libavcodec/bytestream.h
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 /*
  * Bytestream functions
  * copyright (c) 2006 Baptiste Coudurier <baptiste.coudurier@free.fr>
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  * Copyright (c) 2012 Aneesh Dogra (lionaneesh) <lionaneesh@gmail.com>
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  *
  * 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
  */
 
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 #ifndef AVCODEC_BYTESTREAM_H
 #define AVCODEC_BYTESTREAM_H
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 #include <stdint.h>
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 #include <string.h>
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 #include "libavutil/avassert.h"
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 #include "libavutil/common.h"
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 #include "libavutil/intreadwrite.h"
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 typedef struct GetByteContext {
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     const uint8_t *buffer, *buffer_end, *buffer_start;
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 } GetByteContext;
 
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 typedef struct PutByteContext {
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     uint8_t *buffer, *buffer_end, *buffer_start;
     int eof;
 } PutByteContext;
 
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 #define DEF(type, name, bytes, read, write)                                  \
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 static av_always_inline type bytestream_get_ ## name(const 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;                                                             \
 }                                                                              \
 static av_always_inline void bytestream2_put_ ## name ## u(PutByteContext *p,  \
                                                            const type value)   \
 {                                                                              \
     bytestream_put_ ## name(&p->buffer, value);                                \
 }                                                                              \
 static av_always_inline void bytestream2_put_ ## name(PutByteContext *p,       \
                                                       const type value)        \
 {                                                                              \
     if (!p->eof && (p->buffer_end - p->buffer >= bytes)) {                     \
         write(p->buffer, value);                                               \
         p->buffer += bytes;                                                    \
     } else                                                                     \
         p->eof = 1;                                                            \
 }                                                                              \
 static av_always_inline type bytestream2_get_ ## name ## u(GetByteContext *g)  \
 {                                                                              \
     return bytestream_get_ ## name(&g->buffer);                                \
 }                                                                              \
 static av_always_inline type bytestream2_get_ ## name(GetByteContext *g)       \
 {                                                                              \
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     if (g->buffer_end - g->buffer < bytes) {                                   \
         g->buffer = g->buffer_end;                                             \
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         return 0;                                                              \
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     }                                                                          \
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     return bytestream2_get_ ## name ## u(g);                                   \
 }                                                                              \
 static av_always_inline type bytestream2_peek_ ## name(GetByteContext *g)      \
 {                                                                              \
     if (g->buffer_end - g->buffer < bytes)                                     \
         return 0;                                                              \
     return read(g->buffer);                                                    \
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 }
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 DEF(uint64_t,     le64, 8, AV_RL64, AV_WL64)
 DEF(unsigned int, le32, 4, AV_RL32, AV_WL32)
 DEF(unsigned int, le24, 3, AV_RL24, AV_WL24)
 DEF(unsigned int, le16, 2, AV_RL16, AV_WL16)
 DEF(uint64_t,     be64, 8, AV_RB64, AV_WB64)
 DEF(unsigned int, be32, 4, AV_RB32, AV_WB32)
 DEF(unsigned int, be24, 3, AV_RB24, AV_WB24)
 DEF(unsigned int, be16, 2, AV_RB16, AV_WB16)
 DEF(unsigned int, byte, 1, AV_RB8 , AV_WB8)
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 #if HAVE_BIGENDIAN
 #   define bytestream2_get_ne16  bytestream2_get_be16
 #   define bytestream2_get_ne24  bytestream2_get_be24
 #   define bytestream2_get_ne32  bytestream2_get_be32
 #   define bytestream2_get_ne64  bytestream2_get_be64
 #   define bytestream2_get_ne16u bytestream2_get_be16u
 #   define bytestream2_get_ne24u bytestream2_get_be24u
 #   define bytestream2_get_ne32u bytestream2_get_be32u
 #   define bytestream2_get_ne64u bytestream2_get_be64u
 #   define bytestream2_put_ne16  bytestream2_put_be16
 #   define bytestream2_put_ne24  bytestream2_put_be24
 #   define bytestream2_put_ne32  bytestream2_put_be32
 #   define bytestream2_put_ne64  bytestream2_put_be64
 #   define bytestream2_peek_ne16 bytestream2_peek_be16
 #   define bytestream2_peek_ne24 bytestream2_peek_be24
 #   define bytestream2_peek_ne32 bytestream2_peek_be32
 #   define bytestream2_peek_ne64 bytestream2_peek_be64
 #else
 #   define bytestream2_get_ne16  bytestream2_get_le16
 #   define bytestream2_get_ne24  bytestream2_get_le24
 #   define bytestream2_get_ne32  bytestream2_get_le32
 #   define bytestream2_get_ne64  bytestream2_get_le64
 #   define bytestream2_get_ne16u bytestream2_get_le16u
 #   define bytestream2_get_ne24u bytestream2_get_le24u
 #   define bytestream2_get_ne32u bytestream2_get_le32u
 #   define bytestream2_get_ne64u bytestream2_get_le64u
 #   define bytestream2_put_ne16  bytestream2_put_le16
 #   define bytestream2_put_ne24  bytestream2_put_le24
 #   define bytestream2_put_ne32  bytestream2_put_le32
 #   define bytestream2_put_ne64  bytestream2_put_le64
 #   define bytestream2_peek_ne16 bytestream2_peek_le16
 #   define bytestream2_peek_ne24 bytestream2_peek_le24
 #   define bytestream2_peek_ne32 bytestream2_peek_le32
 #   define bytestream2_peek_ne64 bytestream2_peek_le64
 #endif
 
