lalleg  or  /link aldmb.lib alleg.lib dumb.lib
+   Debugging: -laldmd -ldumbd -lalld  or  /link aldmd.lib alld.lib dumbd.lib
+
+   aldmb or aldmd must be linked in first, so the symbols can be resolved
+   when linking in the other two libraries.
+
+
+***************************
+*** Version Information ***
+***************************
+
+
+#define DUMB_MAJOR_VERSION
+#define DUMB_MINOR_VERSION
+#define DUMB_REVISION_VERSION
+
+   Numeric constants representing this version of DUMB. If this were version
+   1.0, DUMB_MAJOR_VERSION would be 1 and DUMB_MINOR_VERSION would be 0.
+   DUMB_REVISION_VERSION will be 0 on any significant releases, and will be
+   incremented as releases with bugfixes and minor features are made.
+
+   Typical usage:
+
+      #if DUMB_MAJOR_VERSION < 1
+      #error This add-on requires DUMB v1.0 or higher. Please upgrade.
+      #endif
+
+
+#define DUMB_VERSION
+
+   A numeric constant which appears in the format MMmmrr when displayed in
+   decimal (M for major, m for minor, r for revision). This is most useful
+   for comparing version numbers; it has little other practical use.
+
+   Typical usage:
+
+      #if DUMB_VERSION < 801
+      #error This game requires DUMB v0.8.1 or higher. Please upgrade.
+      #endif
+
+      #if DUMB_VERSION < 10002
+      #error This game requires DUMB v1.0.2 or higher. Please upgrade.
+      #endif
+
+
+#define DUMB_VERSION_STR
+
+   String constant representing this version of DUMB. If this were Version
+   1.0, DUMB_VERSION_STR would be "1.0". DUMB_REVISION_VERSION will only
+   appear on the end if it is nonzero; then DUMB_VERSION_STR might be
+   "1.0.1".
+
+
+#define DUMB_NAME
+
+   A string identifying DUMB and its version. If this were Version 1.0,
+   DUMB_NAME might be "DUMB v1.0". This constant is suitable for use in your
+   Credits screen if you wish to acknowledge the use of DUMB there.
+
+
+#define DUMB_YEAR
+#define DUMB_MONTH
+#define DUMB_DAY
+
+   Numeric constants representing the year, month and day of this release of
+   DUMB. All four digits are included in the year. Please note that
+   DUMB_MONTH and DUMB_DAY were inadvertently swapped in the v0.8 release.
+
+
+#define DUMB_YEAR_STR4
+#define DUMB_YEAR_STR2
+#define DUMB_MONTH_STR2
+#define DUMB_MONTH_STR1
+#define DUMB_DAY_STR2
+#define DUMB_DAY_STR1
+
+   String constants representing the year, month and day of this release of
+   DUMB. DUMB_MONTH_STR2 and DUMB_DAY_STR2 include a leading zero if the
+   month or day respectively are less than ten; the STR1 variations do not.
+   DUMB_YEAR_STR2 contains only the two rightmost digits of the year, while
+   DUMB_YEAR_STR4 contains all four. I recommend using DUMB_YEAR_STR4,
+   especially so soon after the turn of the century (indeed the millennium).
+   However, it is a matter of personal preference which you use.
+
+   Please note that the month and day were inadvertently swapped in the v0.8
+   release.
+
+
+#define DUMB_DATE
+
+   A numeric constant that appears in the form yyyymmdd when displayed in
+   decimal. This is most useful for comparing release dates; it has little
+   other practical use.
+
+   WARNING: The month and day were inadvertently swapped in the v0.8 release.
+            Please do not compare this constant against any date in 2002. In
+            any case, DUMB_VERSION is probably more useful for this purpose.
+
+
+#define DUMB_DATE_STR
+
+   The date as a string. The format is "d.m.yyyy", with dots used as
+   separators, the day written first, four digits for the year, and no
+   leading zeros on the day or month. This is my preferred format. If you
+   don't like it, you can construct your own format using the other
+   constants. For example, "mm/dd/yy" could be constructed as follows:
+
+      DUMB_MONTH_STR2 "/" DUMB_DAY_STR2 "/" DUMB_YEAR_STR2
+
+   Please note that the month and day were inadvertently swapped in the v0.8
+   release.
+
+
+*************************
+*** Basic Sample Type ***
+*************************
+
+
+typedef int sample_t;
+
+   DUMB works internally with 32-bit integer samples, with a 'normal range'
+   from -0x800000 to 0x7FFFFF (as of DUMB v0.9.2; previously they ranged from
+   -0x8000 to 0x7FFF). Any samples that exceed this range will eventually be
+   clipped, and could cause integer overflow in extreme cases.
+
+
+***********************************
+*** Library Clean-up Management ***
+***********************************
+
+
+int dumb_atexit(void (*proc)(void));
+
+   Registers a function to be called at the end of your program. You can
+   register multiple functions to be called, and the one you register last
+   will be called first. If you try to register the same function twice, the
+   second attempt will have no effect.
+
+   See fnptr.txt for help with function pointers.
+
+   You must call dumb_exit() before exiting your program for this to work
+   properly. The library itself registers functions with dumb_atexit(), so it
+   is important to call dumb_exit() even if you do not use dumb_atexit()
+   yourself.
+
+   This function will return zero on success. It will return zero when
+   trying to install the same function twice. If it fails through lack of
+   memory, it will return nonzero. Generally you can ignore the return code;
+   in the worst case some memory will not be freed at the end. If it is
+   crucial that your function be called (e.g. to shut down some hardware or
+   save critical data), then you should call your function manually at the
+   end of the program instead of registering it here - or use the stdlib
+   function atexit(), guaranteed under ANSI C to succeed for at least 32
+   functions.
+
+
+void dumb_exit(void);
+
+   You should call this before exiting your program if you have used any part
+   of DUMB in the program. Some parts of DUMB will allocate memory, and this
+   function will free it all up.
+
+   More specifically, this function will call any functions that have been
+   registered with dumb_atexit(). If a part of DUMB needs shutting down, the
+   shutdown procedure will have been registered in this way.
+
+   dumb_exit() will, of course, also call any functions you registered with
+   dumb_atexit() yourself.
+
+   After a call to dumb_exit(), the list of functions is erased. If you are
+   not ready to exit your program, you can start using DUMB anew as if your
+   program had just started. (Note that not everything will be reset in
+   practice - dumb_resampling_quality will retain whatever you set it to, for
+   example, though you should not assume it will.)
+
+   If you only need to call dumb_exit() once at the end of the program, you
+   can use the following to register dumb_exit() with stdlib.h atexit():
+
+      #include <stdlib.h>
+
+      atexit(&dumb_exit);
+
+   Then dumb_exit() will be called for you when your program exits. This is
+   the recommended method, since it will ensure clean-up even if your program
+   aborts. You should only call dumb_exit() manually if you need to shut DUMB
+   down prematurely, or if atexit() is unavailable for one reason or another.
+
+
+*****************************
+*** Sequential File Input ***
+*****************************
+
+
+   DUMB provides a strictly sequential file input system which uses the
+   DUMBFILE struct. "Strictly sequential" means you cannot seek backwards.
+   However, the system will keep track of how many bytes you have read,
+   enabling you to seek forwards. DUMBFILEs provide a convenient error
+   detection system, so you do not have to check the return value from every
+   function call in the way you do with the ANSI C functions.
+
+   Note that DUMBFILEs cannot be used for output, nor can they be used
+   portably for text files.
+
+   If an error occurs when reading data from a DUMBFILE, the DUMBFILE will
+   become inoperative. All subsequent activities on the DUMBFILE will return
+   error codes without attempting to read from the file. The position in the
+   file will also be forgotten. You can find out if this has happened at any
+   stage with the dumbfile_error() function. You are still required to close
+   the DUMBFILE, and the return value from dumbfile_close() will tell you if
+   an error has occurred.
+
+   This system allows you to input large chunks of your file, neither
+   checking every return value nor wasting time accessing a file that has
+   already experienced an error. However, before you allocate an amount of
+   memory or read in a quantity of data depending on previous input from the
+   file, you should always check that such input was valid. In particular you
+   should avoid passing zero or negative numbers to malloc(), and avoid
+   passing negative numbers to dumbfile_skip() and dumbfile_getnc().
+
+   DUMBFILEs can be hooked. In other words, you can specify your own
+   functions to do the work of reading from a file. While DUMB contains two
+   modules for this purpose, it does not set them up for you automatically.
+   In most cases you must register one of these modules yourself, or provide
+   your own module. See register_dumbfile_system(), dumb_register_stdfiles()
+   and dumb_register_packfiles().
+
+
+void register_dumbfile_system(DUMBFILE_SYSTEM *dfs);
+
+   Use this function to register a set of functions for use by the DUMBFILEs
+   (a DUMBFILE system). The DUMBFILE_SYSTEM struct contains the following
+   fields:
+
+      void *(*open)(const char *filename);
+      int (*skip)(void *f, long n);
+      int (*getc)(void *f);
+      long (*getnc)(char *ptr, long n, void *f);
+      void (*close)(void *f);
+
+   See fnptr.txt for help with function pointers such as these.
+
+   Your 'open' function should open the file specified and return a pointer
+   to a struct representing the open file. This pointer will be passed to
+   your other functions as 'f'. Your 'close' function should close the file
+   and free all memory pointed to by 'f'. Note that the 'close' operation
+   should never be able to fail; if you are calling a function with a return
+   value, you can generally ignore it.
+
+   Your 'getc' function should read one byte from the file and return its
+   value in the range 0 to 255. If an error occurs, you should return -1. Do
+   not worry about remembering that an error has occurred; DUMB will do that
+   for you.
+
+   'skip' is for skipping parts of the file, and should skip n bytes,
+   returning 0 on success or any other number on failure. 'getnc' should read
+   n bytes from the file, store them at 'ptr', and return the number of bytes
+   read (n on success, fewer on failure). However, these two functions are
+   optional, and you should only provide them if the operations can be done
+   more efficiently than with repeated calls to your 'getc' function. If this
+   is not the case, specify NULL for 'skip', 'getnc' or both, and DUMB will
+   use your 'getc' function to do the work.
+
+   Once you have written all your functions, you need to create a
+   DUMBFILE_SYSTEM struct to hold them, and pass its pointer to
+   register_dumbfile_system().
+
+   The DUMBFILE_SYSTEM struct must be permanent. In other words, it must be
+   either global or static, and you should not modify it later. DUMB will not
+   make its own copy.
+
+   You will most likely create your own struct to represent the open file,
+   but do not be tempted to specify that struct in the function prototypes
+   and pacify the compiler warnings by casting your function pointers. There
+   exist computer systems where a (void *) pointer and a (MY_STRUCT *)
+   pointer are represented differently in memory, and a cast of such a
+   pointer causes a tangible conversion to take place. If you cast the
+   function pointers, the computer cannot know when such a conversion is
+   necessary. Instead, use the following structure:
+
+      int myskip(void *f, long n)
+      {
+         FILE *file = f;
+         /* Do some stuff with 'file' */
+         return something;
+      }
+
+   If you need examples, have a look at the two existing DUMBFILE systems in
+   dumb/src/core/stdfile.c and dumb/src/allegro/packfile.c.
+
+
+DUMBFILE *dumbfile_open(const char *filename);
+
+   Open the specified file for input. You must pass the DUMBFILE pointer
+   whenever you wish to operate on this file. When you have finished with the
+   file, you must pass it to dumbfile_close().
+
+   Before you use this function, make sure you have registered a DUMBFILE
+   system. See register_dumbfile_system(), dumb_register_stdfiles() and
+   dumb_register_packfiles().
+
+   You must check the return value from this function. If it is NULL, the
+   file could not be opened, and you must not pass the DUMBFILE to any other
+   function. The debugging library will abort if you get this wrong; the
+   optimised library will act weird.
+
+
+DUMBFILE *dumbfile_open_ex(void *file, DUMBFILE_SYSTEM *dfs);
+
+   This function is provided for more specialised use. You should create a
+   DUMBFILE_SYSTEM specially for the purpose. Its 'open' field is irrelevant;
+   for neatness, set it to NULL, unless you are using this DUMBFILE_SYSTEM
+   with register_dumbfile_system() as well.
+
+   When you have called this function, the DUMBFILE struct it returned can be
+   used as normal. The specified DUMBFILE_SYSTEM will be used for all input,
+   with 'file' passed to your 'skip', 'getc' and 'getnc' functions as 'f'.
+   This can be used, for example, to read from an already open file.
+
+   Note that the position will always be initialised to 0 for this DUMBFILE.
+   This means for example that offsets in the file do not need adjusting when
+   embedding data in a larger file.
+
+   There are two ways to use this function. If you want 'file' to persist
+   after using a DUMBFILE returned by this function, you should make sure the
+   'close' field in the DUMBFILE is set to NULL. When the DUMBFILE is closed,
+   'file' will be left alone, and you can and should deal with it yourself
+   when the DUMBFILE has been closed.
+
+   Alternatively, you can provide a 'close' function to get rid of 'file' for
+   you when the DUMBFILE is closed. If you do this, you should not otherwise
+   use 'file' after a call to this function.
+
+   If dumbfile_open_ex() has to return NULL, owing to lack of memory, then
+   your 'close' function will be called if provided. In other words, if you
+   have provided a 'close' function, then you no longer need to worry about
+   'file' whether this function succeeds or not.
+
+   See dumb/src/helpers/stdfile.c and dumb/src/allegro/packfile.c for
+   examples of how to use this function. Neither provides a 'close' function,
+   so I hope my explanation here will suffice. If not, please feel free to
+   contact me so I can make the explanation clearer and help you do what you
+   want to do. Contact details are at the end of this file.
+
+
+long dumbfile_pos(DUMBFILE *f);
+
+   Returns the number of bytes read from the DUMBFILE (or skipped) since it
+   was opened, or -1 if an error has occurred while reading.
+
+
+int dumbfile_skip(DUMBFILE *f, long n);
+
+   Skips n bytes of the specified DUMBFILE. Returns zero on success.
+
+
+int dumbfile_getc(DUMBFILE *f);
+
+   Reads one byte from the DUMBFILE and returns it in unsigned format (from 0
+   to 255). If an error occurs, or occurred before, this function returns -1.
+
+
+int dumbfile_igetw(DUMBFILE *f);
+
+   Reads two bytes from the DUMBFILE and combines them into a word ranging
+   from 0 to 65535. The first byte read is the least significant byte, as
+   with Intel processors. This function returns -1 on error.
+
+
+int dumbfile_mgetw(DUMBFILE *f);
+
+   Reads two bytes from the DUMBFILE and combines them into a word ranging
+   from 0 to 65535. The first byte read is the most significant byte, as
+   with the Apple Macintosh. This function returns -1 on error.
+
+
+long dumbfile_igetl(DUMBFILE *f);
+
+   Reads four bytes from the DUMBFILE and combines them into a long integer
+   ranging from -2147483648 to 2147483647. The first byte read is the least
+   significant byte, as with Intel processors. This function returns -1 on
+   error, but -1 is also a valid return value. After a call to this function,
+   you can use dumbfile_error() to find out if an error occurred.
+
+
+long dumbfile_mgetl(DUMBFILE *f);
+
+   Reads four bytes from the DUMBFILE and combines them into a long integer
+   ranging from -2147483648 to 2147483647. The first byte read is the most
+   significant byte, as with the Apple Macintosh. This function returns -1 on
+   error, but -1 is also a valid return value. After a call to this function,
+   you can use dumbfile_error() to find out if an error occurred.
+
+
+unsigned long dumbfile_cgetul(DUMBFILE *f);
+
+   Reads an unsigned (nonnegative) integer from the DUMBFILE. The integer is
+   stored in a condensed format where smaller numbers use less space:
+
+           0 to 127         1 byte
+         128 to 16383       2 bytes
+       16384 to 2097151     3 bytes
+     2097152 to 268435455   4 bytes
+   268435456 to 4294967295  5 bytes
+
+   This format is the same as that used for the times between notes in MIDI
+   files.
+
+   If an error occurs, this function returns (unsigned long)(-1), but that
+   may be a valid return value. After a call to this function, you can use
+   dumbfile_error() to find out if an error occurred.
