mirror of
https://git.videolan.org/git/ffmpeg.git
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692 lines
19 KiB
C
692 lines
19 KiB
C
/*
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* copyright (c) 2004 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 reader API header.
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*/
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#ifndef AVCODEC_GET_BITS_H
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#define AVCODEC_GET_BITS_H
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#include <stdint.h>
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#include <stdlib.h>
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#include <assert.h>
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#include "libavutil/bswap.h"
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#include "libavutil/common.h"
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#include "libavutil/intreadwrite.h"
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#include "libavutil/log.h"
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#include "mathops.h"
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#if defined(ALT_BITSTREAM_READER_LE) && !defined(ALT_BITSTREAM_READER)
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# define ALT_BITSTREAM_READER
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#endif
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#if !defined(LIBMPEG2_BITSTREAM_READER) && !defined(A32_BITSTREAM_READER) && !defined(ALT_BITSTREAM_READER)
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# if ARCH_ARM && !HAVE_FAST_UNALIGNED
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# define A32_BITSTREAM_READER
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# else
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# define ALT_BITSTREAM_READER
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//#define LIBMPEG2_BITSTREAM_READER
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//#define A32_BITSTREAM_READER
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# endif
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#endif
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/* bit input */
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/* buffer, buffer_end and size_in_bits must be present and used by every reader */
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typedef struct GetBitContext {
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const uint8_t *buffer, *buffer_end;
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#ifdef ALT_BITSTREAM_READER
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int index;
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#elif defined LIBMPEG2_BITSTREAM_READER
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uint8_t *buffer_ptr;
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uint32_t cache;
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int bit_count;
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#elif defined A32_BITSTREAM_READER
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uint32_t *buffer_ptr;
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uint32_t cache0;
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uint32_t cache1;
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int bit_count;
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#endif
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int size_in_bits;
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} GetBitContext;
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#define VLC_TYPE int16_t
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typedef struct VLC {
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int bits;
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VLC_TYPE (*table)[2]; ///< code, bits
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int table_size, table_allocated;
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} VLC;
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typedef struct RL_VLC_ELEM {
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int16_t level;
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int8_t len;
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uint8_t run;
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} RL_VLC_ELEM;
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/* Bitstream reader API docs:
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name
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arbitrary name which is used as prefix for the internal variables
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gb
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getbitcontext
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OPEN_READER(name, gb)
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loads gb into local variables
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CLOSE_READER(name, gb)
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stores local vars in gb
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UPDATE_CACHE(name, gb)
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refills the internal cache from the bitstream
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after this call at least MIN_CACHE_BITS will be available,
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GET_CACHE(name, gb)
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will output the contents of the internal cache, next bit is MSB of 32 or 64 bit (FIXME 64bit)
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SHOW_UBITS(name, gb, num)
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will return the next num bits
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SHOW_SBITS(name, gb, num)
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will return the next num bits and do sign extension
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SKIP_BITS(name, gb, num)
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will skip over the next num bits
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note, this is equivalent to SKIP_CACHE; SKIP_COUNTER
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SKIP_CACHE(name, gb, num)
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will remove the next num bits from the cache (note SKIP_COUNTER MUST be called before UPDATE_CACHE / CLOSE_READER)
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SKIP_COUNTER(name, gb, num)
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will increment the internal bit counter (see SKIP_CACHE & SKIP_BITS)
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LAST_SKIP_CACHE(name, gb, num)
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will remove the next num bits from the cache if it is needed for UPDATE_CACHE otherwise it will do nothing
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LAST_SKIP_BITS(name, gb, num)
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is equivalent to LAST_SKIP_CACHE; SKIP_COUNTER
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for examples see get_bits, show_bits, skip_bits, get_vlc
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*/
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#ifdef ALT_BITSTREAM_READER
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# define MIN_CACHE_BITS 25
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# define OPEN_READER(name, gb)\
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unsigned int name##_index= (gb)->index;\
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int name##_cache= 0;\
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# define CLOSE_READER(name, gb)\
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(gb)->index= name##_index;\
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# ifdef ALT_BITSTREAM_READER_LE
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# define UPDATE_CACHE(name, gb)\
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name##_cache= AV_RL32( ((const uint8_t *)(gb)->buffer)+(name##_index>>3) ) >> (name##_index&0x07);\
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# define SKIP_CACHE(name, gb, num)\
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name##_cache >>= (num);
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# else
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# define UPDATE_CACHE(name, gb)\
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name##_cache= AV_RB32( ((const uint8_t *)(gb)->buffer)+(name##_index>>3) ) << (name##_index&0x07);\
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# define SKIP_CACHE(name, gb, num)\
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name##_cache <<= (num);
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# endif
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// FIXME name?
