mixer: fade: Handle empty mood strings gracefully.
[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 * Copyright (C) 2009 Andre Noll <maan@tuebingen.mpg.de>
10 *
11 * Licensed under the GNU Lesser General Public License. see file COPYING.LIB.
12 */
13
14 /** \file bitstream.c Bitstream API for the wma decoder. */
15
16 #include <regex.h>
17
18 #include "para.h"
19 #include "error.h"
20 #include "string.h"
21 #include "wma.h"
22 #include "portable_io.h"
23 #include "bitstream.h"
24
25 static inline uint32_t get_data(const void *table, int i, int size)
26 {
27 const uint8_t *ptr = (const uint8_t *)table + i * size;
28 uint32_t v;
29
30 switch (size) {
31 case 1:
32 v = *(const uint8_t *)ptr;
33 break;
34 case 2:
35 v = *(const uint16_t *)ptr;
36 break;
37 default:
38 v = *(const uint32_t *)ptr;
39 break;
40 }
41 return v;
42 }
43
44 static void alloc_table(struct vlc *vlc, int size)
45 {
46 vlc->table_size += size;
47 if (vlc->table_size > vlc->table_allocated) {
48 vlc->table_allocated += (1 << vlc->bits);
49 vlc->table = para_realloc(vlc->table,
50 sizeof(int16_t) * 2 * vlc->table_allocated);
51 }
52 }
53
54 static int build_table(struct vlc *vlc, int table_nb_bits, int nb_codes,
55 const void *bits, const void *codes, int codes_size,
56 uint32_t code_prefix, int n_prefix)
57 {
58 int i, j, k, n, table_size, table_index, nb, n1, idx;
59 uint32_t code;
60 int16_t (*table)[2];
61
62 table_size = 1 << table_nb_bits;
63 table_index = vlc->table_size;
64 alloc_table(vlc, table_size);
65 table = &vlc->table[table_index];
66
67 for (i = 0; i < table_size; i++) {
68 table[i][1] = 0; /* bits */
69 table[i][0] = -1; /* codes */
70 }
71
72 /* map codes and compute auxiliary table sizes */
73 for (i = 0; i < nb_codes; i++) {
74 n = get_data(bits, i, 1);
75 /* we accept tables with holes */
76 n -= n_prefix;
77 if (n <= 0)
78 continue;
79 code = get_data(codes, i, codes_size);
80 /* if code matches the prefix, it is in the table */
81 if ((code >> n) != code_prefix)
82 continue;
83 if (n <= table_nb_bits) {
84 /* no need to add another table */
85 j = (code << (table_nb_bits - n)) & (table_size - 1);
86 nb = 1 << (table_nb_bits - n);
87 for (k = 0; k < nb; k++) {
88 assert(table[j][1] == 0); /* incorrect code */
89 table[j][1] = n; /* bits */
90 table[j][0] = i;
91 j++;
92 }
93 } else {
94 n -= table_nb_bits;
95 j = (code >> n) & ((1 << table_nb_bits) - 1);
96 /* compute table size */
97 n1 = -table[j][1]; /* bits */
98 if (n > n1)
99 n1 = n;
100 table[j][1] = -n1; /* bits */
101 }
102 }
103
104 /* fill auxiliary tables recursively */
105 for (i = 0; i < table_size; i++) {
106 n = table[i][1]; /* bits */
107 if (n < 0) {
108 n = -n;
109 if (n > table_nb_bits) {
110 n = table_nb_bits;
111 table[i][1] = -n; /* bits */
112 }
113 idx = build_table(vlc, n, nb_codes, bits, codes,
114 codes_size, (code_prefix << table_nb_bits) | i,
115 n_prefix + table_nb_bits);
116 /* vlc->table might have changed */
117 table = &vlc->table[table_index];
118 table[i][0] = idx; /* code */
119 }
120 }
121 return table_index;
122 }
123
124 /**
125 * Build VLC decoding tables suitable for use with get_vlc().
126 *
127 * \param vlc The structure to be initialized.
128 * \param nb_bits Set the decoding table size (2^nb_bits) entries.
129 * \param nb_codes Number of vlc codes.
130 * \param bits Table which gives the size (in bits) of each vlc code.
131 * \param codes Table which gives the bit pattern of of each vlc code.
132 * \param codes_size The number of bytes of each entry of the \a codes tables.
133 *
134 * The bigger \a nb_bits is, the faster is the decoding. But it should not be
135 * too big to save memory and L1 cache. '9' is a good compromise.
136 *
137 * The wrap and size parameters allow to use any memory configuration and
138 * types (byte/word/long) to store the bits and codes tables.
139 */
140 void init_vlc(struct vlc *vlc, int nb_bits, int nb_codes, const void *bits,
141 const void *codes, int codes_size)
142 {
143 PARA_INFO_LOG("nb_codes: %d\n", nb_codes);
144 vlc->bits = nb_bits;
145 vlc->table = NULL;
146 vlc->table_allocated = 0;
147 vlc->table_size = 0;
148 build_table(vlc, nb_bits, nb_codes, bits, codes, codes_size, 0, 0);
149 }
150
151 /**
152 * Deallocate all resources of a VLC table.
153 *
154 * \param vlc Pointer to an initialized vlc structure.
155 *
156 * The table given by \a vlc must have been initialized earlier via \ref
157 * init_vlc().
158 */
159 void free_vlc(struct vlc *vlc)
160 {
161 freep(&vlc->table);
162 }
163
164 /**
165 * Parse a vlc code.
166 *
167 * \param gbc The getbit context structure.
168 * \param vlc The vlc tables to use.
169 *
170 * \return The vlc code.
171 */
172 int get_vlc(struct getbit_context *gbc, const struct vlc *vlc)
173 {
174 int n, idx, nb_bits, code;
175
176 idx = show_bits(gbc, vlc->bits);
177 code = vlc->table[idx][0];
178 n = vlc->table[idx][1];
179 if (n < 0) {
180 skip_bits(gbc, vlc->bits);
181 nb_bits = -n;
182 idx = show_bits(gbc, nb_bits) + code;
183 code = vlc->table[idx][0];
184 n = vlc->table[idx][1];
185 if (n < 0) {
186 skip_bits(gbc, nb_bits);
187 nb_bits = -n;
188 idx = show_bits(gbc, nb_bits) + code;
189 code = vlc->table[idx][0];
190 n = vlc->table[idx][1];
191 }
192 }
193 skip_bits(gbc, n);
194 return code >= 0? code : -E_VLC;
195 }