+
+
+signed long dumbfile_cgetsl(DUMBFILE *f);
+
+   Reads a signed integer from the DUMBFILE. The integer is stored in a
+   condensed format where numbers closer to zero use less space:
+
+           -64 to 63          1 byte
+         -8192 to 8191        2 bytes
+      -1048576 to 1048575     3 bytes
+    -134217728 to 134217727   4 bytes
+   -2147483648 to 2147483647  5 bytes
+
+   If an error occurs, this function returns -1, but -1 is also a valid
+   return value. After a call to this function, you can use dumbfile_error()
+   to find out if an error occurred.
+
+
+long dumbfile_getnc(char *ptr, long n, DUMBFILE *f);
+
+   Reads n bytes from the DUMBFILE and stores them at 'ptr'. Note that the
+   pointer is to a series of chars. You may also use this function to read in
+   a series of signed chars or unsigned chars (which are both officially
+   distinct types from char), but do not use this to read ints, structs or
+   any other data type from the file. Integers must be read one at a time
+   using dumbfile_igetl(), dumbfile_cgetul(), etc. To load a struct in, you
+   must read each field separately using an appropriate function for each
+   one. For complicated data types, you can simplify this process by writing
+   a function for each struct.
+
+   dumbfile_getnc() returns the number of bytes successfully read, which will
+   be less than n if an error occurs, and may be as low as zero. If
+   dumbfile_getnc() returns -1, that means an error occurred on this DUMBFILE
+   earlier, before this function was called.
+
+
+int dumbfile_error(DUMBFILE *f);
+
+   This function returns -1 if an error has occurred with the specified
+   DUMBFILE, or 0 if all is well.
+
+
+int dumbfile_close(DUMBFILE *f);
+
+   This function closes the DUMBFILE, after which the pointer will be
+   invalid. dumbfile_close() returns the value that dumbfile_error() would
+   have returned, which is -1 if an error occurred while reading or 0
+   otherwise. Regardless of the return value, the file will always be closed
+   properly.
+
+
+*******************************
+*** stdio File Input Module ***
+*******************************
+
+
+void dumb_register_stdfiles(void);
+
+   This function registers the stdio file input module for use by DUMBFILEs.
+   FILE structs and their corresponding functions, as defined by the ANSI C
+   header stdio.h, will be used internally for all DUMBFILE input (unless
+   opened with dumbfile_open_ex()).
+
+   This must be called before dumbfile_open() is used, or else an alternative
+   system must be registered (see register_dumbfile_system() and
+   dumb_register_packfiles()).
+
+
+DUMBFILE *dumbfile_open_stdfile(FILE *p);
+
+   If you have a stdio FILE struct representing an open file, you can call
+   this if you wish to read from it using a DUMBFILE. This is useful when you
+   need to pass a DUMBFILE struct to a library function, to read an embedded
+   music file for example. When you close the DUMBFILE, you can continue
+   using the FILE struct to read what follows the embedded data.
+
+
+********************************
+*** Memory File Input Module ***
+********************************
+
+
+DUMBFILE *dumbfile_open_memory(const char *data, long size);
+
+   This function is useful if you have an image of a music file in memory.
+   You might have such an image if you use dat2s to encode a datafile
+   directly into the executable. Pass a pointer to the start of the memory,
+   and the size of the image to make sure DUMB doesn't overrun the buffer.
+   The resulting DUMBFILE will feed the contents of the image to you.
+
+   Note that the pointer is of type 'char *'. Files are series of chars, and
+   interpreting them directly as anything else isn't portable.
+
+
+**********************
+*** DUH Management ***
+**********************
+
+
+void unload_duh(DUH *duh);
+
+   Removes a DUH from memory. You must call this for all DUHs you load,
+   making sure they're not playing at the time.
+
+
+long duh_get_length(DUH *duh);
+
+   Returns the length of a DUH; 65536 represents one second. This value is
+   calculated when the DUH is created, and this function simply lifts it from
+   the struct. It may not truly correspond to the time for which the DUH will
+   generate sound. For module files, it will represent the point at which the
+   module first loops (or, in the case of some XM and MOD files, freezes).
+   Any add-ons to DUMB will provide their own code for calculating this.
+
+   The algorithm for calculating the length of a module file can be fooled,
+   but only by very deliberate methods. In the early days, when modules could
+   only be played by their editors and had to be exported to .wav or similar
+   in order to be used elsewhere, musicians would sometimes make the player
+   think it was looping when it wasn't in order to prevent their music from
+   being exported properly. If the length of a module seems a lot less than
+   it should be, the module is probably protected in this way.
+
+   Getting around this protection reliably would be extremely difficult, but
+   after considering it for a while I decided it would be better not to. The
+   musician has a right to protect his or her music in this way, and I have
+   no interest in actively breaking that protection.
+
+   (On the other hand, some musicians were just showing off!)
+
+
+***********************************
+*** IT, XM, S3M and MOD Support ***
+***********************************
+
+
+int dumb_it_max_to_mix;
+
+   Specifies the maximum number of samples DUMB will mix at any one time. The
+   default number is 64. Regardless of this value, all samples will continue
+   to be processed up to an internal maximum of 256 (roughly speaking; in
+   fact it will process one sample for each channel plus up to 192 extra
+   samples that are continuing to play owing to Impulse Tracker's New Note
+   Actions), and samples that have been cut will sound again as soon as the
+   congestion clears. Samples are given priority according to their final
+   volume after all factors affecting the volume of a sample have been
+   considered.
+
+   If you play two or more modules at once, this value represents the
+   maximum number of samples for each one. You will have to reduce it further
+   if your computer cannot keep up.
+
+   Despite the name, this variable controls XM, S3M and MOD files as well as
+   IT files.
+
+
+DUMB_IT_SIGDATA *duh_get_it_sigdata(DUH *duh);
+
+   This function attempts to retrieve the DUMB_IT_SIGDATA struct from a DUH.
+   This struct will exist for any IT, XM, S3M or MOD file, and you can use it
+   to obtain or override module-specific information. If 'duh' is NULL, or if
+   the DUH you pass contains something other than a music module, then this
+   function will return NULL (which can safely be passed to any other
+   function).
+
+
+DUMB_IT_SIGRENDERER *duh_get_it_sigrenderer(DUH_SIGRENDERER *sigrenderer);
+
+   This function attempts to retrieve the DUMB_IT_SIGRENDERER struct from a
+   DUH_SIGRENDERER. This struct will exist for any currently playing IT, XM,
+   S3M or MOD file, and you can use it to obtain or override information
+   specific to module playback. If 'sigrenderer' is NULL, or if the
+   DUH_SIGRENDERER you pass is rendering something other than a music module,
+   then this function will return NULL (which can safely be passed to any
+   other function).
+
+
+DUH_SIGRENDERER *dumb_it_start_at_order
+                                  (DUH *duh, int n_channels, int startorder);
+
+   This function, given a DUH containing an IT, XM, S3M or MOD file, will
+   start playing it at the specified order. If the DUH does not contain a
+   module, this function will fail and return NULL.
+
+   Note that starting at an arbitrary order may result in missing notes or
+   other playback oddities. It should be used primarily for modules that
+   contain multiple songs that start on different orders. If you wish just to
+   start some music in the middle, consider using duh_start_sigrenderer() or
+   al_start_duh() with the pos parameter set appropriately.
+
+
+void dumb_it_set_loop_callback(DUMB_IT_SIGRENDERER *sigrenderer,
+                               int (*callback)(void *data), void *data);
+
+   Installs a callback which will be called every time the module loops. You
+   can pass any data pointer you like, and it will be passed to the callback
+   for you. DUMB considers a file to loop when it reaches the end, or when a
+   'Jump to order' effect (Bxx in both IT/S3M and XM/MOD) jumps to the same
+   order or a preceding order. This can result in the loop callback being
+   called when the module isn't really looping, but this only happens if the
+   module has a very deliberate design. See duh_get_length() for further
+   musings on this subject.
+
+   If your callback returns nonzero, the music will stop abruptly. Samples
+   will be cut, and the main program will be notified that the
+   DUH_SIGRENDERER has ended.
+
+   Alternatively, if you pass the DUMB_IT_SIGRENDERER for 'data', or
+   otherwise arrange for it to be available to the callback, then you can
+   call:
+
+      dumb_it_sr_set_speed(sigrenderer, 0);
+
+   from inside the callback, and this will cause the music to freeze but
+   samples will be able to continue playing. The xm_speed_zero callback will
+   NOT be called in this case (see below for information on this callback).
+   Note also that setting the speed in this way will work equally for IT and
+   S3M files, even though a 'speed zero' effect can only exist in XM and MOD
+   files. Beware when using this method; samples might not fade at all!
+
+   A helper callback, dumb_it_callback_terminate(), is provided; installing
+   this will cause the music to terminate when it tries to loop for the first
+   time.
+
+   Pass NULL to remove the callback function; the module will then loop as
+   normal.
+
+
+void dumb_it_set_xm_speed_zero_callback(DUMB_IT_SIGRENDERER *sigrenderer,
+                                    int (*callback)(void *data), void *data);
+
+   Installs a callback which is in many ways similar to the loop callback
+   (see dumb_it_set_loop_callback()). This callback will be called whenever
+   an F00 effect is encountered in a MOD or XM file, setting the speed to
+   zero. If the callback returns nonzero, the music will terminate. If not,
+   any currently playing samples will continue to play. You can pass any data
+   pointer you like to this function, and it will be passed to your callback
+   for you.
+
+   The helper callback, dumb_it_callback_terminate(), will also work here;
+   installing it will cause the music to terminate as soon as an F00 effect
+   is encountered.
+
+   Pass NULL to remove the callback function.
+
+
+void dumb_it_set_midi_callback(DUMB_IT_SIGRENDERER *sigrenderer,
+                int (*callback)(void *data, int channel, unsigned char byte),
+                void *data);
+
+   Installs a callback function which will be called whenever MIDI data are
+   generated by an IT file. (No other module formats are capable of
+   generating MIDI data, so your callback will never be called.)
+
+   Zxx macros will generate MIDI data. These are most often used to set the
+   parameters for IT's low-pass resonant filters, and DUMB will handle these
+   messages by itself by default. See Impulse Tracker's documentation for
+   the MIDI messages that control filters. However, Zxx macros can be used
+   to send any kind of MIDI data.
+
+   If you wish to interpret MIDI messages yourself, you can use this
+   callback. Note that the only MIDI messages generated by DUMB at present
+   are from Zxx macros; there are no messages for note start, stop, or
+   anything else.
+
+   If you return 1 from this callback, DUMB will subsequently ignore the byte
+   of MIDI data. You can use this to prevent Zxx macros from controlling the
+   filters, useful if they were intended to do something else. Note that this
+   is NOT an effective way to disable filters, since instruments can have
+   filter envelopes and initial filter parameters. DUMB provides no means to
+   disable filters, as any IT file that uses them will sound wrong without
+   them. If you want lower processor consumption, use a different piece of
+   music.
+
+   A helper callback, dumb_it_callback_midi_block(), is provided for blocking
+   all MIDI messages and making Zxx macros do nothing.
+
+   Pass NULL to remove the callback.
+
+
+int dumb_it_callback_terminate(void *data);
+
+   This is a helper callback that can be installed with both
+   dumb_it_set_loop_callback() and dumb_it_set_xm_speed_zero_callback(). In
+   each case it will cause the music to terminate abruptly.
+
+
+int dumb_it_callback_midi_block(void *data, int channel, unsigned char byte);
+
+   This helper callback, for use with dumb_it_set_midi_callback(), will
+   absorb all MIDI messages, returning 1 to prevent DUMB from interpreting
+   them itself.
+
+
+DUH *dumb_load_it(const char *filename);
+
+   Loads the specified Impulse Tracker file, encapsulating it in a DUH
+   struct. Once the file is loaded, it can be treated exactly the same as any
+   other DUH in memory. If this fails it will return NULL, but you can safely
+   pass this NULL value to DUMB's other functions, so you do not need to
+   check the return value explicitly.
+
+
+DUH *dumb_read_it(DUMBFILE *f);
+
+   Reads an Impulse Tracker file from an already open DUMBFILE. This leaves
+   the DUMBFILE open, but the DUMBFILE may not be positioned at the end of
+   the IT data. If you are embedding an IT in another file, you are advised
+   to store the size of the IT file and make up for it at the end using
+   dumbfile_pos().
+
+   Otherwise, this function is identical to dumb_load_it().
+
+   WARNING: The behaviour of this function is undefined if you pass a
+            DUMBFILE from which data have already been read; it is likely not
+            to work. This oversight will be fixed in future releases.
+
+
+DUH *dumb_load_xm(const char *filename);
+
+   Loads the specified Fast Tracker II file, encapsulating it in a DUH
+   struct. Once the file is loaded, it can be treated exactly the same as any
+   other DUH in memory. If this fails it will return NULL, but you can safely
+   pass this NULL value to DUMB's other functions, so you do not need to
+   check the return value explicitly.
+
+
+DUH *dumb_read_xm(DUMBFILE *f);
+
+   Reads a Fast Tracker II file from an already open DUMBFILE. This leaves
+   the DUMBFILE open, but the DUMBFILE may not be positioned at the end of
+   the XM data. If you are embedding an XM in another file, you are advised
+   to store the size of the XM file and make up for it at the end using
+   dumbfile_pos().
+
+   Otherwise, this function is identical to dumb_load_xm().
+
+   WARNING: The behaviour of this function is undefined if you pass a
+            DUMBFILE from which data have already been read; it is likely not
+            to work. This oversight will be fixed in future releases.
+
+
+DUH *dumb_load_s3m(const char *filename);
+
+   Loads the specified Scream Tracker 3 file, encapsulating it in a DUH
+   struct. Once the file is loaded, it can be treated exactly the same as any
+   other DUH in memory. If this fails it will return NULL, but you can safely
+   pass this NULL value to DUMB's other functions, so you do not need to
+   check the return value explicitly.
+
+
+DUH *dumb_read_s3m(DUMBFILE *f);
+
+   Reads a Scream Tracker 3 file from an already open DUMBFILE. This leaves
+   the DUMBFILE open, but the DUMBFILE may not be positioned at the end of
+   the S3M data. If you are embedding an S3M in another file, you are advised
+   to store the size of the S3M file and make up for it at the end using
+   dumbfile_pos().
+
+   Otherwise, this function is identical to dumb_load_s3m().
+
+   WARNING: The behaviour of this function is undefined if you pass a
+            DUMBFILE from which data have already been read; it is likely not
+            to work. This oversight will be fixed in future releases.
+
+
+DUH *dumb_load_mod(const char *filename);
+
+   Loads the specified Amiga module file, encapsulating it in a DUH struct.
+   Once the file is loaded, it can be treated exactly the same as any other
+   DUH in memory. If this fails it will return NULL, but you can safely pass
+   this NULL value to DUMB's other functions, so you do not need to check the
+   return value explicitly.
+
+
+DUH *dumb_read_mod(DUMBFILE *f);
+
+   Reads an Amiga module file from an already open DUMBFILE. This leaves the
+   DUMBFILE open, but the DUMBFILE may not be positioned at the end of the
+   MOD data. If you are embedding a MOD in another file, you are advised to
+   store the size of the MOD file and make up for it at the end using
+   dumbfile_pos().
+
+   Otherwise, this function is identical to dumb_load_mod().
+
+   WARNING: The behaviour of this function is undefined if you pass a
+            DUMBFILE from which data have already been read; it is likely not
+            to work. This oversight will be fixed in future releases.
+
+
+int dumb_it_sd_get_n_orders(DUMB_IT_SIGDATA *sd);
+
+   This function returns the number of orders in the module.
+
+
+int dumb_it_sd_get_initial_global_volume(DUMB_IT_SIGDATA *sd);
+void dumb_it_sd_set_initial_global_volume(DUMB_IT_SIGDATA *sd, int gv);
+
+   These functions obtain and set the initial global volume for the module.
+   This value ranges from 0 to 128 inclusive. The module can set the global
+   volume itself during playback, so your change may not last throughout the
+   playback.
+
+
+int dumb_it_sd_get_mixing_volume(DUMB_IT_SIGDATA *sd);
+void dumb_it_sd_set_mixing_volume(DUMB_IT_SIGDATA *sd, int mv);
+
+   These functions obtain and set the mixing volume for the module. This
+   value ranges from 0 to 128 inclusive, and does not change during playback.
