libavcodec/utils.c

   1 /*
   2  * utils for libavcodec
   3  * Copyright (c) 2001 Fabrice Bellard.
   4  *
   5  * This library is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Lesser General Public
   7  * License as published by the Free Software Foundation; either
   8  * version 2 of the License, or (at your option) any later version.
   9  *
  10  * This library is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * Lesser General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General Public
  16  * License along with this library; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18  */
  19
  20 /**
  21  * @file utils.c
  22  * utils.
  23  */
  24
  25 #include "avcodec.h"
  26 #include "dsputil.h"
  27 #include "mpegvideo.h"
  28
  29 void *av_mallocz(unsigned int size)
  30 {
  31     void *ptr;
  32
  33     ptr = av_malloc(size);
  34     if (!ptr)
  35         return NULL;
  36     memset(ptr, 0, size);
  37     return ptr;
  38 }
  39
  40 char *av_strdup(const char *s)
  41 {
  42     char *ptr;
  43     int len;
  44     len = strlen(s) + 1;
  45     ptr = av_malloc(len);
  46     if (!ptr)
  47         return NULL;
  48     memcpy(ptr, s, len);
  49     return ptr;
  50 }
  51
  52 /**
  53  * realloc which does nothing if the block is large enough
  54  */
  55 void *av_fast_realloc(void *ptr, unsigned int *size, unsigned int min_size)
  56 {
  57     if(min_size < *size)
  58         return ptr;
  59
  60     *size= min_size + 10*1024;
  61
  62     return av_realloc(ptr, *size);
  63 }
  64
  65
  66 /* allocation of static arrays - do not use for normal allocation */
  67 static unsigned int last_static = 0;
  68 static char*** array_static = NULL;
  69 static const unsigned int grow_static = 64; // ^2
  70 void *__av_mallocz_static(void** location, unsigned int size)
  71 {
  72     unsigned int l = (last_static + grow_static) & ~(grow_static - 1);
  73     void *ptr = av_mallocz(size);
  74     if (!ptr)
  75         return NULL;
  76
  77     if (location)
  78     {
  79         if (l > last_static)
  80             array_static = av_realloc(array_static, l);
  81         array_static[last_static++] = (char**) location;
  82         *location = ptr;
  83     }
  84     return ptr;
  85 }
  86 /* free all static arrays and reset pointers to 0 */
  87 void av_free_static(void)
  88 {
  89     if (array_static)
  90     {
  91         unsigned i;
  92         for (i = 0; i < last_static; i++)
  93         {
  94             av_free(*array_static[i]);
  95             *array_static[i] = NULL;
  96         }
  97         av_free(array_static);
  98         array_static = 0;
  99     }
 100     last_static = 0;
 101 }
 102
 103 /* cannot call it directly because of 'void **' casting is not automatic */
 104 void __av_freep(void **ptr)
 105 {
 106     av_free(*ptr);
 107     *ptr = NULL;
 108 }
 109
 110 /* encoder management */
 111 AVCodec *first_avcodec;
 112
 113 void register_avcodec(AVCodec *format)
 114 {
 115     AVCodec **p;
 116     p = &first_avcodec;
 117     while (*p != NULL) p = &(*p)->next;
 118     *p = format;
 119     format->next = NULL;
 120 }
 121
 122 typedef struct InternalBuffer{
 123     int last_pic_num;
 124     uint8_t *base[4];
 125     uint8_t *data[4];
 126 }InternalBuffer;
 127
 128 #define INTERNAL_BUFFER_SIZE 32
