3 * Copyright (c) 2000, 2001 Fabrice Bellard
4 * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
5 * Copyright (c) 2010 Loren Merritt
7 * alternative bitstream reader & writer by Michael Niedermayer <michaelni@gmx.at>
9 * This file is part of FFmpeg.
11 * FFmpeg is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU Lesser General Public
13 * License as published by the Free Software Foundation; either
14 * version 2.1 of the License, or (at your option) any later version.
16 * FFmpeg is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
19 * Lesser General Public License for more details.
21 * You should have received a copy of the GNU Lesser General Public
22 * License along with FFmpeg; if not, write to the Free Software
23 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
31 #include "libavutil/atomic.h"
32 #include "libavutil/avassert.h"
38 const uint8_t ff_log2_run
[41]={
39 0, 0, 0, 0, 1, 1, 1, 1,
40 2, 2, 2, 2, 3, 3, 3, 3,
41 4, 4, 5, 5, 6, 6, 7, 7,
42 8, 9,10,11,12,13,14,15,
43 16,17,18,19,20,21,22,23,
47 void avpriv_align_put_bits(PutBitContext
*s
)
49 put_bits(s
, s
->bit_left
& 7, 0);
52 void avpriv_put_string(PutBitContext
*pb
, const char *string
,
56 put_bits(pb
, 8, *string
);
63 void avpriv_copy_bits(PutBitContext
*pb
, const uint8_t *src
, int length
)
65 int words
= length
>> 4;
66 int bits
= length
& 15;
72 if (CONFIG_SMALL
|| words
< 16 || put_bits_count(pb
) & 7) {
73 for (i
= 0; i
< words
; i
++)
74 put_bits(pb
, 16, AV_RB16(src
+ 2 * i
));
76 for (i
= 0; put_bits_count(pb
) & 31; i
++)
77 put_bits(pb
, 8, src
[i
]);
79 memcpy(put_bits_ptr(pb
), src
+ i
, 2 * words
- i
);
80 skip_put_bytes(pb
, 2 * words
- i
);
83 put_bits(pb
, bits
, AV_RB16(src
+ 2 * words
) >> (16 - bits
));
88 #define GET_DATA(v, table, i, wrap, size) \
90 const uint8_t *ptr = (const uint8_t *)table + i * wrap; \
93 v = *(const uint8_t *)ptr; \
96 v = *(const uint16_t *)ptr; \
99 v = *(const uint32_t *)ptr; \
105 static int alloc_table(VLC
*vlc
, int size
, int use_static
)
107 int index
= vlc
->table_size
;
109 vlc
->table_size
+= size
;
110 if (vlc
->table_size
> vlc
->table_allocated
) {
112 abort(); // cannot do anything, init_vlc() is used with too little memory
113 vlc
->table_allocated
+= (1 << vlc
->bits
);
114 vlc
->table
= av_realloc_f(vlc
->table
, vlc
->table_allocated
, sizeof(VLC_TYPE
) * 2);
116 vlc
->table_allocated
= 0;
118 return AVERROR(ENOMEM
);
120 memset(vlc
->table
+ vlc
->table_allocated
- (1 << vlc
->bits
), 0, sizeof(VLC_TYPE
) * 2 << vlc
->bits
);
125 static av_always_inline
uint32_t bitswap_32(uint32_t x
)
127 return (uint32_t)ff_reverse
[ x
& 0xFF] << 24 |
128 (uint32_t)ff_reverse
[(x
>> 8) & 0xFF] << 16 |
129 (uint32_t)ff_reverse
[(x
>> 16) & 0xFF] << 8 |
130 (uint32_t)ff_reverse
[ x
>> 24];
136 /** codeword, with the first bit-to-be-read in the msb
137 * (even if intended for a little-endian bitstream reader) */
141 static int compare_vlcspec(const void *a
, const void *b
)
143 const VLCcode
*sa
= a
, *sb
= b
;
144 return (sa
->code
>> 1) - (sb
->code
>> 1);
147 * Build VLC decoding tables suitable for use with get_vlc().
