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FFmpeg/libavcodec/put_bits.h

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/*
* copyright (c) 2004 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 libavcodec/put_bits.h
* bitstream writer API
*/
#ifndef AVCODEC_PUT_BITS_H
#define AVCODEC_PUT_BITS_H
#include <stdint.h>
#include <stdlib.h>
#include <assert.h>
#include "libavutil/bswap.h"
#include "libavutil/common.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/log.h"
#include "mathops.h"
//#define ALT_BITSTREAM_WRITER
//#define ALIGNED_BITSTREAM_WRITER
/* buf and buf_end must be present and used by every alternative writer. */
typedef struct PutBitContext {
#ifdef ALT_BITSTREAM_WRITER
uint8_t *buf, *buf_end;
int index;
#else
uint32_t bit_buf;
int bit_left;
uint8_t *buf, *buf_ptr, *buf_end;
#endif
int size_in_bits;
} PutBitContext;
/**
* Initializes the PutBitContext s.
*
* @param buffer the buffer where to put bits
* @param buffer_size the size in bytes of buffer
*/
static inline void init_put_bits(PutBitContext *s, uint8_t *buffer, int buffer_size)
{
if(buffer_size < 0) {
buffer_size = 0;
buffer = NULL;
}
s->size_in_bits= 8*buffer_size;
s->buf = buffer;
s->buf_end = s->buf + buffer_size;
#ifdef ALT_BITSTREAM_WRITER
s->index=0;
((uint32_t*)(s->buf))[0]=0;
// memset(buffer, 0, buffer_size);
#else
s->buf_ptr = s->buf;
s->bit_left=32;
s->bit_buf=0;
#endif
}
/**
* Returns the total number of bits written to the bitstream.
*/
static inline int put_bits_count(PutBitContext *s)
{
#ifdef ALT_BITSTREAM_WRITER
return s->index;
#else
return (s->buf_ptr - s->buf) * 8 + 32 - s->bit_left;
#endif
}
/**
* Pads the end of the output stream with zeros.
*/
static inline void flush_put_bits(PutBitContext *s)
{
#ifdef ALT_BITSTREAM_WRITER
align_put_bits(s);
#else
#ifndef BITSTREAM_WRITER_LE
s->bit_buf<<= s->bit_left;
#endif
while (s->bit_left < 32) {
/* XXX: should test end of buffer */
#ifdef BITSTREAM_WRITER_LE
*s->buf_ptr++=s->bit_buf;
s->bit_buf>>=8;
#else
*s->buf_ptr++=s->bit_buf >> 24;
s->bit_buf<<=8;
#endif
s->bit_left+=8;
}
s->bit_left=32;
s->bit_buf=0;
#endif
}
/**
* Pads the bitstream with zeros up to the next byte boundary.
*/
void align_put_bits(PutBitContext *s);
/**
* Puts the string string in the bitstream.
*
* @param terminate_string 0-terminates the written string if value is 1
*/
void ff_put_string(PutBitContext *pb, const char *string, int terminate_string);
/**
* Copies the content of src to the bitstream.
*
* @param length the number of bits of src to copy
*/
void ff_copy_bits(PutBitContext *pb, const uint8_t *src, int length);
/**
* Writes up to 31 bits into a bitstream.
* Use put_bits32 to write 32 bits.
*/
static inline void put_bits(PutBitContext *s, int n, unsigned int value)
#ifndef ALT_BITSTREAM_WRITER
{
unsigned int bit_buf;
int bit_left;
// printf("put_bits=%d %x\n", n, value);
assert(n <= 31 && value < (1U << n));
bit_buf = s->bit_buf;
bit_left = s->bit_left;
// printf("n=%d value=%x cnt=%d buf=%x\n", n, value, bit_cnt, bit_buf);
/* XXX: optimize */
#ifdef BITSTREAM_WRITER_LE
bit_buf |= value << (32 - bit_left);
if (n >= bit_left) {
#if !HAVE_FAST_UNALIGNED
if (3 & (intptr_t) s->buf_ptr) {
AV_WL32(s->buf_ptr, bit_buf);
} else
#endif
*(uint32_t *)s->buf_ptr = le2me_32(bit_buf);
s->buf_ptr+=4;
bit_buf = (bit_left==32)?0:value >> bit_left;
bit_left+=32;
}
bit_left-=n;
#else
if (n < bit_left) {
bit_buf = (bit_buf<<n) | value;
