5b0d74a7d3
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@19236 a1c6a512-1295-4272-9138-f99709370657
461 lines
12 KiB
C
461 lines
12 KiB
C
/*
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libdemac - A Monkey's Audio decoder
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$Id$
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Copyright (C) Dave Chapman 2007
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110, USA
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*/
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#include <inttypes.h>
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#include <string.h>
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#include "parser.h"
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#include "entropy.h"
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#include "demac_config.h"
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#define MODEL_ELEMENTS 64
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/*
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The following counts arrays for use with the range decoder are
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hard-coded in the Monkey's Audio decoder.
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*/
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static const int counts_3970[65] ICONST_ATTR =
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{
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0,14824,28224,39348,47855,53994,58171,60926,
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62682,63786,64463,64878,65126,65276,65365,65419,
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65450,65469,65480,65487,65491,65493,65494,65495,
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65496,65497,65498,65499,65500,65501,65502,65503,
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65504,65505,65506,65507,65508,65509,65510,65511,
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65512,65513,65514,65515,65516,65517,65518,65519,
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65520,65521,65522,65523,65524,65525,65526,65527,
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65528,65529,65530,65531,65532,65533,65534,65535,
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65536
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};
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/* counts_diff_3970[i] = counts_3970[i+1] - counts_3970[i] */
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static const int counts_diff_3970[64] ICONST_ATTR =
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{
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14824,13400,11124,8507,6139,4177,2755,1756,
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1104,677,415,248,150,89,54,31,
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19,11,7,4,2,1,1,1,
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1,1,1,1,1,1,1,1,
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1,1,1,1,1,1,1,1,
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1,1,1,1,1,1,1,1,
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1,1,1,1,1,1,1,1,
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1,1,1,1,1,1,1,1
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};
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static const int counts_3980[65] ICONST_ATTR =
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{
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0,19578,36160,48417,56323,60899,63265,64435,
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64971,65232,65351,65416,65447,65466,65476,65482,
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65485,65488,65490,65491,65492,65493,65494,65495,
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65496,65497,65498,65499,65500,65501,65502,65503,
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65504,65505,65506,65507,65508,65509,65510,65511,
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65512,65513,65514,65515,65516,65517,65518,65519,
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65520,65521,65522,65523,65524,65525,65526,65527,
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65528,65529,65530,65531,65532,65533,65534,65535,
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65536
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};
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/* counts_diff_3980[i] = counts_3980[i+1] - counts_3980[i] */
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static const int counts_diff_3980[64] ICONST_ATTR =
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{
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19578,16582,12257,7906,4576,2366,1170,536,
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261,119,65,31,19,10,6,3,
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3,2,1,1,1,1,1,1,
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1,1,1,1,1,1,1,1,
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1,1,1,1,1,1,1,1,
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1,1,1,1,1,1,1,1,
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1,1,1,1,1,1,1,1,
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1,1,1,1,1,1,1,1
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};
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/*
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Range decoder adapted from rangecod.c included in:
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http://www.compressconsult.com/rangecoder/rngcod13.zip
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rangecod.c range encoding
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(c) Michael Schindler
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1997, 1998, 1999, 2000
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http://www.compressconsult.com/
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michael@compressconsult.com
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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The encoding functions were removed, and functions turned into "static
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inline" functions. Some minor cosmetic changes were made (e.g. turning
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pre-processor symbols into upper-case, removing the rc parameter from
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each function (and the RNGC macro)).
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*/
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/* BITSTREAM READING FUNCTIONS */
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/* We deal with the input data one byte at a time - to ensure
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functionality on CPUs of any endianness regardless of any requirements
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for aligned reads.
