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+/* libmspack -- a library for working with Microsoft compression formats.
+ * (C) 2003-2011 Stuart Caie <kyzer@4u.net>
+ *
+ * libmspack is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU Lesser General Public License (LGPL) version 2.1
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+/** \mainpage
+ *
+ * \section intro Introduction
+ *
+ * libmspack is a library which provides compressors and decompressors,
+ * archivers and dearchivers for Microsoft compression formats.
+ *
+ * \section formats Formats supported
+ *
+ * The following file formats are supported:
+ * - SZDD files, which use LZSS compression
+ * - KWAJ files, which use LZSS, LZSS+Huffman or deflate compression
+ * - .HLP (MS Help) files, which use LZSS compression
+ * - .CAB (MS Cabinet) files, which use deflate, LZX or Quantum compression
+ * - .CHM (HTML Help) files, which use LZX compression
+ * - .LIT (MS EBook) files, which use LZX compression and DES encryption
+ *
+ * To determine the capabilities of the library, and the binary
+ * compatibility version of any particular compressor or decompressor, use
+ * the mspack_version() function. The UNIX library interface version is
+ * defined as the highest-versioned library component.
+ *
+ * \section starting Getting started
+ *
+ * The macro MSPACK_SYS_SELFTEST() should be used to ensure the library can
+ * be used. In particular, it checks if the caller is using 32-bit file I/O
+ * when the library is compiled for 64-bit file I/O and vice versa.
+ *
+ * If compiled normally, the library includes basic file I/O and memory
+ * management functionality using the standard C library. This can be
+ * customised and replaced entirely by creating a mspack_system structure.
+ *
+ * A compressor or decompressor for the required format must be
+ * instantiated before it can be used. Each construction function takes
+ * one parameter, which is either a pointer to a custom mspack_system
+ * structure, or NULL to use the default. The instantiation returned, if
+ * not NULL, contains function pointers (methods) to work with the given
+ * file format.
+ * 
+ * For compression:
+ * - mspack_create_cab_compressor() creates a mscab_compressor
+ * - mspack_create_chm_compressor() creates a mschm_compressor
+ * - mspack_create_lit_compressor() creates a mslit_compressor
+ * - mspack_create_hlp_compressor() creates a mshlp_compressor
+ * - mspack_create_szdd_compressor() creates a msszdd_compressor
+ * - mspack_create_kwaj_compressor() creates a mskwaj_compressor
+ *
+ * For decompression:
+ * - mspack_create_cab_decompressor() creates a mscab_decompressor
+ * - mspack_create_chm_decompressor() creates a mschm_decompressor
+ * - mspack_create_lit_decompressor() creates a mslit_decompressor
+ * - mspack_create_hlp_decompressor() creates a mshlp_decompressor
+ * - mspack_create_szdd_decompressor() creates a msszdd_decompressor
+ * - mspack_create_kwaj_decompressor() creates a mskwaj_decompressor
+ *
+ * Once finished working with a format, each kind of
+ * compressor/decompressor has its own specific destructor:
+ * - mspack_destroy_cab_compressor()
+ * - mspack_destroy_cab_decompressor()
+ * - mspack_destroy_chm_compressor()
+ * - mspack_destroy_chm_decompressor()
+ * - mspack_destroy_lit_compressor()
+ * - mspack_destroy_lit_decompressor()
+ * - mspack_destroy_hlp_compressor()
+ * - mspack_destroy_hlp_decompressor()
+ * - mspack_destroy_szdd_compressor()
+ * - mspack_destroy_szdd_decompressor()
+ * - mspack_destroy_kwaj_compressor()
+ * - mspack_destroy_kwaj_decompressor()
+ *
+ * Destroying a compressor or decompressor does not destroy any objects,
+ * structures or handles that have been created using that compressor or
+ * decompressor. Ensure that everything created or opened is destroyed or
+ * closed before compressor/decompressor is itself destroyed.
+ *
+ * \section errors Error codes
+ *
+ * All compressors and decompressors use the same set of error codes. Most
+ * methods return an error code directly. For methods which do not
+ * return error codes directly, the error code can be obtained with the
+ * last_error() method.
+ *
+ * - #MSPACK_ERR_OK is used to indicate success. This error code is defined
+ *   as zero, all other code are non-zero.
+ * - #MSPACK_ERR_ARGS indicates that a method was called with inappropriate
+ *   arguments.
+ * - #MSPACK_ERR_OPEN indicates that mspack_system::open() failed.
+ * - #MSPACK_ERR_READ indicates that mspack_system::read() failed.
+ * - #MSPACK_ERR_WRITE indicates that mspack_system::write() failed.
+ * - #MSPACK_ERR_SEEK indicates that mspack_system::seek() failed.
+ * - #MSPACK_ERR_NOMEMORY indicates that mspack_system::alloc() failed.
+ * - #MSPACK_ERR_SIGNATURE indicates that the file being read does not
+ *   have the correct "signature". It is probably not a valid file for
+ *   whatever format is being read.
+ * - #MSPACK_ERR_DATAFORMAT indicates that the file being used or read
+ *   is corrupt.
+ * - #MSPACK_ERR_CHECKSUM indicates that a data checksum has failed.
+ * - #MSPACK_ERR_CRUNCH indicates an error occured during compression.
+ * - #MSPACK_ERR_DECRUNCH indicates an error occured during decompression.
+ *
+ * \section threading Multi-threading
+ *
+ * libmspack methods are reentrant and multithreading-safe when each
+ * thread has its own compressor or decompressor.
+
+ * You should not call multiple methods simultaneously on a single
+ * compressor or decompressor instance.
+ *
+ * If this may happen, you can either use one compressor or
+ * decompressor per thread, or you can use your preferred lock,
+ * semaphore or mutex library to ensure no more than one method on a
+ * compressor/decompressor is called simultaneously. libmspack will
+ * not do this locking for you.
+ *
+ * Example of incorrect behaviour:
+ * - thread 1 calls mspack_create_cab_decompressor()
+ * - thread 1 calls open()
+ * - thread 1 calls extract() for one file
+ * - thread 2 simultaneously calls extract() for another file
+ *
+ * Correct behaviour:
+ * - thread 1 calls mspack_create_cab_decompressor()
+ * - thread 2 calls mspack_create_cab_decompressor()
+ * - thread 1 calls its own open() / extract()
+ * - thread 2 simultaneously calls its own open() / extract()
+ *
+ * Also correct behaviour:
+ * - thread 1 calls mspack_create_cab_decompressor()
+ * - thread 1 locks a mutex for with the decompressor before
+ *   calling any methods on it, and unlocks the mutex after each
+ *   method returns.
+ * - thread 1 can share the results of open() with thread 2, and both
+ *   can call extract(), provided they both guard against simultaneous
+ *   use of extract(), and any other methods, with the mutex
+ */
+
+#ifndef LIB_MSPACK_H
+#define LIB_MSPACK_H 1
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <sys/types.h>
+#include <stdlib.h>
+
+/**
+ * System self-test function, to ensure both library and calling program
+ * can use one another.
+ *
+ * A result of MSPACK_ERR_OK means the library and caller are
+ * compatible. Any other result indicates that the library and caller are
+ * not compatible and should not be used. In particular, a value of
+ * MSPACK_ERR_SEEK means the library and caller use different off_t
+ * datatypes.
+ *
+ * It should be used like so:
+ *
+ * @code
+ * int selftest_result;
+ * MSPACK_SYS_SELFTEST(selftest_result);
+ * if (selftest_result != MSPACK_ERR_OK) {
+ *   fprintf(stderr, "incompatible with this build of libmspack\n");
+ *   exit(0);
+ * }
+ * @endcode
+ *
+ * @param  result   an int variable to store the result of the self-test
+ */
+#define MSPACK_SYS_SELFTEST(result)  do { \
+  (result) = mspack_sys_selftest_internal(sizeof(off_t)); \
+} while (0)
+
+/** Part of the MSPACK_SYS_SELFTEST() macro, must not be used directly. */
+extern int mspack_sys_selftest_internal(int);
+
+/**
+ * Enquire about the binary compatibility version of a specific interface in
+ * the library. Currently, the following interfaces are defined:
+ *
+ * - #MSPACK_VER_LIBRARY: the overall library
+ * - #MSPACK_VER_SYSTEM: the mspack_system interface
+ * - #MSPACK_VER_MSCABD: the mscab_decompressor interface
+ * - #MSPACK_VER_MSCABC: the mscab_compressor interface
+ * - #MSPACK_VER_MSCHMD: the mschm_decompressor interface
+ * - #MSPACK_VER_MSCHMC: the mschm_compressor interface
+ * - #MSPACK_VER_MSLITD: the mslit_decompressor interface
+ * - #MSPACK_VER_MSLITC: the mslit_compressor interface
+ * - #MSPACK_VER_MSHLPD: the mshlp_decompressor interface
+ * - #MSPACK_VER_MSHLPC: the mshlp_compressor interface
+ * - #MSPACK_VER_MSSZDDD: the msszdd_decompressor interface
+ * - #MSPACK_VER_MSSZDDC: the msszdd_compressor interface
+ * - #MSPACK_VER_MSKWAJD: the mskwaj_decompressor interface
+ * - #MSPACK_VER_MSKWAJC: the mskwaj_compressor interface
+ *
+ * The result of the function should be interpreted as follows:
+ * - -1: this interface is completely unknown to the library
+ * - 0: this interface is known, but non-functioning
+ * - 1: this interface has all basic functionality
+ * - 2, 3, ...: this interface has additional functionality, clearly marked
+ *   in the documentation as "version 2", "version 3" and so on.
