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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 
00038 //#define ALT_BITSTREAM_WRITER
00039 //#define ALIGNED_BITSTREAM_WRITER
00040 
00041 /* buf and buf_end must be present and used by every alternative writer. */
00042 typedef struct PutBitContext {
00043 #ifdef ALT_BITSTREAM_WRITER
00044     uint8_t *buf, *buf_end;
00045     int index;
00046 #else
00047     uint32_t bit_buf;
00048     int bit_left;
00049     uint8_t *buf, *buf_ptr, *buf_end;
00050 #endif
00051     int size_in_bits;
00052 } PutBitContext;
00053 
00060 static inline void init_put_bits(PutBitContext *s, uint8_t *buffer, int buffer_size)
00061 {
00062     if(buffer_size < 0) {
00063         buffer_size = 0;
00064         buffer = NULL;
00065     }
00066 
00067     s->size_in_bits= 8*buffer_size;
00068     s->buf = buffer;
00069     s->buf_end = s->buf + buffer_size;
00070 #ifdef ALT_BITSTREAM_WRITER
00071     s->index=0;
00072     ((uint32_t*)(s->buf))[0]=0;
00073 //    memset(buffer, 0, buffer_size);
00074 #else
00075     s->buf_ptr = s->buf;
00076     s->bit_left=32;
00077     s->bit_buf=0;
00078 #endif
00079 }
00080 
00084 static inline int put_bits_count(PutBitContext *s)
00085 {
00086 #ifdef ALT_BITSTREAM_WRITER
00087     return s->index;
00088 #else
00089     return (s->buf_ptr - s->buf) * 8 + 32 - s->bit_left;
00090 #endif
00091 }
00092 
00096 static inline void flush_put_bits(PutBitContext *s)
00097 {
00098 #ifdef ALT_BITSTREAM_WRITER
00099     align_put_bits(s);
00100 #else
00101 #ifndef BITSTREAM_WRITER_LE
00102     s->bit_buf<<= s->bit_left;
00103 #endif
00104     while (s->bit_left < 32) {
00105         /* XXX: should test end of buffer */
00106 #ifdef BITSTREAM_WRITER_LE
00107         *s->buf_ptr++=s->bit_buf;
00108         s->bit_buf>>=8;
00109 #else
00110         *s->buf_ptr++=s->bit_buf >> 24;
00111         s->bit_buf<<=8;
00112 #endif
00113         s->bit_left+=8;
00114     }
00115     s->bit_left=32;
00116     s->bit_buf=0;
00117 #endif
00118 }
00119 
00120 #if defined(ALT_BITSTREAM_WRITER) || defined(BITSTREAM_WRITER_LE)
00121 #define align_put_bits align_put_bits_unsupported_here
00122 #define ff_put_string ff_put_string_unsupported_here
00123 #define ff_copy_bits ff_copy_bits_unsupported_here
00124 #else
00125 
00128 void align_put_bits(PutBitContext *s);
00129 
00135 void ff_put_string(PutBitContext *pb, const char *string, int terminate_string);
00136 
00142 void ff_copy_bits(PutBitContext *pb, const uint8_t *src, int length);
00143 #endif
00144 
00149 static inline void put_bits(PutBitContext *s, int n, unsigned int value)
00150 #ifndef ALT_BITSTREAM_WRITER
00151 {
00152     unsigned int bit_buf;
00153     int bit_left;
00154 
00155     //    printf("put_bits=%d %x\n", n, value);
00156     assert(n <= 31 && value < (1U << n));
00157 
00158     bit_buf = s->bit_buf;
00159     bit_left = s->bit_left;
00160 
00161     //    printf("n=%d value=%x cnt=%d buf=%x\n", n, value, bit_cnt, bit_buf);
00162     /* XXX: optimize */
00163 #ifdef BITSTREAM_WRITER_LE
00164     bit_buf |= value << (32 - bit_left);
00165     if (n >= bit_left) {
00166 #if !HAVE_FAST_UNALIGNED
00167         if (3 & (intptr_t) s->buf_ptr) {
00168             AV_WL32(s->buf_ptr, bit_buf);
00169         } else
00170 #endif
00171         *(uint32_t *)s->buf_ptr = le2me_32(bit_buf);
00172         s->buf_ptr+=4;
00173         bit_buf = (bit_left==32)?0:value >> bit_left;
00174         bit_left+=32;
00175     }
00176     bit_left-=n;
00177 #else
00178     if (n < bit_left) {
00179         bit_buf = (bit_buf<<n) | value;
00180         bit_left-=n;
00181     } else {
00182         bit_buf<<=bit_left;
00183         bit_buf |= value >> (n - bit_left);
00184 #if !HAVE_FAST_UNALIGNED
00185         if (3 & (intptr_t) s->buf_ptr) {
00186             AV_WB32(s->buf_ptr, bit_buf);
00187         } else
00188 #endif
00189         *(uint32_t *)s->buf_ptr = be2me_32(bit_buf);
00190         //printf("bitbuf = %08x\n", bit_buf);
00191         s->buf_ptr+=4;
00192         bit_left+=32 - n;
00193         bit_buf = value;
00194     }
00195 #endif
00196 
00197     s->bit_buf = bit_buf;
