1 files changed, 180 insertions, 0 deletions

diff --git a/apps/codecs/demac/libdemac/rangecoding.h b/apps/codecs/demac/libdemac/rangecoding.h
new file mode 100644
index 0000000000..8be5e923ba
--- /dev/null
+++ b/apps/codecs/demac/libdemac/rangecoding.h
@@ -0,0 +1,180 @@
+/*
+
+libdemac - A Monkey's Audio decoder
+
+$Id:$
+
+Copyright (C) Dave Chapman 2007
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+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 General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110, USA
+
+*/
+
+/*
+
+Range decoder adapted from rangecod.c included in:
+
+  http://www.compressconsult.com/rangecoder/rngcod13.zip
+
+  rangecod.c     range encoding
+
+  (c) Michael Schindler
+  1997, 1998, 1999, 2000
+  http://www.compressconsult.com/
+  michael@compressconsult.com
+
+  This program is free software; you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation; either version 2 of the License, or
+  (at your option) any later version.
+
+
+The encoding functions were removed, and functions turned into "static
+inline" functions and moved to a .h file.  Some minor cosmetic changes
+were made (e.g. turning pre-processor symbols into upper-case,
+removing the rc parameter from each function (and the RNGC macro)).
+
+
+*/
+
+
+/* BITSTREAM READING FUNCTIONS */
+
+/* We deal with the input data one byte at a time - to ensure
+   functionality on CPUs of any endianness regardless of any requirements
+   for aligned reads. 
+*/
+
+static unsigned char* bytebuffer IBSS_ATTR;
+static int bytebufferoffset IBSS_ATTR;
+
+static inline void skip_byte(void)
+{
+    if (bytebufferoffset) {
+        bytebufferoffset--;
+    } else {
+        bytebufferoffset = 3;
+        bytebuffer += 4;
+    }
+}
+
+static inline int read_byte(void)
+{
+    int ch = bytebuffer[bytebufferoffset];
+
+    skip_byte();
+
+    return ch;
+}
+
+/* RANGE DECODING FUNCTIONS */
+
+/* SIZE OF RANGE ENCODING CODE VALUES. */
+
+#define CODE_BITS 32
+#define TOP_VALUE ((unsigned int)1 << (CODE_BITS-1))
+#define SHIFT_BITS (CODE_BITS - 9)
+#define EXTRA_BITS ((CODE_BITS-2) % 8 + 1)
+#define BOTTOM_VALUE (TOP_VALUE >> 8)
+
+struct rangecoder_t
+{
+    uint32_t low;        /* low end of interval */
+    uint32_t range;      /* length of interval */
+    uint32_t help;       /* bytes_to_follow resp. intermediate value */
+    unsigned int buffer; /* buffer for input/output */
+};
+
+static struct rangecoder_t rc;
+
+/* Start the decoder */
+static inline void range_start_decoding(void)
+{
+    rc.buffer = read_byte();
+    rc.low = rc.buffer >> (8 - EXTRA_BITS);
+    rc.range = (uint32_t) 1 << EXTRA_BITS;
+}
+
+static inline void range_dec_normalize(void)
+{
+    while (rc.range <= BOTTOM_VALUE)
+    {   
+        rc.buffer = (rc.buffer << 8) | read_byte();
+        rc.low = (rc.low << 8) | ((rc.buffer >> 1) & 0xff);
+        rc.range <<= 8;
+    }
+}
+
+/* Calculate culmulative frequency for next symbol. Does NO update!*/
+/* tot_f is the total frequency                              */
+/* or: totf is (code_value)1<<shift                                      */
+/* returns the culmulative frequency                         */
+static inline int range_decode_culfreq(int tot_f)
+{   int tmp;
+
+    range_dec_normalize();
+
+    rc.help = rc.range / tot_f;
+    tmp = rc.low / rc.help;
+
+    return tmp;
+}
+
+static inline int range_decode_culshift(int shift)
+{
+    int tmp;
+    range_dec_normalize();
+    rc.help = rc.range>>shift;
+    tmp = rc.low/rc.help;
+    return tmp;
+}
+
+
+/* Update decoding state                                     */
+/* sy_f is the interval length (frequency of the symbol)     */
+/* lt_f is the lower end (frequency sum of < symbols)        */
+static inline void range_decode_update(int sy_f, int lt_f)
+{   int tmp;
+    tmp = rc.help * lt_f;
+    rc.low -= tmp;
+    rc.range = rc.help * sy_f;
+}
+
+
+/* Decode a byte/short without modelling                     */
+static inline unsigned char decode_byte(void)
+{   int tmp = range_decode_culshift(8);
+    range_decode_update( 1,tmp);
+    return tmp;
+}
+
+static inline int short range_decode_short(void)
+{   int tmp = range_decode_culshift(16);
+    range_decode_update( 1,tmp);
+    return tmp;
+}
+
+/* Decode n bits (n <= 16) without modelling - based on range_decode_short */
+static inline int range_decode_bits(int n)
+{   int tmp = range_decode_culshift(n);
+    range_decode_update( 1,tmp);
+    return tmp;
+}
+
+
+/* Finish decoding                                           */
+static inline void range_done_decoding(void)
+{   range_dec_normalize();      /* normalize to use up all bytes */
+}