Merge branch 't/opus'
[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 /** Read an 8, 16, or 32 bit entity from a VLC table. */
31 #define GET_DATA(v, table, i, size) \
32 {\
33 const uint8_t *ptr = (const uint8_t *)table + i * size; \
34 switch (size) { \
35 case 1: \
36 v = *(const uint8_t *)ptr; \
37 break; \
38 case 2: \
39 v = *(const uint16_t *)ptr; \
40 break; \
41 default: \
42 v = *(const uint32_t *)ptr; \
43 break; \
44 } \
45 }
46
47 static void alloc_table(struct vlc *vlc, int size)
48 {
49 vlc->table_size += size;
50 if (vlc->table_size > vlc->table_allocated) {
51 vlc->table_allocated += (1 << vlc->bits);
52 vlc->table = para_realloc(vlc->table,
53 sizeof(VLC_TYPE) * 2 * vlc->table_allocated);
54 }
55 }
56
57 static int build_table(struct vlc *vlc, int table_nb_bits, int nb_codes,
58 const void *bits, const void *codes, int codes_size,
59 uint32_t code_prefix, int n_prefix)
60 {
61 int i, j, k, n, table_size, table_index, nb, n1, idx, code_prefix2,
62 symbol;
63 uint32_t code;
64 VLC_TYPE(*table)[2];
65
66 table_size = 1 << table_nb_bits;
67 table_index = vlc->table_size;
68 alloc_table(vlc, table_size);
69 table = &vlc->table[table_index];
70
71 for (i = 0; i < table_size; i++) {
72 table[i][1] = 0; //bits
73 table[i][0] = -1; //codes
74 }
75
76 /* map codes and compute auxillary table sizes */
77 for (i = 0; i < nb_codes; i++) {
78 GET_DATA(n, bits, i, 1);
79 GET_DATA(code, codes, i, codes_size);
80 /* we accept tables with holes */
81 if (n <= 0)
82 continue;
83 symbol = i;
84 /* if code matches the prefix, it is in the table */
85 n -= n_prefix;
86 code_prefix2 = code >> n;
87 if (n <= 0 || code_prefix2 != code_prefix)
88 continue;
89 if (n <= table_nb_bits) {
90 /* no need to add another table */
91 j = (code << (table_nb_bits - n)) & (table_size - 1);
92 nb = 1 << (table_nb_bits - n);
93 for (k = 0; k < nb; k++) {
94 if (table[j][1] /* bits */ != 0) {
95 PARA_EMERG_LOG("incorrect code\n");
96 exit(EXIT_FAILURE);
97 }
98 table[j][1] = n; //bits
99 table[j][0] = symbol;
100 j++;
101 }
102 } else {
103 n -= table_nb_bits;
104 j = (code >> n) & ((1 << table_nb_bits) - 1);
105 /* compute table size */
106 n1 = -table[j][1]; //bits
107 if (n > n1)
108 n1 = n;
109 table[j][1] = -n1; //bits
110 }
111 }
112
113 /* fill auxillary tables recursively */
114 for (i = 0; i < table_size; i++) {
115 n = table[i][1]; //bits
116 if (n < 0) {
117 n = -n;
118 if (n > table_nb_bits) {
119 n = table_nb_bits;
120 table[i][1] = -n; //bits
121 }
122 idx = build_table(vlc, n, nb_codes, bits, codes,
123 codes_size, (code_prefix << table_nb_bits) | i,
124 n_prefix + table_nb_bits);
125 /* vlc->table might have changed */
126 table = &vlc->table[table_index];
127 table[i][0] = idx; //code
128 }
129 }
130 return table_index;
131 }
132
133 /**
134 * Build VLC decoding tables suitable for use with get_vlc().
135 *
136 * \param vlc The structure to be initialized.
137 *
138 * \param nb_bits Set the decoding table size (2^nb_bits) entries. The bigger
139 * it is, the faster is the decoding. But it should not be too big to save
140 * memory and L1 cache. '9' is a good compromise.
141 *
142 * \param nb_codes Number of vlcs codes.
143 *
144 * \param bits Table which gives the size (in bits) of each vlc code.
145 *
146 * \param codes Table which gives the bit pattern of of each vlc code.
147 *
148 * \param codes_size The number of bytes of each entry of the \a codes tables.
149 *
150 * The wrap and size parameters allow to use any memory configuration and
151 * types (byte/word/long) to store the bits and codes tables.
152 */
153 void init_vlc(struct vlc *vlc, int nb_bits, int nb_codes, const void *bits,
154 const void *codes, int codes_size)
155 {
156 PARA_INFO_LOG("nb_codes: %d\n", nb_codes);
157 vlc->bits = nb_bits;
158 vlc->table = NULL;
159 vlc->table_allocated = 0;
160 vlc->table_size = 0;
161 build_table(vlc, nb_bits, nb_codes, bits, codes, codes_size, 0, 0);
162 }
163
164 /**
165 * Deallocate all resources of a VLC table.
166 *
167 * \param vlc Pointer to an initialized vlc structure.
168 *
169 * The table given by \a vlc must have been initialized earlier via \ref
170 * init_vlc().
171 */
172 void free_vlc(struct vlc *vlc)
173 {
174 freep(&vlc->table);
175 }
176
177 /**
178 * Parse a vlc code.
179 *
180 * \param gbc The getbit context structure.
181 *
182 * \param table The vlc tables to use.
183 *
184 * \param bits The number of bits which will be read at once, must be
185 * identical to nb_bits in init_vlc().
186 *
187 * \param max_depth The number of times bits bits must be read to completely
188 * read the longest vlc code = (max_vlc_length + bits - 1) / bits.
189 *
190 * \return The vlc code.
191 */
192 int get_vlc(struct getbit_context *gbc, VLC_TYPE(*table)[2], int bits,
193 int max_depth)
194 {
195 int n, idx, nb_bits, code;
196
197 idx = show_bits(gbc, bits);
198 code = table[idx][0];
199 n = table[idx][1];
200 if (max_depth > 1 && n < 0) {
201 skip_bits(gbc, bits);
202 nb_bits = -n;
203 idx = show_bits(gbc, nb_bits) + code;
204 code = table[idx][0];
205 n = table[idx][1];
206 if (max_depth > 2 && n < 0) {
207 skip_bits(gbc, nb_bits);
208 nb_bits = -n;
209 idx = show_bits(gbc, nb_bits) + code;
210 code = table[idx][0];
211 n = table[idx][1];
212 }
213 }
214 skip_bits(gbc, n);
215 return code >= 0? code : -E_VLC;
216 }