mirror of
https://git.ffmpeg.org/ffmpeg.git
synced 2024-12-28 02:12:28 +00:00
b629deab3d
Right now the allocated size of the VLC table of a static VLC has to
exactly match the size actually used for the VLC: If it is not enough,
abort is called; if it is more than enough, an error message is
emitted. This is no problem when one wants to initialize an individual
VLC via one of the INIT_VLC macros as one just hardcodes the needed
size. Yet it is an obstacle when one wants to initialize several VLCs
in a loop as one then needs to add an array for the sizes/offsets of
the VLC tables (unless max_depth of all arrays is one in which case
the sizes are derivable from the number of bits used).
Yet said size array is not necessary if one disables the warning for too
big buffers. The reason is that the amount of entries needed for the
table is of course generated as a byproduct of initializing the VLC.
To this end a flag that disables the warning has been added.
So one can proceed as follows:
static VLC vlcs[NUM];
static VLC_TYPE vlc_table[BUF_SIZE][2];
for (int i = 0, offset = 0; i < NUM; i++) {
vlcs[i].table = &vlc_table[offset];
vlcs[i].table_allocated = BUF_SIZE - offset;
init_vlc(); /* With INIT_VLC_STATIC_OVERLONG flag */
offset += vlcs[i].table_size;
}
Of course, BUF_SIZE should be equal to the number of entries actually
needed.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
435 lines
16 KiB
C
435 lines
16 KiB
C
/*
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* Common bit i/o utils
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* Copyright (c) 2000, 2001 Fabrice Bellard
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* Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
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* Copyright (c) 2010 Loren Merritt
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*
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* alternative bitstream reader & writer by Michael Niedermayer <michaelni@gmx.at>
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* bitstream api.
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*/
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#include "libavutil/avassert.h"
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#include "libavutil/qsort.h"
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#include "avcodec.h"
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#include "internal.h"
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#include "mathops.h"
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#include "put_bits.h"
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#include "vlc.h"
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const uint8_t ff_log2_run[41]={
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0, 0, 0, 0, 1, 1, 1, 1,
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2, 2, 2, 2, 3, 3, 3, 3,
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4, 4, 5, 5, 6, 6, 7, 7,
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8, 9,10,11,12,13,14,15,
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16,17,18,19,20,21,22,23,
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24,
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};
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#if FF_API_AVPRIV_PUT_BITS
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void avpriv_align_put_bits(PutBitContext *s)
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{
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align_put_bits(s);
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}
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void avpriv_copy_bits(PutBitContext *pb, const uint8_t *src, int length)
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{
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ff_copy_bits(pb, src, length);
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}
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#endif
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void ff_put_string(PutBitContext *pb, const char *string, int terminate_string)
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{
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while (*string) {
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put_bits(pb, 8, *string);
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string++;
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}
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if (terminate_string)
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put_bits(pb, 8, 0);
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}
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void ff_copy_bits(PutBitContext *pb, const uint8_t *src, int length)
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{
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int words = length >> 4;
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int bits = length & 15;
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int i;
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if (length == 0)
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return;
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av_assert0(length <= put_bits_left(pb));
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if (CONFIG_SMALL || words < 16 || put_bits_count(pb) & 7) {
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for (i = 0; i < words; i++)
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put_bits(pb, 16, AV_RB16(src + 2 * i));
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} else {
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for (i = 0; put_bits_count(pb) & 31; i++)
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put_bits(pb, 8, src[i]);
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flush_put_bits(pb);
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memcpy(put_bits_ptr(pb), src + i, 2 * words - i);
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skip_put_bytes(pb, 2 * words - i);
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}
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put_bits(pb, bits, AV_RB16(src + 2 * words) >> (16 - bits));
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}
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/* VLC decoding */
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#define GET_DATA(v, table, i, wrap, size) \
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{ \
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const uint8_t *ptr = (const uint8_t *)table + i * wrap; \
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switch(size) { \
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case 1: \
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v = *(const uint8_t *)ptr; \
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break; \
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case 2: \
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v = *(const uint16_t *)ptr; \
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break; \
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case 4: \
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v = *(const uint32_t *)ptr; \
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break; \
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default: \
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av_assert1(0); \
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} \
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}
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static int alloc_table(VLC *vlc, int size, int use_static)
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{
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int index = vlc->table_size;
