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ppsspp/ext/ffmpeg/libavcodec/bitstream.c
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Henrik RydgårdandClaude Opus 5.5 d0e3141f43 FFmpeg: Vendor what PPSSPP uses into ext/ffmpeg, drop the submodule 
The ffmpeg submodule held prebuilt libraries for every platform next to the
sources (about 1.5 GB checked out), and nothing uses those any more. Only the
needed sources are copied in, from the submodule's commit, along with every
header and template they include. The path is new, so checking out commits on
either side of this works.

It's also cut down to what PPSSPP uses: the H.264, AAC, MP3, ATRAC3 and ATRAC3+
decoders, the H.264 parser, the demuxers as before, and the FFV1 encoder, AVI
muxer and file protocol for AVI dumping. config.h takes its CONFIG_ values from
FFmpeg 3.0.2's own configure run with just those enabled. The raw H.264 demuxer
stays even though nothing opens raw H.264: probing PSMF data uses it to identify
the video stream's codec, which otherwise comes out as none.

On top of that:
- The files nothing links (configure would build them, but they're never pulled
  out of the static library, going by the GCC link map) are left out: mostly
  libavutil's crypto and hashing and the alternative DCT/IDCT/FFT versions.
- libswresample isn't built, now that nothing uses it.
- The H.264 decoder only does 8-bit video, which is all the PSP has. The SPS
  parser rejects any other bit depth, and the DSP files no longer build their 9-
  to 16-bit variants, which the linker kept because the init functions pick one
  by bit depth at run time.

That's 160 files to compile instead of 277, and 391 of FFmpeg's vendored, about
5.8 MB. The README in ext/ffmpeg has what was done, the PPSSPP patches in the
copy, how to add a component, and the tradeoffs.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
2026-10-25 22:27:54 +01:00

364 lines
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/*
* Common bit i/o utils
* Copyright (c) 2000, 2001 Fabrice Bellard
* Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
* Copyright (c) 2010 Loren Merritt
*
* alternative bitstream reader & writer by Michael Niedermayer <michaelni@gmx.at>
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* bitstream api.
*/
#include "libavutil/atomic.h"
#include "libavutil/avassert.h"
#include "libavutil/qsort.h"
#include "avcodec.h"
#include "internal.h"
#include "mathops.h"
#include "get_bits.h"
#include "put_bits.h"
const uint8_t ff_log2_run[41]={
0, 0, 0, 0, 1, 1, 1, 1,
2, 2, 2, 2, 3, 3, 3, 3,
4, 4, 5, 5, 6, 6, 7, 7,
8, 9,10,11,12,13,14,15,
16,17,18,19,20,21,22,23,
24,
};
void avpriv_align_put_bits(PutBitContext *s)
{
put_bits(s, s->bit_left & 7, 0);
}
void avpriv_put_string(PutBitContext *pb, const char *string,
int terminate_string)
{
while (*string) {
put_bits(pb, 8, *string);
string++;
}
if (terminate_string)
put_bits(pb, 8, 0);
}
void avpriv_copy_bits(PutBitContext *pb, const uint8_t *src, int length)
{
int words = length >> 4;
int bits = length & 15;
int i;
if (length == 0)
return;
av_assert0(length <= put_bits_left(pb));
if (CONFIG_SMALL || words < 16 || put_bits_count(pb) & 7) {
for (i = 0; i < words; i++)
put_bits(pb, 16, AV_RB16(src + 2 * i));
} else {
for (i = 0; put_bits_count(pb) & 31; i++)
put_bits(pb, 8, src[i]);
flush_put_bits(pb);
memcpy(put_bits_ptr(pb), src + i, 2 * words - i);
skip_put_bytes(pb, 2 * words - i);
}
put_bits(pb, bits, AV_RB16(src + 2 * words) >> (16 - bits));
}
/* VLC decoding */
#define GET_DATA(v, table, i, wrap, size) \
{ \
const uint8_t *ptr = (const uint8_t *)table + i * wrap; \
switch(size) { \
case 1: \
v = *(const uint8_t *)ptr; \
break; \
case 2: \
v = *(const uint16_t *)ptr; \
break; \
default: \
v = *(const uint32_t *)ptr; \
break; \
} \
}
static int alloc_table(VLC *vlc, int size, int use_static)
{
int index = vlc->table_size;
vlc->table_size += size;
if (vlc->table_size > vlc->table_allocated) {
if (use_static)
abort(); // cannot do anything, init_vlc() is used with too little memory
vlc->table_allocated += (1 << vlc->bits);
vlc->table = av_realloc_f(vlc->table, vlc->table_allocated, sizeof(VLC_TYPE) * 2);
if (!vlc->table) {
vlc->table_allocated = 0;
vlc->table_size = 0;
return AVERROR(ENOMEM);
}
memset(vlc->table + vlc->table_allocated - (1 << vlc->bits), 0, sizeof(VLC_TYPE) * 2 << vlc->bits);
}
return index;
}
static av_always_inline uint32_t bitswap_32(uint32_t x)
{
return (uint32_t)ff_reverse[ x & 0xFF] << 24 |
(uint32_t)ff_reverse[(x >> 8) & 0xFF] << 16 |
(uint32_t)ff_reverse[(x >> 16) & 0xFF] << 8 |
(uint32_t)ff_reverse[ x >> 24];
}
typedef struct VLCcode {
uint8_t bits;
uint16_t symbol;
/** codeword, with the first bit-to-be-read in the msb
* (even if intended for a little-endian bitstream reader) */
uint32_t code;
} VLCcode;
static int compare_vlcspec(const void *a, const void *b)
{
const VLCcode *sa = a, *sb = b;
return (sa->code >> 1) - (sb->code >> 1);
}
/**
* Build VLC decoding tables suitable for use with get_vlc().