00198     s->bit_left = bit_left;
00199 }
00200 #else  /* ALT_BITSTREAM_WRITER defined */
00201 {
00202 #    ifdef ALIGNED_BITSTREAM_WRITER
00203 #        if ARCH_X86
00204     __asm__ volatile(
00205         "movl %0, %%ecx                 \n\t"
00206         "xorl %%eax, %%eax              \n\t"
00207         "shrdl %%cl, %1, %%eax          \n\t"
00208         "shrl %%cl, %1                  \n\t"
00209         "movl %0, %%ecx                 \n\t"
00210         "shrl $3, %%ecx                 \n\t"
00211         "andl $0xFFFFFFFC, %%ecx        \n\t"
00212         "bswapl %1                      \n\t"
00213         "orl %1, (%2, %%ecx)            \n\t"
00214         "bswapl %%eax                   \n\t"
00215         "addl %3, %0                    \n\t"
00216         "movl %%eax, 4(%2, %%ecx)       \n\t"
00217         : "=&r" (s->index), "=&r" (value)
00218         : "r" (s->buf), "r" (n), "0" (s->index), "1" (value<<(-n))
00219         : "%eax", "%ecx"
00220     );
00221 #        else
00222     int index= s->index;
00223     uint32_t *ptr= ((uint32_t *)s->buf)+(index>>5);
00224 
00225     value<<= 32-n;
00226 
00227     ptr[0] |= be2me_32(value>>(index&31));
00228     ptr[1]  = be2me_32(value<<(32-(index&31)));
00229 //if(n>24) printf("%d %d\n", n, value);
00230     index+= n;
00231     s->index= index;
00232 #        endif
00233 #    else //ALIGNED_BITSTREAM_WRITER
00234 #        if ARCH_X86
00235     __asm__ volatile(
00236         "movl $7, %%ecx                 \n\t"
00237         "andl %0, %%ecx                 \n\t"
00238         "addl %3, %%ecx                 \n\t"
00239         "negl %%ecx                     \n\t"
00240         "shll %%cl, %1                  \n\t"
00241         "bswapl %1                      \n\t"
00242         "movl %0, %%ecx                 \n\t"
00243         "shrl $3, %%ecx                 \n\t"
00244         "orl %1, (%%ecx, %2)            \n\t"
00245         "addl %3, %0                    \n\t"
00246         "movl $0, 4(%%ecx, %2)          \n\t"
00247         : "=&r" (s->index), "=&r" (value)
00248         : "r" (s->buf), "r" (n), "0" (s->index), "1" (value)
00249         : "%ecx"
00250     );
00251 #        else
00252     int index= s->index;
00253     uint32_t *ptr= (uint32_t*)(((uint8_t *)s->buf)+(index>>3));
00254 
00255     ptr[0] |= be2me_32(value<<(32-n-(index&7) ));
00256     ptr[1] = 0;
00257 //if(n>24) printf("%d %d\n", n, value);
00258     index+= n;
00259     s->index= index;
00260 #        endif
00261 #    endif //!ALIGNED_BITSTREAM_WRITER
00262 }
00263 #endif
00264 
00265 static inline void put_sbits(PutBitContext *pb, int n, int32_t value)
00266 {
00267     assert(n >= 0 && n <= 31);
00268 
00269     put_bits(pb, n, value & ((1<<n)-1));
00270 }
00271 
00275 static void av_unused put_bits32(PutBitContext *s, uint32_t value)
00276 {
00277     int lo = value & 0xffff;
00278     int hi = value >> 16;
00279 #ifdef BITSTREAM_WRITER_LE
00280     put_bits(s, 16, lo);
00281     put_bits(s, 16, hi);
00282 #else
00283     put_bits(s, 16, hi);
00284     put_bits(s, 16, lo);
00285 #endif
00286 }
00287 
00292 static inline uint8_t* put_bits_ptr(PutBitContext *s)
00293 {
00294 #ifdef ALT_BITSTREAM_WRITER
00295         return s->buf + (s->index>>3);
00296 #else
00297         return s->buf_ptr;
00298 #endif
00299 }
00300 
00305 static inline void skip_put_bytes(PutBitContext *s, int n)
00306 {
00307         assert((put_bits_count(s)&7)==0);
00308 #ifdef ALT_BITSTREAM_WRITER
00309         FIXME may need some cleaning of the buffer
00310         s->index += n<<3;
00311 #else
00312         assert(s->bit_left==32);
00313         s->buf_ptr += n;
00314 #endif
00315 }
00316 
00322 static inline void skip_put_bits(PutBitContext *s, int n)
00323 {
00324 #ifdef ALT_BITSTREAM_WRITER
00325     s->index += n;
00326 #else
00327     s->bit_left -= n;
00328     s->buf_ptr-= 4*(s->bit_left>>5);
00329     s->bit_left &= 31;
00330 #endif
00331 }
00332 
00338 static inline void set_put_bits_buffer_size(PutBitContext *s, int size)
00339 {
00340     s->buf_end= s->buf + size;
00341 }
00342 
00343 #endif /* AVCODEC_PUT_BITS_H */

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