Kill codes_wrap parameter from init_vlc().
[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, size) \
31 {\
32 const uint8_t *ptr = (const uint8_t *)table + i * size; \
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 void alloc_table(struct vlc *vlc, int size)
47 {
48 vlc->table_size += size;
49 if (vlc->table_size > vlc->table_allocated) {
50 vlc->table_allocated += (1 << vlc->bits);
51 vlc->table = para_realloc(vlc->table,
52 sizeof(VLC_TYPE) * 2 * vlc->table_allocated);
53 }
54 }
55
56 static int build_table(struct vlc *vlc, int table_nb_bits, int nb_codes,
57 const void *bits, const void *codes, int codes_size,
58 uint32_t code_prefix, int n_prefix)
59 {
60 int i, j, k, n, table_size, table_index, nb, n1, idx, code_prefix2,
61 symbol;
62 uint32_t code;
63 VLC_TYPE(*table)[2];
64
65 table_size = 1 << table_nb_bits;
66 table_index = vlc->table_size;
67 alloc_table(vlc, table_size);
68 table = &vlc->table[table_index];
69
70 for (i = 0; i < table_size; i++) {
71 table[i][1] = 0; //bits
72 table[i][0] = -1; //codes
73 }
74
75 /* map codes and compute auxillary table sizes */
76 for (i = 0; i < nb_codes; i++) {
77 GET_DATA(n, bits, i, 1);
78 GET_DATA(code, codes, i, codes_size);
79 /* we accept tables with holes */
80 if (n <= 0)
81 continue;
82 symbol = i;
83 /* if code matches the prefix, it is in the table */
84 n -= n_prefix;
85 code_prefix2 = code >> n;
86 if (n > 0 && code_prefix2 == code_prefix) {
87 if (n <= table_nb_bits) {
88 /* no need to add another table */
89 j = (code << (table_nb_bits - n)) & (table_size - 1);
90 nb = 1 << (table_nb_bits - n);
91 for (k = 0; k < nb; k++) {
92 if (table[j][1] /* bits */ != 0) {
93 PARA_EMERG_LOG("detected incorrect code\n");
94 exit(EXIT_FAILURE);
95 }
96 table[j][1] = n; //bits
97 table[j][0] = symbol;
98 j++;
99 }
100 } else {
101 n -= table_nb_bits;
102 j = (code >> n) & ((1 << table_nb_bits) - 1);
103 /* compute table size */
104 n1 = -table[j][1]; //bits
105 if (n > n1)
106 n1 = n;
107 table[j][1] = -n1; //bits
108 }
109 }
110 }
111
112 /* fill auxillary tables recursively */
113 for (i = 0; i < table_size; i++) {
114 n = table[i][1]; //bits
115 if (n < 0) {
116 n = -n;
117 if (n > table_nb_bits) {
118 n = table_nb_bits;
119 table[i][1] = -n; //bits
120 }
121 idx = build_table(vlc, n, nb_codes, bits, codes,
122 codes_size, (code_prefix << table_nb_bits) | i,
123 n_prefix + table_nb_bits);
124 /* vlc->table might have changed */
125 table = &vlc->table[table_index];
126 table[i][0] = idx; //code
127 }
128 }
129 return table_index;
130 }
131
132 /**
133 * Build VLC decoding tables suitable for use with get_vlc().
134 *
135 * \param nb_bits Set the decoding table size (2^nb_bits)
136 * entries. The bigger it is, the faster is the decoding. But
137 * it should not be too big to save memory and L1 cache. '9'
138 * is a good compromise.
139 *
140 * \param nb_codes Number of vlcs codes.
141 *
142 * \param bits Table which gives the size (in bits) of each vlc code.
143 *
144 * \param codes Table which gives the bit pattern of of each vlc code.
145 *
146 * \param codes_size The number of bytes of each entry of the \a codes tables.
147 *
148 * The wrap and size parameters allow to use any memory configuration and
149 * types (byte/word/long) to store the bits and codes tables.
150 */
151 void init_vlc(struct vlc *vlc, int nb_bits, int nb_codes, const void *bits,
152 const void *codes, int codes_size)
153 {
154 PARA_INFO_LOG("nb_codes: %d\n", nb_codes);
155 vlc->bits = nb_bits;
156 vlc->table = NULL;
157 vlc->table_allocated = 0;
158 vlc->table_size = 0;
159 build_table(vlc, nb_bits, nb_codes, bits,
160 codes, codes_size, 0, 0);
161 }
162
163 void free_vlc(struct vlc *vlc)
164 {
165 freep(&vlc->table);
166 }