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# define SKIP_COUNTER(name, gb, num)\
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name##_index += (num);\
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# define SKIP_BITS(name, gb, num)\
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{\
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SKIP_CACHE(name, gb, num)\
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SKIP_COUNTER(name, gb, num)\
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}\
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# define LAST_SKIP_BITS(name, gb, num) SKIP_COUNTER(name, gb, num)
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# define LAST_SKIP_CACHE(name, gb, num) ;
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# ifdef ALT_BITSTREAM_READER_LE
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# define SHOW_UBITS(name, gb, num)\
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zero_extend(name##_cache, num)
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# define SHOW_SBITS(name, gb, num)\
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sign_extend(name##_cache, num)
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# else
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# define SHOW_UBITS(name, gb, num)\
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NEG_USR32(name##_cache, num)
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# define SHOW_SBITS(name, gb, num)\
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NEG_SSR32(name##_cache, num)
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# endif
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# define GET_CACHE(name, gb)\
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((uint32_t)name##_cache)
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static inline int get_bits_count(const GetBitContext *s){
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return s->index;
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}
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static inline void skip_bits_long(GetBitContext *s, int n){
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s->index += n;
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}
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#elif defined LIBMPEG2_BITSTREAM_READER
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//libmpeg2 like reader
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# define MIN_CACHE_BITS 17
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# define OPEN_READER(name, gb)\
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int name##_bit_count=(gb)->bit_count;\
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int name##_cache= (gb)->cache;\
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uint8_t * name##_buffer_ptr=(gb)->buffer_ptr;\
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# define CLOSE_READER(name, gb)\
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(gb)->bit_count= name##_bit_count;\
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(gb)->cache= name##_cache;\
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(gb)->buffer_ptr= name##_buffer_ptr;\
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# define UPDATE_CACHE(name, gb)\
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if(name##_bit_count >= 0){\
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name##_cache+= AV_RB16(name##_buffer_ptr) << name##_bit_count; \
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name##_buffer_ptr+=2;\
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name##_bit_count-= 16;\
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}\
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# define SKIP_CACHE(name, gb, num)\
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name##_cache <<= (num);\
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# define SKIP_COUNTER(name, gb, num)\
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name##_bit_count += (num);\
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# define SKIP_BITS(name, gb, num)\
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{\
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SKIP_CACHE(name, gb, num)\
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SKIP_COUNTER(name, gb, num)\
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}\
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# define LAST_SKIP_BITS(name, gb, num) SKIP_BITS(name, gb, num)
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# define LAST_SKIP_CACHE(name, gb, num) SKIP_CACHE(name, gb, num)
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# define SHOW_UBITS(name, gb, num)\
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NEG_USR32(name##_cache, num)
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# define SHOW_SBITS(name, gb, num)\
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NEG_SSR32(name##_cache, num)
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# define GET_CACHE(name, gb)\
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((uint32_t)name##_cache)
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static inline int get_bits_count(const GetBitContext *s){
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return (s->buffer_ptr - s->buffer)*8 - 16 + s->bit_count;
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}
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static inline void skip_bits_long(GetBitContext *s, int n){
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OPEN_READER(re, s)
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re_bit_count += n;
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re_buffer_ptr += 2*(re_bit_count>>4);
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re_bit_count &= 15;
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re_cache = ((re_buffer_ptr[-2]<<8) + re_buffer_ptr[-1]) << (16+re_bit_count);
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UPDATE_CACHE(re, s)
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CLOSE_READER(re, s)
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}
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#elif defined A32_BITSTREAM_READER
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# define MIN_CACHE_BITS 32
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# define OPEN_READER(name, gb)\
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int name##_bit_count=(gb)->bit_count;\
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uint32_t name##_cache0= (gb)->cache0;\
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uint32_t name##_cache1= (gb)->cache1;\
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uint32_t * name##_buffer_ptr=(gb)->buffer_ptr;\
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# define CLOSE_READER(name, gb)\
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(gb)->bit_count= name##_bit_count;\
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(gb)->cache0= name##_cache0;\
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(gb)->cache1= name##_cache1;\
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(gb)->buffer_ptr= name##_buffer_ptr;\
