libavcodec/bytestream.h
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00001 /*
00002  * Bytestream functions
00003  * copyright (c) 2006 Baptiste Coudurier <baptiste.coudurier@free.fr>
00004  *
00005  * This file is part of Libav.
00006  *
00007  * Libav is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * Libav is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with Libav; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00022 #ifndef AVCODEC_BYTESTREAM_H
00023 #define AVCODEC_BYTESTREAM_H
00024 
00025 #include <string.h>
00026 #include "libavutil/common.h"
00027 #include "libavutil/intreadwrite.h"
00028 
00029 typedef struct {
00030     const uint8_t *buffer, *buffer_end, *buffer_start;
00031 } GetByteContext;
00032 
00033 #define DEF_T(type, name, bytes, read, write)                             \
00034 static av_always_inline type bytestream_get_ ## name(const uint8_t **b){\
00035     (*b) += bytes;\
00036     return read(*b - bytes);\
00037 }\
00038 static av_always_inline void bytestream_put_ ##name(uint8_t **b, const type value){\
00039     write(*b, value);\
00040     (*b) += bytes;\
00041 }\
00042 static av_always_inline type bytestream2_get_ ## name ## u(GetByteContext *g)\
00043 {\
00044     return bytestream_get_ ## name(&g->buffer);\
00045 }\
00046 static av_always_inline type bytestream2_get_ ## name(GetByteContext *g)\
00047 {\
00048     if (g->buffer_end - g->buffer < bytes)\
00049         return 0;\
00050     return bytestream2_get_ ## name ## u(g);\
00051 }\
00052 static av_always_inline type bytestream2_peek_ ## name(GetByteContext *g)\
00053 {\
00054     if (g->buffer_end - g->buffer < bytes)\
00055         return 0;\
00056     return read(g->buffer);\
00057 }
00058 
00059 #define DEF(name, bytes, read, write) \
00060     DEF_T(unsigned int, name, bytes, read, write)
00061 #define DEF64(name, bytes, read, write) \
00062     DEF_T(uint64_t, name, bytes, read, write)
00063 
00064 DEF64(le64, 8, AV_RL64, AV_WL64)
00065 DEF  (le32, 4, AV_RL32, AV_WL32)
00066 DEF  (le24, 3, AV_RL24, AV_WL24)
00067 DEF  (le16, 2, AV_RL16, AV_WL16)
00068 DEF64(be64, 8, AV_RB64, AV_WB64)
00069 DEF  (be32, 4, AV_RB32, AV_WB32)
00070 DEF  (be24, 3, AV_RB24, AV_WB24)
00071 DEF  (be16, 2, AV_RB16, AV_WB16)
00072 DEF  (byte, 1, AV_RB8 , AV_WB8 )
00073 
00074 #undef DEF
00075 #undef DEF64
00076 #undef DEF_T
00077 
00078 #if HAVE_BIGENDIAN
00079 #   define bytestream2_get_ne16  bytestream2_get_be16
00080 #   define bytestream2_get_ne24  bytestream2_get_be24
00081 #   define bytestream2_get_ne32  bytestream2_get_be32
00082 #   define bytestream2_get_ne64  bytestream2_get_be64
00083 #   define bytestream2_get_ne16u bytestream2_get_be16u
00084 #   define bytestream2_get_ne24u bytestream2_get_be24u
00085 #   define bytestream2_get_ne32u bytestream2_get_be32u
00086 #   define bytestream2_get_ne64u bytestream2_get_be64u
00087 #   define bytestream2_put_ne16  bytestream2_put_be16
00088 #   define bytestream2_put_ne24  bytestream2_put_be24
00089 #   define bytestream2_put_ne32  bytestream2_put_be32
00090 #   define bytestream2_put_ne64  bytestream2_put_be64
00091 #   define bytestream2_peek_ne16 bytestream2_peek_be16
00092 #   define bytestream2_peek_ne24 bytestream2_peek_be24
00093 #   define bytestream2_peek_ne32 bytestream2_peek_be32
00094 #   define bytestream2_peek_ne64 bytestream2_peek_be64
00095 #else
00096 #   define bytestream2_get_ne16  bytestream2_get_le16