+   IT files have the mixing volume stored in them; for other formats it is
+   set to 48 on loading.
+
+
+int dumb_it_sd_get_initial_speed(DUMB_IT_SIGDATA *sd);
+void dumb_it_sd_set_initial_speed(DUMB_IT_SIGDATA *sd, int speed);
+int dumb_it_sd_get_initial_tempo(DUMB_IT_SIGDATA *sd);
+void dumb_it_sd_set_initial_tempo(DUMB_IT_SIGDATA *sd, int tempo);
+
+   These functions obtain and set the initial speed and tempo for the module.
+   During module playback, everything happens on a tick. If a beat is 24
+   ticks, then the tempo is measured in beats per second. The speed is then
+   the number of ticks per row. With a speed of 6, a beat is then four rows.
+
+   Modules can set these values during playback, so your change may not last
+   throughout the playback. MOD files have to set the speed and tempo on the
+   first row if they want anything other than the default 6/125, so your
+   change may not be noticed at all!
+
+
+int dumb_it_sd_get_initial_channel_volume(DUMB_IT_SIGDATA *sd, int channel);
+void dumb_it_sd_set_initial_channel_volume(DUMB_IT_SIGDATA *sd, int channel,
+                                                                 int volume);
+
+   These functions obtain and set the initial volume for the specified
+   channel. The channel parameter is 0-based (contrary to the display in most
+   trackers so be careful), and can range from 0 to DUMB_IT_N_CHANNELS - 1,
+   i.e. from 0 to 63.
+
+   Modules can set their channel volumes during playback, so your changes may
+   not last throughout the playback.
+
+
+int dumb_it_sr_get_current_order(DUMB_IT_SIGRENDERER *sr);
+int dumb_it_sr_get_current_row(DUMB_IT_SIGRENDERER *sr);
+
+   These functions return the current order and row of playback. Both are
+   0-based. If the DUMB_IT_SIGRENDERER is invalid, or has been terminated
+   by a callback (see dumb_it_set_loop_callback() and
+   dumb_it_set_xm_speed_zero_callback()), these functions will both return
+   -1.
+
+
+int dumb_it_sr_get_global_volume(DUMB_IT_SIGRENDERER *sr);
+void dumb_it_sr_set_global_volume(DUMB_IT_SIGRENDERER *sr, int gv);
+
+   These functions obtain and set the current global volume for the module.
+   This value ranges from 0 to 128 inclusive. The module can set the global
+   volume itself during playback, so your change may not last.
+
+
+int dumb_it_sr_get_tempo(DUMB_IT_SIGRENDERER *sr);
+void dumb_it_sr_set_tempo(DUMB_IT_SIGRENDERER *sr, int tempo);
+int dumb_it_sr_get_speed(DUMB_IT_SIGRENDERER *sr);
+void dumb_it_sr_set_speed(DUMB_IT_SIGRENDERER *sr, int speed);
+
+   These functions obtain and set the current speed and tempo of the module.
+   See the dumb_it_sd_*() equivalents of these functions for details on what
+   the speed and tempo mean.
+
+   Modules can set these values during playback, so your change may not last.
+
+
+int dumb_it_sr_get_channel_volume(DUMB_IT_SIGRENDERER *sr, int channel);
+void dumb_it_sr_set_channel_volume(DUMB_IT_SIGRENDERER *sr, int channel,
+                                                                 int volume);
+
+   These functions obtain and set the current volume for the specified
+   channel. The channel parameter is 0-based (contrary to the display in most
+   trackers so be careful), and can range from 0 to DUMB_IT_N_CHANNELS - 1,
+   i.e. from 0 to 63.
+
+   Modules can set their channel volumes during playback, so your changes may
+   not last.
+
+
+void dumb_it_sr_get_channel_state(DUMB_IT_SIGRENDERER *sr, int channel,
+                                               DUMB_IT_CHANNEL_STATE *state);
+
+   Returns the current playback state of the given channel. If you pass a
+   channel in the range 0 to DUMB_IT_N_CHANNELS-1 (0 to 63), you will get the
+   state of the most recently played note on that physical channel, if it is
+   still playing. For MOD, S3M and XM files, that's all there is to it.
+
+   IT files can have more than one note playing on a single channel, courtesy
+   of New Note Actions. This function also lets you query all the notes that
+   have been forced into the background and are still playing. For this, set
+   'channel' to a value from DUMB_IT_N_CHANNELS to DUMB_IT_TOTAL_CHANNELS-1.
+   DUMB_IT_TOTAL_CHANNELS is defined as follows:
+
+      #define DUMB_IT_TOTAL_CHANNELS \
+                                (DUMB_IT_N_CHANNELS + DUMB_IT_N_NNA_CHANNELS)
+
+   Querying these background channels for MOD, S3M and XM files will not do
+   any harm; the function will report that these channels are inactive. For
+   all files, be sure not to query any channel numbers greater than or equal
+   to DUMB_IT_TOTAL_CHANNELS.
+
+   You must provide a pointer to a preallocated DUMB_IT_CHANNEL_STATE struct.
+   The easiest way to do this is as follows:
+
+      DUMB_IT_CHANNEL_STATE state;
+      dumb_it_sr_get_channel_state(sr, channel, &state);
+
+   or:
+
+      DUMB_IT_CHANNEL_STATE state[IT_TOTAL_CHANNELS];
+      dumb_it_sr_get_channel_state(sr, channel, &state[channel]);
+
+   This struct contains the following fields:
+
+          int channel;
+          int sample;
+          int freq;
+          float volume;
+          unsigned char pan;
+          signed char subpan;
+          unsigned char filter_cutoff;
+          unsigned char filter_subcutoff;
+          unsigned char filter_resonance;
+
+   The first field to check is 'sample'; if this is 0, then the channel is
+   inactive and the other fields are undefined. Otherwise, it is the index of
+   the currently playing sample, and is 1-based.
+
+   The channel number is returned, 0-based. This will be the same as the
+   channel number you passed, unless you are querying a background channel in
+   which case it will represent the channel the note originated on.
+
+   The freq field is the current playback frequency, taking into account all
+   phenomena such as slides, vibrato and arpeggio.
+
+   The volume field ranges from 0.0f to 1.0f. In practical terms, it will
+   rarely reach 1.0f; if it does, the module is probably clipping a lot. This
+   takes mixing volume into account, along with all the other volume
+   phenomena in the IT file. The only one it doesn't take into account is the
+   one you pass to duh_render() or duh_sigrenderer_get_samples(), or the one
+   you passed to al_start_duh() (these are in fact the same thing).
+
+   The pan field ranges from 0 to 64 for a normally panned sample, but will
+   be 100 if the sample is playing using IT's surround mode where the right-
+   hand channel is inverted. If you want a more accurate pan reading, use one
+   of the following to get one:
+
+      int scaled_pan = ((int)state.pan << 8) + state.subpan;
+      float float_pan = state.pan + state.subpan / 256.0f;
+
+   The first will give a scaled value ranging (strictly) from 0 to 64*256.
+   The second will give a floating-point value whose scale corresponds to
+   that of the pan field. These results will only be valid if surround mode
+   is off, so you should check that pan <= 64 before using the above
+   expressions. At the time of writing, pitch-pan separation and panning
+   envelopes take advantage of the extra accuracy offered by subpan.
+
+   Note that subpan is signed. This means applications that only look at the
+   pan field will get an unbiased reading.
+
+   The filter cut-off and resonance both range from 0 to 127. If the cut-off
+   is 127 and the resonance is 0, then no filters are applied. These
+   parameters only ever change from the default values for IT files.
+
+   While IT allows you to set 127 different filter cut-off levels in the
+   patterns and as a default value per instrument, it also allows you to
+   create a filter envelope, which will result in an actual cut-off somewhere
+   between 0 and the first-mentioned value. By the time this has been
+   calculated, the actual cut-off may lie in between two levels on the
+   original scale. If this is the case, filter_subcutoff will be nonzero and
+   you can combine it with filter_cutoff. Typically you will want to use one
+   of the following:
+
+      int scaled_cutoff = ((int)state.filter_cutoff << 8) +
+                                state.filter_subcutoff;
+
+      float float_cutoff = state.filter_cutoff +
+                           state.filter_subcutoff / 256.0f;
+
+   The first will give you a scaled value whose maximum is 127*256. The
+   second will give you a floating-point value whose scale corresponds to the
+   scale used by filter_cutoff. These match the expressions given further up
+   for pan and subpan, but in this case, filter_subcutoff is unsigned.
+
+   Note that filter_subcutoff will always be zero if filter_cutoff is 127, so
+   you need not check it if you simply wish to determine whether filters are
+   being applied.
+
+
+*******************************
+*** DUH Rendering Functions ***
+*******************************
+
+
+   Use these functions to generate samples from a DUH. First you call
+   duh_start_sigrenderer() with the DUH, the number of channels you want and
+   the position at which you want to start. Then you use duh_render() or
+   duh_sigrenderer_get_samples() to generate the samples. You can call these
+   functions as many times as you like, and they will generate as many or as
+   few samples as you require. When you have finished, call
+   duh_end_sigrenderer().
+
+
+DUH_SIGRENDERER *duh_start_sigrenderer
+                               (DUH *duh, int sig, int n_channels, long pos);
+
+   Starts a DUH_SIGRENDERER off. This is the struct you can use to get
+   samples from a DUH. This function does not generate any samples; you must
+   pass the struct to duh_render() or duh_sigrenderer_get_samples() for that.
+   When you have finished with it, you must pass it to duh_end_sigrenderer().
+   You can use as many DUH_SIGRENDERER structs as you like at the same time.
+
+   Set sig to 0 for now. Currently, n_channels can only be 1 or 2, for
+   monaural and stereo sound respectively. The debugging library will cause
+   your program to abort if you pass anything else. Future versions will be
+   enhanced to support more channels as soon as someone needs them.
+
+   When specifying the position, 0 represents the start of the DUH, and 65536
+   represents one second. Unlike most other music systems, DUMB will always
+   make sure every note is there right from the start (assuming you aren't
+   using any broken add-ons). In other words, you can start a DUH at a point
+   halfway through a long note, and you will still hear the long note.
+
+
+void duh_sigrenderer_set_analyser_callback(DUH_SIGRENDERER *sigrenderer,
+                     DUH_SIGRENDERER_ANALYSER_CALLBACK callback, void *data);
+
+   Installs a callback function which will be called every time the given
+   sigrenderer is used to generate some samples. This can be used to create
+   an oscilloscope or spectrum analyser. DUH_SIGRENDERER_ANALYSER_CALLBACK is
+   defined as follows:
+
+      typedef void (*DUH_SIGRENDERER_ANALYSER_CALLBACK)(void *data,
+                const sample_t *const *samples, int n_channels, long length);
+
+   If the above confuses you, see fnptr.txt. As for the 'samples' parameter,
+   the first 'const' says that the samples are read-only; the second says
+   that each channel's sample pointer is also read-only. If you don't
+   understand this, don't worry about it.
+
+   Beware: your callback function may occasionally be called with
+   samples == NULL. This means the main program has decided to skip through
+   the music without generating any data (see duh_sigrenderer_get_samples()).
+   You should handle this case elegantly, typically by returning immediately,
+   but you may wish to make a note of the fact that the music is being
+   skipped, for whatever reason.
+
+   Beware again: if the main program ever calls duh_sigrenderer_get_samples()
+   on a buffer that isn't all silence, this callback function will be passed
+   the existing buffer after mixing, and thus it will include the original
+   data. This will not be an issue if you stick to duh_render(), which always
+   starts with a buffer filled with silence.
+
+   The samples array is two-dimensional. Refer to it as follows:
+
+      samples[channel_number][sample_position]
+
+   where 0 <= channel_number < n_channels,
+     and 0 <= sample_position < length.
+
+   In addition you can pass any 'data' pointer you like to
+   duh_sigrenderer_set_analyser_callback(), and this pointer will be relayed
+   to your callback function each time.
+
+   To remove the callback function, pass NULL to
+   duh_sigrenderer_set_analyser_callback().
+
+
+int duh_sigrenderer_get_n_channels(DUH_SIGRENDERER *sigrenderer);
+
+   Tells you how many channels a DUH_SIGRENDERER is set up to generate, or 0
+   if it is invalid (perhaps owing to lack of memory). This will be 1 for
+   monaural sound or 2 for stereo, in this release.
+
+
+long duh_sigrenderer_get_position(DUH_SIGRENDERER *sigrenderer);
+
+   Tells you what position a DUH_SIGRENDERER is up to, or -1 if it is invalid
+   (perhaps owing to lack of memory). As usual, 65536 is one second.
+
+
+long duh_sigrenderer_get_samples(DUH_SIGRENDERER *sigrenderer,
+                                 float volume, float delta,
+                                 long size, sample_t **samples);
+
+   Generates some samples in DUMB's internal 32-bit format (see sample_t; see
+   also duh_render()). The samples buffer is a two-dimensional array, and can
+   be allocated with create_sample_buffer(); see
+   duh_sigrenderer_set_analyser_callback() for details.
+   duh_sigrenderer_get_samples() mixes sample data with what's already in the
+   buffer, so you have to call dumb_silence() first.
+
+   The volume is a float. 1.0f is the pseudo-maximum. If you pass 1.0f, any
+   properly designed DUH will play nice and loud, but will not clip. You can
+   pass a greater volume if you like, but be prepared for the possibility of
+   distortion due to integer overflow. Of course you can pass smaller values
+   to play the DUH more quietly, and this will also resolve clipping issues
+   in badly designed DUHs.
+
+   Use delta to control the speed of the output signal. If you pass 1.0f, the
+   resultant signal will be suitable for a 65536-Hz sampling rate (which
+   isn't a commonly used rate). The most common sampling rates are 11025 Hz,
+   22050 Hz, 44100 Hz and 48000 Hz. You can work out the required delta value
+   as follows:
+
+      delta = 65536.0f / sampling_rate;
+
+   If you then increase this value, the DUH will speed up and increase in
+   pitch. If you decrease it, the DUH will slow down and decrease in pitch.
+
+   This function will attempt to render 'size' samples. In most cases it will
+   succeed. However, if the end of the DUH is reached, it may render fewer.
+   The number of samples rendered will be returned. Therefore, if the return
+   value is less than the value of 'size' passed, you know the DUH has
+   finished. It is safe to continue calling duh_sigrenderer_get_samples() if
+   you wish, and it will continually return 0.
+
+   If the DUH_SIGRENDERER is a null pointer, this function will generate
+   precisely 0 samples. If you pass NULL for 'samples', the function will
+   behave exactly the same as if you provided a sample buffer, except the
+   samples won't be stored anywhere and the function will execute very
+   quickly. This can be used to skip ahead in the audio.
+
+
+long duh_render(DUH_SIGRENDERER *sigrenderer,
+                int bits, int unsign,
+                float volume, float delta,
+                long size, void *sptr);
+
+   Generates some samples and converts them to an 8-bit or 16-bit format (see
+   also duh_sigrenderer_get_samples()). Pass the DUH_SIGRENDERER as returned
+   by duh_start_sigrenderer(). Pass the number of bits, which should be 8 or
+   16. If unsign is nonzero, the samples will be unsigned (centred on 0x80 or
+   0x8000 for 8 bits and 16 bits respectively). If unsign is zero, the
+   samples will be signed.
+
+   Allegro's audio streams always take unsigned samples. 8-bit .wav files
+   always take unsigned samples. 16-bit .wav files always take signed
+   samples.
+
+   The volume and delta parameters work the same as for
+   duh_sigrenderer_get_samples().
+
+   This function will attempt to render 'size' samples. In most cases it will
+   succeed. However, if the end of the DUH is reached, it may render fewer.
+   The number of samples rendered will be returned. Therefore, if the return
+   value is less than the value of 'size' passed, you know the DUH has
+   finished. It is safe to continue calling duh_render() if you wish, and it
+   will continually return 0. However, if you wish to do this, you will
+   probably have to fill the rest of the buffer with silence, which is 0 for
+   signed, 0x80 for 8-bit unsigned or 0x8000 for 16-bit unsigned.
+
+   The samples will be placed at sptr. Use an array of chars for 8 bits or an
+   array of shorts for 16 bits. Stereo samples will be interleaved, left
+   first. Your array should contain at least (size * n_channels) elements of
+   the appropriate bit resolution.
