libavcodec/put_bits.h
Go to the documentation of this file.
00001 /*
00002  * copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at>
00003  *
00004  * This file is part of Libav.
00005  *
00006  * Libav 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  * Libav 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 Libav; 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 int put_bits_left(PutBitContext* s)
00079 {
00080     return (s->buf_end - s->buf_ptr) * 8 - 32 + s->bit_left;
00081 }
00082 
00086 static inline void flush_put_bits(PutBitContext *s)
00087 {
00088 #ifndef BITSTREAM_WRITER_LE
00089     if (s->bit_left < 32)
00090         s->bit_buf<<= s->bit_left;
00091 #endif
00092     while (s->bit_left < 32) {
00093         /* XXX: should test end of buffer */
00094 #ifdef BITSTREAM_WRITER_LE
00095         *s->buf_ptr++=s->bit_buf;
00096         s->bit_buf>>=8;
00097 #else
00098         *s->buf_ptr++=s->bit_buf >> 24;
00099         s->bit_buf<<=8;
00100 #endif
00101         s->bit_left+=8;
00102     }
00103     s->bit_left=32;
00104     s->bit_buf=0;
00105 }
00106 
00107 #ifdef BITSTREAM_WRITER_LE
00108 #define avpriv_align_put_bits align_put_bits_unsupported_here
00109 #define ff_put_string ff_put_string_unsupported_here
00110 #define avpriv_copy_bits avpriv_copy_bits_unsupported_here
00111 #else
00112 
00115 void avpriv_align_put_bits(PutBitContext *s);
00116 
00122 void ff_put_string(PutBitContext *pb, const char *string, int terminate_string);
00123 
00129 void avpriv_copy_bits(PutBitContext *pb, const uint8_t *src, int length);
00130 #endif
00131 
00136 static inline void put_bits(PutBitContext *s, int n, unsigned int value)
00137 {
00138     unsigned int bit_buf;
00139     int bit_left;
00140 
00141     //    printf("put_bits=%d %x\n", n, value);
00142     assert(n <= 31 && value < (1U << n));
00143 
00144     bit_buf = s->bit_buf;
00145     bit_left = s->bit_left;
00146 
00147     //    printf("n=%d value=%x cnt=%d buf=%x\n", n, value, bit_cnt, bit_buf);
00148     /* XXX: optimize */
00149 #ifdef BITSTREAM_WRITER_LE
00150     bit_buf |= value << (32 - bit_left);
00151     if (n >= bit_left) {
00152         AV_WL32(s->buf_ptr, bit_buf);
00153         s->buf_ptr+=4;
00154         bit_buf = (bit_left==32)?0:value >> bit_left;
00155         bit_left+=32;
00156     }
00157     bit_left-=n;
00158 #else
00159     if (n < bit_left) {
00160         bit_buf = (bit_buf<<n) | value;
00161         bit_left-=n;
00162     } else {
00163         bit_buf<<=bit_left;
00164         bit_buf |= value >> (n - bit_left);
00165         AV_WB32(s->buf_ptr, bit_buf);
00166         //printf("bitbuf = %08x\n", bit_buf);
00167         s->buf_ptr+=4;
00168         bit_left+=32 - n;
00169         bit_buf = value;
00170     }
00171 #endif
00172 
00173     s->bit_buf = bit_buf;
00174     s->bit_left = bit_left;
00175 }
00176 
00177 static inline void put_sbits(PutBitContext *pb, int n, int32_t value)
00178 {
00179     assert(n >= 0 && n <= 31);
00180 
00181     put_bits(pb, n, value & ((1<<n)-1));
00182 }
00183 
00187 static void av_unused put_bits32(PutBitContext *s, uint32_t value)
00188 {
00189     int lo = value & 0xffff;
00190     int hi = value >> 16;
00191 #ifdef BITSTREAM_WRITER_LE
00192     put_bits(s, 16, lo);
00193     put_bits(s, 16, hi);
00194 #else
00195     put_bits(s, 16, hi);
00196     put_bits(s, 16, lo);
00197 #endif
00198 }
00199 
00204 static inline uint8_t* put_bits_ptr(PutBitContext *s)
00205 {
00206         return s->buf_ptr;
00207 }
00208 
00213 static inline void skip_put_bytes(PutBitContext *s, int n)
00214 {
00215         assert((put_bits_count(s)&7)==0);
00216         assert(s->bit_left==32);
00217         s->buf_ptr += n;
00218 }
00219 
00225 static inline void skip_put_bits(PutBitContext *s, int n)
00226 {
00227     s->bit_left -= n;
00228     s->buf_ptr-= 4*(s->bit_left>>5);
00229     s->bit_left &= 31;
00230 }
00231 
00237 static inline void set_put_bits_buffer_size(PutBitContext *s, int size)
00238 {
00239     s->buf_end= s->buf + size;
00240 }
00241 
00242 #endif /* AVCODEC_PUT_BITS_H */