 129
 130 #define ALIGN(x, a) (((x)+(a)-1)&~((a)-1))
 131
 132 void avcodec_align_dimensions(AVCodecContext *s, int *width, int *height){
 133     int w_align= 1;
 134     int h_align= 1;
 135
 136     switch(s->pix_fmt){
 137     case PIX_FMT_YUV420P:
 138     case PIX_FMT_YUV422:
 139     case PIX_FMT_YUV422P:
 140     case PIX_FMT_YUV444P:
 141     case PIX_FMT_GRAY8:
 142     case PIX_FMT_YUVJ420P:
 143     case PIX_FMT_YUVJ422P:
 144     case PIX_FMT_YUVJ444P:
 145         w_align= 16; //FIXME check for non mpeg style codecs and use less alignment
 146         h_align= 16;
 147         break;
 148     case PIX_FMT_YUV411P:
 149         w_align=32;
 150         h_align=8;
 151         break;
 152     case PIX_FMT_YUV410P:
 153         if(s->codec_id == CODEC_ID_SVQ1){
 154             w_align=64;
 155             h_align=64;
 156         }
 157         break;
 158     default:
 159         w_align= 1;
 160         h_align= 1;
 161         break;
 162     }
 163
 164     *width = ALIGN(*width , w_align);
 165     *height= ALIGN(*height, h_align);
 166 }
 167
 168 int avcodec_default_get_buffer(AVCodecContext *s, AVFrame *pic){
 169     int i;
 170     int w= s->width;
 171     int h= s->height;
 172     InternalBuffer *buf;
 173
 174     assert(pic->data[0]==NULL);
 175     assert(INTERNAL_BUFFER_SIZE > s->internal_buffer_count);
 176
 177     if(s->internal_buffer==NULL){
 178         s->internal_buffer= av_mallocz(INTERNAL_BUFFER_SIZE*sizeof(InternalBuffer));
 179     }
 180 #if 0
 181     s->internal_buffer= av_fast_realloc(
 182         s->internal_buffer,
 183         &s->internal_buffer_size,
 184         sizeof(InternalBuffer)*FFMAX(99,  s->internal_buffer_count+1)/*FIXME*/
 185         );
 186 #endif
 187
 188     buf= &((InternalBuffer*)s->internal_buffer)[s->internal_buffer_count];
 189
 190     if(buf->base[0]){
 191         pic->age= pic->coded_picture_number - buf->last_pic_num;
 192         buf->last_pic_num= pic->coded_picture_number;
 193     }else{
 194         int h_chroma_shift, v_chroma_shift;
 195         int s_align, pixel_size;
 196
 197         avcodec_get_chroma_sub_sample(s->pix_fmt, &h_chroma_shift, &v_chroma_shift);
 198
 199         switch(s->pix_fmt){
 200         case PIX_FMT_RGB555:
 201         case PIX_FMT_RGB565:
 202         case PIX_FMT_YUV422:
 203             pixel_size=2;
 204             break;
 205         case PIX_FMT_RGB24:
 206         case PIX_FMT_BGR24:
 207             pixel_size=3;
 208             break;
 209         case PIX_FMT_RGBA32:
 210             pixel_size=4;
 211             break;
 212         default:
 213             pixel_size=1;
 214         }
 215
 216         avcodec_align_dimensions(s, &w, &h);
 217 #if defined(ARCH_POWERPC) || defined(HAVE_MMI) //FIXME some cleaner check
 218         s_align= 16;
 219 #else
 220         s_align= 8;
 221 #endif
 222
 223         if(!(s->flags&CODEC_FLAG_EMU_EDGE)){
 224             w+= EDGE_WIDTH*2;
 225             h+= EDGE_WIDTH*2;
 226         }
 227
 228         buf->last_pic_num= -256*256*256*64;
 229
 230         for(i=0; i<3; i++){
 231             const int h_shift= i==0 ? 0 : h_chroma_shift;
 232             const int v_shift= i==0 ? 0 : v_chroma_shift;
 233
 234             pic->linesize[i]= ALIGN(pixel_size*w>>h_shift, s_align);
 235