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 static av_always_inline void bytestream2_init(GetByteContext *g,
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                                               const uint8_t *buf,
                                               int buf_size)
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 {
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     av_assert0(buf_size >= 0);
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     g->buffer       = buf;
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     g->buffer_start = buf;
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     g->buffer_end   = buf + buf_size;
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 }
 
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 static av_always_inline void bytestream2_init_writer(PutByteContext *p,
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                                                      uint8_t *buf,
                                                      int buf_size)
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 {
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     av_assert0(buf_size >= 0);
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     p->buffer       = buf;
     p->buffer_start = buf;
     p->buffer_end   = buf + buf_size;
     p->eof          = 0;
 }
 
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 static av_always_inline unsigned int bytestream2_get_bytes_left(GetByteContext *g)
 {
     return g->buffer_end - g->buffer;
 }
 
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 static av_always_inline unsigned int bytestream2_get_bytes_left_p(PutByteContext *p)
 {
     return p->buffer_end - p->buffer;
 }
 
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 static av_always_inline void bytestream2_skip(GetByteContext *g,
                                               unsigned int size)
 {
     g->buffer += FFMIN(g->buffer_end - g->buffer, size);
 }
 
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 static av_always_inline void bytestream2_skipu(GetByteContext *g,
                                                unsigned int size)
 {
     g->buffer += size;
 }
 
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 static av_always_inline void bytestream2_skip_p(PutByteContext *p,
                                                 unsigned int size)
 {
     int size2;
     if (p->eof)
         return;
     size2 = FFMIN(p->buffer_end - p->buffer, size);
     if (size2 != size)
         p->eof = 1;
     p->buffer += size2;
 }
 
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 static av_always_inline int bytestream2_tell(GetByteContext *g)
 {
     return (int)(g->buffer - g->buffer_start);
 }
 
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 static av_always_inline int bytestream2_tell_p(PutByteContext *p)
 {
     return (int)(p->buffer - p->buffer_start);
 }
 
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 static av_always_inline int bytestream2_size(GetByteContext *g)
 {
     return (int)(g->buffer_end - g->buffer_start);
 }
 
 static av_always_inline int bytestream2_size_p(PutByteContext *p)
 {
     return (int)(p->buffer_end - p->buffer_start);
 }
 
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 static av_always_inline int bytestream2_seek(GetByteContext *g,
                                              int offset,
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                                              int whence)
 {
     switch (whence) {
     case SEEK_CUR:
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         offset     = av_clip(offset, -(g->buffer - g->buffer_start),
                              g->buffer_end - g->buffer);
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         g->buffer += offset;
         break;
     case SEEK_END:
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         offset    = av_clip(offset, -(g->buffer_end - g->buffer_start), 0);
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         g->buffer = g->buffer_end + offset;
         break;
     case SEEK_SET:
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         offset    = av_clip(offset, 0, g->buffer_end - g->buffer_start);
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         g->buffer = g->buffer_start + offset;
         break;
     default:
         return AVERROR(EINVAL);
     }
     return bytestream2_tell(g);
 }
 
