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libavcodec/put_bits.h

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00001 /*
00002  * copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at>
00003  *
00004  * This file is part of FFmpeg.
00005  *
00006  * FFmpeg is free software; you can redistribute it and/or
00007  * modify it under the terms of the GNU Lesser General Public
00008  * License as published by the Free Software Foundation; either
00009  * version 2.1 of the License, or (at your option) any later version.
00010  *
00011  * FFmpeg is distributed in the hope that it will be useful,
00012  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00013  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00014  * Lesser General Public License for more details.
00015  *
00016  * You should have received a copy of the GNU Lesser General Public
00017  * License along with FFmpeg; if not, write to the Free Software
00018  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00019  */
00020 
00026 #ifndef AVCODEC_PUT_BITS_H
00027 #define AVCODEC_PUT_BITS_H
00028 
00029 #include <stdint.h>
00030 #include <stdlib.h>
00031 #include <assert.h>
00032 #include "libavutil/bswap.h"
00033 #include "libavutil/common.h"
00034 #include "libavutil/intreadwrite.h"
00035 #include "libavutil/log.h"
00036 #include "mathops.h"
00037 #include "config.h"
00038 
00039 typedef struct PutBitContext {
00040     uint32_t bit_buf;
00041     int bit_left;
00042     uint8_t *buf, *buf_ptr, *buf_end;
00043     int size_in_bits;
00044 } PutBitContext;
00045 
00052 static inline void init_put_bits(PutBitContext *s, uint8_t *buffer, int buffer_size)
00053 {
00054     if(buffer_size < 0) {
00055         buffer_size = 0;
00056         buffer = NULL;
00057     }
00058 
00059     s->size_in_bits= 8*buffer_size;
00060     s->buf = buffer;
00061     s->buf_end = s->buf + buffer_size;
00062     s->buf_ptr = s->buf;
00063     s->bit_left=32;
00064     s->bit_buf=0;
00065 }
00066 
00070 static inline int put_bits_count(PutBitContext *s)
00071 {
00072     return (s->buf_ptr - s->buf) * 8 + 32 - s->bit_left;
00073 }
00074 
00078 static inline void flush_put_bits(PutBitContext *s)
00079 {
00080 #ifndef BITSTREAM_WRITER_LE
00081     if (s->bit_left < 32)
00082         s->bit_buf<<= s->bit_left;
00083 #endif
00084     while (s->bit_left < 32) {
00085         /* XXX: should test end of buffer */
00086 #ifdef BITSTREAM_WRITER_LE
00087         *s->buf_ptr++=s->bit_buf;
00088         s->bit_buf>>=8;
00089 #else
00090         *s->buf_ptr++=s->bit_buf >> 24;
00091         s->bit_buf<<=8;
00092 #endif
00093         s->bit_left+=8;
00094     }
00095     s->bit_left=32;
00096     s->bit_buf=0;
00097 }
00098 
00099 #ifdef BITSTREAM_WRITER_LE
00100 #define avpriv_align_put_bits align_put_bits_unsupported_here
00101 #define ff_put_string ff_put_string_unsupported_here
00102 #define avpriv_copy_bits avpriv_copy_bits_unsupported_here
00103 #else
00104 
00107 void avpriv_align_put_bits(PutBitContext *s);
00108 
00114 void ff_put_string(PutBitContext *pb, const char *string, int terminate_string);
00115 
00121 void avpriv_copy_bits(PutBitContext *pb, const uint8_t *src, int length);
00122 #endif
00123 
00128 static inline void put_bits(PutBitContext *s, int n, unsigned int value)
00129 {
00130     unsigned int bit_buf;
00131     int bit_left;
00132 
00133     //    printf("put_bits=%d %x\n", n, value);
00134     assert(n <= 31 && value < (1U << n));
00135 
00136     bit_buf = s->bit_buf;
00137     bit_left = s->bit_left;
00138 
00139     //    printf("n=%d value=%x cnt=%d buf=%x\n", n, value, bit_cnt, bit_buf);
00140     /* XXX: optimize */
00141 #ifdef BITSTREAM_WRITER_LE
00142     bit_buf |= value << (32 - bit_left);
00143     if (n >= bit_left) {
00144         AV_WL32(s->buf_ptr, bit_buf);
00145         s->buf_ptr+=4;
00146         bit_buf = (bit_left==32)?0:value >> bit_left;
00147         bit_left+=32;
00148     }
00149     bit_left-=n;
00150 #else
00151     if (n < bit_left) {
00152         bit_buf = (bit_buf<<n) | value;
00153         bit_left-=n;
00154     } else {
00155         bit_buf<<=bit_left;
00156         bit_buf |= value >> (n - bit_left);
00157         AV_WB32(s->buf_ptr, bit_buf);
00158         //printf("bitbuf = %08x\n", bit_buf);
00159         s->buf_ptr+=4;
00160         bit_left+=32 - n;
00161         bit_buf = value;
00162     }
00163 #endif
00164 
00165     s->bit_buf = bit_buf;
00166     s->bit_left = bit_left;
00167 }
00168 
00169 static inline void put_sbits(PutBitContext *pb, int n, int32_t value)
00170 {
00171     assert(n >= 0 && n <= 31);
00172 
00173     put_bits(pb, n, value & ((1<<n)-1));
00174 }
00175 
00179 static void av_unused put_bits32(PutBitContext *s, uint32_t value)
00180 {
00181     int lo = value & 0xffff;
00182     int hi = value >> 16;
00183 #ifdef BITSTREAM_WRITER_LE
00184     put_bits(s, 16, lo);
00185     put_bits(s, 16, hi);
00186 #else
00187     put_bits(s, 16, hi);
00188     put_bits(s, 16, lo);
00189 #endif
00190 }
00191 
00196 static inline uint8_t* put_bits_ptr(PutBitContext *s)
00197 {
00198         return s->buf_ptr;
00199 }
00200 
00205 static inline void skip_put_bytes(PutBitContext *s, int n)
00206 {
00207         assert((put_bits_count(s)&7)==0);
00208         assert(s->bit_left==32);
00209         s->buf_ptr += n;
00210 }
00211 
00217 static inline void skip_put_bits(PutBitContext *s, int n)
00218 {
00219     s->bit_left -= n;
00220     s->buf_ptr-= 4*(s->bit_left>>5);
00221     s->bit_left &= 31;
00222 }
00223 
00229 static inline void set_put_bits_buffer_size(PutBitContext *s, int size)
00230 {
00231     s->buf_end= s->buf + size;
00232 }
00233 
00234 #endif /* AVCODEC_PUT_BITS_H */
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