 236             buf->base[i]= av_mallocz((pic->linesize[i]*h>>v_shift)+16); //FIXME 16
 237             if(buf->base[i]==NULL) return -1;
 238             memset(buf->base[i], 128, pic->linesize[i]*h>>v_shift);
 239
 240             if(s->flags&CODEC_FLAG_EMU_EDGE)
 241                 buf->data[i] = buf->base[i];
 242             else
 243                 buf->data[i] = buf->base[i] + ALIGN((pic->linesize[i]*EDGE_WIDTH>>v_shift) + (EDGE_WIDTH>>h_shift), s_align);
 244         }
 245         pic->age= 256*256*256*64;
 246         pic->type= FF_BUFFER_TYPE_INTERNAL;
 247     }
 248
 249     for(i=0; i<4; i++){
 250         pic->base[i]= buf->base[i];
 251         pic->data[i]= buf->data[i];
 252     }
 253     s->internal_buffer_count++;
 254
 255     return 0;
 256 }
 257
 258 void avcodec_default_release_buffer(AVCodecContext *s, AVFrame *pic){
 259     int i;
 260     InternalBuffer *buf, *last, temp;
 261
 262     assert(pic->type==FF_BUFFER_TYPE_INTERNAL);
 263     assert(s->internal_buffer_count);
 264
 265     buf = NULL; /* avoids warning */
 266     for(i=0; i<s->internal_buffer_count; i++){ //just 3-5 checks so is not worth to optimize
 267         buf= &((InternalBuffer*)s->internal_buffer)[i];
 268         if(buf->data[0] == pic->data[0])
 269             break;
 270     }
 271     assert(i < s->internal_buffer_count);
 272     s->internal_buffer_count--;
 273     last = &((InternalBuffer*)s->internal_buffer)[s->internal_buffer_count];
 274
 275     temp= *buf;
 276     *buf= *last;
 277     *last= temp;
 278
 279     for(i=0; i<3; i++){
 280         pic->data[i]=NULL;
 281 //        pic->base[i]=NULL;
 282     }
 283 //printf("R%X\n", pic->opaque);
 284 }
 285
 286 enum PixelFormat avcodec_default_get_format(struct AVCodecContext *s, enum PixelFormat * fmt){
 287     return fmt[0];
 288 }
 289
 290 void avcodec_get_context_defaults(AVCodecContext *s){
 291     s->bit_rate= 800*1000;
 292     s->bit_rate_tolerance= s->bit_rate*10;
 293     s->qmin= 2;
 294     s->qmax= 31;
 295     s->mb_qmin= 2;
 296     s->mb_qmax= 31;
 297     s->rc_eq= "tex^qComp";
 298     s->qcompress= 0.5;
 299     s->max_qdiff= 3;
 300     s->b_quant_factor=1.25;
 301     s->b_quant_offset=1.25;
 302     s->i_quant_factor=-0.8;
 303     s->i_quant_offset=0.0;
 304     s->error_concealment= 3;
 305     s->error_resilience= 1;
 306     s->workaround_bugs= FF_BUG_AUTODETECT;
 307     s->frame_rate_base= 1;
 308     s->frame_rate = 25;
 309     s->gop_size= 50;
 310     s->me_method= ME_EPZS;
 311     s->get_buffer= avcodec_default_get_buffer;
 312     s->release_buffer= avcodec_default_release_buffer;
 313     s->get_format= avcodec_default_get_format;
 314     s->me_subpel_quality=8;
 315     s->lmin= FF_QP2LAMBDA * s->qmin;
 316     s->lmax= FF_QP2LAMBDA * s->qmax;
 317
 318     s->intra_quant_bias= FF_DEFAULT_QUANT_BIAS;
 319     s->inter_quant_bias= FF_DEFAULT_QUANT_BIAS;
 320 }
 321
 322 /**
 323  * allocates a AVCodecContext and set it to defaults.
 324  * this can be deallocated by simply calling free()
 325  */
 326 AVCodecContext *avcodec_alloc_context(void){
 327     AVCodecContext *avctx= av_mallocz(sizeof(AVCodecContext));
 328
 329     if(avctx==NULL) return NULL;
 330
 331     avcodec_get_context_defaults(avctx);
 332
 333     return avctx;
 334 }
 335
 336 /**
 337  * allocates a AVPFrame and set it to defaults.