00097 #   define bytestream2_get_ne24  bytestream2_get_le24
00098 #   define bytestream2_get_ne32  bytestream2_get_le32
00099 #   define bytestream2_get_ne64  bytestream2_get_le64
00100 #   define bytestream2_get_ne16u bytestream2_get_le16u
00101 #   define bytestream2_get_ne24u bytestream2_get_le24u
00102 #   define bytestream2_get_ne32u bytestream2_get_le32u
00103 #   define bytestream2_get_ne64u bytestream2_get_le64u
00104 #   define bytestream2_put_ne16  bytestream2_put_le16
00105 #   define bytestream2_put_ne24  bytestream2_put_le24
00106 #   define bytestream2_put_ne32  bytestream2_put_le32
00107 #   define bytestream2_put_ne64  bytestream2_put_le64
00108 #   define bytestream2_peek_ne16 bytestream2_peek_le16
00109 #   define bytestream2_peek_ne24 bytestream2_peek_le24
00110 #   define bytestream2_peek_ne32 bytestream2_peek_le32
00111 #   define bytestream2_peek_ne64 bytestream2_peek_le64
00112 #endif
00113 
00114 static av_always_inline void bytestream2_init(GetByteContext *g,
00115                                               const uint8_t *buf, int buf_size)
00116 {
00117     g->buffer =  buf;
00118     g->buffer_start = buf;
00119     g->buffer_end = buf + buf_size;
00120 }
00121 
00122 static av_always_inline unsigned int bytestream2_get_bytes_left(GetByteContext *g)
00123 {
00124     return g->buffer_end - g->buffer;
00125 }
00126 
00127 static av_always_inline void bytestream2_skip(GetByteContext *g,
00128                                               unsigned int size)
00129 {
00130     g->buffer += FFMIN(g->buffer_end - g->buffer, size);
00131 }
00132 
00133 static av_always_inline int bytestream2_tell(GetByteContext *g)
00134 {
00135     return (int)(g->buffer - g->buffer_start);
00136 }
00137 
00138 static av_always_inline int bytestream2_seek(GetByteContext *g, int offset,
00139                                              int whence)
00140 {
00141     switch (whence) {
00142     case SEEK_CUR:
00143         offset = av_clip(offset, -(g->buffer - g->buffer_start),
00144                          g->buffer_end - g->buffer);
00145         g->buffer += offset;
00146         break;
00147     case SEEK_END:
00148         offset = av_clip(offset, -(g->buffer_end - g->buffer_start), 0);
00149         g->buffer = g->buffer_end + offset;
00150         break;
00151     case SEEK_SET:
00152         offset = av_clip(offset, 0, g->buffer_end - g->buffer_start);
00153         g->buffer = g->buffer_start + offset;
00154         break;
00155     default:
00156         return AVERROR(EINVAL);
00157     }
00158     return bytestream2_tell(g);
00159 }
00160 
00161 static av_always_inline unsigned int bytestream2_get_buffer(GetByteContext *g,
00162                                                             uint8_t *dst,
00163                                                             unsigned int size)
00164 {
00165     int size2 = FFMIN(g->buffer_end - g->buffer, size);
00166     memcpy(dst, g->buffer, size2);
00167     g->buffer += size2;
00168     return size2;
00169 }
00170 
00171 static av_always_inline unsigned int bytestream_get_buffer(const uint8_t **b, uint8_t *dst, unsigned int size)
00172 {
00173     memcpy(dst, *b, size);
00174     (*b) += size;
00175     return size;
00176 }
00177 
00178 static av_always_inline void bytestream_put_buffer(uint8_t **b, const uint8_t *src, unsigned int size)
00179 {
00180     memcpy(*b, src, size);
00181     (*b) += size;
00182 }
00183 
00184 #endif /* AVCODEC_BYTESTREAM_H */