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# define UPDATE_CACHE(name, gb)\
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if(name##_bit_count > 0){\
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const uint32_t next= av_be2ne32( *name##_buffer_ptr );\
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name##_cache0 |= NEG_USR32(next,name##_bit_count);\
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name##_cache1 |= next<<name##_bit_count;\
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name##_buffer_ptr++;\
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name##_bit_count-= 32;\
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}\
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#if ARCH_X86
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# define SKIP_CACHE(name, gb, num)\
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__asm__(\
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"shldl %2, %1, %0 \n\t"\
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"shll %2, %1 \n\t"\
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: "+r" (name##_cache0), "+r" (name##_cache1)\
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: "Ic" ((uint8_t)(num))\
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);
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#else
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# define SKIP_CACHE(name, gb, num)\
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name##_cache0 <<= (num);\
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name##_cache0 |= NEG_USR32(name##_cache1,num);\
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name##_cache1 <<= (num);
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#endif
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# define SKIP_COUNTER(name, gb, num)\
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name##_bit_count += (num);\
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# define SKIP_BITS(name, gb, num)\
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{\
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SKIP_CACHE(name, gb, num)\
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SKIP_COUNTER(name, gb, num)\
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}\
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# define LAST_SKIP_BITS(name, gb, num) SKIP_BITS(name, gb, num)
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# define LAST_SKIP_CACHE(name, gb, num) SKIP_CACHE(name, gb, num)
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# define SHOW_UBITS(name, gb, num)\
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NEG_USR32(name##_cache0, num)
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# define SHOW_SBITS(name, gb, num)\
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NEG_SSR32(name##_cache0, num)
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# define GET_CACHE(name, gb)\
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(name##_cache0)
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static inline int get_bits_count(const GetBitContext *s){
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return ((uint8_t*)s->buffer_ptr - s->buffer)*8 - 32 + s->bit_count;
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}
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static inline void skip_bits_long(GetBitContext *s, int n){
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OPEN_READER(re, s)
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re_bit_count += n;
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re_buffer_ptr += re_bit_count>>5;
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re_bit_count &= 31;
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re_cache0 = av_be2ne32( re_buffer_ptr[-1] ) << re_bit_count;
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re_cache1 = 0;
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UPDATE_CACHE(re, s)
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CLOSE_READER(re, s)
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}
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#endif
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/**
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* read mpeg1 dc style vlc (sign bit + mantisse with no MSB).
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* if MSB not set it is negative
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* @param n length in bits
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* @author BERO
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*/
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static inline int get_xbits(GetBitContext *s, int n){
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register int sign;
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register int32_t cache;
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OPEN_READER(re, s)
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UPDATE_CACHE(re, s)
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cache = GET_CACHE(re,s);
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sign=(~cache)>>31;
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LAST_SKIP_BITS(re, s, n)
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CLOSE_READER(re, s)
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return (NEG_USR32(sign ^ cache, n) ^ sign) - sign;
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}
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static inline int get_sbits(GetBitContext *s, int n){
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register int tmp;
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OPEN_READER(re, s)
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UPDATE_CACHE(re, s)
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tmp= SHOW_SBITS(re, s, n);
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LAST_SKIP_BITS(re, s, n)
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CLOSE_READER(re, s)
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return tmp;
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}
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/**
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* reads 1-17 bits.
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* Note, the alt bitstream reader can read up to 25 bits, but the libmpeg2 reader can't
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*/
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static inline unsigned int get_bits(GetBitContext *s, int n){
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register int tmp;
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OPEN_READER(re, s)
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UPDATE_CACHE(re, s)
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tmp= SHOW_UBITS(re, s, n);
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LAST_SKIP_BITS(re, s, n)
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CLOSE_READER(re, s)
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return tmp;
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}
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/**
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* shows 1-17 bits.