+
+   From an aesthetic standpoint if nothing else, it is wise to use the C
+   qualifiers 'signed' or 'unsigned' depending on whether the samples are
+   signed or unsigned. This is also convenient if you wish to process the
+   samples further yourself.
+
+   If the DUH_SIGRENDERER is a null pointer, this function will generate
+   precisely 0 samples. Unlike with duh_sigrenderer_get_samples(), you must
+   specify a sample buffer.
+
+
+void duh_end_sigrenderer(DUH_SIGRENDERER *dr);
+
+   Terminates a DUH_SIGRENDERER. Be sure to call this when you've finished
+   with one. You can safely pass a null pointer.
+
+
+********************************
+*** Allegro Packfile Support ***
+********************************
+
+
+void dumb_register_packfiles(void);
+
+   This function registers the Allegro PACKFILE input module for use by
+   DUMBFILEs. PACKFILE structs and their corresponding functions, as defined
+   by Allegro's header file allegro.h, will be used internally for all
+   DUMBFILE input (unless opened with dumbfile_open_ex()).
+
+   This must be called before dumbfile_open() is used, or else an alternative
+   system must be registered (see register_dumbfile_system() and
+   dumb_register_stdfiles()). Note that you don't have to call this function
+   in order to load datafiles that contain music.
+
+
+DUMBFILE *dumbfile_open_packfile(PACKFILE *p);
+
+   If you have an Allegro PACKFILE struct representing an open file, you can
+   call this if you wish to read from it using a DUMBFILE. This is useful
+   when you need to pass a DUMBFILE struct to a library function, to read an
+   embedded music file for example. When you close the DUMBFILE, you can
+   continue using the PACKFILE struct to read what follows the embedded data.
+
+
+DUMBFILE *dumbfile_from_packfile(PACKFILE *p);
+
+   This function is the same as dumbfile_open_packfile(), except it will
+   check if p is NULL, and arrange for pack_fclose() to be called on the
+   PACKFILE when you close the DUMBFILE. It can be seen as a function for
+   converting a PACKFILE to a DUMBFILE, but it will only work for a PACKFILE
+   you obtained with pack_fopen(), not pack_fopen_chunk(). If this function
+   fails, which may happen if memory is short, then the PACKFILE will be
+   closed immediately, so you need not worry about potential memory leaks or
+   files being left open when this happens.
+
+   The following is typical usage, and will open the compressed file foo.bin:
+
+      DUMBFILE *f = dumbfile_from_packfile(pack_fopen("foo.bin",
+                                                      F_READ_PACKED));
+
+   This differs from calling dumb_register_packfiles() and dumbfile_open() in
+   that the latter will only read uncompressed files (and is thus a method
+   suitable for reading music modules).
+
+
+***********************************************
+*** Allegro Datafile Registration Functions ***
+***********************************************
+
+
+void dumb_register_dat_it(long type);
+
+   If you wish to embed an IT file in an Allegro datafile, it is recommended
+   that you use "IT  " for the type. The grabber will have a box for the type
+   when you insert a new object. The grabber will treat the IT file as binary
+   data, which means the datafile will contain an exact copy of the IT file
+   on disk.
+
+   You must then call dumb_register_dat_it(DUMB_DAT_IT) in your program
+   before you load the datafile. Once you've done this, you'll be able to
+   access the DUH using the usual datafile[n].dat notation. You do not need
+   to call unload_duh() on this DUH; unload_datafile() will do that for you.
+
+   If you are using a different type for whatever reason, you can use
+   Allegro's DAT_ID() macro for encoding it and passing it to this function.
+   For example:
+
+      dumb_register_dat_it(DAT_ID('B','L','A','H'));
+
+   Assuming you used the recommended type, the following example iterates
+   through all the ITs in disan.dat:
+
+      DATAFILE *dat;
+      int n;
+
+      dumb_register_dat_it();
+      dat = load_datafile("disan.dat");
+
+      for (n = 0; dat[n].type != DAT_END; n++) {
+         if (dat[n].type == DUMB_DAT_IT) {
+            DUH *duh = dat[n].dat;
+            /* Insert code here to play 'duh' or whatever you want to do. */
+         }
+      }
+
+      unload_datafile(dat);
+
+
+void dumb_register_dat_xm(long type);
+
+   Inserting an XM file in an Allegro datafile is the same as inserting an IT
+   file, except that the recommended type is "XM  ", the registration
+   function is dumb_register_dat_xm(), and the macro DUMB_DAT_XM is provided
+   for the type. The intuitive process of substituting XM for IT in the above
+   method will work.
+
+
+void dumb_register_dat_s3m(long type);
+
+   Inserting an S3M file in an Allegro datafile is the same as inserting an
+   IT file, except that the recommended type is "S3M ", the registration
+   function is dumb_register_dat_s3m(), and the macro DUMB_DAT_S3M is
+   provided for the type. The intuitive process of substituting S3M for IT in
+   the above method will work.
+
+
+void dumb_register_dat_mod(long type);
+
+   Inserting a MOD file in an Allegro datafile is the same as inserting an IT
+   file, except that the recommended type is "MOD ", the registration
+   function is dumb_register_dat_mod(), and the macro DUMB_DAT_MOD is
+   provided for the type. The intuitive process of substituting MOD for IT in
+   the above method will work.
+
+
+****************************************
+*** Sample Buffer Allocation Helpers ***
+****************************************
+
+
+   Many parts of DUMB require sample buffers allocated in a special way. A
+   pointer to one looks like this:
+
+      sample_t **samples;
+
+   and it can be indexed as follows:
+
+      samples[channel_number][sample_position]
+
+   where 0 <= channel_number < n_channels
+     and 0 <= sample_position < length.
+
+   The following helpers will allocate and deallocate such buffers for you.
+   They will not initialise them, and DUMB always writes into these buffers
+   by adding to what's already there, so you will generally have to call
+   dumb_silence() too.
+
+
+sample_t **create_sample_buffer(int n_channels, long length);
+
+   This will allocate a sample buffer to hold the specified number of samples
+   for the specified number of channels. Don't forget to check the return
+   value!
+
+   You will generally have to initialise the buffer by calling
+   dumb_silence(); the channels will be stored consecutively in memory, so
+   the following technique is officially supported:
+
+      dumb_silence(samples[0], n_channels * length);
+
+   See dumb_silence() for general information on what this function does.
+
+
+void destroy_sample_buffer(sample_t **samples);
+
+   This function does the obvious: it frees up a sample buffer when you've
+   finished with it. It is safe to pass a null pointer to this function.
+
+
+************************
+*** Silencing Helper ***
+************************
+
+
+void dumb_silence(sample_t *samples, long length);
+
+   This function simply stores 'length' samples' worth of silence in the
+   array. It is typically used straight after allocating a sample buffer with
+   create_sample_buffer().
+
+
+**************************
+*** Resampling Helpers ***
+**************************
+
+
+   Please forgive the odd section name; it has to do with DUMB's internal
+   structure and the fact that the resampling algorithm is there not just for
+   use in rendering module files but for use anywhere that a waveform needs
+   resampling. Unfortunately DUMB's resampling algorithm is not ready to be
+   documented and used yet. However, one thing can be documented, and that's
+   the global variable controlling the resampling quality.
+
+   (Ironically, even this variable has changed! See deprec.txt for
+   information on what it used to do.)
+
+
+int dumb_resampling_quality;
+
+   Allows you to control the quality of all resampling that takes place. This
+   may be set to any DUMB_RQ_* constant (except DUMB_RQ_N_LEVELS). Higher
+   values will sound better, but lower values will use up less processor
+   time. You may compare any two DUMB_RQ_* constants or values using the
+   integer inequalities <, <=, > and >=; higher numbers represent higher-
+   quality algorithms.
+
+   #define DUMB_RQ_ALIASING
+
+      |     --___         'Aliasing' has very noticeable and usually unwanted
+      |__---     __       overtones. It will occasionally produce acceptable
+      |            ___--  results for noisy (impure) samples (or for cheap
+                          speakers!), but usually you will want to pay for
+      the extra processor time, which isn't much, and go for linear
+      interpolation.
+
+   #define DUMB_RQ_LINEAR
+
+      |  __          Linear interpolation is a pretty good algorithm in most
+      | /  \  /\     cases. When resampling down a few octaves, however, you
+      |/    \/  \__  may begin to notice unwanted high frequencies. You can
+                     reduce these by switching to cubic interpolation, but it
+      will cost you some processor time.
+
+   #define DUMB_RQ_CUBIC
+
+      Cubic interpolation looks like a smooth curve to the eye, and will
+      produce good results in most cases. At present this is the highest
+      quality offered by DUMB, and also the default. While this may seem
+      extravagant, GCC 3.x and an AthlonXP handle it quite well - and the
+      general trend is for processors to get better!
+
+   #define DUMB_RQ_N_LEVELS
+
+      This represents the number of resampling quality levels DUMB provides.
+      Values of dumb_resampling_quality from 0 to DUMB_RQ_N_LEVELS - 1 are
+      valid. You can use this constant if you wish to offer the resampling
+      quality as an option for the user.
+
+
+*************************************
+*** Allegro DUH Playing Functions ***
+*************************************
+
+
+   The functions in this section allow you to play back a DUH through
+   Allegro's sound system. You must call Allegro's install_sound() function
+   before you use them.
+
+
+AL_DUH_PLAYER *al_start_duh(DUH *duh, int n_channels, long pos,
+                            float volume, long bufsize, int freq);
+
+   Starts playing the specified DUH.
+
+   An AL_DUH_PLAYER represents one instance of the DUH playing. If you wish,
+   you can have two or more AL_DUH_PLAYERs going at the same time, for the
+   same DUH or for different ones. Each uses one of Allegro's audio streams
+   and hence one voice. The voice will be given priority 255 initially, so a
+   build-up of sound effects will not cause your music streams to cut off (as
+   long as you don't give all your sound effects priority 255!). You can
+   change the priority of a stream with al_duh_set_priority(). See Allegro's
+   documentation for more information on how voice priorities work.
+
+   At present, n_channels can either be 1 or 2 for monaural or stereo
+   respectively. If you use the debugging library, your program will abort if
+   other values are passed; otherwise weird things will happen.
+
+   The DUH will start playing from position 'pos'. 0 represents the start of
+   the DUH, and 65536 represents one second. Unlike other music systems, DUMB
+   will always make sure every note is there right from the start. In other
+   words, you can start a DUH at a point halfway through a long note, and you
+   will still hear the long note.
+
+   The volume is a float. 1.0f is the pseudo-maximum. If you pass 1.0f, any
+   properly designed DUH file will play nice and loud, but will not clip. You
+   can pass a greater volume if you like, but be prepared for clipping to
+   occur. Of course you can pass smaller values to play the DUH more quietly,
+   and this will also resolve clipping issues in badly designed DUH files.
+
+   You will need to pass the AL_DUH_PLAYER to other functions when you need
+   to stop or pause the DUH, change its volume, or otherwise modify the way
+   it is playing. You will also need to pass it to al_poll_duh() at regular
+   intervals; if the sound is choppy, try calling al_poll_duh() more often.
+
+   'bufsize' is the number of samples that will be rendered at once. 1024 is
+   a suitable value for most purposes. The greater this is, the less often
+   you will have to call al_poll_duh() - but when al_poll_duh() decides to
+   fill the buffer, it will take longer doing so. If your game exhibits
+   regular brief freezes, try reducing the buffer size. If the sound is
+   choppy, however, you may have to increase it.
+
+   'freq' specifies the sampling frequency at which the DUH should be
+   rendered. At present there is no (official and portable) way of knowing
+   the frequency at which Allegro is mixing - but if you do know that
+   frequency, passing it here will give the highest quality sound. If you
+   reduce it, the DUH will sound less crisp but use less processor time.
+
+   When you have finished, you must pass the AL_DUH_PLAYER to al_stop_duh()
+   to free up memory. Do not destroy the DUH beforehand.
+
+   There is no real need to check the return value from this function. The
+   other functions can be called safely with null pointers, so if there is a
+   problem, your music will simply not play.
+
+
+void al_stop_duh(AL_DUH_PLAYER *dp);
+
+   This will stop an AL_DUH_PLAYER. You must call this when you have finished
+   with it, before destroying the DUH. The pointer will no longer be valid on
+   return from this function.
+
+
+void al_pause_duh(AL_DUH_PLAYER *dp);
+
+   This will pause an AL_DUH_PLAYER. Use al_resume_duh() when you want it to
+   continue. You can safely call al_poll_duh() while the music is paused, and
+   it will do nothing.
+
+
+void al_resume_duh(AL_DUH_PLAYER *dp);
+
+   Causes a paused AL_DUH_PLAYER to resume playing (see al_pause_duh()).
+
+
+void al_duh_set_priority(AL_DUH_PLAYER *dp, int priority);
+
+   This will set the priority of the audio stream underlying an
+   AL_DUH_PLAYER. The priority is an integer ranging from 0 to 255. When
+   too many samples play at the same time, those with lower priorities will
+   be cut. 128 is the usual default with Allegro, but DUMB overrides the
+   default for all AL_DUH_PLAYER structs: they will be set up initially with
+   priority 255, so your music won't be cut (unless you play too many other
+   streams or samples with priority 255). See Allegro's documentation for
+   more information on priorities.
+
+
+void al_duh_set_volume(AL_DUH_PLAYER *dp, float volume);
+
+   This will set the volume of an AL_DUH_PLAYER. See al_start_duh() for
+   details on the volume parameter.
+
+
+int al_poll_duh(AL_DUH_PLAYER *dp);
+
+   An AL_DUH_PLAYER is not interrupt-driven. That means it will not play by
+   itself. You must keep it alive from your main program. Call this function
+   at regular intervals. If the sound crackles, try calling it more often.
+   (There is nothing you can do if Windows decides to play with the hard
+   disk; that will make your sound crackle no matter what you do.)
+
+   Normally this function will return zero. However, if it returns nonzero,
+   that means the AL_DUH_PLAYER will not generate any more sound. Indeed the
+   underlying audio stream and DUH_SIGRENDERER have been destroyed. When this
+   happens, you can call al_stop_duh() whenever you wish - but you do not
+   have to. Note that this function will wait two buffers' worth of samples
+   before taking this action, allowing Allegro to mix the trailing sound
+   before the audio stream is destroyed. This is an attempt to make sure your
+   music does not get cut off prematurely, and it should work when using
+   Allegro's mixer (the only option on DOS, the default on Linux as far as I
+   know, but not the default on Windows). That said, if you immediately call
+   Allegro's remove_sound() or exit your program, the music may get cut off.
+   If you are using another mixer and experience problems, let me know (but I
+   don't guarantee to be able to come up with an elegant solution, i.e. it
+   might not get fixed).
+
+   In case you were wondering, it is not safe on all platforms to call
+   al_poll_duh() from an interrupt context (that means an Allegro timer
+   handler). Not only is no part of DUMB locked in memory, but many parts of
+   DUMB allocate and free their memory on a call-by-call basis! Remember that
+   any disk access that occurs in interrupt context is likely to crash the
+   machine; this is explained more fully in howto.txt. This limitation only
+   applies to DOS at present, and is due to the fact that the DOS file access
+   functions are not re-entrant.
+
+   Multitasking systems are generally safe. If you are sure you don't want to
+   target DOS, you can call al_poll_duh() from inside a timer handler, but I
+   recommend including a construction like the following!
+
+      #ifdef ALLEGRO_DOS
+      #error calling al_poll_duh() from a timer handler will not work in DOS!
+      #endif
+
+   Furthermore, if you call al_poll_duh() from inside a timer handler, you
+   must use a semaphore or other threading mechanism to make sure it is not
+   executing when you call al_stop_duh(). If you don't know what a semaphore
+   is, for Heaven's sake follow my advice and call al_poll_duh() from your
+   main loop!
+
+
+long al_duh_get_position(AL_DUH_PLAYER *dp);
+
+   Tells you what position an AL_DUH_PLAYER is up to, or -1 if it is invalid
+   (perhaps owing to lack of memory). As usual, 65536 is one second. Note
+   that this is a whole number, whereas a fractional part is stored
+   internally; the sample will not be continuous if you terminate the
+   AL_DUH_PLAYER and then reinitiate it with the same position. Furthermore,
+   note that Allegro will not have mixed in all the sound up to this point;
+   if you wait for this to reach a certain position and then terminate the
+   AL_DUH_PLAYER, the sound will cut off too early. Please contact me if you
+   need to get around this.
