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ffmpeg / libavcodec / put_bits.h @ 28f2db96

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1 b2755007 Stefano Sabatini
/*
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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 */