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*/
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static unsigned char* bytebuffer IBSS_ATTR;
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static int bytebufferoffset IBSS_ATTR;
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static inline void skip_byte(void)
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{
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bytebufferoffset--;
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bytebuffer += bytebufferoffset & 4;
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bytebufferoffset &= 3;
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}
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static inline int read_byte(void)
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{
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int ch = bytebuffer[bytebufferoffset];
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skip_byte();
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return ch;
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}
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/* RANGE DECODING FUNCTIONS */
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/* SIZE OF RANGE ENCODING CODE VALUES. */
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#define CODE_BITS 32
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#define TOP_VALUE ((unsigned int)1 << (CODE_BITS-1))
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#define SHIFT_BITS (CODE_BITS - 9)
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#define EXTRA_BITS ((CODE_BITS-2) % 8 + 1)
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#define BOTTOM_VALUE (TOP_VALUE >> 8)
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struct rangecoder_t
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{
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uint32_t low; /* low end of interval */
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uint32_t range; /* length of interval */
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uint32_t help; /* bytes_to_follow resp. intermediate value */
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unsigned int buffer; /* buffer for input/output */
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};
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static struct rangecoder_t rc IBSS_ATTR;
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/* Start the decoder */
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static inline void range_start_decoding(void)
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{
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rc.buffer = read_byte();
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rc.low = rc.buffer >> (8 - EXTRA_BITS);
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rc.range = (uint32_t) 1 << EXTRA_BITS;
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}
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static inline void range_dec_normalize(void)
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{
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while (rc.range <= BOTTOM_VALUE)
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{
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rc.buffer = (rc.buffer << 8) | read_byte();
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rc.low = (rc.low << 8) | ((rc.buffer >> 1) & 0xff);
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rc.range <<= 8;
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}
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}
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/* Calculate culmulative frequency for next symbol. Does NO update!*/
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/* tot_f is the total frequency */
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/* or: totf is (code_value)1<<shift */
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/* returns the culmulative frequency */
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static inline int range_decode_culfreq(int tot_f)
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{
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range_dec_normalize();
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rc.help = UDIV32(rc.range, tot_f);
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return UDIV32(rc.low, rc.help);
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}
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static inline int range_decode_culshift(int shift)
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{
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range_dec_normalize();
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rc.help = rc.range >> shift;
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return UDIV32(rc.low, rc.help);
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}
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/* Update decoding state */
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/* sy_f is the interval length (frequency of the symbol) */
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/* lt_f is the lower end (frequency sum of < symbols) */
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static inline void range_decode_update(int sy_f, int lt_f)
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{
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rc.low -= rc.help * lt_f;
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rc.range = rc.help * sy_f;
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}
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/* Decode a byte/short without modelling */
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static inline unsigned char decode_byte(void)
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{ int tmp = range_decode_culshift(8);
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range_decode_update( 1,tmp);
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return tmp;
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}
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static inline int short range_decode_short(void)
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{ int tmp = range_decode_culshift(16);
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range_decode_update( 1,tmp);
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return tmp;
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}
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/* Decode n bits (n <= 16) without modelling - based on range_decode_short */
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static inline int range_decode_bits(int n)
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{ int tmp = range_decode_culshift(n);
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range_decode_update( 1,tmp);
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return tmp;
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}
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/* Finish decoding */
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static inline void range_done_decoding(void)
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{ range_dec_normalize(); /* normalize to use up all bytes */
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}
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/*
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range_get_symbol_* functions based on main decoding loop in simple_d.c from
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http://www.compressconsult.com/rangecoder/rngcod13.zip
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(c) Michael Schindler
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*/
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static inline int range_get_symbol_3980(void)
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{
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int symbol, cf;
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cf = range_decode_culshift(16);
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/* figure out the symbol inefficiently; a binary search would be much better */
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for (symbol = 0; counts_3980[symbol+1] <= cf; symbol++);
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range_decode_update(counts_diff_3980[symbol],counts_3980[symbol]);
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return symbol;
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}
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static inline int range_get_symbol_3970(void)
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{
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int symbol, cf;
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cf = range_decode_culshift(16);
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/* figure out the symbol inefficiently; a binary search would be much better */
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for (symbol = 0; counts_3970[symbol+1] <= cf; symbol++);
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range_decode_update(counts_diff_3970[symbol],counts_3970[symbol]);
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return symbol;
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}
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/* MAIN DECODING FUNCTIONS */
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struct rice_t
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{
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uint32_t k;
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uint32_t ksum;
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};
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static struct rice_t riceX IBSS_ATTR;
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static struct rice_t riceY IBSS_ATTR;
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static inline void update_rice(struct rice_t* rice, int x)
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{
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rice->ksum += ((x + 1) / 2) - ((rice->ksum + 16) >> 5);
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if (UNLIKELY(rice->k == 0)) {
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rice->k = 1;
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} else {
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uint32_t lim = 1 << (rice->k + 4);
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if (UNLIKELY(rice->ksum < lim)) {
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rice->k--;
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} else if (UNLIKELY(rice->ksum >= 2 * lim)) {
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rice->k++;
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}
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}