+
+
+AL_DUH_PLAYER *al_duh_encapsulate_sigrenderer
+        (DUH_SIGRENDERER *sigrenderer, float volume, long bufsize, int freq);
+
+   If you have a DUH_SIGRENDERER, and would like to start playing music from
+   it through an Allegro audio stream, use this function. Beware that it may
+   return NULL, in which case you will have to call duh_end_sigrenderer()
+   yourself instead of relying on the encapsulating AL_DUH_PLAYER to do it
+   for you.
+
+
+DUH_SIGRENDERER *al_duh_get_sigrenderer(AL_DUH_PLAYER *dp);
+
+   This returns the DUH_SIGRENDERER contained in an AL_DUH_PLAYER, useful for
+   controlling playback, installing callbacks, etc.
+
+
+DUH_SIGRENDERER *al_duh_decompose_to_sigrenderer(AL_DUH_PLAYER *dp);
+
+   This destroys an AL_DUH_PLAYER, but preserves the DUH_SIGRENDERER it
+   contains, and returns it to you. You can then continue rendering samples
+   from the DUH_SIGRENDERER and do whatever you like with them.
+
+
+*********************
+*** Thread Safety ***
+*********************
+
+
+The following points should pretty much sum up the essence of DUMB's thread
+safety. If I haven't covered the one thing you'd like to do, please don't
+hesitate to ask about it.
+
+DOs:
+
+- You may load and use multiple DUHs in separate threads.
+
+- You may change dumb_resampling_quality and dumb_it_max_to_mix while another
+  thread is generating samples.
+
+DON'Ts:
+
+- You may not generate samples from the same DUH in multiple threads, even if
+  you are using separate DUH_RENDERERs (separate AL_DUH_PLAYERS).
+
+
+******************
+*** Conclusion ***
+******************
+
+
+"DUMB is the bestest music player in the world because ..."
+
+Complete this sentence in fifteen words or fewer and receive a free copy of
+DUMB! (Your Internet Service Provider may issue charges for your connection,
+required for download of the Product. Your electricity supplier may issue
+charges for the electricity consumed in writing the Product to a Permanent
+Storage Device. You may have been charged for a Permanent Storage Device on
+which to store the Product.)
+
+
+Ben Davis
+entheh@users.sf.net
+IRC EFnet #dumb
+See readme.txt for details on using IRC.
diff --git a/apps/codecs/dumb/docs/faq.txt b/apps/codecs/dumb/docs/faq.txt
new file mode 100644
index 0000000000..48b5ef3fff
--- /dev/null
+++ b/apps/codecs/dumb/docs/faq.txt
@@ -0,0 +1,263 @@
+TO DO: add question regarding set_close_button_callback vs set_window_close_hook
+
+/*  _______         ____    __         ___    ___
+ * \    _  \       \    /  \  /       \   \  /   /       '   '  '
+ *  |  | \  \       |  |    ||         |   \/   |         .      .
+ *  |  |  |  |      |  |    ||         ||\  /|  |
+ *  |  |  |  |      |  |    ||         || \/ |  |         '  '  '
+ *  |  |  |  |      |  |    ||         ||    |  |         .      .
+ *  |  |_/  /        \  \__//          ||    |  |
+ * /_______/ynamic    \____/niversal  /__\  /____\usic   /|  .  . ibliotheque
+ *                                                      /  \
+ *                                                     / .  \
+ * faq.txt - Frequently Asked Questions.              / / \  \
+ *                                                   | <  /   \_
+ * This file covers some of the common problems      |  \/ /\   /
+ * and misconceptions people have with DUMB. If       \_  /  > /
+ * your problem is not covered here, please             | \ / /
+ * contact me. I'll do my best to help - but            |  ' /
+ * don't be offended if I just direct you to the         \__/
+ * manual!
+ */
+
+
+*****************************************************************************
+* I get a lot of strange warnings and errors when I compile my projects     *
+* with this release of DUMB. They work with older versions! What happened?  *
+*****************************************************************************
+
+   Some parts of DUMB's API have been deprecated. See docs/deprec.txt for
+   full details, including an explanation as to why your compiler warnings
+   and errors are so unfriendly, and information on how to fix each warning
+   or error.
+
+
+*****************************************************************************
+* When I try to compile DUMB with Allegro, it complains that it cannot find *
+* 'internal/alconfig.h'! What's wrong?                                      *
+*****************************************************************************
+
+   In Allegro 4.0.1, and quite likely some other versions of Allegro, the
+   msvcmake batch file does not install Allegro properly. I believe this was
+   fixed in Allegro 4.0.2, but don't take my word for it. Some include files
+   are neglected, including alconfig.h. The fix is quite easy; you need to
+   copy all of Allegro's include files to your compiler's directory. The
+   following should do this for you (alter it accordingly depending on where
+   MSVC and Allegro are installed):
+
+      cd\progra~1\msvc\include
+      xcopy/s \allegro\include\*.*
+
+   You can safely tell it to overwrite all files.
+
+
+*****************************************************************************
+* When I build a project that uses DUMB, I get an error that it doesn't     *
+* find -laldmbd! What's wrong?                                              *
+*****************************************************************************
+
+   See the notes for DUMB v0.8 in release.txt; the existence of libaldmbd.a
+   in DUMB v0.7 was due to a mistake in the makefiles. It should be
+   libaldmd.a, in order to maintain DOS compatibility. All subsequent
+   releases get it right, but you will have to change your project files to
+   allow for the change. If this is someone else's project, please let them
+   know that it needs changing.
+
+
+*****************************************************************************
+* When I build a project that uses DUMB, I get some linker errors about     *
+* _free, _malloc, etc. already being defined in LIBC.lib! What's wrong?     *
+*****************************************************************************
+
+   MSVC offers three different implementations of the standard libraries.
+   When you link statically with a library, you have to use the same
+   implementation that the library uses. You need the multithreaded DLL
+   implementation, which you can select by passing /MD when you compile (not
+   when you link). See howto.txt for details.
+
+
+*****************************************************************************
+* I created an IT file with Impulse Tracker, but DUMB won't play it! Why?   *
+*****************************************************************************
+
+   You probably created some patterns but didn't give any information on the
+   order in which they should be played. Impulse Tracker will also fail to
+   play your music if you press F5. Press F11 and you will have an
+   opportunity to create an order list, required for playback.
+
+
+*****************************************************************************
+* I created an IT file with ModPlug Tracker and I have it fading out at the *
+* end. Why won't it loop when I play it with DUMB?                          *
+*****************************************************************************
+
+   It loops at zero volume. This is what Impulse Tracker itself does. Fix the
+   IT file by setting the global volume explicitly (Vxx in the effects
+   column), either at the start, or right at the end before looping. Also see
+   the next two questions.
+
+
+*****************************************************************************
+* My module plays too loud and distorts badly with DUMB! What can I do?     *
+*****************************************************************************
+
+   This problem is most often caused by ModPlug Tracker, which has a complete
+   lack of regard for the playback volume of the original tracker. See the
+   next question for DUMB's official position with regard to ModPlug Tracker.
+   If you wrote your module with ModPlug Tracker, please try loading it with
+   the original tracker and see if it distorts there too. If it does, reduce
+   the volume. If not, then it's a problem with DUMB; please let me know.
+
+   If for whatever reason you cannot modify the module file itself, you can
+   make it sound better by reducing the volume passed to al_start_duh().
+
+
+*****************************************************************************
+* I created a music module with ModPlug Tracker, and DUMB doesn't play it   *
+* right!                                                                    *
+*****************************************************************************
+
+   DUMB cannot and will not support ModPlug Tracker. Please see
+   docs/modplug.txt for details. The original trackers, which DUMB is
+   designed to mimic as closely as possible, are listed in readme.txt.
+   If you find DUMB plays your module differently from the original tracker,
+   then please contact me.
+
+
+*****************************************************************************
+* My program crashes as soon as I try to load anything with DUMB!           *
+*****************************************************************************
+
+   Please take my advice and use the debugging build of DUMB, not the
+   optimised build. Then you'll probably find it aborts instead of crashing.
+   In this case you probably forgot to register a DUMBFILE system; this is
+   necessary for loading stand-alone files, though not for loading Allegro
+   datafiles with embedded music. Follow the instructions in docs/howto.txt
+   carefully and you shouldn't have this problem.
+
+   If DUMB crashes with a specific music module, please let me know.
+
+
+*****************************************************************************
+* I want to use the stdio file access functions to load stand-alone music   *
+* files, but I also want to load datafiles containing music files. The docs *
+* say I shouldn't call both dumb_register_stdfiles() and                    *
+* dumb_register_packfiles(). What shall I do?                               *
+*****************************************************************************
+
+   When you register a DUMBFILE system, it only applies to files opened with
+   dumbfile_open(), i.e. separate files. When a file is embedded in a
+   datafile, dumbfile_open_ex() is used to read it, enabling it to use
+   PACKFILEs regardless of which DUMBFILE system is registered. In short, you
+   do not need to call dumb_register_packfiles() in order to load datafiles
+   with embedded music. See the section on "Sequential File Input" in
+   docs/dumb.txt if you're interested in how all this works.
+
+
+*****************************************************************************
+* I want to read a specific object in a datafile using Allegro's            *
+* "demo.dat#MY_MUSIC" syntax. Why won't it work?                            *
+*****************************************************************************
+
+   Did you call dumb_register_packfiles(), or did you call
+   dumb_register_stdfiles()? It will only work if you use the former.
+
+
+*****************************************************************************
+* My program runs, but no music plays! What am I doing wrong?               *
+*****************************************************************************
+
+   There are a number of possible causes for this. The most likely reason is
+   that you aren't calling al_poll_duh(); see docs/howto.txt for further
+   information.
+
+   Other possible causes are as follows:
+
+   - The speakers are turned down (duh)
+   - The volume of some system mixer is turned down
+   - Another program is using the sound card (not a problem for most modern
+     systems)
+   - You didn't initialise Allegro's sound system; see install_sound() in
+     Allegro's docs
+   - Allegro's drivers don't work on your system and chosen platform
+
+   In order to narrow down the cause, consider the following:
+
+   - Do you get any other sound from your program?
+   - Do other Allegro+DUMB programs generate sound?
+   - Do other Allegro programs generate sound?
+   - Do other non-Allegro programs generate sound?
+   - Does your program fail only on a specific platform (e.g. DOS but not
+     Windows)?
+
+   This problem is highly system-specific; please try hard to solve it by
+   yourself before contacting me. However, if you think this problem could
+   affect other people, please let me know what the problem is and how you
+   fixed it, if you did. Be as specific as possible.
+
+
+*****************************************************************************
+* The music stutters! What can I do?                                        *
+*****************************************************************************
+
+   If you have an older computer, it may not be able to cope with the load.
+   Try reducing quality options; look up dumb_resampling_quality and
+   dumb_it_max_to_mix in docs/dumb.txt, and consider changing the frequency
+   you pass to al_start_duh().
+
+   Stuttering may not be caused by excessive load. To find out, try
+   increasing the buffer size passed to al_start_duh(). Beware of making it
+   too big though; older systems will freeze periodically if it's too big,
+   because they render larger chunks less frequently. The timing of callbacks
+   will also be less accurate, if you are using those.
+
+   If you're using the 'dumbplay' example, you can control these parameters
+   by editing dumb.ini.
+
+
+*****************************************************************************
+* Why does DUMB use so much processor time compared with other players?     *
+*****************************************************************************
+
+   This should be less so in this release than in previous releases; the
+   resampling and filtering algorithms have been optimised.
+
+   By default, DUMB uses the most expensive resampling quality option. I've
+   found on an AthlonXP 1800+ and on a Pentium 233 that it typically uses
+   about twice as much processor time as the least expensive option.
+
+   Try setting dumb_resampling_quality to DUMB_RQ_ALIASING or DUMB_RQ_LINEAR.
+   See dumb.txt for more information. If you're using the example programs,
+   you can control this variable by editing dumb.ini.
+
+   DUMB uses 32-bit ints for mixing. Some players use 16-bit ints, and are
+   therefore marginally faster (not much!) and lower quality. So you can't
+   expect DUMB to beat these players. Furthermore, DUMB is currently written
+   entirely in C. GCC does an impressive job on the C code, but that's not to
+   say some custom-written assembly language couldn't beat it ...
+
+
+*****************************************************************************
+* Why does DUMB generate so much background noise?                          *
+*****************************************************************************
+
+   You're probably using the DOS build on a system with bad Sound Blaster
+   compatibility (most Windows XP systems fall in this category). This would
+   mean DUMB could only access an 8-bit driver. The Windows build will almost
+   certainly give better results. Your DOS binary will still give good
+   results on systems with better compatibility (like my Windows 98 system).
+
+
+*****************************************************************************
+* I e-mailed you and you replied with "RTFM"! What does that mean?          *
+*****************************************************************************
+
+   Read The Manual. If it's a specific problem, I'll probably be kind and
+   tell you where to look in the manual. However, if I get the impression you
+   haven't even looked for a solution in the manual, expect no mercy ...
+
+
+Ben Davis
+entheh@users.sf.net
+IRC EFnet #dumb
+See readme.txt for details on using IRC.
diff --git a/apps/codecs/dumb/docs/fnptr.txt b/apps/codecs/dumb/docs/fnptr.txt
new file mode 100644
index 0000000000..a5fb216822
--- /dev/null
+++ b/apps/codecs/dumb/docs/fnptr.txt
@@ -0,0 +1,113 @@
+/*  _______         ____    __         ___    ___
+ * \    _  \       \    /  \  /       \   \  /   /       '   '  '
+ *  |  | \  \       |  |    ||         |   \/   |         .      .
+ *  |  |  |  |      |  |    ||         ||\  /|  |
+ *  |  |  |  |      |  |    ||         || \/ |  |         '  '  '
+ *  |  |  |  |      |  |    ||         ||    |  |         .      .
+ *  |  |_/  /        \  \__//          ||    |  |
+ * /_______/ynamic    \____/niversal  /__\  /____\usic   /|  .  . ibliotheque
+ *                                                      /  \
+ *                                                     / .  \
+ * fnptr.txt - Function pointer explanation.          / / \  \
+ *                                                   | <  /   \_
+ *                                                   |  \/ /\   /
+ *                                                    \_  /  > /
+ *                                                      | \ / /
+ *                                                      |  ' /
+ *                                                       \__/
+ */
+
+
+C allows you to create and use function pointers. A function pointer is a
+variable that points to a function, and you can use it to call that function.
+Why is this useful?
+
+Function pointers can be passed as parameters. As an example, here's a
+function from Allegro:
+
+   void create_light_table(COLOR_MAP *table, const PALETTE pal, int r, g, b,
+                                                  void (*callback)(int pos));
+
+Don't worry about the syntax just yet, but the last parameter, 'callback', is
+a pointer to a function that takes an int parameter. create_light_table() can
+take some time to complete its work, and you may want to display a progress
+indicator. So you write a function to draw the progress indicator, and then,
+for 'callback', you specify a pointer to your function. This will enable
+create_light_table() to call your function at intervals during its
+processing. (If you don't want to use the callback, you can pass NULL, but
+this only works because create_light_table() checks actively for NULL. You
+can't always specify NULL when you want nothing to happen.)
+
+There are many other uses. In addition to using function pointers as
+parameters, Allegro has some global function pointers you can set to point to
+your functions. Function pointers can also be used in structs, and this is
+where DUMB makes the most use of them.
+
+So how are they used?
+
+   void bar(void) { ... }    /* Here's a function */
+   void (*foo)(void) = &bar; /* Take a pointer */
+   (*foo)();                 /* Call the function */
+
+   char *baz(float a) { ... }          /* Here's another function */
+   char *(*foobarbaz)(float a) = &baz; /* Take a pointer */
+   char *rv = (*foobarbaz)(0.1);       /* Call the function */
+
+In both these cases, note how the statement for calling the pointed-to
+function (third line) resembles the definition of the function pointer
+(second line). This is true of any variable in C, and can lead to some truly
+obfuscated definitions if you are that way inclined. Such definitions can be
+clarified with typedefs, but before you use those, it is important you
+understand how the above statements work. I speak from experience: function
+pointer notation looks random and scary, until you understand why it's the
+way it is; then it makes perfect sense.