149 * @param vlc the context to be initted
151 * @param table_nb_bits max length of vlc codes to store directly in this table
152 * (Longer codes are delegated to subtables.)
154 * @param nb_codes number of elements in codes[]
156 * @param codes descriptions of the vlc codes
157 * These must be ordered such that codes going into the same subtable are contiguous.
158 * Sorting by VLCcode.code is sufficient, though not necessary.
160 static int build_table(VLC
*vlc
, int table_nb_bits
, int nb_codes
,
161 VLCcode
*codes
, int flags
)
163 int table_size
, table_index
, index
, code_prefix
, symbol
, subtable_bits
;
164 int i
, j
, k
, n
, nb
, inc
;
166 volatile VLC_TYPE (* volatile table
)[2]; // the double volatile is needed to prevent a internal compiler error in gcc 4.2
168 table_size
= 1 << table_nb_bits
;
169 if (table_nb_bits
> 30)
171 table_index
= alloc_table(vlc
, table_size
, flags
& INIT_VLC_USE_NEW_STATIC
);
172 av_dlog(NULL
, "new table index=%d size=%d\n", table_index
, table_size
);
175 table
= (volatile VLC_TYPE (*)[2])&vlc
->table
[table_index
];
177 /* first pass: map codes and compute auxiliary table sizes */
178 for (i
= 0; i
< nb_codes
; i
++) {
180 code
= codes
[i
].code
;
181 symbol
= codes
[i
].symbol
;
182 av_dlog(NULL
, "i=%d n=%d code=0x%x\n", i
, n
, code
);
183 if (n
<= table_nb_bits
) {
184 /* no need to add another table */
185 j
= code
>> (32 - table_nb_bits
);
186 nb
= 1 << (table_nb_bits
- n
);
188 if (flags
& INIT_VLC_LE
) {
189 j
= bitswap_32(code
);
192 for (k
= 0; k
< nb
; k
++) {
193 int bits
= table
[j
][1];
194 av_dlog(NULL
, "%4x: code=%d n=%d\n", j
, i
, n
);
195 if (bits
!= 0 && bits
!= n
) {
196 av_log(NULL
, AV_LOG_ERROR
, "incorrect codes\n");
197 return AVERROR_INVALIDDATA
;
199 table
[j
][1] = n
; //bits
200 table
[j
][0] = symbol
;
204 /* fill auxiliary table recursively */
206 code_prefix
= code
>> (32 - table_nb_bits
);
209 codes
[i
].code
= code
<< table_nb_bits
;
210 for (k
= i
+1; k
< nb_codes
; k
++) {
211 n
= codes
[k
].bits
- table_nb_bits
;
214 code
= codes
[k
].code
;
215 if (code
>> (32 - table_nb_bits
) != code_prefix
)
218 codes
[k
].code
= code
<< table_nb_bits
;
219 subtable_bits
= FFMAX(subtable_bits
, n
);
221 subtable_bits
= FFMIN(subtable_bits
, table_nb_bits
);
222 j
= (flags
& INIT_VLC_LE
) ? bitswap_32(code_prefix
) >> (32 - table_nb_bits
) : code_prefix
;
223 table
[j
][1] = -subtable_bits
;
224 av_dlog(NULL
, "%4x: n=%d (subtable)\n",
225 j
, codes
[i
].bits
+ table_nb_bits
);
226 index
= build_table(vlc
, subtable_bits
, k
-i
, codes
+i
, flags
);
229 /* note: realloc has been done, so reload tables */
230 table
= (volatile VLC_TYPE (*)[2])&vlc
->table
[table_index
];
231 table
[j
][0] = index
; //code
236 for (i
= 0; i
< table_size
; i
++) {
237 if (table
[i
][1] == 0) //bits
238 table
[i
][0] = -1; //codes
245 /* Build VLC decoding tables suitable for use with get_vlc().
