bytestream.h

ffmpeg的完整源代码和作者自己写的文档。不但有在Linux的工程哦

/*
 * Bytestream functions
 * copyright (c) 2006 Baptiste Coudurier <[e-mail]>
 *
 * 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
 */

#ifndef FFMPEG_BYTESTREAM_H
#define FFMPEG_BYTESTREAM_H

#include "common.h"

#define DEF_T(type, name, bytes, read, write)                             \
static av_always_inline type bytestream_get_ ## name(uint8_t **b){\
    (*b) += bytes;\
    return read(*b - bytes);\
}\
static av_always_inline void bytestream_put_ ##name(uint8_t **b, const type value){\
    write(*b, value);\
    (*b) += bytes;\
}

#define DEF(name, bytes, read, write) \
    DEF_T(unsigned int, name, bytes, read, write)
#define DEF64(name, bytes, read, write) \
    DEF_T(uint64_t, name, bytes, read, write)

DEF64(le64, 8, AV_RL64, AV_WL64)
DEF  (le32, 4, AV_RL32, AV_WL32)
DEF  (le24, 3, AV_RL24, AV_WL24)
DEF  (le16, 2, AV_RL16, AV_WL16)
DEF64(be64, 8, AV_RB64, AV_WB64)
DEF  (be32, 4, AV_RB32, AV_WB32)
DEF  (be24, 3, AV_RB24, AV_WB24)
DEF  (be16, 2, AV_RB16, AV_WB16)
DEF  (byte, 1, AV_RB8 , AV_WB8 )

#undef DEF
#undef DEF64
#undef DEF_T

static av_always_inline unsigned int bytestream_get_buffer(uint8_t **b, uint8_t *dst, unsigned int size)
{
    memcpy(dst, *b, size);
    (*b) += size;
    return size;
}

static av_always_inline void bytestream_put_buffer(uint8_t **b, const uint8_t *src, unsigned int size)
{
    memcpy(*b, src, size);
    (*b) += size;
}

#endif /* FFMPEG_BYTESTREAM_H */