+ *
+ * @param entity the interface to request current version of
+ * @return the version of the requested interface
+ */
+extern int mspack_version(int entity);
+
+/** Pass to mspack_version() to get the overall library version */
+#define MSPACK_VER_LIBRARY   (0)
+/** Pass to mspack_version() to get the mspack_system version */
+#define MSPACK_VER_SYSTEM    (1)
+/** Pass to mspack_version() to get the mscab_decompressor version */
+#define MSPACK_VER_MSCABD    (2)
+/** Pass to mspack_version() to get the mscab_compressor version */
+#define MSPACK_VER_MSCABC    (3)
+/** Pass to mspack_version() to get the mschm_decompressor version */
+#define MSPACK_VER_MSCHMD    (4)
+/** Pass to mspack_version() to get the mschm_compressor version */
+#define MSPACK_VER_MSCHMC    (5)
+/** Pass to mspack_version() to get the mslit_decompressor version */
+#define MSPACK_VER_MSLITD    (6)
+/** Pass to mspack_version() to get the mslit_compressor version */
+#define MSPACK_VER_MSLITC    (7)
+/** Pass to mspack_version() to get the mshlp_decompressor version */
+#define MSPACK_VER_MSHLPD    (8)
+/** Pass to mspack_version() to get the mshlp_compressor version */
+#define MSPACK_VER_MSHLPC    (9)
+/** Pass to mspack_version() to get the msszdd_decompressor version */
+#define MSPACK_VER_MSSZDDD   (10)
+/** Pass to mspack_version() to get the msszdd_compressor version */
+#define MSPACK_VER_MSSZDDC   (11)
+/** Pass to mspack_version() to get the mskwaj_decompressor version */
+#define MSPACK_VER_MSKWAJD   (12)
+/** Pass to mspack_version() to get the mskwaj_compressor version */
+#define MSPACK_VER_MSKWAJC   (13)
+
+/* --- file I/O abstraction ------------------------------------------------ */
+
+/**
+ * A structure which abstracts file I/O and memory management.
+ *
+ * The library always uses the mspack_system structure for interaction
+ * with the file system and to allocate, free and copy all memory. It also
+ * uses it to send literal messages to the library user.
+ *
+ * When the library is compiled normally, passing NULL to a compressor or
+ * decompressor constructor will result in a default mspack_system being
+ * used, where all methods are implemented with the standard C library.
+ * However, all constructors support being given a custom created
+ * mspack_system structure, with the library user's own methods. This
+ * allows for more abstract interaction, such as reading and writing files
+ * directly to memory, or from a network socket or pipe.
+ *
+ * Implementors of an mspack_system structure should read all
+ * documentation entries for every structure member, and write methods
+ * which conform to those standards.
+ */
+struct mspack_system {
+  /**
+   * Opens a file for reading, writing, appending or updating.
+   *
+   * @param self     a self-referential pointer to the mspack_system
+   *                 structure whose open() method is being called. If
+   *                 this pointer is required by close(), read(), write(),
+   *                 seek() or tell(), it should be stored in the result
+   *                 structure at this time.
+   * @param filename the file to be opened. It is passed directly from the
+   *                 library caller without being modified, so it is up to
+   *                 the caller what this parameter actually represents.
+   * @param mode     one of #MSPACK_SYS_OPEN_READ (open an existing file
+   *                 for reading), #MSPACK_SYS_OPEN_WRITE (open a new file
+   *                 for writing), #MSPACK_SYS_OPEN_UPDATE (open an existing
+   *                 file for reading/writing from the start of the file) or
+   *                 #MSPACK_SYS_OPEN_APPEND (open an existing file for
+   *                 reading/writing from the end of the file)
+   * @return a pointer to a mspack_file structure. This structure officially
+   *         contains no members, its true contents are up to the
+   *         mspack_system implementor. It should contain whatever is needed
+   *         for other mspack_system methods to operate. Returning the NULL
+   *         pointer indicates an error condition.
+   * @see close(), read(), write(), seek(), tell(), message()
+   */
+  struct mspack_file * (*open)(struct mspack_system *self,
+                               const char *filename,
+                               int mode);
+
+  /**
+   * Closes a previously opened file. If any memory was allocated for this
+   * particular file handle, it should be freed at this time.
+   * 
+   * @param file the file to close
+   * @see open()
+   */
+  void (*close)(struct mspack_file *file);
+
+  /**
+   * Reads a given number of bytes from an open file.
+   *
+   * @param file    the file to read from
+   * @param buffer  the location where the read bytes should be stored
+   * @param bytes   the number of bytes to read from the file.
+   * @return the number of bytes successfully read (this can be less than
+   *         the number requested), zero to mark the end of file, or less
+   *         than zero to indicate an error.
+   * @see open(), write()
+   */
+  int (*read)(struct mspack_file *file,
+              void *buffer,
+              int bytes);
+
+  /**
+   * Writes a given number of bytes to an open file.
+   *
+   * @param file    the file to write to
+   * @param buffer  the location where the written bytes should be read from
+   * @param bytes   the number of bytes to write to the file.
+   * @return the number of bytes successfully written, this can be less
+   *         than the number requested. Zero or less can indicate an error
+   *         where no bytes at all could be written. All cases where less
+   *         bytes were written than requested are considered by the library
+   *         to be an error.
+   * @see open(), read()
+   */
+  int (*write)(struct mspack_file *file,
+               void *buffer,
+               int bytes);
+
+  /**
+   * Seeks to a specific file offset within an open file.
+   *
+   * Sometimes the library needs to know the length of a file. It does
+   * this by seeking to the end of the file with seek(file, 0,
+   * MSPACK_SYS_SEEK_END), then calling tell(). Implementations may want
+   * to make a special case for this.
+   *
+   * Due to the potentially varying 32/64 bit datatype off_t on some
+   * architectures, the #MSPACK_SYS_SELFTEST macro MUST be used before
+   * using the library. If not, the error caused by the library passing an
+   * inappropriate stackframe to seek() is subtle and hard to trace.
+   *
+   * @param file   the file to be seeked
+   * @param offset an offset to seek, measured in bytes
+   * @param mode   one of #MSPACK_SYS_SEEK_START (the offset should be
+   *               measured from the start of the file), #MSPACK_SYS_SEEK_CUR
+   *               (the offset should be measured from the current file offset)
+   *               or #MSPACK_SYS_SEEK_END (the offset should be measured from
+   *               the end of the file)
+   * @return zero for success, non-zero for an error
+   * @see open(), tell()
+   */
+  int (*seek)(struct mspack_file *file,
+              off_t offset,
+              int mode);
+
+  /**
+   * Returns the current file position (in bytes) of the given file.
+   *
+   * @param file the file whose file position is wanted
+   * @return the current file position of the file
+   * @see open(), seek()
+   */
+  off_t (*tell)(struct mspack_file *file);
+  
+  /**
+   * Used to send messages from the library to the user.
+   *
+   * Occasionally, the library generates warnings or other messages in
+   * plain english to inform the human user. These are informational only
+   * and can be ignored if not wanted.
+   *
+   * @param file   may be a file handle returned from open() if this message
+   *               pertains to a specific open file, or NULL if not related to
+   *               a specific file.
+   * @param format a printf() style format string. It does NOT include a
+   *               trailing newline.
+   * @see open()
+   */
+  void (*message)(struct mspack_file *file,
+                  const char *format,
+                  ...);
+
+  /**
+   * Allocates memory.
+   *
+   * @param self     a self-referential pointer to the mspack_system
+   *                 structure whose alloc() method is being called.
+   * @param bytes    the number of bytes to allocate
+   * @result a pointer to the requested number of bytes, or NULL if
+   *         not enough memory is available
+   * @see free()
+   */
+  void * (*alloc)(struct mspack_system *self,
+                  size_t bytes);
+  
+  /**
+   * Frees memory.
+   * 
+   * @param ptr the memory to be freed.
+   * @see alloc()
+   */
+  void (*free)(void *ptr);
+
+  /**
+   * Copies from one region of memory to another.
+   * 
+   * The regions of memory are guaranteed not to overlap, are usually less
+   * than 256 bytes, and may not be aligned. Please note that the source
+   * parameter comes before the destination parameter, unlike the standard
+   * C function memcpy().
+   *
+   * @param src   the region of memory to copy from
+   * @param dest  the region of memory to copy to
+   * @param bytes the size of the memory region, in bytes
+   */
+  void (*copy)(void *src,
+               void *dest,
+               size_t bytes);
+
+  /**
+   * A null pointer to mark the end of mspack_system. It must equal NULL.
+   *
+   * Should the mspack_system structure extend in the future, this NULL
+   * will be seen, rather than have an invalid method pointer called.
+   */
+  void *null_ptr;
+};
+
+/** mspack_system::open() mode: open existing file for reading. */
+#define MSPACK_SYS_OPEN_READ   (0)
+/** mspack_system::open() mode: open new file for writing */
+#define MSPACK_SYS_OPEN_WRITE  (1)
+/** mspack_system::open() mode: open existing file for writing */
+#define MSPACK_SYS_OPEN_UPDATE (2)
+/** mspack_system::open() mode: open existing file for writing */
+#define MSPACK_SYS_OPEN_APPEND (3)
+
+/** mspack_system::seek() mode: seek relative to start of file */
+#define MSPACK_SYS_SEEK_START  (0)
+/** mspack_system::seek() mode: seek relative to current offset */
+#define MSPACK_SYS_SEEK_CUR    (1)
+/** mspack_system::seek() mode: seek relative to end of file */
+#define MSPACK_SYS_SEEK_END    (2)
+
+/** 
+ * A structure which represents an open file handle. The contents of this
+ * structure are determined by the implementation of the
+ * mspack_system::open() method.
+ */
+struct mspack_file {
+  int dummy;
+};
+
+/* --- error codes --------------------------------------------------------- */
+
+/** Error code: no error */
+#define MSPACK_ERR_OK          (0)
+/** Error code: bad arguments to method */
+#define MSPACK_ERR_ARGS        (1)
+/** Error code: error opening file */
+#define MSPACK_ERR_OPEN        (2)
+/** Error code: error reading file */
+#define MSPACK_ERR_READ        (3)
+/** Error code: error writing file */
+#define MSPACK_ERR_WRITE       (4)
+/** Error code: seek error */
+#define MSPACK_ERR_SEEK        (5)
+/** Error code: out of memory */
+#define MSPACK_ERR_NOMEMORY    (6)
+/** Error code: bad "magic id" in file */
+#define MSPACK_ERR_SIGNATURE   (7)
+/** Error code: bad or corrupt file format */
+#define MSPACK_ERR_DATAFORMAT  (8)
+/** Error code: bad checksum or CRC */
+#define MSPACK_ERR_CHECKSUM    (9)
+/** Error code: error during compression */
+#define MSPACK_ERR_CRUNCH      (10)
+/** Error code: error during decompression */
+#define MSPACK_ERR_DECRUNCH    (11)
+
+/* --- functions available in library -------------------------------------- */
+
+/** Creates a new CAB compressor.
+ * @param sys a custom mspack_system structure, or NULL to use the default
+ * @return a #mscab_compressor or NULL
+ */
+extern struct mscab_compressor *
+  mspack_create_cab_compressor(struct mspack_system *sys);
+
+/** Creates a new CAB decompressor.
+ * @param sys a custom mspack_system structure, or NULL to use the default
+ * @return a #mscab_decompressor or NULL
+ */
+extern struct mscab_decompressor *
+  mspack_create_cab_decompressor(struct mspack_system *sys);
+
+/** Destroys an existing CAB compressor.