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* Note, the alt bitstream reader can read up to 25 bits, but the libmpeg2 reader can't
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*/
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static inline unsigned int show_bits(GetBitContext *s, int n){
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register int tmp;
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OPEN_READER(re, s)
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UPDATE_CACHE(re, s)
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tmp= SHOW_UBITS(re, s, n);
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// CLOSE_READER(re, s)
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return tmp;
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}
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static inline void skip_bits(GetBitContext *s, int n){
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//Note gcc seems to optimize this to s->index+=n for the ALT_READER :))
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OPEN_READER(re, s)
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UPDATE_CACHE(re, s)
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LAST_SKIP_BITS(re, s, n)
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CLOSE_READER(re, s)
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}
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static inline unsigned int get_bits1(GetBitContext *s){
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#ifdef ALT_BITSTREAM_READER
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unsigned int index= s->index;
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uint8_t result= s->buffer[ index>>3 ];
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#ifdef ALT_BITSTREAM_READER_LE
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result>>= (index&0x07);
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result&= 1;
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#else
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result<<= (index&0x07);
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result>>= 8 - 1;
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#endif
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index++;
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s->index= index;
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return result;
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#else
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return get_bits(s, 1);
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#endif
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}
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static inline unsigned int show_bits1(GetBitContext *s){
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return show_bits(s, 1);
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}
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static inline void skip_bits1(GetBitContext *s){
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skip_bits(s, 1);
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}
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/**
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* reads 0-32 bits.
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*/
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static inline unsigned int get_bits_long(GetBitContext *s, int n){
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if(n<=MIN_CACHE_BITS) return get_bits(s, n);
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else{
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#ifdef ALT_BITSTREAM_READER_LE
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int ret= get_bits(s, 16);
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return ret | (get_bits(s, n-16) << 16);
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#else
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int ret= get_bits(s, 16) << (n-16);
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return ret | get_bits(s, n-16);
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#endif
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}
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}
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/**
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* reads 0-32 bits as a signed integer.
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*/
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static inline int get_sbits_long(GetBitContext *s, int n) {
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return sign_extend(get_bits_long(s, n), n);
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}
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/**
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* shows 0-32 bits.
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*/
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static inline unsigned int show_bits_long(GetBitContext *s, int n){
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if(n<=MIN_CACHE_BITS) return show_bits(s, n);
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else{
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GetBitContext gb= *s;
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return get_bits_long(&gb, n);
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}
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}
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static inline int check_marker(GetBitContext *s, const char *msg)
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{
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int bit= get_bits1(s);
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if(!bit)
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av_log(NULL, AV_LOG_INFO, "Marker bit missing %s\n", msg);
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return bit;
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}
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/**
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* init GetBitContext.
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* @param buffer bitstream buffer, must be FF_INPUT_BUFFER_PADDING_SIZE bytes larger then the actual read bits
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* because some optimized bitstream readers read 32 or 64 bit at once and could read over the end
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* @param bit_size the size of the buffer in bits
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*
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* While GetBitContext stores the buffer size, for performance reasons you are
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* responsible for checking for the buffer end yourself (take advantage of the padding)!
