338 lines
8.5 KiB
C
338 lines
8.5 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 libavcodec/put_bits.h
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* bitstream writer API
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*/
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#ifndef AVCODEC_PUT_BITS_H
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#define AVCODEC_PUT_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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//#define ALT_BITSTREAM_WRITER
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//#define ALIGNED_BITSTREAM_WRITER
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/* buf and buf_end must be present and used by every alternative writer. */
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typedef struct PutBitContext {
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#ifdef ALT_BITSTREAM_WRITER
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uint8_t *buf, *buf_end;
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int index;
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#else
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uint32_t bit_buf;
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int bit_left;
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uint8_t *buf, *buf_ptr, *buf_end;
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#endif
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int size_in_bits;
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} PutBitContext;
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/**
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* Initializes the PutBitContext s.
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*
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* @param buffer the buffer where to put bits
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* @param buffer_size the size in bytes of buffer
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*/
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static inline void init_put_bits(PutBitContext *s, uint8_t *buffer, int buffer_size)
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{
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if(buffer_size < 0) {
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buffer_size = 0;
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buffer = NULL;
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}
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s->size_in_bits= 8*buffer_size;
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s->buf = buffer;
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s->buf_end = s->buf + buffer_size;
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#ifdef ALT_BITSTREAM_WRITER
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s->index=0;
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((uint32_t*)(s->buf))[0]=0;
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// memset(buffer, 0, buffer_size);
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#else
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s->buf_ptr = s->buf;
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s->bit_left=32;
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s->bit_buf=0;
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#endif
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}
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/**
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* Returns the total number of bits written to the bitstream.
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*/
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static inline int put_bits_count(PutBitContext *s)
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{
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#ifdef ALT_BITSTREAM_WRITER
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return s->index;
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#else
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return (s->buf_ptr - s->buf) * 8 + 32 - s->bit_left;
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#endif
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}
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/**
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* Pads the end of the output stream with zeros.
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*/
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static inline void flush_put_bits(PutBitContext *s)
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{
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#ifdef ALT_BITSTREAM_WRITER
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align_put_bits(s);
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#else
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#ifndef BITSTREAM_WRITER_LE
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s->bit_buf<<= s->bit_left;
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#endif
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while (s->bit_left < 32) {
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/* XXX: should test end of buffer */
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#ifdef BITSTREAM_WRITER_LE
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*s->buf_ptr++=s->bit_buf;
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s->bit_buf>>=8;
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#else
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*s->buf_ptr++=s->bit_buf >> 24;
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s->bit_buf<<=8;
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#endif
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s->bit_left+=8;
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}
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s->bit_left=32;
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s->bit_buf=0;
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#endif
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}
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/**
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* Pads the bitstream with zeros up to the next byte boundary.
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*/
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void align_put_bits(PutBitContext *s);
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/**
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* Puts the string string in the bitstream.
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*
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* @param terminate_string 0-terminates the written string if value is 1
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*/
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void ff_put_string(PutBitContext *pb, const char *string, int terminate_string);
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/**
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* Copies the content of src to the bitstream.
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*
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* @param length the number of bits of src to copy
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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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* Writes up to 31 bits into a bitstream.
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* Use put_bits32 to write 32 bits.
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*/
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static inline void put_bits(PutBitContext *s, int n, unsigned int value)
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#ifndef ALT_BITSTREAM_WRITER
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{
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unsigned int bit_buf;
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int bit_left;
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// printf("put_bits=%d %x\n", n, value);
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assert(n <= 31 && value < (1U << n));
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bit_buf = s->bit_buf;
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bit_left = s->bit_left;
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// printf("n=%d value=%x cnt=%d buf=%x\n", n, value, bit_cnt, bit_buf);
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/* XXX: optimize */
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#ifdef BITSTREAM_WRITER_LE
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bit_buf |= value << (32 - bit_left);
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if (n >= bit_left) {
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#if !HAVE_FAST_UNALIGNED
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if (3 & (intptr_t) s->buf_ptr) {
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AV_WL32(s->buf_ptr, bit_buf);
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} else
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#endif
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*(uint32_t *)s->buf_ptr = le2me_32(bit_buf);
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s->buf_ptr+=4;
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bit_buf = (bit_left==32)?0:value >> bit_left;
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bit_left+=32;
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}
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bit_left-=n;
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#else
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if (n < bit_left) {
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bit_buf = (bit_buf<<n) | value;
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bit_left-=n;
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} else {
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bit_buf<<=bit_left;
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bit_buf |= value >> (n - bit_left);
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#if !HAVE_FAST_UNALIGNED
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if (3 & (intptr_t) s->buf_ptr) {
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AV_WB32(s->buf_ptr, bit_buf);
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} else
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#endif
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*(uint32_t *)s->buf_ptr = be2me_32(bit_buf);
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//printf("bitbuf = %08x\n", bit_buf);