+ * @param self the #mscab_compressor to destroy
+ */
+extern void mspack_destroy_cab_compressor(struct mscab_compressor *self);
+
+/** Destroys an existing CAB decompressor.
+ * @param self the #mscab_decompressor to destroy
+ */
+extern void mspack_destroy_cab_decompressor(struct mscab_decompressor *self);
+
+
+/** Creates a new CHM compressor.
+ * @param sys a custom mspack_system structure, or NULL to use the default
+ * @return a #mschm_compressor or NULL
+ */
+extern struct mschm_compressor *
+  mspack_create_chm_compressor(struct mspack_system *sys);
+
+/** Creates a new CHM decompressor.
+ * @param sys a custom mspack_system structure, or NULL to use the default
+ * @return a #mschm_decompressor or NULL
+ */
+extern struct mschm_decompressor *
+  mspack_create_chm_decompressor(struct mspack_system *sys);
+
+/** Destroys an existing CHM compressor.
+ * @param self the #mschm_compressor to destroy
+ */
+extern void mspack_destroy_chm_compressor(struct mschm_compressor *self);
+
+/** Destroys an existing CHM decompressor.
+ * @param self the #mschm_decompressor to destroy
+ */
+extern void mspack_destroy_chm_decompressor(struct mschm_decompressor *self);
+
+
+/** Creates a new LIT compressor.
+ * @param sys a custom mspack_system structure, or NULL to use the default
+ * @return a #mslit_compressor or NULL
+ */
+extern struct mslit_compressor *
+  mspack_create_lit_compressor(struct mspack_system *sys);
+
+/** Creates a new LIT decompressor.
+ * @param sys a custom mspack_system structure, or NULL to use the default
+ * @return a #mslit_decompressor or NULL
+ */
+extern struct mslit_decompressor *
+  mspack_create_lit_decompressor(struct mspack_system *sys);
+
+/** Destroys an existing LIT compressor.
+ * @param self the #mslit_compressor to destroy
+ */
+extern void mspack_destroy_lit_compressor(struct mslit_compressor *self);
+
+/** Destroys an existing LIT decompressor.
+ * @param self the #mslit_decompressor to destroy
+ */
+extern void mspack_destroy_lit_decompressor(struct mslit_decompressor *self);
+
+
+/** Creates a new HLP compressor.
+ * @param sys a custom mspack_system structure, or NULL to use the default
+ * @return a #mshlp_compressor or NULL
+ */
+extern struct mshlp_compressor *
+  mspack_create_hlp_compressor(struct mspack_system *sys);
+
+/** Creates a new HLP decompressor.
+ * @param sys a custom mspack_system structure, or NULL to use the default
+ * @return a #mshlp_decompressor or NULL
+ */
+extern struct mshlp_decompressor *
+  mspack_create_hlp_decompressor(struct mspack_system *sys);
+
+/** Destroys an existing hlp compressor.
+ * @param self the #mshlp_compressor to destroy
+ */
+extern void mspack_destroy_hlp_compressor(struct mshlp_compressor *self);
+
+/** Destroys an existing hlp decompressor.
+ * @param self the #mshlp_decompressor to destroy
+ */
+extern void mspack_destroy_hlp_decompressor(struct mshlp_decompressor *self);
+
+
+/** Creates a new SZDD compressor.
+ * @param sys a custom mspack_system structure, or NULL to use the default
+ * @return a #msszdd_compressor or NULL
+ */
+extern struct msszdd_compressor *
+  mspack_create_szdd_compressor(struct mspack_system *sys);
+
+/** Creates a new SZDD decompressor.
+ * @param sys a custom mspack_system structure, or NULL to use the default
+ * @return a #msszdd_decompressor or NULL
+ */
+extern struct msszdd_decompressor *
+  mspack_create_szdd_decompressor(struct mspack_system *sys);
+
+/** Destroys an existing SZDD compressor.
+ * @param self the #msszdd_compressor to destroy
+ */
+extern void mspack_destroy_szdd_compressor(struct msszdd_compressor *self);
+
+/** Destroys an existing SZDD decompressor.
+ * @param self the #msszdd_decompressor to destroy
+ */
+extern void mspack_destroy_szdd_decompressor(struct msszdd_decompressor *self);
+
+
+/** Creates a new KWAJ compressor.
+ * @param sys a custom mspack_system structure, or NULL to use the default
+ * @return a #mskwaj_compressor or NULL
+ */
+extern struct mskwaj_compressor *
+  mspack_create_kwaj_compressor(struct mspack_system *sys);
+
+/** Creates a new KWAJ decompressor.
+ * @param sys a custom mspack_system structure, or NULL to use the default
+ * @return a #mskwaj_decompressor or NULL
+ */
+extern struct mskwaj_decompressor *
+  mspack_create_kwaj_decompressor(struct mspack_system *sys);
+
+/** Destroys an existing KWAJ compressor.
+ * @param self the #mskwaj_compressor to destroy
+ */
+extern void mspack_destroy_kwaj_compressor(struct mskwaj_compressor *self);
+
+/** Destroys an existing KWAJ decompressor.
+ * @param self the #mskwaj_decompressor to destroy
+ */
+extern void mspack_destroy_kwaj_decompressor(struct mskwaj_decompressor *self);
+
+
+/* --- support for .CAB (MS Cabinet) file format --------------------------- */
+
+/**
+ * A structure which represents a single cabinet file.
+ *
+ * All fields are READ ONLY.
+ *
+ * If this cabinet is part of a merged cabinet set, the #files and #folders
+ * fields are common to all cabinets in the set, and will be identical.
+ *
+ * @see mscab_decompressor::open(), mscab_decompressor::close(),
+ *      mscab_decompressor::search()
+ */
+struct mscabd_cabinet {
+  /**
+   * The next cabinet in a chained list, if this cabinet was opened with
+   * mscab_decompressor::search(). May be NULL to mark the end of the
+   * list.
+   */
+  struct mscabd_cabinet *next;
+
+  /**
+   * The filename of the cabinet. More correctly, the filename of the
+   * physical file that the cabinet resides in. This is given by the
+   * library user and may be in any format.
+   */
+  const char *filename;
+  
+  /** The file offset of cabinet within the physical file it resides in. */
+  off_t base_offset;
+
+  /** The length of the cabinet file in bytes. */
+  unsigned int length;
+
+  /** The previous cabinet in a cabinet set, or NULL. */
+  struct mscabd_cabinet *prevcab;
+
+  /** The next cabinet in a cabinet set, or NULL. */
+  struct mscabd_cabinet *nextcab;
+
+  /** The filename of the previous cabinet in a cabinet set, or NULL. */
+  char *prevname;
+
+  /** The filename of the next cabinet in a cabinet set, or NULL. */
+  char *nextname;
+
+  /** The name of the disk containing the previous cabinet in a cabinet
+   * set, or NULL.
+   */
+  char *previnfo;
+
+  /** The name of the disk containing the next cabinet in a cabinet set,
+   * or NULL.
+   */
+  char *nextinfo;
+
+  /** A list of all files in the cabinet or cabinet set. */
+  struct mscabd_file *files;
+
+  /** A list of all folders in the cabinet or cabinet set. */
+  struct mscabd_folder *folders;
+
+  /** 
+   * The set ID of the cabinet. All cabinets in the same set should have
+   * the same set ID.
+   */
+  unsigned short set_id;
+
+  /**
+   * The index number of the cabinet within the set. Numbering should
+   * start from 0 for the first cabinet in the set, and increment by 1 for
+   * each following cabinet.
+   */
+  unsigned short set_index;
+
+  /**
+   * The number of bytes reserved in the header area of the cabinet.
+   *
+   * If this is non-zero and flags has MSCAB_HDR_RESV set, this data can
+   * be read by the calling application. It is of the given length,
+   * located at offset (base_offset + MSCAB_HDR_RESV_OFFSET) in the
+   * cabinet file.
+   *
+   * @see flags
+   */
+  unsigned short header_resv;
+
+  /**
+   * Header flags.
+   *
+   * - MSCAB_HDR_PREVCAB indicates the cabinet is part of a cabinet set, and
+   *                     has a predecessor cabinet.
+   * - MSCAB_HDR_NEXTCAB indicates the cabinet is part of a cabinet set, and
+   *                     has a successor cabinet.
+   * - MSCAB_HDR_RESV indicates the cabinet has reserved header space.
+   *
+   * @see prevname, previnfo, nextname, nextinfo, header_resv
+   */
+  int flags;
+};
+
+/** Offset from start of cabinet to the reserved header data (if present). */
+#define MSCAB_HDR_RESV_OFFSET (0x28)
+
+/** Cabinet header flag: cabinet has a predecessor */
+#define MSCAB_HDR_PREVCAB (0x01)
+/** Cabinet header flag: cabinet has a successor */
+#define MSCAB_HDR_NEXTCAB (0x02)
+/** Cabinet header flag: cabinet has reserved header space */
+#define MSCAB_HDR_RESV    (0x04)
+
+/**
+ * A structure which represents a single folder in a cabinet or cabinet set.
+ *
+ * All fields are READ ONLY.
+ *
+ * A folder is a single compressed stream of data. When uncompressed, it
+ * holds the data of one or more files. A folder may be split across more
+ * than one cabinet.
+ */
+struct mscabd_folder {
+  /**
+   * A pointer to the next folder in this cabinet or cabinet set, or NULL
+   * if this is the final folder.
+   */
+  struct mscabd_folder *next;
+
+  /** 
+   * The compression format used by this folder.
+   *
+   * The macro MSCABD_COMP_METHOD() should be used on this field to get
+   * the algorithm used. The macro MSCABD_COMP_LEVEL() should be used to get
+   * the "compression level".
+   *
+   * @see MSCABD_COMP_METHOD(), MSCABD_COMP_LEVEL()
+   */
+  int comp_type;
+
+  /**
+   * The total number of data blocks used by this folder. This includes
+   * data blocks present in other files, if this folder spans more than
+   * one cabinet.
+   */
+  unsigned int num_blocks;
+};
+
+/**
+ * Returns the compression method used by a folder.
+ *
+ * @param comp_type a mscabd_folder::comp_type value
+ * @return one of #MSCAB_COMP_NONE, #MSCAB_COMP_MSZIP, #MSCAB_COMP_QUANTUM
+ *         or #MSCAB_COMP_LZX
+ */
+#define MSCABD_COMP_METHOD(comp_type) ((comp_type) & 0x0F)
+/**
+ * Returns the compression level used by a folder.