247 'nb_bits' set thee decoding table size (2^nb_bits) entries. The
248 bigger it is, the faster is the decoding. But it should not be too
249 big to save memory and L1 cache. '9' is a good compromise.
251 'nb_codes' : number of vlcs codes
253 'bits' : table which gives the size (in bits) of each vlc code.
255 'codes' : table which gives the bit pattern of of each vlc code.
257 'symbols' : table which gives the values to be returned from get_vlc().
259 'xxx_wrap' : give the number of bytes between each entry of the
260 'bits' or 'codes' tables.
262 'xxx_size' : gives the number of bytes of each entry of the 'bits'
265 'wrap' and 'size' allows to use any memory configuration and types
266 (byte/word/long) to store the 'bits', 'codes', and 'symbols' tables.
268 'use_static' should be set to 1 for tables, which should be freed
269 with av_free_static(), 0 if ff_free_vlc() will be used.
271 int ff_init_vlc_sparse(VLC
*vlc_arg
, int nb_bits
, int nb_codes
,
272 const void *bits
, int bits_wrap
, int bits_size
,
273 const void *codes
, int codes_wrap
, int codes_size
,
274 const void *symbols
, int symbols_wrap
, int symbols_size
,
279 VLCcode localbuf
[1500]; // the maximum currently needed is 1296 by rv34
284 if (flags
& INIT_VLC_USE_NEW_STATIC
) {
285 av_assert0(nb_codes
+ 1 <= FF_ARRAY_ELEMS(localbuf
));
292 vlc
->table_allocated
= 0;
295 buf
= av_malloc_array((nb_codes
+ 1), sizeof(VLCcode
));
297 return AVERROR(ENOMEM
);
301 av_assert0(symbols_size
<= 2 || !symbols
);
303 #define COPY(condition)\
304 for (i = 0; i < nb_codes; i++) { \
305 GET_DATA(buf[j].bits, bits, i, bits_wrap, bits_size); \
308 if (buf[j].bits > 3*nb_bits || buf[j].bits>32) { \
309 av_log(NULL, AV_LOG_ERROR, "Too long VLC (%d) in init_vlc\n", buf[j].bits);\
310 if (!(flags & INIT_VLC_USE_NEW_STATIC)) \
314 GET_DATA(buf[j].code, codes, i, codes_wrap, codes_size); \
315 if (buf[j].code >= (1LL<<buf[j].bits)) { \
316 av_log(NULL, AV_LOG_ERROR, "Invalid code in init_vlc\n"); \
317 if (!(flags & INIT_VLC_USE_NEW_STATIC)) \
321 if (flags & INIT_VLC_LE) \
322 buf[j].code = bitswap_32(buf[j].code); \
324 buf[j].code <<= 32 - buf[j].bits; \
326 GET_DATA(buf[j].symbol, symbols, i, symbols_wrap, symbols_size) \
331 COPY(buf
[j
].bits
> nb_bits
);
332 // qsort is the slowest part of init_vlc, and could probably be improved or avoided
333 qsort(buf
, j
, sizeof(VLCcode
), compare_vlcspec
);
334 COPY(buf
[j
].bits
&& buf
[j
].bits
<= nb_bits
);
337 ret
= build_table(vlc
, nb_bits
, nb_codes
, buf
, flags
);
339 if (flags
& INIT_VLC_USE_NEW_STATIC
) {
340 if(vlc
->table_size
!= vlc
->table_allocated
)
341 av_log(NULL
, AV_LOG_ERROR
, "needed %d had %d\n", vlc
->table_size
, vlc
->table_allocated
);
343 av_assert0(ret
>= 0);
348 av_freep(&vlc
->table
);
356 void ff_free_vlc(VLC
*vlc
)
358 av_freep(&vlc
->table
);