e36faaf861ae4de3f3a0470d55a404851e55d946
[paraslash.git] / bitstream.c
1 /*
2 * Common bit I/O utils.
3 *
4 * Extracted 2009 from mplayer 2009-02-10 libavcodec/bitstream.c.
5 *
6 * Copyright (c) 2000, 2001 Fabrice Bellard
7 * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
8 * alternative bitstream reader & writer by Michael Niedermayer <michaelni@gmx.at>
9 *
10 * Licensed under the GNU Lesser General Public License.
11 * For licencing details see COPYING.LIB.
12 */
13
14 /**
15 * \file bitstream.c Bitstream API.
16 */
17
18 #include <stdlib.h>
19 #include <inttypes.h>
20 #include <stdio.h>
21 #include <string.h>
22 #include <regex.h>
23
24 #include "para.h"
25 #include "error.h"
26 #include "string.h"
27 #include "wma.h"
28 #include "bitstream.h"
29
30 #define GET_DATA(v, table, i, wrap, size) \
31 {\
32 const uint8_t *ptr = (const uint8_t *)table + i * wrap;\
33 switch(size) {\
34 case 1:\
35 v = *(const uint8_t *)ptr;\
36 break;\
37 case 2:\
38 v = *(const uint16_t *)ptr;\
39 break;\
40 default:\
41 v = *(const uint32_t *)ptr;\
42 break;\
43 }\
44 }
45
46 static int alloc_table(struct vlc *vlc, int size)
47 {
48 int idx;
49
50 idx = vlc->table_size;
51 vlc->table_size += size;
52 if (vlc->table_size > vlc->table_allocated) {
53 vlc->table_allocated += (1 << vlc->bits);
54 vlc->table = para_realloc(vlc->table,
55 sizeof(VLC_TYPE) * 2 * vlc->table_allocated);
56 }
57 return idx;
58 }
59
60 static int build_table(struct vlc *vlc, int table_nb_bits,
61 int nb_codes, const void *bits, int bits_wrap, int bits_size,
62 const void *codes, int codes_wrap, int codes_size,
63 uint32_t code_prefix, int n_prefix)
64 {
65 int ret, i, j, k, n, table_size, table_index, nb, n1, idx, code_prefix2,
66 symbol;
67 uint32_t code;
68 VLC_TYPE(*table)[2];
69
70 table_size = 1 << table_nb_bits;
71 ret = alloc_table(vlc, table_size);
72 if (ret < 0)
73 return ret;
74 table_index = ret;
75 table = &vlc->table[table_index];
76
77 for (i = 0; i < table_size; i++) {
78 table[i][1] = 0; //bits
79 table[i][0] = -1; //codes
80 }
81
82 /* first pass: map codes and compute auxillary table sizes */
83 for (i = 0; i < nb_codes; i++) {
84 GET_DATA(n, bits, i, bits_wrap, bits_size);
85 GET_DATA(code, codes, i, codes_wrap, codes_size);
86 /* we accept tables with holes */
87 if (n <= 0)
88 continue;
89 symbol = i;
90 /* if code matches the prefix, it is in the table */
91 n -= n_prefix;
92 code_prefix2 = code >> n;
93 if (n > 0 && code_prefix2 == code_prefix) {
94 if (n <= table_nb_bits) {
95 /* no need to add another table */
96 j = (code << (table_nb_bits - n)) & (table_size - 1);
97 nb = 1 << (table_nb_bits - n);
98 for (k = 0; k < nb; k++) {
99 if (table[j][1] /* bits */ != 0)
100 return -E_BAD_CODES;
101 table[j][1] = n; //bits
102 table[j][0] = symbol;
103 j++;
104 }
105 } else {
106 n -= table_nb_bits;
107 j = (code >> n) & ((1 << table_nb_bits) - 1);
108 /* compute table size */
109 n1 = -table[j][1]; //bits
110 if (n > n1)
111 n1 = n;
112 table[j][1] = -n1; //bits
113 }
114 }
115 }
116
117 /* second pass : fill auxillary tables recursively */
118 for (i = 0; i < table_size; i++) {
119 n = table[i][1]; //bits
120 if (n < 0) {
121 n = -n;
122 if (n > table_nb_bits) {
123 n = table_nb_bits;
124 table[i][1] = -n; //bits
125 }
126 ret = build_table(vlc, n, nb_codes,
127 bits, bits_wrap, bits_size,
128 codes, codes_wrap, codes_size,
129 (code_prefix << table_nb_bits) | i,
130 n_prefix + table_nb_bits);
131 if (ret < 0)
132 return ret;
133 idx = ret;
134 /* note: realloc has been done, so reload tables */
135 table = &vlc->table[table_index];
136 table[i][0] = idx; //code
137 }
138 }
139 return table_index;
140 }
141
142 /**
143 * Build VLC decoding tables suitable for use with get_vlc().
144 *
145 * \param nb_bits Set the decoding table size (2^nb_bits)
146 * entries. The bigger it is, the faster is the decoding. But
147 * it should not be too big to save memory and L1 cache. '9'
148 * is a good compromise.
149 *
150 * \param nb_codes Number of vlcs codes.
151 *
152 * \param bits Table which gives the size (in bits) of each
153 * vlc code.
154 *
155 * \param codes Table which gives the bit pattern of of each
156 * vlc code.
157 *
158 * \param bits_wrap The number of bytes between each entry of the
159 * 'bits' or 'codes' tables.
160 *
161 *
162 * \param bits_size The number of bytes of each entry of the
163 * 'bits' or 'codes' tables.
164 *
165 * \param codes_wrap Same as bits_wrap but uses the 'codes' table.
166 * \param codes_size Same as bits_size but for the 'codes' table.
167 *
168 * The wrap and size parameters allow to use any memory configuration and
169 * types (byte/word/long) to store the bits and codes tables.
170 */
171 int init_vlc(struct vlc *vlc, int nb_bits, int nb_codes,
172 const void *bits, int bits_wrap, int bits_size,
173 const void *codes, int codes_wrap, int codes_size)
174 {
175 int ret;
176
177 PARA_INFO_LOG("nb_codes=%d\n", nb_codes);
178 vlc->bits = nb_bits;
179 vlc->table = NULL;
180 vlc->table_allocated = 0;
181 vlc->table_size = 0;
182 ret = build_table(vlc, nb_bits, nb_codes, bits, bits_wrap, bits_size,
183 codes, codes_wrap, codes_size, 0, 0);
184 if (ret < 0)
185 freep(&vlc->table);
186 return ret;
187 }
188
189 void free_vlc(struct vlc *vlc)
190 {
191 freep(&vlc->table);
192 }