+ *
+ * @param comp_type a mscabd_folder::comp_type value
+ * @return the compression level. This is only defined by LZX and Quantum
+ *         compression
+ */
+#define MSCABD_COMP_LEVEL(comp_type) (((comp_type) >> 8) & 0x1F)
+
+/** Compression mode: no compression. */
+#define MSCAB_COMP_NONE       (0)
+/** Compression mode: MSZIP (deflate) compression. */
+#define MSCAB_COMP_MSZIP      (1)
+/** Compression mode: Quantum compression */
+#define MSCAB_COMP_QUANTUM    (2)
+/** Compression mode: LZX compression */
+#define MSCAB_COMP_LZX        (3)
+
+/**
+ * A structure which represents a single file in a cabinet or cabinet set.
+ *
+ * All fields are READ ONLY.
+ */
+struct mscabd_file {
+  /**
+   * The next file in the cabinet or cabinet set, or NULL if this is the
+   * final file.
+   */
+  struct mscabd_file *next;
+
+  /**
+   * The filename of the file.
+   *
+   * A null terminated string of up to 255 bytes in length, it may be in
+   * either ISO-8859-1 or UTF8 format, depending on the file attributes.
+   *
+   * @see attribs
+   */
+  char *filename;
+
+  /** The uncompressed length of the file, in bytes. */
+  unsigned int length;
+
+  /**
+   * File attributes.
+   *
+   * The following attributes are defined:
+   * - #MSCAB_ATTRIB_RDONLY indicates the file is write protected.
+   * - #MSCAB_ATTRIB_HIDDEN indicates the file is hidden.
+   * - #MSCAB_ATTRIB_SYSTEM indicates the file is a operating system file.
+   * - #MSCAB_ATTRIB_ARCH indicates the file is "archived".
+   * - #MSCAB_ATTRIB_EXEC indicates the file is an executable program.
+   * - #MSCAB_ATTRIB_UTF_NAME indicates the filename is in UTF8 format rather
+   *   than ISO-8859-1.
+   */
+  int attribs;
+
+  /** File's last modified time, hour field. */
+  char time_h;
+  /** File's last modified time, minute field. */
+  char time_m;
+  /** File's last modified time, second field. */
+  char time_s;
+
+  /** File's last modified date, day field. */
+  char date_d;
+  /** File's last modified date, month field. */
+  char date_m;
+  /** File's last modified date, year field. */
+  int date_y;
+
+  /** A pointer to the folder that contains this file. */
+  struct mscabd_folder *folder;
+
+  /** The uncompressed offset of this file in its folder. */
+  unsigned int offset;
+};
+
+/** mscabd_file::attribs attribute: file is read-only. */
+#define MSCAB_ATTRIB_RDONLY   (0x01)
+/** mscabd_file::attribs attribute: file is hidden. */
+#define MSCAB_ATTRIB_HIDDEN   (0x02)
+/** mscabd_file::attribs attribute: file is an operating system file. */
+#define MSCAB_ATTRIB_SYSTEM   (0x04)
+/** mscabd_file::attribs attribute: file is "archived". */
+#define MSCAB_ATTRIB_ARCH     (0x20)
+/** mscabd_file::attribs attribute: file is an executable program. */
+#define MSCAB_ATTRIB_EXEC     (0x40)
+/** mscabd_file::attribs attribute: filename is UTF8, not ISO-8859-1. */
+#define MSCAB_ATTRIB_UTF_NAME (0x80)
+
+/** mscab_decompressor::set_param() parameter: search buffer size. */
+#define MSCABD_PARAM_SEARCHBUF (0)
+/** mscab_decompressor::set_param() parameter: repair MS-ZIP streams? */
+#define MSCABD_PARAM_FIXMSZIP  (1)
+/** mscab_decompressor::set_param() parameter: size of decompression buffer */
+#define MSCABD_PARAM_DECOMPBUF (2)
+
+/** TODO */
+struct mscab_compressor {
+  int dummy; 
+};
+
+/**
+ * A decompressor for .CAB (Microsoft Cabinet) files
+ *
+ * All fields are READ ONLY.
+ *
+ * @see mspack_create_cab_decompressor(), mspack_destroy_cab_decompressor()
+ */
+struct mscab_decompressor {
+  /**
+   * Opens a cabinet file and reads its contents.
+   *
+   * If the file opened is a valid cabinet file, all headers will be read
+   * and a mscabd_cabinet structure will be returned, with a full list of
+   * folders and files.
+   *
+   * In the case of an error occuring, NULL is returned and the error code
+   * is available from last_error().
+   *
+   * The filename pointer should be considered "in use" until close() is
+   * called on the cabinet.
+   *
+   * @param  self     a self-referential pointer to the mscab_decompressor
+   *                  instance being called
+   * @param  filename the filename of the cabinet file. This is passed
+   *                  directly to mspack_system::open().
+   * @return a pointer to a mscabd_cabinet structure, or NULL on failure
+   * @see close(), search(), last_error()
+   */
+  struct mscabd_cabinet * (*open) (struct mscab_decompressor *self,
+                                   const char *filename);
+
+  /**
+   * Closes a previously opened cabinet or cabinet set.
+   *
+   * This closes a cabinet, all cabinets associated with it via the
+   * mscabd_cabinet::next, mscabd_cabinet::prevcab and
+   * mscabd_cabinet::nextcab pointers, and all folders and files. All
+   * memory used by these entities is freed.
+   *
+   * The cabinet pointer is now invalid and cannot be used again. All
+   * mscabd_folder and mscabd_file pointers from that cabinet or cabinet
+   * set are also now invalid, and cannot be used again.
+   *
+   * If the cabinet pointer given was created using search(), it MUST be
+   * the cabinet pointer returned by search() and not one of the later
+   * cabinet pointers further along the mscabd_cabinet::next chain.
+
+   * If extra cabinets have been added using append() or prepend(), these
+   * will all be freed, even if the cabinet pointer given is not the first
+   * cabinet in the set. Do NOT close() more than one cabinet in the set.
+   *
+   * The mscabd_cabinet::filename is not freed by the library, as it is
+   * not allocated by the library. The caller should free this itself if
+   * necessary, before it is lost forever.
+   *
+   * @param  self     a self-referential pointer to the mscab_decompressor
+   *                  instance being called
+   * @param  cab      the cabinet to close
+   * @see open(), search(), append(), prepend()
+   */
+  void (*close)(struct mscab_decompressor *self,
+                struct mscabd_cabinet *cab);
+
+  /**
+   * Searches a regular file for embedded cabinets.
+   *
+   * This opens a normal file with the given filename and will search the
+   * entire file for embedded cabinet files
+   *
+   * If any cabinets are found, the equivalent of open() is called on each
+   * potential cabinet file at the offset it was found. All successfully
+   * open()ed cabinets are kept in a list.
+   *
+   * The first cabinet found will be returned directly as the result of
+   * this method. Any further cabinets found will be chained in a list
+   * using the mscabd_cabinet::next field.
+   *
+   * In the case of an error occuring anywhere other than the simulated
+   * open(), NULL is returned and the error code is available from
+   * last_error().
+   *
+   * If no error occurs, but no cabinets can be found in the file, NULL is
+   * returned and last_error() returns MSPACK_ERR_OK.
+   *
+   * The filename pointer should be considered in use until close() is
+   * called on the cabinet.
+   *
+   * close() should only be called on the result of search(), not on any
+   * subsequent cabinets in the mscabd_cabinet::next chain.
+   *
+   * @param  self     a self-referential pointer to the mscab_decompressor
+   *                  instance being called
+   * @param  filename the filename of the file to search for cabinets. This
+   *                  is passed directly to mspack_system::open().
+   * @return a pointer to a mscabd_cabinet structure, or NULL
+   * @see close(), open(), last_error()
+   */
+  struct mscabd_cabinet * (*search) (struct mscab_decompressor *self,
+                                     const char *filename);
+
+  /**
+   * Appends one mscabd_cabinet to another, forming or extending a cabinet
+   * set.
+   *
+   * This will attempt to append one cabinet to another such that
+   * <tt>(cab->nextcab == nextcab) && (nextcab->prevcab == cab)</tt> and
+   * any folders split between the two cabinets are merged.
+   *
+   * The cabinets MUST be part of a cabinet set -- a cabinet set is a
+   * cabinet that spans more than one physical cabinet file on disk -- and
+   * must be appropriately matched.
+   *
+   * It can be determined if a cabinet has further parts to load by
+   * examining the mscabd_cabinet::flags field:
+   *
+   * - if <tt>(flags & MSCAB_HDR_PREVCAB)</tt> is non-zero, there is a
+   *   predecessor cabinet to open() and prepend(). Its MS-DOS
+   *   case-insensitive filename is mscabd_cabinet::prevname
+   * - if <tt>(flags & MSCAB_HDR_NEXTCAB)</tt> is non-zero, there is a
+   *   successor cabinet to open() and append(). Its MS-DOS case-insensitive
+   *   filename is mscabd_cabinet::nextname
+   *
+   * If the cabinets do not match, an error code will be returned. Neither
+   * cabinet has been altered, and both should be closed seperately.
+   *
+   * Files and folders in a cabinet set are a single entity. All cabinets
+   * in a set use the same file list, which is updated as cabinets in the
+   * set are added. All pointers to mscabd_folder and mscabd_file
+   * structures in either cabinet must be discarded and re-obtained after
+   * merging.
+   *
+   * @param  self     a self-referential pointer to the mscab_decompressor
+   *                  instance being called
+   * @param  cab      the cabinet which will be appended to,
+   *                  predecessor of nextcab
+   * @param  nextcab  the cabinet which will be appended,
+   *                  successor of cab
+   * @return an error code, or MSPACK_ERR_OK if successful
+   * @see prepend(), open(), close()
+   */
+  int (*append) (struct mscab_decompressor *self,
+                 struct mscabd_cabinet *cab,
+                 struct mscabd_cabinet *nextcab);
+
+  /**
+   * Prepends one mscabd_cabinet to another, forming or extending a
+   * cabinet set.
+   *
+   * This will attempt to prepend one cabinet to another, such that
+   * <tt>(cab->prevcab == prevcab) && (prevcab->nextcab == cab)</tt>. In
+   * all other respects, it is identical to append(). See append() for the
+   * full documentation.
+   *
+   * @param  self     a self-referential pointer to the mscab_decompressor
+   *                  instance being called
+   * @param  cab      the cabinet which will be prepended to,
+   *                  successor of prevcab
+   * @param  prevcab  the cabinet which will be prepended,
+   *                  predecessor of cab
+   * @return an error code, or MSPACK_ERR_OK if successful
+   * @see append(), open(), close()
+   */
+  int (*prepend) (struct mscab_decompressor *self,
+                  struct mscabd_cabinet *cab,
+                  struct mscabd_cabinet *prevcab);
+
+  /**
+   * Extracts a file from a cabinet or cabinet set.