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vlc->table_size += size;
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if (vlc->table_size > vlc->table_allocated) {
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if (use_static)
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abort(); // cannot do anything, init_vlc() is used with too little memory
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vlc->table_allocated += (1 << vlc->bits);
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vlc->table = av_realloc_f(vlc->table, vlc->table_allocated, sizeof(VLC_TYPE) * 2);
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if (!vlc->table) {
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vlc->table_allocated = 0;
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vlc->table_size = 0;
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return AVERROR(ENOMEM);
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}
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memset(vlc->table + vlc->table_allocated - (1 << vlc->bits), 0, sizeof(VLC_TYPE) * 2 << vlc->bits);
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}
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return index;
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}
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#define LOCALBUF_ELEMS 1500 // the maximum currently needed is 1296 by rv34
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typedef struct VLCcode {
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uint8_t bits;
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VLC_TYPE symbol;
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/** codeword, with the first bit-to-be-read in the msb
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* (even if intended for a little-endian bitstream reader) */
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uint32_t code;
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} VLCcode;
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static int vlc_common_init(VLC *vlc_arg, int nb_bits, int nb_codes,
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VLC **vlc, VLC *localvlc, VLCcode **buf,
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int flags)
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{
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*vlc = vlc_arg;
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(*vlc)->bits = nb_bits;
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if (flags & INIT_VLC_USE_NEW_STATIC) {
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av_assert0(nb_codes <= LOCALBUF_ELEMS);
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*localvlc = *vlc_arg;
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*vlc = localvlc;
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(*vlc)->table_size = 0;
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} else {
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(*vlc)->table = NULL;
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(*vlc)->table_allocated = 0;
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(*vlc)->table_size = 0;
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}
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if (nb_codes > LOCALBUF_ELEMS) {
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*buf = av_malloc_array(nb_codes, sizeof(VLCcode));
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if (!*buf)
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return AVERROR(ENOMEM);
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}
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return 0;
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}
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static int compare_vlcspec(const void *a, const void *b)
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{
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const VLCcode *sa = a, *sb = b;
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return (sa->code >> 1) - (sb->code >> 1);
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}
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/**
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* Build VLC decoding tables suitable for use with get_vlc().
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*
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* @param vlc the context to be initialized
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*
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* @param table_nb_bits max length of vlc codes to store directly in this table
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* (Longer codes are delegated to subtables.)
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*
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* @param nb_codes number of elements in codes[]
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*
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* @param codes descriptions of the vlc codes
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* These must be ordered such that codes going into the same subtable are contiguous.
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* Sorting by VLCcode.code is sufficient, though not necessary.
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*/
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static int build_table(VLC *vlc, int table_nb_bits, int nb_codes,
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VLCcode *codes, int flags)
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{
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int table_size, table_index, index, code_prefix, symbol, subtable_bits;
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int i, j, k, n, nb, inc;
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uint32_t code;
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volatile VLC_TYPE (* volatile table)[2]; // the double volatile is needed to prevent an internal compiler error in gcc 4.2
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if (table_nb_bits > 30)
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return AVERROR(EINVAL);
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table_size = 1 << table_nb_bits;
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table_index = alloc_table(vlc, table_size, flags & INIT_VLC_USE_NEW_STATIC);
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ff_dlog(NULL, "new table index=%d size=%d\n", table_index, table_size);
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if (table_index < 0)
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return table_index;
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table = (volatile VLC_TYPE (*)[2])&vlc->table[table_index];
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/* first pass: map codes and compute auxiliary table sizes */
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for (i = 0; i < nb_codes; i++) {
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n = codes[i].bits;
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code = codes[i].code;
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symbol = codes[i].symbol;
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ff_dlog(NULL, "i=%d n=%d code=0x%"PRIx32"\n", i, n, code);
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if (n <= table_nb_bits) {
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/* no need to add another table */
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j = code >> (32 - table_nb_bits);
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nb = 1 << (table_nb_bits - n);
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inc = 1;
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if (flags & INIT_VLC_OUTPUT_LE) {