*
* @param vlc the context to be initted
*
* @param table_nb_bits max length of vlc codes to store directly in this table
* (Longer codes are delegated to subtables.)
*
* @param nb_codes number of elements in codes[]
*
* @param codes descriptions of the vlc codes
* These must be ordered such that codes going into the same subtable are contiguous.
* Sorting by VLCcode.code is sufficient, though not necessary.
*/
static int build_table(VLC *vlc, int table_nb_bits, int nb_codes,
VLCcode *codes, int flags)
{
int table_size, table_index, index, code_prefix, symbol, subtable_bits;
int i, j, k, n, nb, inc;
uint32_t code;
volatile VLC_TYPE (* volatile table)[2]; // the double volatile is needed to prevent a internal compiler error in gcc 4.2
table_size = 1 << table_nb_bits;
if (table_nb_bits > 30)
return -1;
table_index = alloc_table(vlc, table_size, flags & INIT_VLC_USE_NEW_STATIC);
ff_dlog(NULL, "new table index=%d size=%d\n", table_index, table_size);
if (table_index < 0)
return table_index;
table = (volatile VLC_TYPE (*)[2])&vlc->table[table_index];
/* first pass: map codes and compute auxiliary table sizes */
for (i = 0; i < nb_codes; i++) {
n = codes[i].bits;
code = codes[i].code;
symbol = codes[i].symbol;
ff_dlog(NULL, "i=%d n=%d code=0x%x\n", i, n, code);
if (n <= table_nb_bits) {
/* no need to add another table */
j = code >> (32 - table_nb_bits);
nb = 1 << (table_nb_bits - n);
inc = 1;
if (flags & INIT_VLC_LE) {
j = bitswap_32(code);
inc = 1 << n;
}
for (k = 0; k < nb; k++) {
int bits = table[j][1];
ff_dlog(NULL, "%4x: code=%d n=%d\n", j, i, n);
if (bits != 0 && bits != n) {
av_log(NULL, AV_LOG_ERROR, "incorrect codes\n");
return AVERROR_INVALIDDATA;
}
table[j][1] = n; //bits
table[j][0] = symbol;
j += inc;
}
} else {
/* fill auxiliary table recursively */
n -= table_nb_bits;
code_prefix = code >> (32 - table_nb_bits);
subtable_bits = n;
codes[i].bits = n;
codes[i].code = code << table_nb_bits;
for (k = i+1; k < nb_codes; k++) {
n = codes[k].bits - table_nb_bits;
if (n <= 0)
break;
code = codes[k].code;
if (code >> (32 - table_nb_bits) != code_prefix)
break;
codes[k].bits = n;
codes[k].code = code << table_nb_bits;
subtable_bits = FFMAX(subtable_bits, n);
}
subtable_bits = FFMIN(subtable_bits, table_nb_bits);
j = (flags & INIT_VLC_LE) ? bitswap_32(code_prefix) >> (32 - table_nb_bits) : code_prefix;
table[j][1] = -subtable_bits;
ff_dlog(NULL, "%4x: n=%d (subtable)\n",
j, codes[i].bits + table_nb_bits);
index = build_table(vlc, subtable_bits, k-i, codes+i, flags);
if (index < 0)
return index;
/* note: realloc has been done, so reload tables */
table = (volatile VLC_TYPE (*)[2])&vlc->table[table_index];
table[j][0] = index; //code
i = k-1;
}
}
for (i = 0; i < table_size; i++) {
if (table[i][1] == 0) //bits
table[i][0] = -1; //codes
}
return table_index;
}
/* Build VLC decoding tables suitable for use with get_vlc().