+   *
+   * This extracts a compressed file in a cabinet and writes it to the given
+   * filename.
+   *
+   * The MS-DOS filename of the file, mscabd_file::filename, is NOT USED
+   * by extract(). The caller must examine this MS-DOS filename, copy and
+   * change it as necessary, create directories as necessary, and provide
+   * the correct filename as a parameter, which will be passed unchanged
+   * to the decompressor's mspack_system::open()
+   *
+   * If the file belongs to a split folder in a multi-part cabinet set,
+   * and not enough parts of the cabinet set have been loaded and appended
+   * or prepended, an error will be returned immediately.
+   *
+   * @param  self     a self-referential pointer to the mscab_decompressor
+   *                  instance being called
+   * @param  file     the file to be decompressed
+   * @param  filename the filename of the file being written to
+   * @return an error code, or MSPACK_ERR_OK if successful
+   */
+  int (*extract)(struct mscab_decompressor *self,
+                 struct mscabd_file *file,
+                 const char *filename);
+
+  /**
+   * Sets a CAB decompression engine parameter.
+   *
+   * The following parameters are defined:
+   * - #MSCABD_PARAM_SEARCHBUF: How many bytes should be allocated as a
+   *   buffer when using search()? The minimum value is 4.  The default
+   *   value is 32768.
+   * - #MSCABD_PARAM_FIXMSZIP: If non-zero, extract() will ignore bad
+   *   checksums and recover from decompression errors in MS-ZIP
+   *   compressed folders. The default value is 0 (don't recover).
+   * - #MSCABD_PARAM_DECOMPBUF: How many bytes should be used as an input
+   *   bit buffer by decompressors? The minimum value is 4. The default
+   *   value is 4096.
+   *
+   * @param  self     a self-referential pointer to the mscab_decompressor
+   *                  instance being called
+   * @param  param    the parameter to set
+   * @param  value    the value to set the parameter to
+   * @return MSPACK_ERR_OK if all is OK, or MSPACK_ERR_ARGS if there
+   *         is a problem with either parameter or value.
+   * @see search(), extract()
+   */
+  int (*set_param)(struct mscab_decompressor *self,
+                   int param,
+                   int value);
+
+  /**
+   * Returns the error code set by the most recently called method.
+   *
+   * This is useful for open() and search(), which do not return an error
+   * code directly.
+   *
+   * @param  self     a self-referential pointer to the mscab_decompressor
+   *                  instance being called
+   * @return the most recent error code
+   * @see open(), search()
+   */
+  int (*last_error)(struct mscab_decompressor *self);
+};
+
+/* --- support for .CHM (HTMLHelp) file format ----------------------------- */
+
+/**
+ * A structure which represents a file to be placed in a CHM helpfile.
+ *
+ * A contiguous array of these structures should be passed to
+ * mschm_compressor::generate(). The array list is terminated with an
+ * entry whose mschmc_file::section field is set to #MSCHMC_ENDLIST, the
+ * other fields in this entry are ignored.
+ */
+struct mschmc_file {
+  /** One of #MSCHMC_ENDLIST, #MSCHMC_UNCOMP or #MSCHMC_MSCOMP. */
+  int section;
+
+  /** The filename of the source file that will be added to the CHM. This
+   * is passed directly to mspack_system::open(). */
+  const char *filename;
+
+  /** The full path and filename of the file within the CHM helpfile, a
+   * UTF-1 encoded null-terminated string. */
+  char *chm_filename;
+
+  /** The length of the file, in bytes. This will be adhered to strictly
+   * and a read error will be issued if this many bytes cannot be read
+   * from the real file at CHM generation time. */
+  off_t length;
+};
+
+/**
+ * A structure which represents a section of a CHM helpfile.
+ *
+ * All fields are READ ONLY.
+ *
+ * Not used directly, but used as a generic base type for
+ * mschmd_sec_uncompressed and mschmd_sec_mscompressed.
+ */
+struct mschmd_section {
+  /** A pointer to the CHM helpfile that contains this section. */
+  struct mschmd_header *chm;
+
+  /**
+   * The section ID. Either 0 for the uncompressed section
+   * mschmd_sec_uncompressed, or 1 for the LZX compressed section
+   * mschmd_sec_mscompressed. No other section IDs are known.
+   */
+  unsigned int id;
+};
+
+/**
+ * A structure which represents the uncompressed section of a CHM helpfile.
+ * 
+ * All fields are READ ONLY.
+ */
+struct mschmd_sec_uncompressed {
+  /** Generic section data. */
+  struct mschmd_section base;
+
+  /** The file offset of where this section begins in the CHM helpfile. */
+  off_t offset;
+};
+
+/**
+ * A structure which represents the LZX compressed section of a CHM helpfile. 
+ * 
+ * All fields are READ ONLY.
+ */
+struct mschmd_sec_mscompressed {
+  /** Generic section data. */
+  struct mschmd_section base;
+
+  /** A pointer to the meta-file which represents all LZX compressed data. */
+  struct mschmd_file *content;
+
+  /** A pointer to the file which contains the LZX control data. */
+  struct mschmd_file *control;
+
+  /** A pointer to the file which contains the LZX reset table. */
+  struct mschmd_file *rtable;
+
+  /** A pointer to the file which contains the LZX span information.
+   * Available only in CHM decoder version 2 and above.
+   */
+  struct mschmd_file *spaninfo;
+};
+
+/**
+ * A structure which represents a CHM helpfile.
+ * 
+ * All fields are READ ONLY.
+ */
+struct mschmd_header {
+  /** The version of the CHM file format used in this file. */
+  unsigned int version;
+
+  /**
+   * The "timestamp" of the CHM helpfile. 
+   *
+   * It is the lower 32 bits of a 64-bit value representing the number of
+   * centiseconds since 1601-01-01 00:00:00 UTC, plus 42. It is not useful
+   * as a timestamp, but it is useful as a semi-unique ID.
+   */
+  unsigned int timestamp;
+      
+  /**
+   * The default Language and Country ID (LCID) of the user who ran the
+   * HTMLHelp Compiler. This is not the language of the CHM file itself.
+   */
+  unsigned int language;
+
+  /**
+   * The filename of the CHM helpfile. This is given by the library user
+   * and may be in any format.
+   */
+  const char *filename;
+
+  /** The length of the CHM helpfile, in bytes. */
+  off_t length;
+
+  /** A list of all non-system files in the CHM helpfile. */
+  struct mschmd_file *files;
+
+  /**
+   * A list of all system files in the CHM helpfile.
+   *
+   * System files are files which begin with "::". They are meta-files
+   * generated by the CHM creation process.
+   */
+  struct mschmd_file *sysfiles;
+
+  /** The section 0 (uncompressed) data in this CHM helpfile. */
+  struct mschmd_sec_uncompressed sec0;
+
+  /** The section 1 (MSCompressed) data in this CHM helpfile. */
+  struct mschmd_sec_mscompressed sec1;
+
+  /** The file offset of the first PMGL/PMGI directory chunk. */
+  off_t dir_offset;
+
+  /** The number of PMGL/PMGI directory chunks in this CHM helpfile. */
+  unsigned int num_chunks;
+
+  /** The size of each PMGL/PMGI chunk, in bytes. */
+  unsigned int chunk_size;
+
+  /** The "density" of the quick-reference section in PMGL/PMGI chunks. */
+  unsigned int density;
+
+  /** The depth of the index tree.
+   *
+   * - if 1, there are no PMGI chunks, only PMGL chunks.
+   * - if 2, there is 1 PMGI chunk. All chunk indices point to PMGL chunks.
+   * - if 3, the root PMGI chunk points to secondary PMGI chunks, which in
+   *         turn point to PMGL chunks.
+   * - and so on...
+   */
+  unsigned int depth;
+
+  /**
+   * The number of the root PMGI chunk.
+   *
+   * If there is no index in the CHM helpfile, this will be 0xFFFFFFFF.
+   */
+  unsigned int index_root;
+
+  /**
+   * The number of the first PMGL chunk. Usually zero.
+   * Available only in CHM decoder version 2 and above.
+   */
+  unsigned int first_pmgl;
+
+  /**
+   * The number of the last PMGL chunk. Usually num_chunks-1.
+   * Available only in CHM decoder version 2 and above.
+   */
+  unsigned int last_pmgl;
+
+  /**
+   * A cache of loaded chunks, filled in by mschm_decoder::fast_find().
+   * Available only in CHM decoder version 2 and above.
+   */
+  unsigned char **chunk_cache;
+};
+
+/**
+ * A structure which represents a file stored in a CHM helpfile.
+ * 
+ * All fields are READ ONLY.
+ */
+struct mschmd_file {
+  /**
+   * A pointer to the next file in the list, or NULL if this is the final
+   * file.
+   */
+  struct mschmd_file *next;
+
+  /**
+   * A pointer to the section that this file is located in. Indirectly,
+   * it also points to the CHM helpfile the file is located in.
+   */
+  struct mschmd_section *section;
+
+  /** The offset within the section data that this file is located at. */
+  off_t offset;
+
+  /** The length of this file, in bytes */
+  off_t length;
+
+  /** The filename of this file -- a null terminated string in UTF-8. */
+  char *filename;
+};
+
+/** mschmc_file::section value: end of CHM file list */
+#define MSCHMC_ENDLIST   (0)
+/** mschmc_file::section value: this file is in the Uncompressed section */
+#define MSCHMC_UNCOMP    (1)
+/** mschmc_file::section value: this file is in the MSCompressed section */
+#define MSCHMC_MSCOMP    (2)
+ 
+/** mschm_compressor::set_param() parameter: "timestamp" header */
+#define MSCHMC_PARAM_TIMESTAMP  (0)
+/** mschm_compressor::set_param() parameter: "language" header */
+#define MSCHMC_PARAM_LANGUAGE   (1)
+/** mschm_compressor::set_param() parameter: LZX window size */
+#define MSCHMC_PARAM_LZXWINDOW  (2)
+/** mschm_compressor::set_param() parameter: intra-chunk quickref density */
+#define MSCHMC_PARAM_DENSITY    (3)
+/** mschm_compressor::set_param() parameter: whether to create indices */
+#define MSCHMC_PARAM_INDEX      (4)
+
+/**
+ * A compressor for .CHM (Microsoft HTMLHelp) files.