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}
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static inline int entropy_decode3980(struct rice_t* rice)
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{
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int base, x, pivot, overflow;
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pivot = rice->ksum >> 5;
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if (UNLIKELY(pivot == 0))
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pivot=1;
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overflow = range_get_symbol_3980();
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if (UNLIKELY(overflow == (MODEL_ELEMENTS-1))) {
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overflow = range_decode_short() << 16;
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overflow |= range_decode_short();
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}
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if (pivot >= 0x10000) {
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/* Codepath for 24-bit streams */
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int nbits, lo_bits, base_hi, base_lo;
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/* Count the number of bits in pivot */
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nbits = 17; /* We know there must be at least 17 bits */
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while ((pivot >> nbits) > 0) { nbits++; }
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/* base_lo is the low (nbits-16) bits of base
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base_hi is the high 16 bits of base
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*/
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lo_bits = (nbits - 16);
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base_hi = range_decode_culfreq((pivot >> lo_bits) + 1);
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range_decode_update(1, base_hi);
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base_lo = range_decode_culshift(lo_bits);
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range_decode_update(1, base_lo);
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base = (base_hi << lo_bits) + base_lo;
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} else {
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/* Codepath for 16-bit streams */
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base = range_decode_culfreq(pivot);
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range_decode_update(1, base);
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}
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x = base + (overflow * pivot);
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update_rice(rice, x);
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/* Convert to signed */
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if (x & 1)
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return (x >> 1) + 1;
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else
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return -(x >> 1);
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}
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static inline int entropy_decode3970(struct rice_t* rice)
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{
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int x, tmpk;
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int overflow = range_get_symbol_3970();
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if (UNLIKELY(overflow == (MODEL_ELEMENTS - 1))) {
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tmpk = range_decode_bits(5);
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overflow = 0;
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} else {
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tmpk = (rice->k < 1) ? 0 : rice->k - 1;
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}
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if (tmpk <= 16) {
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x = range_decode_bits(tmpk);
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} else {
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x = range_decode_short();
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x |= (range_decode_bits(tmpk - 16) << 16);
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}
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x += (overflow << tmpk);
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update_rice(rice, x);
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/* Convert to signed */
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if (x & 1)
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return (x >> 1) + 1;
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else
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return -(x >> 1);
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}
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void init_entropy_decoder(struct ape_ctx_t* ape_ctx,
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unsigned char* inbuffer, int* firstbyte,
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int* bytesconsumed)
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{
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bytebuffer = inbuffer;
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bytebufferoffset = *firstbyte;
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/* Read the CRC */
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ape_ctx->CRC = read_byte();
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ape_ctx->CRC = (ape_ctx->CRC << 8) | read_byte();
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ape_ctx->CRC = (ape_ctx->CRC << 8) | read_byte();
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ape_ctx->CRC = (ape_ctx->CRC << 8) | read_byte();
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/* Read the frame flags if they exist */
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ape_ctx->frameflags = 0;
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if ((ape_ctx->fileversion > 3820) && (ape_ctx->CRC & 0x80000000)) {
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ape_ctx->CRC &= ~0x80000000;
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ape_ctx->frameflags = read_byte();
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ape_ctx->frameflags = (ape_ctx->frameflags << 8) | read_byte();
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ape_ctx->frameflags = (ape_ctx->frameflags << 8) | read_byte();
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ape_ctx->frameflags = (ape_ctx->frameflags << 8) | read_byte();
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}
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/* Keep a count of the blocks decoded in this frame */
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ape_ctx->blocksdecoded = 0;
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/* Initialise the rice structs */
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riceX.k = 10;
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riceX.ksum = (1 << riceX.k) * 16;
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riceY.k = 10;
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riceY.ksum = (1 << riceY.k) * 16;
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/* The first 8 bits of input are ignored. */
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skip_byte();
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range_start_decoding();
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/* Return the new state of the buffer */
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*bytesconsumed = (intptr_t)bytebuffer - (intptr_t)inbuffer;
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*firstbyte = bytebufferoffset;
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}
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void ICODE_ATTR_DEMAC entropy_decode(struct ape_ctx_t* ape_ctx,
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unsigned char* inbuffer, int* firstbyte,
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int* bytesconsumed,
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int32_t* decoded0, int32_t* decoded1,
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int blockstodecode)
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{
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bytebuffer = inbuffer;
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bytebufferoffset = *firstbyte;
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ape_ctx->blocksdecoded += blockstodecode;
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if (ape_ctx->frameflags & APE_FRAMECODE_STEREO_SILENCE) {
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/* We are pure silence, just memset the output buffer. */
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memset(decoded0, 0, blockstodecode * sizeof(int32_t));
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memset(decoded1, 0, blockstodecode * sizeof(int32_t));
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} else {
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if (ape_ctx->fileversion > 3970) {
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while (LIKELY(blockstodecode--)) {
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*(decoded0++) = entropy_decode3980(&riceY);
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if (decoded1 != NULL)
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*(decoded1++) = entropy_decode3980(&riceX);
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}
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} else {
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while (LIKELY(blockstodecode--)) {
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*(decoded0++) = entropy_decode3970(&riceY);
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if (decoded1 != NULL)
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*(decoded1++) = entropy_decode3970(&riceX);
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}
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}
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}
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if (ape_ctx->blocksdecoded == ape_ctx->currentframeblocks)
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{
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range_done_decoding();
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}
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/* Return the new state of the buffer */
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*bytesconsumed = bytebuffer - inbuffer;
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*firstbyte = bytebufferoffset;
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}
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