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s->buf_ptr+=4;
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bit_left+=32 - n;
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bit_buf = value;
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}
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#endif
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s->bit_buf = bit_buf;
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s->bit_left = bit_left;
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}
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#else /* ALT_BITSTREAM_WRITER defined */
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{
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# ifdef ALIGNED_BITSTREAM_WRITER
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# if ARCH_X86
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__asm__ volatile(
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"movl %0, %%ecx \n\t"
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"xorl %%eax, %%eax \n\t"
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"shrdl %%cl, %1, %%eax \n\t"
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"shrl %%cl, %1 \n\t"
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"movl %0, %%ecx \n\t"
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"shrl $3, %%ecx \n\t"
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"andl $0xFFFFFFFC, %%ecx \n\t"
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"bswapl %1 \n\t"
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"orl %1, (%2, %%ecx) \n\t"
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"bswapl %%eax \n\t"
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"addl %3, %0 \n\t"
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"movl %%eax, 4(%2, %%ecx) \n\t"
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: "=&r" (s->index), "=&r" (value)
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: "r" (s->buf), "r" (n), "0" (s->index), "1" (value<<(-n))
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: "%eax", "%ecx"
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);
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# else
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int index= s->index;
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uint32_t *ptr= ((uint32_t *)s->buf)+(index>>5);
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value<<= 32-n;
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ptr[0] |= be2me_32(value>>(index&31));
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ptr[1] = be2me_32(value<<(32-(index&31)));
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//if(n>24) printf("%d %d\n", n, value);
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index+= n;
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s->index= index;
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# endif
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# else //ALIGNED_BITSTREAM_WRITER
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# if ARCH_X86
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__asm__ volatile(
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"movl $7, %%ecx \n\t"
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"andl %0, %%ecx \n\t"
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"addl %3, %%ecx \n\t"
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"negl %%ecx \n\t"
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"shll %%cl, %1 \n\t"
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"bswapl %1 \n\t"
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"movl %0, %%ecx \n\t"
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"shrl $3, %%ecx \n\t"
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"orl %1, (%%ecx, %2) \n\t"
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"addl %3, %0 \n\t"
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"movl $0, 4(%%ecx, %2) \n\t"
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: "=&r" (s->index), "=&r" (value)
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: "r" (s->buf), "r" (n), "0" (s->index), "1" (value)
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: "%ecx"
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);
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# else
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int index= s->index;
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uint32_t *ptr= (uint32_t*)(((uint8_t *)s->buf)+(index>>3));
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ptr[0] |= be2me_32(value<<(32-n-(index&7) ));
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ptr[1] = 0;
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//if(n>24) printf("%d %d\n", n, value);
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index+= n;
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s->index= index;
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# endif
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# endif //!ALIGNED_BITSTREAM_WRITER
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}
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#endif
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static inline void put_sbits(PutBitContext *pb, int n, int32_t value)
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{
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assert(n >= 0 && n <= 31);
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put_bits(pb, n, value & ((1<<n)-1));
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}
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/**
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* Writes exactly 32 bits into a bitstream.
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*/
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static void av_unused put_bits32(PutBitContext *s, uint32_t value)
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{
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int lo = value & 0xffff;
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int hi = value >> 16;
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#ifdef BITSTREAM_WRITER_LE
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put_bits(s, 16, lo);
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put_bits(s, 16, hi);
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#else
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put_bits(s, 16, hi);
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put_bits(s, 16, lo);
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#endif
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}
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/**
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* Returns the pointer to the byte where the bitstream writer will put
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* the next bit.
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*/
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static inline uint8_t* put_bits_ptr(PutBitContext *s)
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{
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#ifdef ALT_BITSTREAM_WRITER
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return s->buf + (s->index>>3);
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#else
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return s->buf_ptr;
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#endif
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}
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/**
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* Skips the given number of bytes.
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* PutBitContext must be flushed & aligned to a byte boundary before calling this.
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*/
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static inline void skip_put_bytes(PutBitContext *s, int n)
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{
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assert((put_bits_count(s)&7)==0);
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#ifdef ALT_BITSTREAM_WRITER
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FIXME may need some cleaning of the buffer
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s->index += n<<3;
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#else
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assert(s->bit_left==32);
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s->buf_ptr += n;
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#endif
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}
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/**
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* Skips the given number of bits.
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* Must only be used if the actual values in the bitstream do not matter.
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* If n is 0 the behavior is undefined.
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*/
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static inline void skip_put_bits(PutBitContext *s, int n)
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{
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#ifdef ALT_BITSTREAM_WRITER
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s->index += n;
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#else
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s->bit_left -= n;
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s->buf_ptr-= 4*(s->bit_left>>5);
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s->bit_left &= 31;
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#endif
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}
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/**
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* Changes the end of the buffer.
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*
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* @param size the new size in bytes of the buffer where to put bits
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*/
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static inline void set_put_bits_buffer_size(PutBitContext *s, int size)
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{
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s->buf_end= s->buf + size;
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}
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#endif /* AVCODEC_PUT_BITS_H */
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