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 static av_always_inline int bytestream2_seek_p(PutByteContext *p,
                                                int offset,
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                                                int whence)
 {
     p->eof = 0;
     switch (whence) {
     case SEEK_CUR:
         if (p->buffer_end - p->buffer < offset)
             p->eof = 1;
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         offset     = av_clip(offset, -(p->buffer - p->buffer_start),
                              p->buffer_end - p->buffer);
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         p->buffer += offset;
         break;
     case SEEK_END:
         if (offset > 0)
             p->eof = 1;
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         offset    = av_clip(offset, -(p->buffer_end - p->buffer_start), 0);
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         p->buffer = p->buffer_end + offset;
         break;
     case SEEK_SET:
         if (p->buffer_end - p->buffer_start < offset)
             p->eof = 1;
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         offset    = av_clip(offset, 0, p->buffer_end - p->buffer_start);
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         p->buffer = p->buffer_start + offset;
         break;
     default:
         return AVERROR(EINVAL);
     }
     return bytestream2_tell_p(p);
 }
 
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 static av_always_inline unsigned int bytestream2_get_buffer(GetByteContext *g,
                                                             uint8_t *dst,
                                                             unsigned int size)
 {
     int size2 = FFMIN(g->buffer_end - g->buffer, size);
     memcpy(dst, g->buffer, size2);
     g->buffer += size2;
     return size2;
 }
 
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 static av_always_inline unsigned int bytestream2_get_bufferu(GetByteContext *g,
                                                              uint8_t *dst,
                                                              unsigned int size)
 {
     memcpy(dst, g->buffer, size);
     g->buffer += size;
     return size;
 }
 
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 static av_always_inline unsigned int bytestream2_put_buffer(PutByteContext *p,
                                                             const uint8_t *src,
                                                             unsigned int size)
 {
     int size2;
     if (p->eof)
         return 0;
     size2 = FFMIN(p->buffer_end - p->buffer, size);
     if (size2 != size)
         p->eof = 1;
     memcpy(p->buffer, src, size2);
     p->buffer += size2;
     return size2;
 }
 
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 static av_always_inline unsigned int bytestream2_put_bufferu(PutByteContext *p,
                                                              const uint8_t *src,
                                                              unsigned int size)
 {
     memcpy(p->buffer, src, size);
     p->buffer += size;
     return size;
 }
 
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 static av_always_inline void bytestream2_set_buffer(PutByteContext *p,
                                                     const uint8_t c,
                                                     unsigned int size)
 {
     int size2;
     if (p->eof)
         return;
     size2 = FFMIN(p->buffer_end - p->buffer, size);
     if (size2 != size)
         p->eof = 1;
     memset(p->buffer, c, size2);
     p->buffer += size2;
 }
 
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 static av_always_inline void bytestream2_set_bufferu(PutByteContext *p,
                                                      const uint8_t c,
                                                      unsigned int size)
 {
     memset(p->buffer, c, size);
     p->buffer += size;
 }
 
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 static av_always_inline unsigned int bytestream2_get_eof(PutByteContext *p)
 {
     return p->eof;
 }
 
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 static av_always_inline unsigned int bytestream2_copy_bufferu(PutByteContext *p,
                                                               GetByteContext *g,
                                                               unsigned int size)
 {
     memcpy(p->buffer, g->buffer, size);
     p->buffer += size;
     g->buffer += size;
     return size;
 }
 
 static av_always_inline unsigned int bytestream2_copy_buffer(PutByteContext *p,
                                                              GetByteContext *g,
                                                              unsigned int size)
 {
     int size2;
 
     if (p->eof)
         return 0;
     size  = FFMIN(g->buffer_end - g->buffer, size);
     size2 = FFMIN(p->buffer_end - p->buffer, size);
     if (size2 != size)
         p->eof = 1;
 
     return bytestream2_copy_bufferu(p, g, size2);
 }
 
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 static av_always_inline unsigned int bytestream_get_buffer(const uint8_t **b,
                                                            uint8_t *dst,
                                                            unsigned int size)
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 {
     memcpy(dst, *b, size);
     (*b) += size;
     return size;
 }
 
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 static av_always_inline void bytestream_put_buffer(uint8_t **b,
                                                    const uint8_t *src,
                                                    unsigned int size)
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 {
     memcpy(*b, src, size);
     (*b) += size;
 }
 
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 #endif /* AVCODEC_BYTESTREAM_H */