+ *
+ * All fields are READ ONLY.
+ *
+ * @see mspack_create_chm_compressor(), mspack_destroy_chm_compressor()
+ */
+struct mschm_compressor {
+  /**
+   * Generates a CHM help file.
+   *
+   * The help file will contain up to two sections, an Uncompressed
+   * section and potentially an MSCompressed (LZX compressed)
+   * section.
+   *
+   * While the contents listing of a CHM file is always in lexical order,
+   * the file list passed in will be taken as the correct order for files
+   * within the sections.  It is in your interest to place similar files
+   * together for better compression.
+   *
+   * There are two modes of generation, to use a temporary file or not to
+   * use one. See use_temporary_file() for the behaviour of generate() in
+   * these two different modes.
+   *
+   * @param  self        a self-referential pointer to the mschm_compressor
+   *                     instance being called
+   * @param  file_list   an array of mschmc_file structures, terminated
+   *                     with an entry whose mschmc_file::section field is
+   *                     #MSCHMC_ENDLIST. The order of the list is
+   *                     preserved within each section. The length of any
+   *                     mschmc_file::chm_filename string cannot exceed
+   *                     roughly 4096 bytes. Each source file must be able
+   *                     to supply as many bytes as given in the
+   *                     mschmc_file::length field.
+   * @param  output_file the file to write the generated CHM helpfile to.
+   *                     This is passed directly to mspack_system::open()
+   * @return an error code, or MSPACK_ERR_OK if successful
+   * @see use_temporary_file() set_param()
+   */
+  int (*generate)(struct mschm_compressor *self,
+                  struct mschmc_file file_list[],
+                  const char *output_file);
+
+  /**
+   * Specifies whether a temporary file is used during CHM generation.
+   *
+   * The CHM file format includes data about the compressed section (such
+   * as its overall size) that is stored in the output CHM file prior to
+   * the compressed section itself. This unavoidably requires that the
+   * compressed section has to be generated, before these details can be
+   * set. There are several ways this can be handled. Firstly, the
+   * compressed section could be generated entirely in memory before
+   * writing any of the output CHM file. This approach is not used in
+   * libmspack, as the compressed section can exceed the addressable
+   * memory space on most architectures.
+   *
+   * libmspack has two options, either to write these unknowable sections
+   * with blank data, generate the compressed section, then re-open the
+   * output file for update once the compressed section has been
+   * completed, or to write the compressed section to a temporary file,
+   * then write the entire output file at once, performing a simple
+   * file-to-file copy for the compressed section.
+   *
+   * The simple solution of buffering the entire compressed section in
+   * memory can still be used, if desired. As the temporary file's
+   * filename is passed directly to mspack_system::open(), it is possible
+   * for a custom mspack_system implementation to hold this file in memory,
+   * without writing to a disk.
+   *
+   * If a temporary file is set, generate() performs the following
+   * sequence of events: the temporary file is opened for writing, the
+   * compression algorithm writes to the temporary file, the temporary
+   * file is closed.  Then the output file is opened for writing and the
+   * temporary file is re-opened for reading. The output file is written
+   * and the temporary file is read from. Both files are then closed. The
+   * temporary file itself is not deleted. If that is desired, the
+   * temporary file should be deleted after the completion of generate(),
+   * if it exists.
+   *
+   * If a temporary file is set not to be used, generate() performs the
+   * following sequence of events: the output file is opened for writing,
+   * then it is written and closed. The output file is then re-opened for
+   * update, the appropriate sections are seek()ed to and re-written, then
+   * the output file is closed.
+   *
+   * @param  self          a self-referential pointer to the
+   *                       mschm_compressor instance being called
+   * @param  use_temp_file non-zero if the temporary file should be used,
+   *                       zero if the temporary file should not be used.
+   * @param  temp_file     a file to temporarily write compressed data to,
+   *                       before opening it for reading and copying the
+   *                       contents to the output file. This is passed
+   *                       directly to mspack_system::open().
+   * @return an error code, or MSPACK_ERR_OK if successful
+   * @see generate()
+   */
+  int (*use_temporary_file)(struct mschm_compressor *self,
+                            int use_temp_file,
+                            const char *temp_file);
+  /**
+   * Sets a CHM compression engine parameter.
+   *
+   * The following parameters are defined:
+
+   * - #MSCHMC_PARAM_TIMESTAMP: Sets the "timestamp" of the CHM file
+   *   generated. This is not a timestamp, see mschmd_header::timestamp
+   *   for a description. If this timestamp is 0, generate() will use its
+   *   own algorithm for making a unique ID, based on the lengths and
+   *   names of files in the CHM itself. Defaults to 0, any value between
+   *   0 and (2^32)-1 is valid.
+   * - #MSCHMC_PARAM_LANGUAGE: Sets the "language" of the CHM file
+   *   generated.  This is not the language used in the CHM file, but the
+   *   language setting of the user who ran the HTMLHelp compiler. It
+   *   defaults to 0x0409. The valid range is between 0x0000 and 0x7F7F.
+   * - #MSCHMC_PARAM_LZXWINDOW: Sets the size of the LZX history window,
+   *   which is also the interval at which the compressed data stream can be
+   *   randomly accessed. The value is not a size in bytes, but a power of
+   *   two. The default value is 16 (which makes the window 2^16 bytes, or
+   *   64 kilobytes), the valid range is from 15 (32 kilobytes) to 21 (2
+   *   megabytes).
+   * - #MSCHMC_PARAM_DENSITY: Sets the "density" of quick reference
+   *   entries stored at the end of directory listing chunk. Each chunk is
+   *   4096 bytes in size, and contains as many file entries as there is
+   *   room for. At the other end of the chunk, a list of "quick reference"
+   *   pointers is included. The offset of every 'N'th file entry is given a
+   *   quick reference, where N = (2^density) + 1. The default density is
+   *   2. The smallest density is 0 (N=2), the maximum is 10 (N=1025). As
+   *   each file entry requires at least 5 bytes, the maximum number of
+   *   entries in a single chunk is roughly 800, so the maximum value 10
+   *   can be used to indicate there are no quickrefs at all.
+   * - #MSCHMC_PARAM_INDEX: Sets whether or not to include quick lookup
+   *   index chunk(s), in addition to normal directory listing chunks. A
+   *   value of zero means no index chunks will be created, a non-zero value
+   *   means index chunks will be created. The default is zero, "don't
+   *   create an index".
+   *
+   * @param  self     a self-referential pointer to the mschm_compressor
+   *                  instance being called
+   * @param  param    the parameter to set
+   * @param  value    the value to set the parameter to
+   * @return MSPACK_ERR_OK if all is OK, or MSPACK_ERR_ARGS if there
+   *         is a problem with either parameter or value.
+   * @see generate()
+   */
+  int (*set_param)(struct mschm_compressor *self,
+                   int param,
+                   unsigned int value);
+
+  /**
+   * Returns the error code set by the most recently called method.
+   *
+   * @param  self     a self-referential pointer to the mschm_compressor
+   *                  instance being called
+   * @return the most recent error code
+   * @see set_param(), generate()
+   */
+  int (*last_error)(struct mschm_compressor *self);
+};
+
+/**
+ * A decompressor for .CHM (Microsoft HTMLHelp) files
+ *
+ * All fields are READ ONLY.
+ *
+ * @see mspack_create_chm_decompressor(), mspack_destroy_chm_decompressor()
+ */
+struct mschm_decompressor {
+  /**
+   * Opens a CHM helpfile and reads its contents.
+   *
+   * If the file opened is a valid CHM helpfile, all headers will be read
+   * and a mschmd_header structure will be returned, with a full list of
+   * files.
+   *
+   * In the case of an error occuring, NULL is returned and the error code
+   * is available from last_error().
+   *
+   * The filename pointer should be considered "in use" until close() is
+   * called on the CHM helpfile.
+   *
+   * @param  self     a self-referential pointer to the mschm_decompressor
+   *                  instance being called
+   * @param  filename the filename of the CHM helpfile. This is passed
+   *                  directly to mspack_system::open().
+   * @return a pointer to a mschmd_header structure, or NULL on failure
+   * @see close()
+   */
+  struct mschmd_header *(*open)(struct mschm_decompressor *self,
+                                const char *filename);
+
+  /**
+   * Closes a previously opened CHM helpfile.
+   *
+   * This closes a CHM helpfile, frees the mschmd_header and all
+   * mschmd_file structures associated with it (if any). This works on
+   * both helpfiles opened with open() and helpfiles opened with
+   * fast_open().
+   *
+   * The CHM header pointer is now invalid and cannot be used again. All
+   * mschmd_file pointers referencing that CHM are also now invalid, and
+   * cannot be used again.
+   *
+   * @param  self     a self-referential pointer to the mschm_decompressor
+   *                  instance being called
+   * @param  chm      the CHM helpfile to close
+   * @see open(), fast_open()
+   */
+  void (*close)(struct mschm_decompressor *self,
+                struct mschmd_header *chm);
+
+  /**
+   * Extracts a file from a CHM helpfile.
+   *
+   * This extracts a file from a CHM helpfile and writes it to the given
+   * filename. The filename of the file, mscabd_file::filename, is not
+   * used by extract(), but can be used by the caller as a guide for
+   * constructing an appropriate filename.
+   *
+   * This method works both with files found in the mschmd_header::files
+   * and mschmd_header::sysfiles list and mschmd_file structures generated
+   * on the fly by fast_find().
+   *
+   * @param  self     a self-referential pointer to the mschm_decompressor
+   *                  instance being called
+   * @param  file     the file to be decompressed
+   * @param  filename the filename of the file being written to
+   * @return an error code, or MSPACK_ERR_OK if successful
+   */
+  int (*extract)(struct mschm_decompressor *self,
+                 struct mschmd_file *file,
+                 const char *filename);
+
+  /**
+   * Returns the error code set by the most recently called method.
+   *
+   * This is useful for open() and fast_open(), which do not return an
+   * error code directly.
+   *
+   * @param  self     a self-referential pointer to the mschm_decompressor
+   *                  instance being called
+   * @return the most recent error code
+   * @see open(), extract()
+   */
+  int (*last_error)(struct mschm_decompressor *self);
+
+  /**
+   * Opens a CHM helpfile quickly.
+   *
+   * If the file opened is a valid CHM helpfile, only essential headers
+   * will be read. A mschmd_header structure will be still be returned, as
+   * with open(), but the mschmd_header::files field will be NULL. No
+   * files details will be automatically read.  The fast_find() method
+   * must be used to obtain file details.
+   *
+   * In the case of an error occuring, NULL is returned and the error code
+   * is available from last_error().