+
+(It is actually permissible to omit the & when taking a pointer and to write
+e.g. foobarbaz(0.1) instead of (*foobarbaz)(0.1). However, I recommend not
+doing this, since the syntax for using the pointer no longer resembles the
+definition. Writing e.g. (*foobarbaz)(0.1) also makes a clear distinction
+between function pointer calls and ordinary function calls, which makes code
+more readable.)
+
+Note that function pointers have the return value and parameter list
+specified. A function pointer can only point to a function with a matching
+return value and matching parameters. (You can break this rule by casting the
+pointer explicitly, but there is no situation where doing so is portable to
+all computers, and I strongly advise against it unless you're writing system
+code. If you're not sure whether you're writing system code or not, then
+you're not.)
+
+The parameter names need not match (although the types must). If you wish to
+rename a parameter in your function, you do not have to change the function
+pointer accordingly. In fact, when you define a function pointer, you don't
+even have to specify the names of parameters if you don't want to. I normally
+do so for clarity.
+
+It is possible to typedef a function pointer. In order to typedef a function
+pointer, you start by declaring the pointer as a variable:
+
+   void (*myfunc)(void);
+
+Then you write 'typedef' before it and replace the variable name, which is
+myfunc, with the type name (this rule can be applied to any variable when you
+want to use typedef):
+
+   typedef void (*MYTYPE)(void);
+
+Now 'MYTYPE' represents a pointer to a function with no parameters and no
+return value. The following two lines are completely equivalent:
+
+   MYTYPE myfunc;
+   void (*myfunc)(void);
+
+Note that we use MYTYPE without an asterisk (*), since it is already a
+pointer.
+
+That's it. If you feel anything should be explained better here, or if you
+feel something should be added, please don't hesitate to let me know!
+
+
+Ben Davis
+entheh@users.sf.net
+IRC EFnet #dumb
+See readme.txt for details on using IRC.
diff --git a/apps/codecs/dumb/docs/howto.txt b/apps/codecs/dumb/docs/howto.txt
new file mode 100644
index 0000000000..0e7057da2c
--- /dev/null
+++ b/apps/codecs/dumb/docs/howto.txt
@@ -0,0 +1,845 @@
+/*  _______         ____    __         ___    ___
+ * \    _  \       \    /  \  /       \   \  /   /       '   '  '
+ *  |  | \  \       |  |    ||         |   \/   |         .      .
+ *  |  |  |  |      |  |    ||         ||\  /|  |
+ *  |  |  |  |      |  |    ||         || \/ |  |         '  '  '
+ *  |  |  |  |      |  |    ||         ||    |  |         .      .
+ *  |  |_/  /        \  \__//          ||    |  |
+ * /_______/ynamic    \____/niversal  /__\  /____\usic   /|  .  . ibliotheque
+ *                                                      /  \
+ *                                                     / .  \
+ * howto.txt - How To Use DUMB.                       / / \  \
+ *                                                   | <  /   \_
+ * See readme.txt for general information on         |  \/ /\   /
+ * DUMB and how to set it up.                         \_  /  > /
+ *                                                      | \ / /
+ *                                                      |  ' /
+ *                                                       \__/
+ */
+
+
+********************
+*** Introduction ***
+********************
+
+
+Welcome to the DUMB How-To! It is assumed here that you have already set DUMB
+up on your system, with or without Allegro. If not, please see readme.txt.
+
+
+*********************************
+*** Adding music to your game ***
+*********************************
+
+
+These instructions will help you add a piece of music to your game, assuming
+your music is stored in a stand-alone IT, XM, S3M or MOD file. If you wish to
+use a different method (such as putting the music file in an Allegro
+datafile), please follow these instructions first, test your program, and
+then follow the instructions further down for adapting your code.
+
+
+1. You need to include DUMB's header file. If you have Allegro, add the
+   following line to the top of your source file (or at the top of each file
+   where you wish to use DUMB):
+
+      #include <aldumb.h>
+
+   If you do not have Allegro or do not wish to use it, use dumb.h instead.
+
+
+2. You need to link with DUMB's library file or files. If you are compiling
+   with GCC from a command line on any platform, you need to add the
+   following to the command line:
+
+      If you are using Allegro: -laldmd -ldumbd
+      If you are not using Allegro: -ldumbd
+
+   If you are using MSVC from the command line:
+
+      If you are using Allegro: /link aldmd.lib dumbd.lib
+      If you are not using Allegro: /link dumbd.lib
+
+   With MSVC, you must also add /MD to the command line when compiling (not
+   when linking).
+
+   Note that -laldmd or aldmd.lib must PRECEDE alleg.lib, -lalleg_s,
+   `allegro-config --libs`, or whatever you are already using to link with
+   Allegro. For MSVC users, the /MD flag selects the multithreaded DLL
+   implementation of the standard libraries; since DUMB is statically linked,
+   you have to use the same library DUMB uses. You would also need this flag
+   to link statically with Allegro; if you already have it, there's no need
+   to put it twice.
+
+   (If anyone would like to contribute instructions for doing the above using
+   MSVC's IDE, please contact me. Contact details are at the end of this
+   file.)
+
+   If you are using RHIDE, go to Options -> Libraries. You will need to type
+   'aldmd' and 'dumbd' in two boxes, making sure 'aldmd' comes above whatever
+   you are using to link with Allegro (or just put 'dumbd' if you are not
+   using Allegro). Make sure the box next to each of these libraries is
+   checked.
+
+   The above are the debugging libraries. It is VERY HIGHLY RECOMMENDED that
+   you use the debugging libraries at first. The reason is as follows.
+   Although DUMB is supposedly robust against corrupt music files and things
+   like lack of memory, it will NOT tolerate programmer error. If you write
+   faulty code, DUMB will probably crash rather than returning an error code
+   for you. However, the debugging libraries will abort in many cases,
+   enabling you to find out what the cause is.
+
+   Once your program is up and running reliably, you can replace 'aldmd' with
+   'aldmb' and 'dumbd' with 'dumb'. Don't forget to do this, or DUMB will be
+   a lot slower than it should be!
+
+
+3. As you use DUMB, it may claim system resources (memory in particular). You
+   will need to arrange for these resources to be freed at the end. Doing so
+   is very easy. Simply write the following line at the top of your main
+   function, but below allegro_init() if you are using Allegro:
+
+      atexit(&dumb_exit);
+
+   This arranges for the function dumb_exit() to be called when your program
+   exits; you do not need to call dumb_exit() yourself. This method is
+   preferable to calling dumb_exit() manually, as it will free resources even
+   if your program aborts unexpectedly.
+
+   If you are happy with this, please skip ahead to Step 4. If you are
+   interested in alternative methods, read on, but read on carefully.
+
+   In fact it mostly doesn't matter where you put the above atexit() line,
+   provided it gets called only once, and before you do anything with DUMB.
+   If you are using DUMB with Allegro, it is recommended that you write the
+   functions in this order:
+
+      allegro_init();
+      atexit(&dumb_exit);
+
+   And then you must NOT call allegro_exit() yourself (because it has to be
+   called after dumb_exit()). Alternatively, if you prefer not to use
+   atexit() (or you cannot), you will have to do the following before
+   exiting:
+
+      dumb_exit();
+      allegro_exit();
+
+
+4. DUMB does not automatically do any of its own file input. You have to tell
+   it how to read files. Don't worry, it's easy. Simply call the following
+   function near the beginning of your program, after your atexit() call:
+
+      dumb_register_stdfiles();
+
+   This tells DUMB to use ordinary stdio FILE structs for reading and writing
+   files. If you are using Allegro and would rather DUMB used PACKFILEs, call
+   the following function INSTEAD:
+
+      dumb_register_packfiles();
+
+   In the latter case, DUMB will be affected by any password you set with
+   packfile_password() in the same way that other PACKFILEs are.
+
+   Note that the procedure for loading datafiles with embedded music is
+   independent of these two functions; even if you will be loading datafiles,
+   you can use either of these functions. If you are loading datafiles, your
+   executable might be slightly smaller if you use dumb_register_packfiles().
+   On the other hand, dumb_register_stdfiles() will probably be faster. If
+   you are only ever going to load datafiles and never stand-alone files, you
+   can actually leave this step out; but I would recommend you put this in,
+   test your code with a stand-alone file, then follow the instructions in
+   the next section in order to adapt your code to use the datafile (you will
+   be reminded that you can remove the function call).
+
+
+5. If you are using Allegro, you'll have to initialise Allegro's sound
+   system. In most cases the following line will do the job:
+
+      install_sound(DIGI_AUTODETECT, MIDI_NONE, NULL);
+
+   You may like to initialise a MIDI driver though; see Allegro's docs for
+   details. Put this line after allegro_init().
+
+
+6. All pieces of music are stored in memory in DUH structs. To handle these,
+   you must define pointers to them. Such pointers look like this:
+
+      DUH *myduh;
+
+   You can of course replace 'myduh' with anything you like. If you are
+   unfamiliar with pointers, please see ptr.txt. It is very important that
+   you understand these if you wish to use DUMB correctly.
+
+   You do not have direct access to the contents of a DUH struct, so do not
+   try. DUMB's functions provide everything you need; if you disagree, please
+   let me know and I shall see what I can do. Contact details are at the end
+   of this file.
+
+   Given the above definition, you can load a piece of music using one of the
+   following lines, depending on what file format you want to load:
+
+      myduh = dumb_load_it("a_one.it");
+      myduh = dumb_load_xm("a_two.xm");
+      myduh = dumb_load_s3m("a_one_two.s3m");
+      myduh = dumb_load_mod("three_four.mod");
+
+   Obviously you can use relative or absolute paths as normal. You should
+   always use forward slash (/), not backslash (\), when coding in C and
+   similar languages.
+
+   Every piece of music you load must be unloaded when you've finished with
+   it. When you type the above line in, it is good practice to type the
+   following line in at the same time, but put it at the end of the program:
+
+      unload_duh(myduh);
+
+   You will now be able to use the DUH struct anywhere in between the two
+   lines you just added. There is no need to check the return value; if the
+   DUH failed to load for one reason or another (this could be due to lack of
+   memory as well as the file not being there), then DUMB will do nothing -
+   safely.
+
+
+7. From this step onwards, it will be assumed you're using Allegro. If not,
+   please read these steps anyway, and then see the section entitled
+   "Rendering music into a buffer". You will have to write your own playback
+   code using whatever sound output system is available. Alternatively you
+   may like to write data to a file (especially if you have a file that
+   consumes a lot of processor time), but beware that any streaming audio
+   format is likely to be substantially larger than the module file you
+   generate it from, and formats like MP3 will be lower quality. You might
+   not be able to hear the difference between the MP3 and the original, but
+   many people can and don't like it, so please consider them. I'm one of
+   them. If you really want to use a lossy compression format, I highly
+   recommend Ogg Vorbis:
+
+      http://www.vorbis.com/
+
+   But I digress.
+
+   In order to play the DUH you loaded, you need to define a pointer to an
+   AL_DUH_PLAYER struct:
+
+      AL_DUH_PLAYER *dp;
+
+   Two of the functions you will need are prototyped as follows:
+
+      AL_DUH_PLAYER *al_start_duh(DUH *duh, int n_channels, long pos,
+                                  float volume, long bufsize, int freq);
+
+      void al_stop_duh(AL_DUH_PLAYER *dp);
+
+   As you can see, al_start_duh() returns a pointer to an AL_DUH_PLAYER
+   struct when you call it. You then pass this pointer to all the other
+   functions. Again, if it is a NULL pointer for whatever reason (usually
+   lack of memory), DUMB will safely do nothing. When you call al_stop_duh(),
+   the pointer becomes invalid and you should not use it again; if there's
+   any risk of the pointer being used again, it is wise to set it to NULL at
+   this point. You can reassign the variable with a new call to
+   al_start_duh() of course.
+
+   Set 'n_channels' to 1 or 2 for mono or stereo respectively. Note that this
+   parameter has nothing to do with the number of samples that can play at
+   once in a music module. Set 'pos' to 0 to play from the beginning; each
+   time you add 65536, you will have advanced one second into the piece. As a
+   general rule, set the volume to 1.0f and adjust it later if the music is
+   too loud or too quiet - but see Allegro's set_volume_per_voice() function
+   first.
+
+   'bufsize' can generally be set to 4096. If your music stutters, try
+   increasing it; if your game freezes periodically, try reducing it. Find a
+   happy medium. Set 'freq' to 48000 for the best quality, though 44100 will
+   do in most cases. 22050 will be fine for a lot of music, though 11025 may
+   sound muffled. You can choose any other value, higher, lower or in
+   between. If your music stutters, and increasing 'bufsize' doesn't fix it,
+   try reducing this value.
+
+   Once you have put in a call to al_start_duh(), it is good practice to
+   insert the call to al_stop_duh() at the same time. You must call
+   al_stop_duh() before the DUH is unloaded (unload_duh(), Step 6 above).
+
+   Don't get impetuous, your program is not ready yet! Proceed to Step 8.
+
+
+8. DUMB does not play music in the background for you; if you were expecting
+   it to do so, please see the explanation at the end of this step. For your
+   music to be played, you have to call another function at regular
+   intervals. Here is its prototype:
+
+      int al_poll_duh(AL_DUH_PLAYER *dp);
+
+   Do NOT call this function from inside a timer function unless you really
+   know what you are doing. The reasons why this is bad are explained
+   further down. You should call it from your main program.
+
+   Simply writing the following line will be sufficient in general, if you
+   have a variable 'dp' that points to your AL_DUH_PLAYER struct.
+
+      al_poll_duh(dp);
+
+   As a general rule, calling this once for each logic update will do the
+   trick. If, however, you are executing time-consuming algorithms such as
+   software 3D rendering, you may wish to insert calls to this function in
+   the middle of those algorithms. You cannot call this function too often
+   (within reason); if it has nothing to do it will return immediately.
+
+   Exactly how often you need to call the function depends on the values for
+   'bufsize' and 'freq' that you passed to al_start_duh():
+
+      n = freq / bufsize;
+
+   You have to call al_poll_duh() at least n times a second. Do not hesitate
+   to call it more often for safety; if the sound stutters, you may need to
+   do just that. (Or you may need to increase the buffer size or reduce the
+   quality settings; the only way to find out is to try.)
+
+   For now, don't worry about al_poll_duh()'s return value. As soon as you
+   need it, it will be explained.
+
+   If you are happy, please skip to Step 9. If you were expecting DUMB to
+   play your music in the background, please read on.
+
+   The natural way to play music in the background on most operating systems
+   nowadays is to use threads. DOS was not built with multithreading in mind,
+   and its system operations (notably disk access) assume they will only be
+   used from a single thread.
+
+   Interrupts are the next best thing to threads. A DOS hardware interrupt
+   could be triggered at any moment, and a handler function will be called.
+   This is how Allegro's timer functions work. Unfortunately, what you can do
+   inside an interrupt handler is very limited. For one thing, all code and
+   data used by the handler must be locked in memory; if not, it could get
+   written to disk (virtual memory). If the main program was accessing the
+   disk when it got interrupted, the system would then die a horrible death.
+   This precludes the possibility of allocating extra memory inside the
+   handler, and DUMB does a lot of that in al_poll_duh().
+
+   Given DUMB's architecture, which cannot change for reasons which will
+   become apparent in future versions, this renders it impossible to come up
+   with a portable solution for making DUMB play music in the background.
+   Having said that, if you wish to write your own wrapper for al_poll_duh()
+   and use it in a thread, there is nothing stopping you. If you do do this,
+   you will have to be very careful when stopping the music; see the
+   description of al_poll_duh() in dumb.txt for more information.
+
+   So why not kill DOS? It is all too common a practice among programmers to
+   quote the phrase, "DOS is as dead as the dodo." Despite being a decidedly
+   derisible demonstation of the dreary device of alliteration, it shows a
+   distinct lack of experience. Many embedded systems still use DOS because
+   it provides hardware access capabilities and real-time possibilities
+   unparalleled by any current multitasking operating system. For an argument
+   closer to home, I used to use RHIDE for DOS before I switched to Linux,
+   and I have not found a single Freeware Windows IDE that measures up to
+   RHIDE. I'm sure many people are in the same boat, and really appreciate
+   DUMB's DOS port.
+
+   We will not be removing DOS support from DUMB. Any blind suggestions to do
+   so will be met with fiery flames. You have been warned.
