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  1. /*
  2.  * MQ-coder encoder
  3.  * Copyright (c) 2007 Kamil Nowosad
  4.  *
  5.  * This file is part of FFmpeg.
  6.  *
  7.  * FFmpeg is free software; you can redistribute it and/or
  8.  * modify it under the terms of the GNU Lesser General Public
  9.  * License as published by the Free Software Foundation; either
  10.  * version 2.1 of the License, or (at your option) any later version.
  11.  *
  12.  * FFmpeg is distributed in the hope that it will be useful,
  13.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15.  * Lesser General Public License for more details.
  16.  *
  17.  * You should have received a copy of the GNU Lesser General Public
  18.  * License along with FFmpeg; if not, write to the Free Software
  19.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20.  */
  21.  
  22. /**
  23.  * MQ-coder encoder
  24.  * @file
  25.  * @author Kamil Nowosad
  26.  */
  27.  
  28. #include "libavutil/avassert.h"
  29. #include "mqc.h"
  30.  
  31. static void byteout(MqcState *mqc)
  32. {
  33. retry:
  34.     if (*mqc->bp == 0xff){
  35.         mqc->bp++;
  36.         *mqc->bp = mqc->c >> 20;
  37.         mqc->c &= 0xfffff;
  38.         mqc->ct = 7;
  39.     } else if ((mqc->c & 0x8000000)){
  40.         (*mqc->bp)++;
  41.         mqc->c &= 0x7ffffff;
  42.         goto retry;
  43.     } else{
  44.         mqc->bp++;
  45.         *mqc->bp = mqc->c >> 19;
  46.         mqc->c &= 0x7ffff;
  47.         mqc->ct = 8;
  48.     }
  49. }
  50.  
  51. static void renorme(MqcState *mqc)
  52. {
  53.     do{
  54.         mqc->a += mqc->a;
  55.         mqc->c += mqc->c;
  56.         if (!--mqc->ct)
  57.             byteout(mqc);
  58.     } while (!(mqc->a & 0x8000));
  59. }
  60.  
  61. static void setbits(MqcState *mqc)
  62. {
  63.     int tmp = mqc->c + mqc->a;
  64.     mqc->c |= 0xffff;
  65.     if (mqc->c >= tmp)
  66.         mqc->c -= 0x8000;
  67. }
  68.  
  69. void ff_mqc_initenc(MqcState *mqc, uint8_t *bp)
  70. {
  71.     ff_mqc_init_contexts(mqc);
  72.     mqc->a = 0x8000;
  73.     mqc->c = 0;
  74.     mqc->bp = bp-1;
  75.     mqc->bpstart = bp;
  76.     mqc->ct = 12 + (*mqc->bp == 0xff);
  77. }
  78.  
  79. void ff_mqc_encode(MqcState *mqc, uint8_t *cxstate, int d)
  80. {
  81.     int qe;
  82.  
  83.     qe = ff_mqc_qe[*cxstate];
  84.     mqc->a -= qe;
  85.     if ((*cxstate & 1) == d){
  86.         if (!(mqc->a & 0x8000)){
  87.             if (mqc->a < qe)
  88.                 mqc->a = qe;
  89.             else
  90.                 mqc->c += qe;
  91.             *cxstate = ff_mqc_nmps[*cxstate];
  92.             renorme(mqc);
  93.         } else
  94.             mqc->c += qe;
  95.     } else{
  96.         if (mqc->a < qe)
  97.             mqc->c += qe;
  98.         else
  99.             mqc->a = qe;
  100.         *cxstate = ff_mqc_nlps[*cxstate];
  101.         renorme(mqc);
  102.     }
  103. }
  104.  
  105. int ff_mqc_length(MqcState *mqc)
  106. {
  107.     return mqc->bp - mqc->bpstart;
  108. }
  109.  
  110. int ff_mqc_flush(MqcState *mqc)
  111. {
  112.     setbits(mqc);
  113.     mqc->c = mqc->c << mqc->ct;
  114.     byteout(mqc);
  115.     mqc->c = mqc->c << mqc->ct;
  116.     byteout(mqc);
  117.     if (*mqc->bp != 0xff)
  118.         mqc->bp++;
  119.     return mqc->bp - mqc->bpstart;
  120. }
  121.  
  122. int ff_mqc_flush_to(MqcState *mqc, uint8_t *dst, int *dst_len)
  123. {
  124.     MqcState mqc2 = *mqc;
  125.     mqc2.bpstart=
  126.     mqc2.bp = dst;
  127.     *mqc2.bp = *mqc->bp;
  128.     ff_mqc_flush(&mqc2);
  129.     *dst_len = mqc2.bp - dst;
  130.     if (mqc->bp < mqc->bpstart) {
  131.         av_assert1(mqc->bpstart - mqc->bp == 1);
  132.         av_assert1(*dst_len > 0);
  133.         av_assert1(mqc->bp[0] == 0 && dst[0] == 0);
  134.         (*dst_len) --;
  135.         memmove(dst, dst+1, *dst_len);
  136.         return mqc->bp - mqc->bpstart + 1 + *dst_len;
  137.     }
  138.     return mqc->bp - mqc->bpstart + *dst_len;
  139. }
  140.