366 lines
9.1 KiB
C
Executable File
366 lines
9.1 KiB
C
Executable File
/*
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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 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 <stddef.h>
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#include "libavutil/intreadwrite.h"
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#include "libavutil/avassert.h"
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typedef struct PutBitContext {
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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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int size_in_bits;
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} PutBitContext;
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/**
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* Initialize 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,
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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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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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}
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/**
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* @return 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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return (s->buf_ptr - s->buf) * 8 + 32 - s->bit_left;
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}
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/**
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* Rebase the bit writer onto a reallocated buffer.
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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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* must be large enough to hold everything written so far
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*/
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static inline void rebase_put_bits(PutBitContext *s, uint8_t *buffer,
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int buffer_size)
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{
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av_assert0(8*buffer_size >= put_bits_count(s));
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s->buf_end = buffer + buffer_size;
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s->buf_ptr = buffer + (s->buf_ptr - s->buf);
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s->buf = buffer;
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s->size_in_bits = 8 * buffer_size;
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}
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/**
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* @return the number of bits available in the bitstream.
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*/
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static inline int put_bits_left(PutBitContext* s)
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{
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return (s->buf_end - s->buf_ptr) * 8 - 32 + s->bit_left;
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}
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/**
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* Pad 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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#ifndef BITSTREAM_WRITER_LE
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if (s->bit_left < 32)
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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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av_assert0(s->buf_ptr < s->buf_end);
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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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}
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static inline void flush_put_bits_le(PutBitContext *s)
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{
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while (s->bit_left < 32) {
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av_assert0(s->buf_ptr < s->buf_end);
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*s->buf_ptr++ = s->bit_buf;
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s->bit_buf >>= 8;
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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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}
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#ifdef BITSTREAM_WRITER_LE
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#define avpriv_align_put_bits align_put_bits_unsupported_here
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#define avpriv_put_string ff_put_string_unsupported_here
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#define avpriv_copy_bits avpriv_copy_bits_unsupported_here
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#else
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/**
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* Pad the bitstream with zeros up to the next byte boundary.
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*/
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void avpriv_align_put_bits(PutBitContext *s);
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/**
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* Put 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 avpriv_put_string(PutBitContext *pb, const char *string,
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int terminate_string);
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/**
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* Copy 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 avpriv_copy_bits(PutBitContext *pb, const uint8_t *src, int length);
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#endif
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/**
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* Write 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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{
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unsigned int bit_buf;
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int bit_left;
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av_assert2(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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/* 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 (3 < s->buf_end - s->buf_ptr) {
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AV_WL32(s->buf_ptr, bit_buf);
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s->buf_ptr += 4;
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} else {
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av_log(NULL, AV_LOG_ERROR, "Internal error, put_bits buffer too small\n");
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av_assert2(0);
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}
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bit_buf = 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 (3 < s->buf_end - s->buf_ptr) {
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AV_WB32(s->buf_ptr, bit_buf);
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s->buf_ptr += 4;
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} else {
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av_log(NULL, AV_LOG_ERROR, "Internal error, put_bits buffer too small\n");
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av_assert2(0);
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}
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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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static inline void put_bits_le(PutBitContext *s, int n, unsigned int value)
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{
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unsigned int bit_buf;
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int bit_left;
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av_assert2(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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bit_buf |= value << (32 - bit_left);
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if (n >= bit_left) {
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if (3 < s->buf_end - s->buf_ptr) {
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AV_WL32(s->buf_ptr, bit_buf);
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s->buf_ptr += 4;
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} else {
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av_log(NULL, AV_LOG_ERROR, "Internal error, put_bits buffer too small\n");
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av_assert2(0);
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}
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bit_buf = 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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s->bit_buf = bit_buf;
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s->bit_left = bit_left;
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}
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static inline void put_sbits(PutBitContext *pb, int n, int32_t value)
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{
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av_assert2(n >= 0 && n <= 31);
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put_bits(pb, n, av_mod_uintp2(value, n));
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}
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/**
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* Write 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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unsigned int bit_buf;
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int bit_left;
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bit_buf = s->bit_buf;
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bit_left = s->bit_left;
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#ifdef BITSTREAM_WRITER_LE
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bit_buf |= value << (32 - bit_left);
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if (3 < s->buf_end - s->buf_ptr) {
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AV_WL32(s->buf_ptr, bit_buf);
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s->buf_ptr += 4;
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} else {
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av_log(NULL, AV_LOG_ERROR, "Internal error, put_bits buffer too small\n");
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av_assert2(0);
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}
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bit_buf = (uint64_t)value >> bit_left;
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#else
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bit_buf = (uint64_t)bit_buf << bit_left;
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bit_buf |= value >> (32 - bit_left);
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if (3 < s->buf_end - s->buf_ptr) {
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AV_WB32(s->buf_ptr, bit_buf);
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s->buf_ptr += 4;
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} else {
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av_log(NULL, AV_LOG_ERROR, "Internal error, put_bits buffer too small\n");
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av_assert2(0);
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}
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bit_buf = value;
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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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/**
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* Write up to 64 bits into a bitstream.
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*/
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static inline void put_bits64(PutBitContext *s, int n, uint64_t value)
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{
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av_assert2((n == 64) || (n < 64 && value < (UINT64_C(1) << n)));
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if (n < 32)
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put_bits(s, n, value);
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else if (n == 32)
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put_bits32(s, value);
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else if (n < 64) {
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uint32_t lo = value & 0xffffffff;
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uint32_t hi = value >> 32;
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#ifdef BITSTREAM_WRITER_LE
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put_bits32(s, lo);
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put_bits(s, n - 32, hi);
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#else
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put_bits(s, n - 32, hi);
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put_bits32(s, lo);
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#endif
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} else {
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uint32_t lo = value & 0xffffffff;
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uint32_t hi = value >> 32;
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#ifdef BITSTREAM_WRITER_LE
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put_bits32(s, lo);
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put_bits32(s, hi);
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#else
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put_bits32(s, hi);
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put_bits32(s, lo);
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#endif
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}
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}
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/**
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* Return 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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return s->buf_ptr;
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}
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/**
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* Skip 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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av_assert2((put_bits_count(s) & 7) == 0);
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av_assert2(s->bit_left == 32);
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av_assert0(n <= s->buf_end - s->buf_ptr);
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s->buf_ptr += n;
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}
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/**
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* Skip 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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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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}
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/**
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* Change 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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av_assert0(size <= INT_MAX/8 - 32);
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s->buf_end = s->buf + size;
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s->size_in_bits = 8*size;
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}
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#endif /* AVCODEC_PUT_BITS_H */
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