'nb_bits' set the decoding table size (2^nb_bits) entries. The
bigger it is, the faster is the decoding. But it should not be too
big to save memory and L1 cache. '9' is a good compromise.
'nb_codes' : number of vlcs codes
'bits' : table which gives the size (in bits) of each vlc code.
'codes' : table which gives the bit pattern of of each vlc code.
'symbols' : table which gives the values to be returned from get_vlc().
'xxx_wrap' : give the number of bytes between each entry of the
'bits' or 'codes' tables.
'xxx_size' : gives the number of bytes of each entry of the 'bits'
or 'codes' tables.
'wrap' and 'size' make it possible to use any memory configuration and types
(byte/word/long) to store the 'bits', 'codes', and 'symbols' tables.
'use_static' should be set to 1 for tables, which should be freed
with av_free_static(), 0 if ff_free_vlc() will be used.
*/
int ff_init_vlc_sparse(VLC *vlc_arg, int nb_bits, int nb_codes,
const void *bits, int bits_wrap, int bits_size,
const void *codes, int codes_wrap, int codes_size,
const void *symbols, int symbols_wrap, int symbols_size,
int flags)
{
VLCcode *buf;
int i, j, ret;
VLCcode localbuf[1500]; // the maximum currently needed is 1296 by rv34
VLC localvlc, *vlc;
vlc = vlc_arg;
vlc->bits = nb_bits;
if (flags & INIT_VLC_USE_NEW_STATIC) {
av_assert0(nb_codes + 1 <= FF_ARRAY_ELEMS(localbuf));
buf = localbuf;
localvlc = *vlc_arg;
vlc = &localvlc;
vlc->table_size = 0;
} else {
vlc->table = NULL;
vlc->table_allocated = 0;
vlc->table_size = 0;
buf = av_malloc_array((nb_codes + 1), sizeof(VLCcode));
if (!buf)
return AVERROR(ENOMEM);
}
av_assert0(symbols_size <= 2 || !symbols);
j = 0;
#define COPY(condition)\
for (i = 0; i < nb_codes; i++) { \
GET_DATA(buf[j].bits, bits, i, bits_wrap, bits_size); \
if (!(condition)) \
continue; \
if (buf[j].bits > 3*nb_bits || buf[j].bits>32) { \
av_log(NULL, AV_LOG_ERROR, "Too long VLC (%d) in init_vlc\n", buf[j].bits);\
if (!(flags & INIT_VLC_USE_NEW_STATIC)) \
av_free(buf); \
return -1; \
} \
GET_DATA(buf[j].code, codes, i, codes_wrap, codes_size); \
if (buf[j].code >= (1LL<<buf[j].bits)) { \
av_log(NULL, AV_LOG_ERROR, "Invalid code in init_vlc\n"); \
if (!(flags & INIT_VLC_USE_NEW_STATIC)) \
av_free(buf); \
return -1; \
} \
if (flags & INIT_VLC_LE) \
buf[j].code = bitswap_32(buf[j].code); \
else \
buf[j].code <<= 32 - buf[j].bits; \
if (symbols) \
GET_DATA(buf[j].symbol, symbols, i, symbols_wrap, symbols_size) \
else \
buf[j].symbol = i; \
j++; \
}
COPY(buf[j].bits > nb_bits);
// qsort is the slowest part of init_vlc, and could probably be improved or avoided
AV_QSORT(buf, j, struct VLCcode, compare_vlcspec);
COPY(buf[j].bits && buf[j].bits <= nb_bits);
nb_codes = j;
ret = build_table(vlc, nb_bits, nb_codes, buf, flags);
if (flags & INIT_VLC_USE_NEW_STATIC) {
if(vlc->table_size != vlc->table_allocated)
av_log(NULL, AV_LOG_ERROR, "needed %d had %d\n", vlc->table_size, vlc->table_allocated);
av_assert0(ret >= 0);
*vlc_arg = *vlc;
} else {
av_free(buf);
if (ret < 0) {
av_freep(&vlc->table);
return ret;
}
}
return 0;
}
void ff_free_vlc(VLC *vlc)
{
av_freep(&vlc->table);
}
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