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j = bitswap_32(code);
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inc = 1 << n;
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}
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for (k = 0; k < nb; k++) {
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int bits = table[j][1];
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int oldsym = table[j][0];
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ff_dlog(NULL, "%4x: code=%d n=%d\n", j, i, n);
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if ((bits || oldsym) && (bits != n || oldsym != symbol)) {
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av_log(NULL, AV_LOG_ERROR, "incorrect codes\n");
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return AVERROR_INVALIDDATA;
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}
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table[j][1] = n; //bits
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table[j][0] = symbol;
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j += inc;
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}
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} else {
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/* fill auxiliary table recursively */
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n -= table_nb_bits;
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code_prefix = code >> (32 - table_nb_bits);
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subtable_bits = n;
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codes[i].bits = n;
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codes[i].code = code << table_nb_bits;
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for (k = i+1; k < nb_codes; k++) {
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n = codes[k].bits - table_nb_bits;
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if (n <= 0)
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break;
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code = codes[k].code;
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if (code >> (32 - table_nb_bits) != code_prefix)
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break;
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codes[k].bits = n;
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codes[k].code = code << table_nb_bits;
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subtable_bits = FFMAX(subtable_bits, n);
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}
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subtable_bits = FFMIN(subtable_bits, table_nb_bits);
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j = (flags & INIT_VLC_OUTPUT_LE) ? bitswap_32(code_prefix) >> (32 - table_nb_bits) : code_prefix;
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table[j][1] = -subtable_bits;
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ff_dlog(NULL, "%4x: n=%d (subtable)\n",
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j, codes[i].bits + table_nb_bits);
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index = build_table(vlc, subtable_bits, k-i, codes+i, flags);
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if (index < 0)
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return index;
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/* note: realloc has been done, so reload tables */
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table = (volatile VLC_TYPE (*)[2])&vlc->table[table_index];
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table[j][0] = index; //code
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if (table[j][0] != index) {
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avpriv_request_sample(NULL, "strange codes");
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return AVERROR_PATCHWELCOME;
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}
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i = k-1;
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}
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}
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for (i = 0; i < table_size; i++) {
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if (table[i][1] == 0) //bits
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table[i][0] = -1; //codes
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}
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return table_index;
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}
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static int vlc_common_end(VLC *vlc, int nb_bits, int nb_codes, VLCcode *codes,
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int flags, VLC *vlc_arg, VLCcode localbuf[LOCALBUF_ELEMS])
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{
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int ret = build_table(vlc, nb_bits, nb_codes, codes, flags);
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if (flags & INIT_VLC_USE_NEW_STATIC) {
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if (vlc->table_size != vlc->table_allocated &&
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!(flags & (INIT_VLC_STATIC_OVERLONG & ~INIT_VLC_USE_NEW_STATIC)))
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av_log(NULL, AV_LOG_ERROR, "needed %d had %d\n", vlc->table_size, vlc->table_allocated);
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av_assert0(ret >= 0);
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*vlc_arg = *vlc;
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} else {
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if (codes != localbuf)
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av_free(codes);
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if (ret < 0) {
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av_freep(&vlc->table);
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return ret;
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}
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}
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return 0;
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}
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/* Build VLC decoding tables suitable for use with get_vlc().
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'nb_bits' sets the decoding table size (2^nb_bits) entries. The
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bigger it is, the faster is the decoding. But it should not be too
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big to save memory and L1 cache. '9' is a good compromise.
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'nb_codes' : number of vlcs codes
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'bits' : table which gives the size (in bits) of each vlc code.
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'codes' : table which gives the bit pattern of of each vlc code.
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'symbols' : table which gives the values to be returned from get_vlc().
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'xxx_wrap' : give the number of bytes between each entry of the
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'bits' or 'codes' tables.
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'xxx_size' : gives the number of bytes of each entry of the 'bits'
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or 'codes' tables. Currently 1,2 and 4 are supported.
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'wrap' and 'size' make it possible to use any memory configuration and types
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(byte/word/long) to store the 'bits', 'codes', and 'symbols' tables.