 338  * this can be deallocated by simply calling free()
 339  */
 340 AVFrame *avcodec_alloc_frame(void){
 341     AVFrame *pic= av_mallocz(sizeof(AVFrame));
 342
 343     return pic;
 344 }
 345
 346 int avcodec_open(AVCodecContext *avctx, AVCodec *codec)
 347 {
 348     int ret;
 349
 350     if(avctx->codec)
 351         return -1;
 352
 353     avctx->codec = codec;
 354     avctx->codec_id = codec->id;
 355     avctx->frame_number = 0;
 356     if (codec->priv_data_size > 0) {
 357         avctx->priv_data = av_mallocz(codec->priv_data_size);
 358         if (!avctx->priv_data)
 359             return -ENOMEM;
 360     } else {
 361         avctx->priv_data = NULL;
 362     }
 363     ret = avctx->codec->init(avctx);
 364     if (ret < 0) {
 365         av_freep(&avctx->priv_data);
 366         return ret;
 367     }
 368     return 0;
 369 }
 370
 371 int avcodec_encode_audio(AVCodecContext *avctx, uint8_t *buf, int buf_size,
 372                          const short *samples)
 373 {
 374     int ret;
 375
 376     ret = avctx->codec->encode(avctx, buf, buf_size, (void *)samples);
 377     avctx->frame_number++;
 378     return ret;
 379 }
 380
 381 int avcodec_encode_video(AVCodecContext *avctx, uint8_t *buf, int buf_size,
 382                          const AVFrame *pict)
 383 {
 384     int ret;
 385
 386     ret = avctx->codec->encode(avctx, buf, buf_size, (void *)pict);
 387
 388     emms_c(); //needed to avoid a emms_c() call before every return;
 389
 390     avctx->frame_number++;
 391     return ret;
 392 }
 393
 394 /**
 395  * decode a frame.
 396  * @param buf bitstream buffer, must be FF_INPUT_BUFFER_PADDING_SIZE larger then the actual read bytes
 397  * because some optimized bitstream readers read 32 or 64 bit at once and could read over the end
 398  * @param buf_size the size of the buffer in bytes
 399  * @param got_picture_ptr zero if no frame could be decompressed, Otherwise, it is non zero
 400  * @return -1 if error, otherwise return the number of
 401  * bytes used.
 402  */
 403 int avcodec_decode_video(AVCodecContext *avctx, AVFrame *picture,
 404                          int *got_picture_ptr,
 405                          uint8_t *buf, int buf_size)
 406 {
 407     int ret;
 408
 409     ret = avctx->codec->decode(avctx, picture, got_picture_ptr,
 410                                buf, buf_size);
 411
 412     emms_c(); //needed to avoid a emms_c() call before every return;
 413
 414     if (*got_picture_ptr)
 415         avctx->frame_number++;
 416     return ret;
 417 }
 418
 419 /* decode an audio frame. return -1 if error, otherwise return the
 420    *number of bytes used. If no frame could be decompressed,
 421    *frame_size_ptr is zero. Otherwise, it is the decompressed frame
 422    *size in BYTES. */
 423 int avcodec_decode_audio(AVCodecContext *avctx, int16_t *samples,
 424                          int *frame_size_ptr,
 425                          uint8_t *buf, int buf_size)
 426 {
 427     int ret;
 428
 429     ret = avctx->codec->decode(avctx, samples, frame_size_ptr,
 430                                buf, buf_size);
 431     avctx->frame_number++;
 432     return ret;
 433 }
 434
 435 int avcodec_close(AVCodecContext *avctx)
 436 {
 437     if (avctx->codec->close)
 438         avctx->codec->close(avctx);
 439     av_freep(&avctx->priv_data);
 440     avctx->codec = NULL;
 441     return 0;
 442 }
 443
 444 AVCodec *avcodec_find_encoder(enum CodecID id)
 445 {
 446     AVCodec *p;
 447     p = first_avcodec;
 448     while (p) {
 449         if (p->encode != NULL && p->id == id)
 450             return p;
 451         p = p->next;
 452     }
 453     return NULL;
 454 }
 455
 456 AVCodec *avcodec_find_encoder_by_name(const char *name)
 457 {
 458     AVCodec *p;
 459     p = first_avcodec;
 460     while (p) {
 461         if (p->encode != NULL && strcmp(name,p->name) == 0)
 462             return p;
 463         p = p->next;
 464     }
 465     return NULL;
 466 }
 467