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*/
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static inline void init_get_bits(GetBitContext *s,
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const uint8_t *buffer, int bit_size)
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{
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int buffer_size= (bit_size+7)>>3;
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if(buffer_size < 0 || bit_size < 0) {
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buffer_size = bit_size = 0;
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buffer = NULL;
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}
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s->buffer= buffer;
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s->size_in_bits= bit_size;
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s->buffer_end= buffer + buffer_size;
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#ifdef ALT_BITSTREAM_READER
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s->index=0;
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#elif defined LIBMPEG2_BITSTREAM_READER
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s->buffer_ptr = (uint8_t*)((intptr_t)buffer&(~1));
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s->bit_count = 16 + 8*((intptr_t)buffer&1);
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skip_bits_long(s, 0);
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#elif defined A32_BITSTREAM_READER
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s->buffer_ptr = (uint32_t*)((intptr_t)buffer&(~3));
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s->bit_count = 32 + 8*((intptr_t)buffer&3);
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skip_bits_long(s, 0);
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#endif
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}
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static inline void align_get_bits(GetBitContext *s)
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{
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int n= (-get_bits_count(s)) & 7;
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if(n) skip_bits(s, n);
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}
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|
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#define init_vlc(vlc, nb_bits, nb_codes,\
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bits, bits_wrap, bits_size,\
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codes, codes_wrap, codes_size,\
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flags)\
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init_vlc_sparse(vlc, nb_bits, nb_codes,\
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bits, bits_wrap, bits_size,\
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codes, codes_wrap, codes_size,\
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NULL, 0, 0, flags)
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|
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int init_vlc_sparse(VLC *vlc, 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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#define INIT_VLC_LE 2
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#define INIT_VLC_USE_NEW_STATIC 4
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void free_vlc(VLC *vlc);
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|
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#define INIT_VLC_STATIC(vlc, bits, a,b,c,d,e,f,g, static_size)\
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|
{\
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static VLC_TYPE table[static_size][2];\
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(vlc)->table= table;\
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(vlc)->table_allocated= static_size;\
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init_vlc(vlc, bits, a,b,c,d,e,f,g, INIT_VLC_USE_NEW_STATIC);\
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}
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|
|
|
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|
/**
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|
*
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* If the vlc code is invalid and max_depth=1, then no bits will be removed.
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* If the vlc code is invalid and max_depth>1, then the number of bits removed
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|
* is undefined.
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|
*/
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|
#define GET_VLC(code, name, gb, table, bits, max_depth)\
|
|
{\
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|
int n, nb_bits;\
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|
unsigned int index;\
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|
\
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index= SHOW_UBITS(name, gb, bits);\
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code = table[index][0];\
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|
n = table[index][1];\
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|
\
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|
if(max_depth > 1 && n < 0){\
