summaryrefslogtreecommitdiff
path: root/apps/codecs/demac/libdemac/rangecoding.h
diff options
context:
space:
mode:
Diffstat (limited to 'apps/codecs/demac/libdemac/rangecoding.h')
-rw-r--r--apps/codecs/demac/libdemac/rangecoding.h178
1 files changed, 0 insertions, 178 deletions
diff --git a/apps/codecs/demac/libdemac/rangecoding.h b/apps/codecs/demac/libdemac/rangecoding.h
deleted file mode 100644
index 645fd1ad92..0000000000
--- a/apps/codecs/demac/libdemac/rangecoding.h
+++ /dev/null
@@ -1,178 +0,0 @@
1/*
2
3libdemac - A Monkey's Audio decoder
4
5$Id$
6
7Copyright (C) Dave Chapman 2007
8
9This program is free software; you can redistribute it and/or modify
10it under the terms of the GNU General Public License as published by
11the Free Software Foundation; either version 2 of the License, or
12(at your option) any later version.
13
14This program is distributed in the hope that it will be useful,
15but WITHOUT ANY WARRANTY; without even the implied warranty of
16MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17GNU General Public License for more details.
18
19You should have received a copy of the GNU General Public License
20along with this program; if not, write to the Free Software
21Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110, USA
22
23*/
24
25/*
26
27Range decoder adapted from rangecod.c included in:
28
29 http://www.compressconsult.com/rangecoder/rngcod13.zip
30
31 rangecod.c range encoding
32
33 (c) Michael Schindler
34 1997, 1998, 1999, 2000
35 http://www.compressconsult.com/
36 michael@compressconsult.com
37
38 This program is free software; you can redistribute it and/or modify
39 it under the terms of the GNU General Public License as published by
40 the Free Software Foundation; either version 2 of the License, or
41 (at your option) any later version.
42
43
44The encoding functions were removed, and functions turned into "static
45inline" functions and moved to a .h file. Some minor cosmetic changes
46were made (e.g. turning pre-processor symbols into upper-case,
47removing the rc parameter from each function (and the RNGC macro)).
48
49
50*/
51
52#ifdef ROCKBOX
53#include "../lib/codeclib.h"
54/* for UDIV32() */
55#endif
56
57#ifndef UDIV32
58#define UDIV32(a, b) (a / b)
59#endif
60
61/* BITSTREAM READING FUNCTIONS */
62
63/* We deal with the input data one byte at a time - to ensure
64 functionality on CPUs of any endianness regardless of any requirements
65 for aligned reads.
66*/
67
68static unsigned char* bytebuffer IBSS_ATTR;
69static int bytebufferoffset IBSS_ATTR;
70
71static inline void skip_byte(void)
72{
73 bytebufferoffset--;
74 bytebuffer += bytebufferoffset & 4;
75 bytebufferoffset &= 3;
76}
77
78static inline int read_byte(void)
79{
80 int ch = bytebuffer[bytebufferoffset];
81
82 skip_byte();
83
84 return ch;
85}
86
87/* RANGE DECODING FUNCTIONS */
88
89/* SIZE OF RANGE ENCODING CODE VALUES. */
90
91#define CODE_BITS 32
92#define TOP_VALUE ((unsigned int)1 << (CODE_BITS-1))
93#define SHIFT_BITS (CODE_BITS - 9)
94#define EXTRA_BITS ((CODE_BITS-2) % 8 + 1)
95#define BOTTOM_VALUE (TOP_VALUE >> 8)
96
97struct rangecoder_t
98{
99 uint32_t low; /* low end of interval */
100 uint32_t range; /* length of interval */
101 uint32_t help; /* bytes_to_follow resp. intermediate value */
102 unsigned int buffer; /* buffer for input/output */
103};
104
105static struct rangecoder_t rc IBSS_ATTR;
106
107/* Start the decoder */
108static inline void range_start_decoding(void)
109{
110 rc.buffer = read_byte();
111 rc.low = rc.buffer >> (8 - EXTRA_BITS);
112 rc.range = (uint32_t) 1 << EXTRA_BITS;
113}
114
115static inline void range_dec_normalize(void)
116{
117 while (rc.range <= BOTTOM_VALUE)
118 {
119 rc.buffer = (rc.buffer << 8) | read_byte();
120 rc.low = (rc.low << 8) | ((rc.buffer >> 1) & 0xff);
121 rc.range <<= 8;
122 }
123}
124
125/* Calculate culmulative frequency for next symbol. Does NO update!*/
126/* tot_f is the total frequency */
127/* or: totf is (code_value)1<<shift */
128/* returns the culmulative frequency */
129static inline int range_decode_culfreq(int tot_f)
130{
131 range_dec_normalize();
132 rc.help = UDIV32(rc.range, tot_f);
133 return UDIV32(rc.low, rc.help);
134}
135
136static inline int range_decode_culshift(int shift)
137{
138 range_dec_normalize();
139 rc.help = rc.range >> shift;
140 return UDIV32(rc.low, rc.help);
141}
142
143
144/* Update decoding state */
145/* sy_f is the interval length (frequency of the symbol) */
146/* lt_f is the lower end (frequency sum of < symbols) */
147static inline void range_decode_update(int sy_f, int lt_f)
148{
149 rc.low -= rc.help * lt_f;
150 rc.range = rc.help * sy_f;
151}
152
153
154/* Decode a byte/short without modelling */
155static inline unsigned char decode_byte(void)
156{ int tmp = range_decode_culshift(8);
157 range_decode_update( 1,tmp);
158 return tmp;
159}
160
161static inline int short range_decode_short(void)
162{ int tmp = range_decode_culshift(16);
163 range_decode_update( 1,tmp);
164 return tmp;
165}
166
167/* Decode n bits (n <= 16) without modelling - based on range_decode_short */
168static inline int range_decode_bits(int n)
169{ int tmp = range_decode_culshift(n);
170 range_decode_update( 1,tmp);
171 return tmp;
172}
173
174
175/* Finish decoding */
176static inline void range_done_decoding(void)
177{ range_dec_normalize(); /* normalize to use up all bytes */
178}
generated by cgit v1.2.3 (git 2.39.1) at 2024-09-26 23:19:22 +0000