 468 AVCodec *avcodec_find_decoder(enum CodecID id)
 469 {
 470     AVCodec *p;
 471     p = first_avcodec;
 472     while (p) {
 473         if (p->decode != NULL && p->id == id)
 474             return p;
 475         p = p->next;
 476     }
 477     return NULL;
 478 }
 479
 480 AVCodec *avcodec_find_decoder_by_name(const char *name)
 481 {
 482     AVCodec *p;
 483     p = first_avcodec;
 484     while (p) {
 485         if (p->decode != NULL && strcmp(name,p->name) == 0)
 486             return p;
 487         p = p->next;
 488     }
 489     return NULL;
 490 }
 491
 492 AVCodec *avcodec_find(enum CodecID id)
 493 {
 494     AVCodec *p;
 495     p = first_avcodec;
 496     while (p) {
 497         if (p->id == id)
 498             return p;
 499         p = p->next;
 500     }
 501     return NULL;
 502 }
 503
 504 void avcodec_string(char *buf, int buf_size, AVCodecContext *enc, int encode)
 505 {
 506     const char *codec_name;
 507     AVCodec *p;
 508     char buf1[32];
 509     char channels_str[100];
 510     int bitrate;
 511
 512     if (encode)
 513         p = avcodec_find_encoder(enc->codec_id);
 514     else
 515         p = avcodec_find_decoder(enc->codec_id);
 516
 517     if (p) {
 518         codec_name = p->name;
 519         if (!encode && enc->codec_id == CODEC_ID_MP3) {
 520             if (enc->sub_id == 2)
 521                 codec_name = "mp2";
 522             else if (enc->sub_id == 1)
 523                 codec_name = "mp1";
 524         }
 525     } else if (enc->codec_name[0] != '\0') {
 526         codec_name = enc->codec_name;
 527     } else {
 528         /* output avi tags */
 529         if (enc->codec_type == CODEC_TYPE_VIDEO) {
 530             snprintf(buf1, sizeof(buf1), "%c%c%c%c",
 531                      enc->codec_tag & 0xff,
 532                      (enc->codec_tag >> 8) & 0xff,
 533                      (enc->codec_tag >> 16) & 0xff,
 534                      (enc->codec_tag >> 24) & 0xff);
 535         } else {
 536             snprintf(buf1, sizeof(buf1), "0x%04x", enc->codec_tag);
 537         }
 538         codec_name = buf1;
 539     }
 540
 541     switch(enc->codec_type) {
 542     case CODEC_TYPE_VIDEO:
 543         snprintf(buf, buf_size,
 544                  "Video: %s%s",
 545                  codec_name, enc->mb_decision ? " (hq)" : "");
 546         if (enc->codec_id == CODEC_ID_RAWVIDEO) {
 547             snprintf(buf + strlen(buf), buf_size - strlen(buf),
 548                      ", %s",
 549                      avcodec_get_pix_fmt_name(enc->pix_fmt));
 550         }
 551         if (enc->width) {
 552             snprintf(buf + strlen(buf), buf_size - strlen(buf),
 553                      ", %dx%d, %0.2f fps",
 554                      enc->width, enc->height,
 555                      (float)enc->frame_rate / enc->frame_rate_base);
 556         }
 557         if (encode) {
 558             snprintf(buf + strlen(buf), buf_size - strlen(buf),
 559                      ", q=%d-%d", enc->qmin, enc->qmax);
 560         }
 561         bitrate = enc->bit_rate;
 562         break;
 563     case CODEC_TYPE_AUDIO:
 564         snprintf(buf, buf_size,
 565                  "Audio: %s",
 566                  codec_name);
 567         switch (enc->channels) {
 568             case 1:
 569                 strcpy(channels_str, "mono");
 570                 break;
 571             case 2:
 572                 strcpy(channels_str, "stereo");
 573                 break;
 574             case 6:
 575                 strcpy(channels_str, "5:1");
 576                 break;
 577             default:
 578                 sprintf(channels_str, "%d channels", enc->channels);
 579                 break;
 580         }
 581         if (enc->sample_rate) {
 582             snprintf(buf + strlen(buf), buf_size - strlen(buf),
 583                      ", %d Hz, %s",
 584                      enc->sample_rate,
 585                      channels_str);
 586         }
 587
 588         /* for PCM codecs, compute bitrate directly */
