First draft of the wma decoder.
[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 = realloc(vlc->table,
55 sizeof(VLC_TYPE) * 2 * vlc->table_allocated);
56 if (!vlc->table)
57 return -E_TABLE_ALLOC;
58 }
59 return idx;
60 }
61
62 static int build_table(struct vlc *vlc, int table_nb_bits,
63 int nb_codes, const void *bits, int bits_wrap, int bits_size,
64 const void *codes, int codes_wrap, int codes_size,
65 uint32_t code_prefix, int n_prefix)
66 {
67 int ret, i, j, k, n, table_size, table_index, nb, n1, idx, code_prefix2,
68 symbol;
69 uint32_t code;
70 VLC_TYPE(*table)[2];
71
72 table_size = 1 << table_nb_bits;
73 ret = alloc_table(vlc, table_size);
74 if (ret < 0)
75 return ret;
76 table_index = ret;
77 table = &vlc->table[table_index];
78
79 for (i = 0; i < table_size; i++) {
80 table[i][1] = 0; //bits
81 table[i][0] = -1; //codes
82 }
83
84 /* first pass: map codes and compute auxillary table sizes */
85 for (i = 0; i < nb_codes; i++) {
86 GET_DATA(n, bits, i, bits_wrap, bits_size);
87 GET_DATA(code, codes, i, codes_wrap, codes_size);
88 /* we accept tables with holes */
89 if (n <= 0)
90 continue;
91 symbol = i;
92 /* if code matches the prefix, it is in the table */
93 n -= n_prefix;
94 code_prefix2 = code >> n;
95 if (n > 0 && code_prefix2 == code_prefix) {
96 if (n <= table_nb_bits) {
97 /* no need to add another table */
98 j = (code << (table_nb_bits - n)) & (table_size - 1);
99 nb = 1 << (table_nb_bits - n);
100 for (k = 0; k < nb; k++) {
101 if (table[j][1] /* bits */ != 0)
102 return -E_BAD_CODES;
103 table[j][1] = n; //bits
104 table[j][0] = symbol;
105 j++;
106 }
107 } else {
108 n -= table_nb_bits;
109 j = (code >> n) & ((1 << table_nb_bits) - 1);
110 /* compute table size */
111 n1 = -table[j][1]; //bits
112 if (n > n1)
113 n1 = n;
114 table[j][1] = -n1; //bits
115 }
116 }
117 }
118
119 /* second pass : fill auxillary tables recursively */
120 for (i = 0; i < table_size; i++) {
121 n = table[i][1]; //bits
122 if (n < 0) {
123 n = -n;
124 if (n > table_nb_bits) {
125 n = table_nb_bits;
126 table[i][1] = -n; //bits
127 }
128 ret = build_table(vlc, n, nb_codes,
129 bits, bits_wrap, bits_size,
130 codes, codes_wrap, codes_size,
131 (code_prefix << table_nb_bits) | i,
132 n_prefix + table_nb_bits);
133 if (ret < 0)
134 return ret;
135 idx = ret;
136 /* note: realloc has been done, so reload tables */
137 table = &vlc->table[table_index];
138 table[i][0] = idx; //code
139 }
140 }
141 return table_index;
142 }
143
144 /**
145 * Build VLC decoding tables suitable for use with get_vlc().
146 *
147 * \param nb_bits Set the decoding table size (2^nb_bits)
148 * entries. The bigger it is, the faster is the decoding. But
149 * it should not be too big to save memory and L1 cache. '9'
150 * is a good compromise.
151 *
152 * \param nb_codes Number of vlcs codes.
153 *
154 * \param bits Table which gives the size (in bits) of each
155 * vlc code.
156 *
157 * \param codes Table which gives the bit pattern of of each
158 * vlc code.
159 *
160 * \param bits_wrap The number of bytes between each entry of the
161 * 'bits' or 'codes' tables.
162 *
163 *
164 * \param bits_size The number of bytes of each entry of the
165 * 'bits' or 'codes' tables.
166 *
167 * \param codes_wrap Same as bits_wrap but uses the 'codes' table.
168 * \param codes_size Same as bits_size but for the 'codes' table.
169 *
170 * The wrap and size parameters allow to use any memory configuration and
171 * types (byte/word/long) to store the bits and codes tables.
172 */
173 int init_vlc(struct vlc *vlc, int nb_bits, int nb_codes,
174 const void *bits, int bits_wrap, int bits_size,
175 const void *codes, int codes_wrap, int codes_size)
176 {
177 int ret;
178
179 PARA_INFO_LOG("nb_codes=%d\n", nb_codes);
180 vlc->bits = nb_bits;
181 vlc->table = NULL;
182 vlc->table_allocated = 0;
183 vlc->table_size = 0;
184 ret = build_table(vlc, nb_bits, nb_codes, bits, bits_wrap, bits_size,
185 codes, codes_wrap, codes_size, 0, 0);
186 if (ret < 0)
187 freep(&vlc->table);
188 return ret;
189 }
190
191 void free_vlc(struct vlc *vlc)
192 {
193 freep(&vlc->table);
194 }