+   *
+   * The filename pointer should be considered "in use" until close() is
+   * called on the CHM helpfile.
+   *
+   * @param  self     a self-referential pointer to the mschm_decompressor
+   *                  instance being called
+   * @param  filename the filename of the CHM helpfile. This is passed
+   *                  directly to mspack_system::open().
+   * @return a pointer to a mschmd_header structure, or NULL on failure
+   * @see open(), close(), fast_find(), extract()
+   */
+  struct mschmd_header *(*fast_open)(struct mschm_decompressor *self,
+                                     const char *filename);
+
+  /**
+   * Finds file details quickly.
+   *
+   * Instead of reading all CHM helpfile headers and building a list of
+   * files, fast_open() and fast_find() are intended for finding file
+   * details only when they are needed. The CHM file format includes an
+   * on-disk file index to allow this.
+   *
+   * Given a case-sensitive filename, fast_find() will search the on-disk
+   * index for that file.
+   *
+   * If the file was found, the caller-provided mschmd_file structure will
+   * be filled out like so:
+   * - section: the correct value for the found file
+   * - offset: the correct value for the found file
+   * - length: the correct value for the found file
+   * - all other structure elements: NULL or 0
+   *
+   * If the file was not found, MSPACK_ERR_OK will still be returned as the
+   * result, but the caller-provided structure will be filled out like so:
+   * - section: NULL
+   * - offset: 0
+   * - length: 0
+   * - all other structure elements: NULL or 0
+   *
+   * This method is intended to be used in conjunction with CHM helpfiles
+   * opened with fast_open(), but it also works with helpfiles opened
+   * using the regular open().
+   *
+   * @param  self     a self-referential pointer to the mschm_decompressor
+   *                  instance being called
+   * @param  chm      the CHM helpfile to search for the file
+   * @param  filename the filename of the file to search for
+   * @param  f_ptr    a pointer to a caller-provded mschmd_file structure
+   * @param  f_size   <tt>sizeof(struct mschmd_file)</tt>
+   * @return an error code, or MSPACK_ERR_OK if successful
+   * @see open(), close(), fast_find(), extract()
+   */
+  int (*fast_find)(struct mschm_decompressor *self,
+                   struct mschmd_header *chm,
+                   const char *filename,
+                   struct mschmd_file *f_ptr,
+                   int f_size);
+};
+
+/* --- support for .LIT (EBook) file format -------------------------------- */
+
+/** TODO */
+struct mslit_compressor {
+  int dummy; 
+};
+
+/** TODO */
+struct mslit_decompressor {
+  int dummy; 
+};
+
+
+/* --- support for .HLP (MS Help) file format ------------------------------ */
+
+/** TODO */
+struct mshlp_compressor {
+  int dummy; 
+};
+
+/** TODO */
+struct mshlp_decompressor {
+  int dummy; 
+};
+
+
+/* --- support for SZDD file format ---------------------------------------- */
+
+/** msszdd_compressor::set_param() parameter: the missing character */
+#define MSSZDDC_PARAM_MISSINGCHAR (0)
+
+/** msszddd_header::format value - a regular SZDD file */
+#define MSSZDD_FMT_NORMAL (0)
+
+/** msszddd_header::format value - a special QBasic SZDD file */
+#define MSSZDD_FMT_QBASIC (1)
+
+/**
+ * A structure which represents an SZDD compressed file.
+ *
+ * All fields are READ ONLY.
+ */
+struct msszddd_header {
+  /** The file format; either #MSSZDD_FMT_NORMAL or #MSSZDD_FMT_QBASIC */
+  int format;
+
+  /** The amount of data in the SZDD file once uncompressed. */
+  off_t length;
+
+  /**
+   * The last character in the filename, traditionally replaced with an
+   * underscore to show the file is compressed. The null character is used
+   * to show that this character has not been stored (e.g. because the
+   * filename is not known). Generally, only characters that may appear in
+   * an MS-DOS filename (except ".") are valid.
+   */
+  char missing_char;
+};
+
+/**
+ * A compressor for the SZDD file format.
+ *
+ * All fields are READ ONLY.
+ *
+ * @see mspack_create_szdd_compressor(), mspack_destroy_szdd_compressor()
+ */
+struct msszdd_compressor {
+  /**
+   * Reads an input file and creates a compressed output file in the
+   * SZDD compressed file format. The SZDD compression format is quick
+   * but gives poor compression. It is possible for the compressed output
+   * file to be larger than the input file.
+   *
+   * Conventionally, SZDD compressed files have the final character in
+   * their filename replaced with an underscore, to show they are
+   * compressed.  The missing character is stored in the compressed file
+   * itself. This is due to the restricted filename conventions of MS-DOS,
+   * most operating systems, such as UNIX, simply append another file
+   * extension to the existing filename. As mspack does not deal with
+   * filenames, this is left up to you. If you wish to set the missing
+   * character stored in the file header, use set_param() with the
+   * #MSSZDDC_PARAM_MISSINGCHAR parameter.
+   *
+   * "Stream" compression (where the length of the input data is not
+   * known) is not possible. The length of the input data is stored in the
+   * header of the SZDD file and must therefore be known before any data
+   * is compressed. Due to technical limitations of the file format, the
+   * maximum size of uncompressed file that will be accepted is 2147483647
+   * bytes.
+   *
+   * @param  self    a self-referential pointer to the msszdd_compressor
+   *                 instance being called
+   * @param  input   the name of the file to compressed. This is passed
+   *                 passed directly to mspack_system::open()
+   * @param  output  the name of the file to write compressed data to.
+   *                 This is passed directly to mspack_system::open().
+   * @param  length  the length of the uncompressed file, or -1 to indicate
+   *                 that this should be determined automatically by using
+   *                 mspack_system::seek() on the input file.
+   * @return an error code, or MSPACK_ERR_OK if successful
+   * @see set_param()
+   */
+  int (*compress)(struct msszdd_compressor *self,
+                  const char *input,
+                  const char *output,
+                  off_t length);
+
+  /**
+   * Sets an SZDD compression engine parameter.
+   *
+   * The following parameters are defined:
+
+   * - #MSSZDDC_PARAM_CHARACTER: the "missing character", the last character
+   *   in the uncompressed file's filename, which is traditionally replaced
+   *   with an underscore to show the file is compressed. Traditionally,
+   *   this can only be a character that is a valid part of an MS-DOS,
+   *   filename, but libmspack permits any character between 0x00 and 0xFF
+   *   to be stored. 0x00 is the default, and it represents "no character
+   *   stored".
+   *
+   * @param  self     a self-referential pointer to the msszdd_compressor
+   *                  instance being called
+   * @param  param    the parameter to set
+   * @param  value    the value to set the parameter to
+   * @return MSPACK_ERR_OK if all is OK, or MSPACK_ERR_ARGS if there
+   *         is a problem with either parameter or value.
+   * @see compress()
+   */
+  int (*set_param)(struct msszdd_compressor *self,
+                   int param,
+                   unsigned int value);
+
+  /**
+   * Returns the error code set by the most recently called method.
+   *
+   * @param  self     a self-referential pointer to the msszdd_compressor
+   *                  instance being called
+   * @return the most recent error code
+   * @see compress()
+   */
+  int (*last_error)(struct mschm_decompressor *self);
+};
+
+/**
+ * A decompressor for SZDD compressed files.
+ *
+ * All fields are READ ONLY.
+ *
+ * @see mspack_create_szdd_decompressor(), mspack_destroy_szdd_decompressor()
+ */
+struct msszdd_decompressor {
+  /**
+   * Opens a SZDD file and reads the header.
+   *
+   * If the file opened is a valid SZDD file, all headers will be read and
+   * a msszddd_header structure will be returned.
+   *
+   * In the case of an error occuring, NULL is returned and the error code
+   * is available from last_error().
+   *
+   * The filename pointer should be considered "in use" until close() is
+   * called on the SZDD file.
+   *
+   * @param  self     a self-referential pointer to the msszdd_decompressor
+   *                  instance being called
+   * @param  filename the filename of the SZDD compressed file. This is
+   *                  passed directly to mspack_system::open().
+   * @return a pointer to a msszddd_header structure, or NULL on failure
+   * @see close()
+   */
+  struct msszddd_header *(*open)(struct msszdd_decompressor *self,
+                                 const char *filename);
+
+  /**
+   * Closes a previously opened SZDD file.
+   *
+   * This closes a SZDD file and frees the msszddd_header associated with
+   * it.
+   *
+   * The SZDD header pointer is now invalid and cannot be used again.
+   *
+   * @param  self     a self-referential pointer to the msszdd_decompressor
+   *                  instance being called
+   * @param  szdd     the SZDD file to close
+   * @see open()
+   */
+  void (*close)(struct msszdd_decompressor *self,
+                struct msszddd_header *szdd);
+
+  /**
+   * Extracts the compressed data from a SZDD file.
+   *
+   * This decompresses the compressed SZDD data stream and writes it to
+   * an output file.
+   *
+   * @param  self     a self-referential pointer to the msszdd_decompressor
+   *                  instance being called
+   * @param  szdd     the SZDD file to extract data from
+   * @param  filename the filename to write the decompressed data to. This
+   *                  is passed directly to mspack_system::open().
+   * @return an error code, or MSPACK_ERR_OK if successful
+   */
+  int (*extract)(struct msszdd_decompressor *self,
+                 struct msszddd_header *szdd,
+                 const char *filename);
+
+  /**
+   * Decompresses an SZDD file to an output file in one step.
+   *
+   * This opens an SZDD file as input, reads the header, then decompresses
+   * the compressed data immediately to an output file, finally closing
+   * both the input and output file. It is more convenient to use than
+   * open() then extract() then close(), if you do not need to know the
+   * SZDD output size or missing character.
+   *
+   * @param  self     a self-referential pointer to the msszdd_decompressor
+   *                  instance being called
+   * @param  input    the filename of the input SZDD file. This is passed
+   *                  directly to mspack_system::open().
+   * @param  output   the filename to write the decompressed data to. This
+   *                  is passed directly to mspack_system::open().
+   * @return an error code, or MSPACK_ERR_OK if successful
+   */
+  int (*decompress)(struct msszdd_decompressor *self,
+                    const char *input,
+                    const char *output);
+
+  /**
+   * Returns the error code set by the most recently called method.
+   *
+   * This is useful for open() which does not return an
+   * error code directly.