+
+
+9. Test your program!
+
+   If you have trouble, check through the above steps to make sure you didn't
+   miss one out. Refer to faq.txt to see if your problem is addressed there.
+   If you still have trouble, contact me; details are at the end of this
+   file.
+
+
+**********************************
+*** Controlling music playback ***
+**********************************
+
+
+Here I describe some common operations you may wish to perform. The method
+for doing so will seem a bit strange sometimes, as will the names of the
+structs. However, there is a reason behind everything. If you would like to
+do more exotic things, or better understand some of the methods used here,
+then see dumb.txt, which covers everything from the ground up.
+
+
+To control playback quality:
+
+   #define DUMB_RQ_ALIASING
+   #define DUMB_RQ_LINEAR
+   #define DUMB_RQ_CUBIC
+   #define DUMB_RQ_N_LEVELS
+   extern int dumb_resampling_quality;
+   extern int dumb_it_max_to_mix;
+
+   Please note that dumb_resampling_quality has changed in DUMB v0.9.2. See
+   deprec.txt for more details on the change.
+
+   dumb_resampling_quality can be set to any of the DUMB_RQ_* constants
+   (except DUMB_RQ_N_LEVELS; see below). Resampling is the term given to the
+   process of adjusting a sample's pitch (in this context).
+   dumb_resampling_quality defaults to DUMB_RQ_CUBIC, which sounds nice but
+   takes a lot of processor power. Try reducing it if you have an older
+   computer or if you are trying to mix an insane number of samples (or
+   both!). See dumb.txt for details on what the different values actually do.
+
+   If you wish to give this option to your user, you can use
+   DUMB_RQ_N_LEVELS. All the values from 0 to DUMB_RQ_N_LEVELS - 1 will be
+   valid resampling levels. If a value outside this range is chosen, it is
+   not the end of the world; DUMB will behave as if you had chosen the value
+   at whichever extreme you went beyond.
+
+   dumb_it_max_to_mix, defaulting to 64, is the maximum number of samples
+   DUMB will ever mix together when playing an IT, XM, S3M or MOD file.
+   Unlike many other music systems, DUMB will still keep track of all samples
+   (up to a fixed maximum of 256 of them, roughly speaking), and then will
+   just render as many of them as this variable permits, starting with the
+   loudest ones. When samples are cut or come back in, the exact timings will
+   not generally be predictable - but nor will they be important.
+
+   dumb_it_max_to_mix applies to each currently playing module file
+   independently. So if you set it to 64, but render two modules
+   simultaneously, DUMB could end up mixing up to 128 samples.
+
+
+To pause and resume playback, set the volume, get the current playback
+position, or get the length of time a DUH will play for before either looping
+or freezing (effect F00 in XM and MOD files, which means no new notes will be
+played but any existing notes will continue):
+
+   void al_pause_duh(AL_DUH_PLAYER *dp);
+   void al_resume_duh(AL_DUH_PLAYER *dp);
+   void al_duh_set_volume(AL_DUH_PLAYER *dp, float volume);
+   long al_duh_get_position(AL_DUH_PLAYER *dp);
+
+   long duh_get_length(DUH *duh);
+
+   These functions are pretty self-explanatory. The volume passed to
+   al_duh_set_volume() and the position returned by al_duh_get_position() are
+   in the same units as those you passed to al_start_duh(). The length
+   returned by duh_get_length() is in the same units as the aforementioned
+   position; see dumb.txt for more information on this function. Be careful
+   with al_duh_get_position(); it will return a position slightly ahead of
+   what you can hear, because the system has to keep ahead slightly to avoid
+   stuttering.
+
+
+To prevent the music from looping and/or freezing:
+
+   DUH_SIGRENDERER *al_duh_get_sigrenderer(AL_DUH_PLAYER *dp);
+   DUMB_IT_SIGRENDERER *duh_get_it_sigrenderer(DUH_SIGRENDERER *sigrenderer);
+
+   void dumb_it_set_loop_callback(DUMB_IT_SIGRENDERER *sigrenderer,
+      int (*callback)(void *data), void *data);
+   void dumb_it_set_xm_speed_zero_callback(DUMB_IT_SIGRENDERER *sigrenderer,
+      int (*callback)(void *data), void *data);
+
+   int dumb_it_callback_terminate(void *data);
+
+   If you are unfamiliar with function pointers, please see fnptr.txt.
+
+   Note that these functions apply to IT, XM, S3M and MOD files - not just to
+   IT files. This holds true throughout DUMB, for all functions with "it" in
+   the name. The xm_speed_zero event can only occur with XM and MOD files.
+
+   The first two functions will return a pointer to a struct contained by the
+   struct you pass. This system is necessary to ensure that these operations
+   are possible when not using Allegro. Typically you would write the
+   following code:
+
+   {
+      DUH_SIGRENDERER *sr = al_duh_get_sigrenderer(dp);
+      DUMB_IT_SIGRENDERER *itsr = duh_get_it_sigrenderer(sigrenderer);
+      dumb_it_set_loop_callback(itsr, &dumb_it_callback_terminate, NULL);
+      dumb_it_set_xm_speed_zero_callback
+                               (itsr, &dumb_it_callback_terminate, NULL);
+   }
+
+   Once you have done this, the return value of al_poll_duh() becomes
+   significant. It will be 0 as long as the music is playing. When the music
+   stops, al_poll_duh() will return nonzero. You can call al_stop_duh() and
+   do something else as soon as you wish, but calling al_poll_duh() some more
+   will not do any harm.
+
+   al_poll_duh() will also return 1 if the music could not be loaded, or if
+   memory was short when trying to play it, or if it was a quirky music file
+   with no music in it (technically one with an empty order list). This
+   happens regardless of whether or not you execute the above code to disable
+   looping. Normally you shouldn't need to worry about this.
+
+   To undo the above and make DUMB loop or freeze again, pass NULL instead of
+   &dumb_it_callback_terminate. If you would like to fade on looping, or loop
+   a finite number of times, or display a message when looping, or whatever,
+   you will have to write your own callback function. In this case, please
+   see dumb.txt.
+
+   Note that the above code can safely be applied for a DUH that doesn't
+   contain a music module but contains some other kind of music.
+   duh_get_it_sigrenderer() will return NULL, and the code will do nothing.
+
+
+To analyse the audio as it's generated:
+
+   typedef int sample_t;
+
+   typedef void (*DUH_SIGRENDERER_ANALYSER_CALLBACK)(void *data,
+                const sample_t *const *samples, int n_channels, long length);
+
+   void duh_sigrenderer_set_analyser_callback(DUH_SIGRENDERER *sigrenderer,
+                     DUH_SIGRENDERER_ANALYSER_CALLBACK callback, void *data);
+
+   If the above confuses you, see fnptr.txt. These functions, along with
+   al_duh_get_sigrenderer() from the last section, enable you to register a
+   callback function. Every time some samples are generated, they will be
+   passed to this function. This enables you to display an oscilloscope or
+   spectrum analyser, for example.
+
+   Beware: your callback function may occasionally be called with
+   samples == NULL. This means the main program has decided to skip through
+   the music without generating any data. You should handle this case
+   elegantly, typically by returning immediately, but you may wish to make a
+   note of the fact that the music is being skipped, for whatever reason.
+
+   Beware again: if the main program ever calls duh_sigrenderer_get_samples()
+   on a buffer that isn't all silence, this callback function will be passed
+   the existing buffer after mixing, and thus it will include the original
+   data. This will not be an issue if you stick to duh_render(), which always
+   starts with a buffer filled with silence.
+
+   The samples array is two-dimensional. Refer to it as follows:
+
+      samples[channel_number][sample_position]
+
+   where 0 <= channel_number < n_channels,
+     and 0 <= sample_position < length.
+
+   In addition you can pass any 'data' pointer you like to
+   duh_sigrenderer_set_analyser_callback(), and this pointer will be relayed
+   to your callback function each time.
+
+   To remove the callback function, pass NULL to
+   duh_sigrenderer_set_analyser_callback().
+
+
+Everything below this point assumes some knowledge of how a music module is
+constructed. If you do not have this knowledge, talk to whoever is writing
+music for you, or download a tracking program and play with it (see
+readme.txt).
+
+
+To start playing an IT, XM, S3M or MOD from an arbitrary order number (the
+default being 0, the beginning of the song), use the following:
+
+   DUH_SIGRENDERER *dumb_it_start_at_order
+                                  (DUH *duh, int n_channels, int startorder);
+   AL_DUH_PLAYER *al_duh_encapsulate_sigrenderer
+        (DUH_SIGRENDERER *sigrenderer, float volume, long bufsize, int freq);
+
+   The usage of these functions is as follows:
+
+   {
+      DUH_SIGRENDERER *sr = dumb_it_start_at_order
+                                               (duh, n_channels, startorder);
+      dp = al_duh_encapsulate_sigrenderer(sr, volume, bufsize, freq);
+   }
+
+   Replace 'dp' with whatever your AL_DUH_PLAYER pointer is. You also need
+   to insert suitable values for n_channels, startorder, volume, bufsize and
+   freq. These have the same meaning as those passed to al_start_duh().
+
+   WARNING: after passing a pointer to an "encapsulate" function, do not use
+            that pointer again. (More specifically, do not use it again if
+            the function returns NULL, because the function will have
+            destroyed the pointer if this happens, to help prevent memory
+            leaks.) There will be a "get" function with which you can obtain
+            the original pointer if it is still valid, or NULL otherwise.
+
+   The above functions will fail (safely) if you try to use them with a DUH
+   that contains a different type of music.
+
+   Notice that there is no 'pos' parameter. If you would like to skip through
+   the music, you can use this function:
+
+   long duh_sigrenderer_get_samples(
+      DUH_SIGRENDERER *sigrenderer,
+      float volume, float delta,
+      long size, sample_t **samples
+   );
+
+   Pass 0 for volume and NULL for samples, and this function will skip
+   through the music nice and quickly. So insert the following between the
+   two above statements:
+
+      duh_sigrenderer_get_samples(sr, 0, 65536.0f / freq, pos, NULL);
+
+   Substitute for 'freq' and 'pos'. An explanation of the 'delta' parameter
+   can be found further down in this file.
+
+   Finally, note that duh_get_length() is only meaningful when you start
+   playing music from order 0.
+
+
+If an IT file contains Zxx effects, DUMB will generate MIDI messages, which
+will control the low-pass resonant filters unless the IT file actively
+specifies something else. In rare cases this may not be what the Zxx effects
+were intended to do; if this is the case, you can block the MIDI messages as
+follows. Note that this does NOT mean filters are disabled; if an instrument
+specifies initial cut-off and resonance values, or has a filter envelope,
+then filters will be applied. It only makes sense to use this procedure at
+the beginning of playback.
+
+   void dumb_it_set_midi_callback(DUMB_IT_SIGRENDERER *sigrenderer,
+      int (*callback)(void *data, int channel, unsigned char byte),
+      void *data);
+
+   int dumb_it_callback_midi_block(void *data, int channel,
+                                   unsigned char byte);
+
+   Using some functions described in the previous section, we arrive at the
+   following code:
+
+   {
+      DUH_SIGRENDERER *sr = al_duh_get_sigrenderer(dp);
+      DUMB_IT_SIGRENDERER *itsr = duh_get_it_sigrenderer(sigrenderer);
+      dumb_it_set_midi_callback(itsr, &dumb_it_callback_midi_block, NULL);
+   }
+
+DUMB offers no way of disabling filters completely. Disabling filters is not
+recommended as a means to reduce processor usage, as it will completely
+damage any piece of music that uses the filters. If you want lower processor
+consumption, use a piece of music that does not use filters.
+
+
+Finally, DUMB offers a myriad of functions for querying and adjusting
+module playback. Those beginning with "dumb_it_sd" operate on the
+DUMB_IT_SIGDATA struct, which represents the piece of music before it starts
+to play. Those beginning with "dumb_it_sr" operate on the DUMB_IT_SIGRENDERER
+struct, which represents a currently playing instance of the music. Note that
+duh_get_length(), described above, becomes meaningless after some of these
+functions are used.
+
+The method for getting a DUMB_IT_SIGRENDERER struct has already been given,
+but the function prototypes are repeated here for convenience:
+
+   DUH_SIGRENDERER *al_duh_get_sigrenderer(AL_DUH_PLAYER *dp);
+   DUMB_IT_SIGRENDERER *duh_get_it_sigrenderer(DUH_SIGRENDERER *sigrenderer);
+
+Getting a DUMB_IT_SIGDATA struct is simpler:
+
+   DUMB_IT_SIGDATA *duh_get_it_sigdata(DUH *duh);
+
+For a list of dumb_it_sd_*() and dumb_it_sr_*() functions, please see
+dumb.txt. These functions are new, and may not provide exactly what you need;
+if not, please let me know.
+
+
+**************************************************
+*** Embedding music files in Allegro datafiles ***
+**************************************************
+
+
+In this section it is assumed you are already reasonably familiar with how
+Allegro datafiles are used. If not, please refer to Allegro's documentation.
+At the time of writing, the documentation you need is off the beaten track,
+so to speak, in allegro/tools/grabber.txt.
+
+To add a piece of music to a datafile, you need to create an object of type
+"IT  ", "XM  ", "S3M " or "MOD " (note the spaces used as padding, although
+you do not need to type these into the grabber). Then grab the piece of music
+in. The grabber will treat it as a binary object. Save the datafile as usual.
+
+
+To use a piece of music you added to the datafile, follow these steps:
+
+
+1. Before loading the datafile, call one or more of these functions,
+   depending on which music format or formats you'd like to support:
+
+      dumb_register_dat_it(DUMB_DAT_IT);
+      dumb_register_dat_xm(DUMB_DAT_XM);
+      dumb_register_dat_s3m(DUMB_DAT_S3M);
+      dumb_register_dat_mod(DUMB_DAT_MOD);
+
+   Remember, do not call multiple functions unless you want to support
+   multiple formats. Calling more functions will add unused code to your
+   executable.
+
+   It is important that you make call these before loading the datafile,
+   since they tell Allegro how to load the respective files straight from
+   datafiles in the future. They will not help Allegro interpret any module
+   files that have already been loaded as binary objects (but if you really
+   need to interpret a module that has been loaded in this fashion, have a
+   look at dumbfile_open_memory() in dumb.txt).
+
+   If for whatever reason your music objects are identified by a different
+   type in the datafile, you can tell DUMB what that type is by changing the
+   parameter to the registration function above. Use Allegro's DAT_ID()
+   macro, e.g. DAT_ID('B','L','A','H'). This is not really recommended
+   though, since it would prevent a hypothetical grabber plug-in from being
+   able to play your music files. Use the above types if possible.
+
+
+2. Whenever you need a pointer to a DUH struct, simply use the 'dat' field.
+   Do this in the same way you would for a pointer to a BITMAP struct or
+   anything else. If it makes you feel more comfortable, you can extract the
+   pointer in advance:
+
+      DATAFILE *dat = load_datafile("smurf.dat");
+      if (!dat) abort(); /* There are much nicer ways of handling failure! */
+      DUH *myduh = (DUH *)dat[GAME_MUSIC].dat;
+
+   Note that the explicit (DUH *) cast is only necessary for C++, not for C.
+   However, it does no harm.
+
+   Be sure that you do NOT call unload_duh() for anything stored in the
+   datafile. These DUHs will be freed when you call unload_datafile(), and
+   freeing them twice is practically guaranteed to crash your program.
+
+
+3. If you only ever load music as part of a datafile, and you never load any
+   stand-alone music files, you do not need to register a file input system
+   for DUMB to use. If you followed the instructions for the first section
+   you will have one of these two lines in your program:
+
+      dumb_register_stdfiles();
+      dumb_register_packfiles();
+
+   You can safely delete this line - but only if you never load any
+   stand-alone music files. The debugging library will bale you out if you
+   delete it when you shouldn't; the optimised library won't.
+
+
+*************************************
+*** Rendering music into a buffer ***
+*************************************
+
+
+NOTE: much of the API formerly described in this section has been deprecated,
+      and you will need to alter your code. See deprec.txt for details. If
+      you are reading this section for the first time, you can ignore this
+      note.