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LAST_SKIP_BITS(name, gb, bits)\
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|
UPDATE_CACHE(name, gb)\
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|
\
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|
nb_bits = -n;\
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|
\
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|
index= SHOW_UBITS(name, gb, nb_bits) + code;\
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|
code = table[index][0];\
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|
n = table[index][1];\
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|
if(max_depth > 2 && n < 0){\
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LAST_SKIP_BITS(name, gb, nb_bits)\
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|
UPDATE_CACHE(name, gb)\
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|
\
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|
nb_bits = -n;\
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|
\
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|
index= SHOW_UBITS(name, gb, nb_bits) + code;\
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|
code = table[index][0];\
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|
n = table[index][1];\
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|
}\
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|
}\
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|
SKIP_BITS(name, gb, n)\
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|
}
|
|
|
|
#define GET_RL_VLC(level, run, name, gb, table, bits, max_depth, need_update)\
|
|
{\
|
|
int n, nb_bits;\
|
|
unsigned int index;\
|
|
\
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|
index= SHOW_UBITS(name, gb, bits);\
|
|
level = table[index].level;\
|
|
n = table[index].len;\
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|
\
|
|
if(max_depth > 1 && n < 0){\
|
|
SKIP_BITS(name, gb, bits)\
|
|
if(need_update){\
|
|
UPDATE_CACHE(name, gb)\
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|
}\
|
|
\
|
|
nb_bits = -n;\
|
|
\
|
|
index= SHOW_UBITS(name, gb, nb_bits) + level;\
|
|
level = table[index].level;\
|
|
n = table[index].len;\
|
|
}\
|
|
run= table[index].run;\
|
|
SKIP_BITS(name, gb, n)\
|
|
}
|
|
|
|
|
|
/**
|
|
* parses a vlc code, faster then get_vlc()
|
|
* @param bits is the number of bits which will be read at once, must be
|
|
* identical to nb_bits in init_vlc()
|
|
* @param max_depth is the number of times bits bits must be read to completely
|
|
* read the longest vlc code
|
|
* = (max_vlc_length + bits - 1) / bits
|
|
*/
|
|
static av_always_inline int get_vlc2(GetBitContext *s, VLC_TYPE (*table)[2],
|
|
int bits, int max_depth)
|
|
{
|
|
int code;
|
|
|
|
OPEN_READER(re, s)
|
|
UPDATE_CACHE(re, s)
|
|
|
|
GET_VLC(code, re, s, table, bits, max_depth)
|
|
|
|
CLOSE_READER(re, s)
|
|
return code;
|
|
}
|
|
|
|
//#define TRACE
|
|
|
|
#ifdef TRACE
|
|
static inline void print_bin(int bits, int n){
|
|
int i;
|
|
|
|
for(i=n-1; i>=0; i--){
|
|
av_log(NULL, AV_LOG_DEBUG, "%d", (bits>>i)&1);
|
|
}
|
|
for(i=n; i<24; i++)
|
|
av_log(NULL, AV_LOG_DEBUG, " ");
|
|
}
|
|
|
|
static inline int get_bits_trace(GetBitContext *s, int n, char *file, const char *func, int line){
|
|
int r= get_bits(s, n);
|
|
|
|
print_bin(r, n);
|
|
av_log(NULL, AV_LOG_DEBUG, "%5d %2d %3d bit @%5d in %s %s:%d\n", r, n, r, get_bits_count(s)-n, file, func, line);
|
|
return r;
|
|
}
|
|
static inline int get_vlc_trace(GetBitContext *s, VLC_TYPE (*table)[2], int bits, int max_depth, char *file, const char *func, int line){
|
|
int show= show_bits(s, 24);
|
|
int pos= get_bits_count(s);
|
|
int r= get_vlc2(s, table, bits, max_depth);
|
|
int len= get_bits_count(s) - pos;
|
|
int bits2= show>>(24-len);
|
|
|
|
print_bin(bits2, len);
|
|
|
|
av_log(NULL, AV_LOG_DEBUG, "%5d %2d %3d vlc @%5d in %s %s:%d\n", bits2, len, r, pos, file, func, line);
|
|
return r;
|
|
}
|
|
static inline int get_xbits_trace(GetBitContext *s, int n, char *file, const char *func, int line){
|
|
int show= show_bits(s, n);
|
|
int r= get_xbits(s, n);
|
|
|
|
print_bin(show, n);
|
|
av_log(NULL, AV_LOG_DEBUG, "%5d %2d %3d xbt @%5d in %s %s:%d\n", show, n, r, get_bits_count(s)-n, file, func, line);
|
|
return r;
|
|
}
|
|
|
|
#define get_bits(s, n) get_bits_trace(s, n, __FILE__, __PRETTY_FUNCTION__, __LINE__)
|
|
#define get_bits1(s) get_bits_trace(s, 1, __FILE__, __PRETTY_FUNCTION__, __LINE__)
|
|
#define get_xbits(s, n) get_xbits_trace(s, n, __FILE__, __PRETTY_FUNCTION__, __LINE__)
|
|
#define get_vlc(s, vlc) get_vlc_trace(s, (vlc)->table, (vlc)->bits, 3, __FILE__, __PRETTY_FUNCTION__, __LINE__)
|
|
#define get_vlc2(s, tab, bits, max) get_vlc_trace(s, tab, bits, max, __FILE__, __PRETTY_FUNCTION__, __LINE__)
|
|
|
|
#define tprintf(p, ...) av_log(p, AV_LOG_DEBUG, __VA_ARGS__)
|
|
|
|
#else //TRACE
|
|
#define tprintf(p, ...) {}
|
|
#endif
|
|
|
|
static inline int decode012(GetBitContext *gb){
|
|
int n;
|
|
n = get_bits1(gb);
|
|
if (n == 0)
|
|
return 0;
|
|
else
|
|
return get_bits1(gb) + 1;
|
|
}
|
|
|
|
static inline int decode210(GetBitContext *gb){
|
|
if (get_bits1(gb))
|
|
return 0;
|
|
else
|
|
return 2 - get_bits1(gb);
|
|
}
|
|
|
|
static inline int get_bits_left(GetBitContext *gb)
|
|
{
|
|
return gb->size_in_bits - get_bits_count(gb);
|
|
}
|
|
|
|
#endif /* AVCODEC_GET_BITS_H */
|