 589         switch(enc->codec_id) {
 590         case CODEC_ID_PCM_S16LE:
 591         case CODEC_ID_PCM_S16BE:
 592         case CODEC_ID_PCM_U16LE:
 593         case CODEC_ID_PCM_U16BE:
 594             bitrate = enc->sample_rate * enc->channels * 16;
 595             break;
 596         case CODEC_ID_PCM_S8:
 597         case CODEC_ID_PCM_U8:
 598         case CODEC_ID_PCM_ALAW:
 599         case CODEC_ID_PCM_MULAW:
 600             bitrate = enc->sample_rate * enc->channels * 8;
 601             break;
 602         default:
 603             bitrate = enc->bit_rate;
 604             break;
 605         }
 606         break;
 607     default:
 608         av_abort();
 609     }
 610     if (encode) {
 611         if (enc->flags & CODEC_FLAG_PASS1)
 612             snprintf(buf + strlen(buf), buf_size - strlen(buf),
 613                      ", pass 1");
 614         if (enc->flags & CODEC_FLAG_PASS2)
 615             snprintf(buf + strlen(buf), buf_size - strlen(buf),
 616                      ", pass 2");
 617     }
 618     if (bitrate != 0) {
 619         snprintf(buf + strlen(buf), buf_size - strlen(buf),
 620                  ", %d kb/s", bitrate / 1000);
 621     }
 622 }
 623
 624 unsigned avcodec_version( void )
 625 {
 626   return LIBAVCODEC_VERSION_INT;
 627 }
 628
 629 unsigned avcodec_build( void )
 630 {
 631   return LIBAVCODEC_BUILD;
 632 }
 633
 634 /* must be called before any other functions */
 635 void avcodec_init(void)
 636 {
 637     static int inited = 0;
 638
 639     if (inited != 0)
 640         return;
 641     inited = 1;
 642
 643     dsputil_static_init();
 644 }
 645
 646 /**
 647  * Flush buffers, should be called when seeking or when swicthing to a different stream.
 648  */
 649 void avcodec_flush_buffers(AVCodecContext *avctx)
 650 {
 651     if(avctx->codec->flush)
 652         avctx->codec->flush(avctx);
 653 }
 654
 655 void avcodec_default_free_buffers(AVCodecContext *s){
 656     int i, j;
 657
 658     if(s->internal_buffer==NULL) return;
 659
 660     for(i=0; i<INTERNAL_BUFFER_SIZE; i++){
 661         InternalBuffer *buf= &((InternalBuffer*)s->internal_buffer)[i];
 662         for(j=0; j<4; j++){
 663             av_freep(&buf->base[j]);
 664             buf->data[j]= NULL;
 665         }
 666     }
 667     av_freep(&s->internal_buffer);
 668
 669     s->internal_buffer_count=0;
 670 }
 671
 672 char av_get_pict_type_char(int pict_type){
 673     switch(pict_type){
 674     case I_TYPE: return 'I';
 675     case P_TYPE: return 'P';
 676     case B_TYPE: return 'B';
 677     case S_TYPE: return 'S';
 678     case SI_TYPE:return 'i';
 679     case SP_TYPE:return 'p';
 680     default:     return '?';
 681     }
 682 }
 683
 684 int av_reduce(int *dst_nom, int *dst_den, int64_t nom, int64_t den, int64_t max){
 685     int exact=1, sign=0;
 686     int64_t gcd, larger;
 687
 688     assert(den != 0);
 689
 690     if(den < 0){
 691         den= -den;
 692         nom= -nom;
 693     }
 694
 695     if(nom < 0){
 696         nom= -nom;
 697         sign= 1;
 698     }
 699
 700     for(;;){ //note is executed 1 or 2 times
 701         gcd = ff_gcd(nom, den);
 702         nom /= gcd;
 703         den /= gcd;
 704
 705         larger= FFMAX(nom, den);
 706
 707         if(larger > max){
 708             int64_t div= (larger + max - 1) / max;
 709             nom =  (nom + div/2)/div;
 710             den =  (den + div/2)/div;
 711             exact=0;
 712         }else
 713             break;
 714     }
 715
 716     if(sign) nom= -nom;
 717
 718     *dst_nom = nom;
 719     *dst_den = den;
 720
 721     return exact;
 722 }
 723
 724 int64_t av_rescale(int64_t a, int b, int c){
 725     uint64_t h, l;
 726     assert(c > 0);
 727     assert(b >=0);
 728
 729     if(a<0) return -av_rescale(-a, b, c);
 730
 731     h= a>>32;
 732     if(h==0) return a*b/c;
 733
 734     l= a&0xFFFFFFFF;
 735     l *= b;
 736     h *= b;
 737
 738     l += (h%c)<<32;
 739
 740     return ((h/c)<<32) + l/c;
 741 }