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*/
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int ff_init_vlc_sparse(VLC *vlc_arg, int nb_bits, int nb_codes,
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const void *bits, int bits_wrap, int bits_size,
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const void *codes, int codes_wrap, int codes_size,
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const void *symbols, int symbols_wrap, int symbols_size,
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int flags)
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{
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VLCcode localbuf[LOCALBUF_ELEMS], *buf = localbuf;
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int i, j, ret;
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VLC localvlc, *vlc;
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ret = vlc_common_init(vlc_arg, nb_bits, nb_codes, &vlc, &localvlc,
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&buf, flags);
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if (ret < 0)
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return ret;
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av_assert0(symbols_size <= 2 || !symbols);
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j = 0;
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#define COPY(condition)\
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for (i = 0; i < nb_codes; i++) { \
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unsigned len; \
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GET_DATA(len, bits, i, bits_wrap, bits_size); \
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if (!(condition)) \
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continue; \
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if (len > 3*nb_bits || len > 32) { \
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av_log(NULL, AV_LOG_ERROR, "Too long VLC (%u) in init_vlc\n", len);\
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if (buf != localbuf) \
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av_free(buf); \
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return AVERROR(EINVAL); \
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} \
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buf[j].bits = len; \
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GET_DATA(buf[j].code, codes, i, codes_wrap, codes_size); \
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if (buf[j].code >= (1LL<<buf[j].bits)) { \
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av_log(NULL, AV_LOG_ERROR, "Invalid code %"PRIx32" for %d in " \
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"init_vlc\n", buf[j].code, i); \
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if (buf != localbuf) \
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av_free(buf); \
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return AVERROR(EINVAL); \
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} \
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if (flags & INIT_VLC_INPUT_LE) \
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buf[j].code = bitswap_32(buf[j].code); \
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else \
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buf[j].code <<= 32 - buf[j].bits; \
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if (symbols) \
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GET_DATA(buf[j].symbol, symbols, i, symbols_wrap, symbols_size) \
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else \
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buf[j].symbol = i; \
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j++; \
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}
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COPY(len > nb_bits);
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// qsort is the slowest part of init_vlc, and could probably be improved or avoided
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AV_QSORT(buf, j, struct VLCcode, compare_vlcspec);
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COPY(len && len <= nb_bits);
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nb_codes = j;
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return vlc_common_end(vlc, nb_bits, nb_codes, buf,
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flags, vlc_arg, localbuf);
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}
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int ff_init_vlc_from_lengths(VLC *vlc_arg, int nb_bits, int nb_codes,
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const int8_t *lens, int lens_wrap,
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const void *symbols, int symbols_wrap, int symbols_size,
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int offset, int flags, void *logctx)
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{
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VLCcode localbuf[LOCALBUF_ELEMS], *buf = localbuf;
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VLC localvlc, *vlc;
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uint64_t code;
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int ret, j, len_max = FFMIN(32, 3 * nb_bits);
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ret = vlc_common_init(vlc_arg, nb_bits, nb_codes, &vlc, &localvlc,
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&buf, flags);
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if (ret < 0)
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return ret;
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j = code = 0;
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for (int i = 0; i < nb_codes; i++, lens += lens_wrap) {
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int len = *lens;
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if (len > 0) {
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unsigned sym;
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buf[j].bits = len;
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if (symbols)
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GET_DATA(sym, symbols, i, symbols_wrap, symbols_size)
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else
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sym = i;
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buf[j].symbol = sym + offset;
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buf[j++].code = code;
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} else if (len < 0) {
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len = -len;
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} else
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continue;
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if (len > len_max || code & ((1U << (32 - len)) - 1)) {
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av_log(logctx, AV_LOG_ERROR, "Invalid VLC (length %u)\n", len);
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goto fail;
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}
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code += 1U << (32 - len);
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if (code > UINT32_MAX + 1ULL) {
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av_log(logctx, AV_LOG_ERROR, "Overdetermined VLC tree\n");
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goto fail;
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}
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}
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return vlc_common_end(vlc, nb_bits, j, buf,
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flags, vlc_arg, localbuf);
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fail:
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if (buf != localbuf)
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av_free(buf);
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return AVERROR_INVALIDDATA;
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}
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void ff_free_vlc(VLC *vlc)
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{
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av_freep(&vlc->table);
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}
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