+
+Rendering to a buffer is similar to playing using an AL_DUH_PLAYER. However,
+you must use a DUH_SIGRENDERER struct instead. Here are the functions:
+
+   DUH_SIGRENDERER *duh_start_sigrenderer
+                               (DUH *duh, int sig, int n_channels, long pos);
+
+   int duh_sigrenderer_get_n_channels(DUH_SIGRENDERER *sigrenderer);
+   long duh_sigrenderer_get_position(DUH_SIGRENDERER *sigrenderer);
+
+   long duh_sigrenderer_get_samples(DUH_SIGRENDERER *sigrenderer,
+                   float volume, float delta, long size, sample_t **samples);
+
+   long duh_render(DUH_SIGRENDERER *sigrenderer,
+     int bits, int unsign, float volume, float delta, long size, void *sptr);
+
+   void duh_end_sigrenderer(DUH_SIGRENDERER *sigrenderer);
+
+The parameters to duh_start_sigrenderer() have the same meanings as those to
+al_start_duh(). However, note that the volume is not set at this stage. You
+pass the desired volume each time you want to render a block. The 'sig'
+parameter should be set to 0 for now.
+
+Notice that there are two rendering functions. duh_sigrenderer_get_samples()
+will generate samples in the internal 32-bit format, with a normal range from
+-0x800000 to 0x7FFFFF and with each channel in a separate array; duh_render()
+will convert to 8 or 16 bits, signed or unsigned, with stereo samples
+interleaved, left first.
+
+When you call duh_render(), pass 8 or 16 for 'bits'. If you pass 8, 'sptr' is
+expected to be an array of chars. If you pass 16, 'sptr' is expected to be an
+array of shorts. Endianness therefore depends on the platform, and you should
+not try to interpret 16-bit wave data as an array of chars (unless you're
+writing highly system-specific code anyway). Because DUMB renders internally
+with 32 bits, there is no significant speed increase in rendering an 8-bit
+stream.
+
+If you are rendering in stereo, make sure your 'sptr' array is twice as big!
+
+If you set 'unsign' to a nonzero value, then the samples generated will be
+centred on 0x80 or 0x8000, suitably stored in an array of unsigned chars or
+unsigned shorts. If 'unsign' is zero, the samples will be centred on 0,
+suitably stored in an array of signed chars or signed shorts. Note that 8-bit
+WAV files are unsigned while 16-bit WAV files are signed. This convention was
+used by the SoundBlaster 16 when receiving samples to be sent to the
+speakers. If you wish to write 16-bit sample data to a WAV file, don't use
+fwrite(); instead, take the shorts one at a time, split them up into chars as
+follows, and write the chars to the file.
+
+   short sptr[n];
+   char lsb = (char)sptr[n];
+   char msb = (char)(sptr[n] >> 8);
+
+For a 16-bit WAV file, write the LSB (less significant byte) first.
+
+The following applies equally to duh_render() and
+duh_sigrenderer_get_samples(), except where otherwise stated.
+
+If you set 'delta' to 1.0f, the sound generated will be suitable for playback
+at 65536 Hz. Increasing 'delta' causes the wave to speed up, given a constant
+sampling rate for playback. Supposing you want to vary the playback sampling
+rate but keep the pitch constant, here's the equation for 'delta':
+
+   delta = 65536.0f / sampling_rate;
+
+'size' is the number of samples you want rendered. For duh_render(), they
+will be rendered into an array which you pass as 'sptr'. Note that stereo
+samples count as one; so if you set n_channels to 2, your array must contain
+(2 * size) elements.
+
+For duh_sigrenderer_get_samples() you will have to use the following
+functions:
+
+   sample_t **create_sample_buffer(int n_channels, long length);
+   void destroy_sample_buffer(sample_t **samples);
+
+   void dumb_silence(sample_t *samples, long length);
+
+create_sample_buffer() allocates the channels sequentially in memory, so the
+following technique is valid:
+
+   sample_t **samples = create_sample_buffer(n_channels, length);
+   dumb_silence(samples[0], n_channels * length);
+
+It is necessary to fill the buffer with silence like this because
+duh_sigrenderer_get_samples() mixes what it renders with the existing
+contents of the buffer.
+
+The return values from duh_render() and duh_sigrenderer_get_samples() tell
+you how many samples were actually generated. In most cases, this will be the
+same as the 'size' parameter. However, if you reach the end of the DUH (which
+will happen if you disable looping or freezing as described further up), this
+function will return less. When that happens, you can assume the stream has
+finished. In the case of duh_render(), the remainder of the array will not
+have been initialised, so you either have to initialise it yourself or avoid
+using it.
+
+If for whatever reason duh_start_sigrenderer() returns NULL, then
+duh_render() and duh_sigrenderer_get_samples() will generate exactly 0
+samples, duh_sigrenderer_get_n_channels() will return 0,
+duh_sigrenderer_get_position() will return -1, and duh_end_sigrenderer() will
+safely do nothing.
+
+
+*********************
+*** Miscellaneous ***
+*********************
+
+
+Please see dumb.txt for an API reference and for information on thread safety
+with DUMB. The API reference has been stripped down, since some functions and
+variables are subject to change. If something does not appear in dumb.txt,
+please do not use it.
+
+
+******************
+*** Conclusion ***
+******************
+
+
+If you have any difficulties, or if you use DUMB successfully, please don't
+hesitate to contact me (see below).
+
+Enjoy!
+
+
+Ben Davis
+entheh@users.sf.net
+IRC EFnet #dumb
+See readme.txt for details on using IRC.
diff --git a/apps/codecs/dumb/docs/modplug.txt b/apps/codecs/dumb/docs/modplug.txt
new file mode 100644
index 0000000000..a02ddd8bdd
--- /dev/null
+++ b/apps/codecs/dumb/docs/modplug.txt
@@ -0,0 +1,137 @@
+/*  _______         ____    __         ___    ___
+ * \    _  \       \    /  \  /       \   \  /   /       '   '  '
+ *  |  | \  \       |  |    ||         |   \/   |         .      .
+ *  |  |  |  |      |  |    ||         ||\  /|  |
+ *  |  |  |  |      |  |    ||         || \/ |  |         '  '  '
+ *  |  |  |  |      |  |    ||         ||    |  |         .      .
+ *  |  |_/  /        \  \__//          ||    |  |
+ * /_______/ynamic    \____/niversal  /__\  /____\usic   /|  .  . ibliotheque
+ *                                                      /  \
+ *                                                     / .  \
+ * modplug.txt - Our official position regarding      / / \  \
+ *               compatibility with ModPlug          | <  /   \_
+ *               Tracker.                            |  \/ /\   /
+ *                                                    \_  /  > /
+ *                                                      | \ / /
+ *                                                      |  ' /
+ *                                                       \__/
+ */
+
+
+********************
+*** Introduction ***
+********************
+
+ModPlug Tracker is a very popular tracker for Windows. Its popularity is due
+to the intuitive interface and its many advanced features. The author has
+done a good job with this piece of software, but sadly in doing so he has
+desecrated the IT file format.
+
+I am not against ModPlug Tracker being used to write music modules. As
+already stated, it has some very advanced and convenient features; I use it
+myself. However, I believe its users should be aware of the entire situation
+before using it for any serious work.
+
+   ModPlug Tracker - http://www.modplug.com/
+
+
+*************************
+*** Incompatibilities ***
+*************************
+
+There are a few situations in which ModPlug Tracker misinterprets the
+original module formats. I shall list the five I am most aware of, from least
+to most annoying:
+
+5. Create a multisample instrument, for example a piano. Play a low note.
+   Then go up the scale, but in the pattern data, make sure the instrument
+   column is blank; put in only the notes. Play this with ModPlug Tracker,
+   and play it with Impulse Tracker. Impulse Tracker changes sample as you go
+   up the scale; ModPlug Tracker does not.
+
+4. Arpeggio and Retrigger Note effects behave badly when combined with
+   Portamento, which can appear in the volume column. While Retrigger Note
+   isn't too bad, Arpeggio sounds completely wrong. Try it and see what
+   happens. Then repeat the experiment in Impulse Tracker.
+
+3. The filter algorithm is incorrect, in more ways than one. When Jeffrey Lim
+   programmed the low-pass resonant filters into Impulse Tracker, he used a
+   standard filter algorithm with a slight modification to achieve greater
+   resonance. ModPlug Tracker does not incorporate this modification.
+   Furthermore, ModPlug Tracker uses integer arithmetic with nowhere near
+   enough precision; the wave output is really poor in some cases. I don't
+   doubt it damages the acoustic properties of the filters in subtle ways.
+
+2. When looping, ModPlug Tracker resets all variables. The original trackers
+   do not do this.
+
+1. Worst of all, ModPlug Tracker has no regard for playback volume, and
+   generally has a much lower output level than the original trackers.
+
+Cases 3, 2 and 1 lead people to write IT files that play badly in the
+original trackers. If some of these problems could be fixed, I'd be all for
+it - but these problems have been reported to the author and he had no
+motivation to fix them. ModPlug Tracker has been around long enough that
+fixing 3, 2 and 1 would be detrimental to too many people's music.
+
+
+******************
+*** Extensions ***
+******************
+
+Worse than the incompatibilities are the extensions ModPlug Tracker makes,
+mostly to the IT format. DUMB currently supports one of these extensions,
+namely stereo samples, but supporting the others is not high on my list of
+priorities.
+
+Other extensions ModPlug Tracker has provided mostly take the form of extra
+effects. For instance, S98 and S99 can be used to enable or disable reverb. I
+believe the latest versions of ModPlug Tracker offer alternative types of
+filter, such as high-pass and band-pass. As soon as an IT file uses any of
+these features, it will play incorrectly with Impulse Tracker.
+
+By far the most evil extension provided by ModPlug Tracker is the effect
+plug-ins. These enable IT files to use VST effects. I recently downloaded an
+IT file that uses some effects from a collection named "DirectX Media Audio
+Effects". When can we expect these effects to be ported to Linux?
+
+
+******************
+*** Conclusion ***
+******************
+
+ModPlug Tracker is trying to be two things at once. It wants to be an editor
+for the existing formats, but at the same time it wants to be proprietary,
+with all its own features and extensions. Unfortunately it is succeeding;
+there are many IT files out there that only play right in ModPlug Tracker. In
+my opinion, ModPlug Tracker should have come out with its own file format, in
+which all these extensions would have found a home.
+
+If you are going to use ModPlug Tracker's extensions, I recommend you
+ultimately convert your music to a streamed format such as Ogg Vorbis. (If
+you were thinking of using MP3, then don't - consider using Ogg Vorbis
+instead.) If you release IT files that use ModPlug Tracker's extensions,
+please state prominently that the files are designed to be played with
+ModPlug Tracker. Finally, don't ask me to support ModPlug Tracker's
+extensions; ModPlug Tracker's playback code is available for use in your
+games, so use that instead.
+
+   Ogg Vorbis - http://www.vorbis.com/
+
+Despite all the above problems, don't forget that ModPlug Tracker does have a
+lot of very useful features for editing files. These include a function for
+removing unused patterns, samples and instruments, drag-and-drop sample and
+instrument ripping, drop-down menus for selecting the effects by name without
+having to memorise the codes or refer to help, and lots of other nice things.
+I do recommend it as an editor, provided you make sure you are aware of the
+situation and do not use ModPlug Tracker's extensions or incompatibilities
+inadvertently.
+
+Oh, and by the way, save your final version with Impulse Tracker. Then the
+samples will be compressed for you!
+
+
+Ben Davis
+entheh@users.sf.net
+IRC EFnet #dumb
+See readme.txt for details on using IRC.
diff --git a/apps/codecs/dumb/docs/ptr.txt b/apps/codecs/dumb/docs/ptr.txt
new file mode 100644
index 0000000000..0eb42ccf02
--- /dev/null
+++ b/apps/codecs/dumb/docs/ptr.txt
@@ -0,0 +1,129 @@
+/*  _______         ____    __         ___    ___
+ * \    _  \       \    /  \  /       \   \  /   /       '   '  '
+ *  |  | \  \       |  |    ||         |   \/   |         .      .
+ *  |  |  |  |      |  |    ||         ||\  /|  |
+ *  |  |  |  |      |  |    ||         || \/ |  |         '  '  '
+ *  |  |  |  |      |  |    ||         ||    |  |         .      .
+ *  |  |_/  /        \  \__//          ||    |  |
+ * /_______/ynamic    \____/niversal  /__\  /____\usic   /|  .  . ibliotheque
+ *                                                      /  \
+ *                                                     / .  \
+ * ptr.txt - Pointer explanation.                     / / \  \
+ *                                                   | <  /   \_
+ *                                                   |  \/ /\   /
+ *                                                    \_  /  > /
+ *                                                      | \ / /
+ *                                                      |  ' /
+ *                                                       \__/
+ */
+
+
+A pointer is a small variable (often the same size as an int BUT NOT ALWAYS)
+that holds the address of something in memory. You create a pointer by adding
+a * to a variable, as follows:
+
+   int x, *y;
+
+   x = 5;
+   y = &x;
+
+The & means 'address of', so &x gives us a pointer to x. We are storing it in
+y.
+
+   (*y)++;
+
+The * here means 'value at'. It's known as the 'dereferencing' operator. When
+written before a pointer, as it is here, it allows you to treat the value
+like a normal variable. In this case we are incrementing the value. If we
+look at x, we'll find that it now contains 6, not 5.
+
+   y++;
+
+Here we are incrementing the pointer itself. This is useful for traversing
+through an array, but in this particular example it is not much use.
+
+   *y++;
+
+Beware; this will increment the pointer, not the value stored there. It will
+return the value stored at the pointer (before incrementing the pointer), so
+you can use this in a bigger expression. This is why we needed brackets in
+the first example.
+
+Note that you will not need these three examples when working with DUMB; they
+are simply to help illustrate the idea of pointers.
+
+Also be aware that when defining pointers you attach the * to the variable,
+not to the type. The following example will create a pointer and an int, not
+two pointers:
+
+   int *a, b;
+
+That is why I believe it's a good idea to put a space before the * and not
+after it, although programmers are divided on this.
+
+   y = 0;
+   y = NULL;
+
+These two statements are equivalent. 0, or NULL, is a special value that is
+guaranteed to have a different value from any valid pointer. This is most
+often used to indicate that something doesn't point anywhere. DUMB's
+functions may return it on occasion. However, in simple usage of DUMB, you
+will not actually need to check for it.
+
+Some of DUMB's functions return pointers to structs. (A struct is an
+aggregration of other variables, such as ints, pointers, or other structs.
+You can generally treat a struct as a single unit.) Here's an example of such
+a function:
+
+   DUH *dumb_load_it(const char *filename);
+
+You do not know what the DUH struct actually contains; dumb.h and aldumb.h
+only give the compiler enough information to deal with pointers to them. DUMB
+will take charge of everything that happens inside a DUH struct.
+
+The above function will create a DUH struct for you. First it allocates
+the memory it needs, then it fills the struct with data, then it returns a
+pointer. This DUH struct will contain the data necessary to play an IT file.
+You can define a suitable variable and store the pointer in it as follows:
+
+   DUH *duh = dumb_load_it("music.it");
+
+Or this can be split up:
+
+   DUH *duh;
+   duh = dumb_load_it("music.it");
+
+In order to use this DUH struct later, you must pass its pointer to other
+functions. To pass the pointer to a function, simply write 'duh' for the
+appropriate parameter.
+
+When you've finished with a DUH struct (this applies equally to the other
+structs DUMB deals with), you must pass it to an appropriate function for
+freeing up the memory:
+
+   unload_duh(duh);
+
+After you've done this, the memory will no longer be allocated, and the
+pointer will have no meaning. You may wish to set it to NULL at this point
+for safety. Alternatively just be sure not to use the present value of the
+pointer any more. You can of course assign a new value to the pointer, e.g.
+by calling dumb_load_it() again.
+
+Note the following:
+
+   DUH *duh2 = duh;
+
+This only duplicates the pointer, not the DUH itself. You still only have one
+copy of the DUH. There is no way of duplicating a DUH, short of loading it
+twice. This is not a problem, because DUMB can play it 'twice at the same
+time' anyway.
+
+That should be all you need to know about pointers in order to use DUMB. If
+there's anything you feel should be explained better here, or anything else
+that should be added, please don't hesitate to let me know!
+
+
+Ben Davis
+entheh@users.sf.net
+IRC EFnet #dumb
+See readme.txt for details on using IRC.