+   *
+   * @param  self     a self-referential pointer to the msszdd_decompressor
+   *                  instance being called
+   * @return the most recent error code
+   * @see open(), extract(), decompress()
+   */
+  int (*last_error)(struct msszdd_decompressor *self);
+};
+
+/* --- support for KWAJ file format ---------------------------------------- */
+
+/** mskwaj_compressor::set_param() parameter: compression type */
+#define MSKWAJC_PARAM_COMP_TYPE  (0)
+
+/** mskwaj_compressor::set_param() parameter: include the length of the
+ * uncompressed file in the header?
+ */
+#define MSKWAJC_PARAM_INCLUDE_LENGTH (1)
+
+/** KWAJ compression type: no compression. */
+#define MSKWAJ_COMP_NONE (0)
+/** KWAJ compression type: no compression, 0xFF XOR "encryption". */
+#define MSKWAJ_COMP_XOR (1)
+/** KWAJ compression type: LZSS (same method as SZDD) */
+#define MSKWAJ_COMP_SZDD (2)
+/** KWAJ compression type: LZ+Huffman compression */
+#define MSKWAJ_COMP_LZH (3)
+
+/** KWAJ optional header flag: decompressed file length is included */
+#define MSKWAJ_HDR_HASLENGTH (0x01)
+
+/** KWAJ optional header flag: unknown 2-byte structure is included */
+#define MSKWAJ_HDR_HASUNKNOWN1 (0x02)
+
+/** KWAJ optional header flag: unknown multi-sized structure is included */
+#define MSKWAJ_HDR_HASUNKNOWN2 (0x04)
+
+/** KWAJ optional header flag: file name (no extension) is included */
+#define MSKWAJ_HDR_HASFILENAME (0x08)
+
+/** KWAJ optional header flag: file extension is included */
+#define MSKWAJ_HDR_HASFILEEXT (0x10)
+
+/** KWAJ optional header flag: extra text is included */
+#define MSKWAJ_HDR_HASEXTRATEXT (0x20)
+
+/**
+ * A structure which represents an KWAJ compressed file.
+ *
+ * All fields are READ ONLY.
+ */
+struct mskwajd_header {
+  /** The compression type; should be one of #MSKWAJ_COMP_NONE,
+   * #MSKWAJ_COMP_XOR, #MSKWAJ_COMP_SZDD or #MSKWAJ_COMP_LZH
+   */
+  unsigned short comp_type;
+
+  /** The offset in the file where the compressed data stream begins */
+  off_t data_offset;
+
+  /** Flags indicating which optional headers were included. */
+  int headers;
+
+  /** The amount of uncompressed data in the file, or 0 if not present. */
+  off_t length;
+
+  /** output filename, or NULL if not present */
+  char *filename;
+
+  /** extra uncompressed data (usually text) in the header.
+   * This data can contain nulls so use extra_length to get the size.
+   */
+  char *extra;
+
+  /** length of extra uncompressed data in the header */
+  unsigned short extra_length;
+};
+
+/**
+ * A compressor for the KWAJ file format.
+ *
+ * All fields are READ ONLY.
+ *
+ * @see mspack_create_kwaj_compressor(), mspack_destroy_kwaj_compressor()
+ */
+struct mskwaj_compressor {
+  /**
+   * Reads an input file and creates a compressed output file in the
+   * KWAJ compressed file format. The KWAJ compression format is quick
+   * but gives poor compression. It is possible for the compressed output
+   * file to be larger than the input file.
+   *
+   * @param  self    a self-referential pointer to the mskwaj_compressor
+   *                 instance being called
+   * @param  input   the name of the file to compressed. This is passed
+   *                 passed directly to mspack_system::open()
+   * @param  output  the name of the file to write compressed data to.
+   *                 This is passed directly to mspack_system::open().
+   * @param  length  the length of the uncompressed file, or -1 to indicate
+   *                 that this should be determined automatically by using
+   *                 mspack_system::seek() on the input file.
+   * @return an error code, or MSPACK_ERR_OK if successful
+   * @see set_param()
+   */
+  int (*compress)(struct mskwaj_compressor *self,
+                  const char *input,
+                  const char *output,
+                  off_t length);
+
+  /**
+   * Sets an KWAJ compression engine parameter.
+   *
+   * The following parameters are defined:
+   *
+   * - #MSKWAJC_PARAM_COMP_TYPE: the compression method to use. Must
+   *   be one of #MSKWAJC_COMP_NONE, #MSKWAJC_COMP_XOR, #MSKWAJ_COMP_SZDD
+   *   or #MSKWAJ_COMP_LZH. The default is #MSKWAJ_COMP_LZH.
+   *
+   * - #MSKWAJC_PARAM_INCLUDE_LENGTH: a boolean; should the compressed
+   *   output file should include the uncompressed length of the input
+   *   file in the header? This adds 4 bytes to the size of the output
+   *   file. A value of zero says "no", non-zero says "yes". The default
+   *   is "no".
+   *
+   * @param  self     a self-referential pointer to the mskwaj_compressor
+   *                  instance being called
+   * @param  param    the parameter to set
+   * @param  value    the value to set the parameter to
+   * @return MSPACK_ERR_OK if all is OK, or MSPACK_ERR_ARGS if there
+   *         is a problem with either parameter or value.
+   * @see generate()
+   */
+  int (*set_param)(struct mskwaj_compressor *self,
+                   int param,
+                   unsigned int value);
+
+
+  /**
+   * Sets the original filename of the file before compression,
+   * which will be stored in the header of the output file.
+   *
+   * The filename should be a null-terminated string, it must be an
+   * MS-DOS "8.3" type filename (up to 8 bytes for the filename, then
+   * optionally a "." and up to 3 bytes for a filename extension).
+   *
+   * If NULL is passed as the filename, no filename is included in the
+   * header. This is the default.
+   *
+   * @param  self     a self-referential pointer to the mskwaj_compressor
+   *                  instance being called
+   * @param  filename the original filename to use
+   * @return MSPACK_ERR_OK if all is OK, or MSPACK_ERR_ARGS if the
+   *         filename is too long
+   */
+  int (*set_filename)(struct mskwaj_compressor *self,
+                      const char *filename);
+
+  /**
+   * Sets arbitrary data that will be stored in the header of the
+   * output file, uncompressed. It can be up to roughly 64 kilobytes,
+   * as the overall size of the header must not exceed 65535 bytes.
+   * The data can contain null bytes if desired.
+   *
+   * If NULL is passed as the data pointer, or zero is passed as the
+   * length, no extra data is included in the header. This is the
+   * default.
+   *
+   * @param  self     a self-referential pointer to the mskwaj_compressor
+   *                  instance being called
+   * @param  data     a pointer to the data to be stored in the header
+   * @param  bytes    the length of the data in bytes
+   * @return MSPACK_ERR_OK if all is OK, or MSPACK_ERR_ARGS extra data
+   *         is too long
+   */
+  int (*set_extra_data)(struct mskwaj_compressor *self,
+                        void *data,
+                        size_t bytes);
+
+  /**
+   * Returns the error code set by the most recently called method.
+   *
+   * @param  self     a self-referential pointer to the mskwaj_compressor
+   *                  instance being called
+   * @return the most recent error code
+   * @see compress()
+   */
+  int (*last_error)(struct mschm_decompressor *self);
+};
+
+/**
+ * A decompressor for KWAJ compressed files.
+ *
+ * All fields are READ ONLY.
+ *
+ * @see mspack_create_kwaj_decompressor(), mspack_destroy_kwaj_decompressor()
+ */
+struct mskwaj_decompressor {
+  /**
+   * Opens a KWAJ file and reads the header.
+   *
+   * If the file opened is a valid KWAJ file, all headers will be read and
+   * a mskwajd_header structure will be returned.
+   *
+   * In the case of an error occuring, NULL is returned and the error code
+   * is available from last_error().
+   *
+   * The filename pointer should be considered "in use" until close() is
+   * called on the KWAJ file.
+   *
+   * @param  self     a self-referential pointer to the mskwaj_decompressor
+   *                  instance being called
+   * @param  filename the filename of the KWAJ compressed file. This is
+   *                  passed directly to mspack_system::open().
+   * @return a pointer to a mskwajd_header structure, or NULL on failure
+   * @see close()
+   */
+  struct mskwajd_header *(*open)(struct mskwaj_decompressor *self,
+                                 const char *filename);
+
+  /**
+   * Closes a previously opened KWAJ file.
+   *
+   * This closes a KWAJ file and frees the mskwajd_header associated
+   * with it. The KWAJ header pointer is now invalid and cannot be
+   * used again.
+   *
+   * @param  self     a self-referential pointer to the mskwaj_decompressor
+   *                  instance being called
+   * @param  kwaj     the KWAJ file to close
+   * @see open()
+   */
+  void (*close)(struct mskwaj_decompressor *self,
+                struct mskwajd_header *kwaj);
+
+  /**
+   * Extracts the compressed data from a KWAJ file.
+   *
+   * This decompresses the compressed KWAJ data stream and writes it to
+   * an output file.
+   *
+   * @param  self     a self-referential pointer to the mskwaj_decompressor
+   *                  instance being called
+   * @param  kwaj     the KWAJ file to extract data from
+   * @param  filename the filename to write the decompressed data to. This
+   *                  is passed directly to mspack_system::open().
+   * @return an error code, or MSPACK_ERR_OK if successful
+   */
+  int (*extract)(struct mskwaj_decompressor *self,
+                 struct mskwajd_header *kwaj,
+                 const char *filename);
+
+  /**
+   * Decompresses an KWAJ file to an output file in one step.
+   *
+   * This opens an KWAJ file as input, reads the header, then decompresses
+   * the compressed data immediately to an output file, finally closing
+   * both the input and output file. It is more convenient to use than
+   * open() then extract() then close(), if you do not need to know the
+   * KWAJ output size or output filename.
+   *
+   * @param  self     a self-referential pointer to the mskwaj_decompressor
+   *                  instance being called
+   * @param  input    the filename of the input KWAJ file. This is passed
+   *                  directly to mspack_system::open().
+   * @param  output   the filename to write the decompressed data to. This
+   *                  is passed directly to mspack_system::open().
+   * @return an error code, or MSPACK_ERR_OK if successful
+   */
+  int (*decompress)(struct mskwaj_decompressor *self,
+                    const char *input,
+                    const char *output);
+
+  /**
+   * Returns the error code set by the most recently called method.
+   *
+   * This is useful for open() which does not return an
+   * error code directly.
+   *
+   * @param  self     a self-referential pointer to the mskwaj_decompressor
+   *                  instance being called
+   * @return the most recent error code
+   * @see open(), search()
+   */
+  int (*last_error)(struct mskwaj_decompressor *self);
+};
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif