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ffmpeg-4.2.2/libavcodec/huffyuvencdsp.c 2.52 KB
aac5773f   hucm   功能基本完成,接口待打磨
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  /*
   * This file is part of FFmpeg.
   *
   * FFmpeg is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   *
   * FFmpeg is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with FFmpeg; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
   */
  
  #include "config.h"
  #include "libavutil/attributes.h"
  #include "huffyuvencdsp.h"
  #include "mathops.h"
  
  // 0x00010001 or 0x0001000100010001 or whatever, depending on the cpu's native arithmetic size
  #define pw_1 (ULONG_MAX / UINT16_MAX)
  
  static void diff_int16_c(uint16_t *dst, const uint16_t *src1, const uint16_t *src2, unsigned mask, int w){
      long i;
  #if !HAVE_FAST_UNALIGNED
      if((long)src2 & (sizeof(long)-1)){
          for(i=0; i+3<w; i+=4){
              dst[i+0] = (src1[i+0]-src2[i+0]) & mask;
              dst[i+1] = (src1[i+1]-src2[i+1]) & mask;
              dst[i+2] = (src1[i+2]-src2[i+2]) & mask;
              dst[i+3] = (src1[i+3]-src2[i+3]) & mask;
          }
      }else
  #endif
      {
          unsigned long pw_lsb = (mask >> 1) * pw_1;
          unsigned long pw_msb = pw_lsb +  pw_1;
  
          for (i = 0; i <= w - (int)sizeof(long)/2; i += sizeof(long)/2) {
              long a = *(long*)(src1+i);
              long b = *(long*)(src2+i);
              *(long*)(dst+i) = ((a|pw_msb) - (b&pw_lsb)) ^ ((a^b^pw_msb)&pw_msb);
          }
      }
      for (; i<w; i++)
          dst[i] = (src1[i] - src2[i]) & mask;
  }
  
  static void sub_hfyu_median_pred_int16_c(uint16_t *dst, const uint16_t *src1, const uint16_t *src2, unsigned mask, int w, int *left, int *left_top){
      int i;
      uint16_t l, lt;
  
      l  = *left;
      lt = *left_top;
  
      for(i=0; i<w; i++){
          const int pred = mid_pred(l, src1[i], (l + src1[i] - lt) & mask);
          lt = src1[i];
          l  = src2[i];
          dst[i] = (l - pred) & mask;
      }
  
      *left     = l;
      *left_top = lt;
  }
  
  av_cold void ff_huffyuvencdsp_init(HuffYUVEncDSPContext *c, AVCodecContext *avctx)
  {
      c->diff_int16           = diff_int16_c;
      c->sub_hfyu_median_pred_int16 = sub_hfyu_median_pred_int16_c;
  
      if (ARCH_X86)
          ff_huffyuvencdsp_init_x86(c, avctx);
  }