bit_left-=n;
} else {
bit_buf<<=bit_left;
bit_buf |= value >> (n - bit_left);
#if !HAVE_FAST_UNALIGNED
if (3 & (intptr_t) s->buf_ptr) {
AV_WB32(s->buf_ptr, bit_buf);
} else
#endif
*(uint32_t *)s->buf_ptr = be2me_32(bit_buf);
//printf("bitbuf = %08x\n", bit_buf);
s->buf_ptr+=4;
bit_left+=32 - n;
bit_buf = value;
}
#endif
s->bit_buf = bit_buf;
s->bit_left = bit_left;
}
#else /* ALT_BITSTREAM_WRITER defined */
{
# ifdef ALIGNED_BITSTREAM_WRITER
# if ARCH_X86
__asm__ volatile(
"movl %0, %%ecx \n\t"
"xorl %%eax, %%eax \n\t"
"shrdl %%cl, %1, %%eax \n\t"
"shrl %%cl, %1 \n\t"
"movl %0, %%ecx \n\t"
"shrl $3, %%ecx \n\t"
"andl $0xFFFFFFFC, %%ecx \n\t"
"bswapl %1 \n\t"
"orl %1, (%2, %%ecx) \n\t"
"bswapl %%eax \n\t"
"addl %3, %0 \n\t"
"movl %%eax, 4(%2, %%ecx) \n\t"
: "=&r" (s->index), "=&r" (value)
: "r" (s->buf), "r" (n), "0" (s->index), "1" (value<<(-n))
: "%eax", "%ecx"
);
# else
int index= s->index;
uint32_t *ptr= ((uint32_t *)s->buf)+(index>>5);
value<<= 32-n;
ptr[0] |= be2me_32(value>>(index&31));
ptr[1] = be2me_32(value<<(32-(index&31)));
//if(n>24) printf("%d %d\n", n, value);
index+= n;
s->index= index;
# endif
# else //ALIGNED_BITSTREAM_WRITER
# if ARCH_X86
__asm__ volatile(
"movl $7, %%ecx \n\t"
"andl %0, %%ecx \n\t"
"addl %3, %%ecx \n\t"
"negl %%ecx \n\t"
"shll %%cl, %1 \n\t"
"bswapl %1 \n\t"
"movl %0, %%ecx \n\t"
"shrl $3, %%ecx \n\t"
"orl %1, (%%ecx, %2) \n\t"
"addl %3, %0 \n\t"
"movl $0, 4(%%ecx, %2) \n\t"
: "=&r" (s->index), "=&r" (value)
: "r" (s->buf), "r" (n), "0" (s->index), "1" (value)
: "%ecx"
);
# else
int index= s->index;
uint32_t *ptr= (uint32_t*)(((uint8_t *)s->buf)+(index>>3));
ptr[0] |= be2me_32(value<<(32-n-(index&7) ));
ptr[1] = 0;
//if(n>24) printf("%d %d\n", n, value);
index+= n;
s->index= index;
# endif
# endif //!ALIGNED_BITSTREAM_WRITER
}
#endif
static inline void put_sbits(PutBitContext *pb, int n, int32_t value)
{
assert(n >= 0 && n <= 31);
put_bits(pb, n, value & ((1<<n)-1));
}
/**
* Writes exactly 32 bits into a bitstream.
*/
static void av_unused put_bits32(PutBitContext *s, uint32_t value)
{
int lo = value & 0xffff;
int hi = value >> 16;
#ifdef BITSTREAM_WRITER_LE
put_bits(s, 16, lo);
put_bits(s, 16, hi);
#else
put_bits(s, 16, hi);
put_bits(s, 16, lo);
#endif
}
/**
* Returns the pointer to the byte where the bitstream writer will put
* the next bit.
*/
static inline uint8_t* put_bits_ptr(PutBitContext *s)
{
#ifdef ALT_BITSTREAM_WRITER
return s->buf + (s->index>>3);
#else
return s->buf_ptr;
#endif
}
/**
* Skips the given number of bytes.
* PutBitContext must be flushed & aligned to a byte boundary before calling this.
*/
static inline void skip_put_bytes(PutBitContext *s, int n)
{
assert((put_bits_count(s)&7)==0);
#ifdef ALT_BITSTREAM_WRITER
FIXME may need some cleaning of the buffer
s->index += n<<3;
#else
assert(s->bit_left==32);
s->buf_ptr += n;
#endif
}
/**
* Skips the given number of bits.
* Must only be used if the actual values in the bitstream do not matter.
* If n is 0 the behavior is undefined.
*/
static inline void skip_put_bits(PutBitContext *s, int n)
{
#ifdef ALT_BITSTREAM_WRITER
s->index += n;
#else
s->bit_left -= n;
s->buf_ptr-= 4*(s->bit_left>>5);
s->bit_left &= 31;
#endif
}
/**
* Changes the end of the buffer.
*
* @param size the new size in bytes of the buffer where to put bits
*/
static inline void set_put_bits_buffer_size(PutBitContext *s, int size)
{
s->buf_end= s->buf + size;
}
#endif /* AVCODEC_PUT_BITS_H */