func: static always_inline uint8_t vc1_mspel_filter(const uint8_t *src, int stride, int mode, int r)
  
  {
  
      switch(mode){
  
      case 0: //no shift
  
          return src[0];
  
      case 1: // 1/4 shift
  
          return (-4*src[-stride] + 53*src[0] + 18*src[stride] - 3*src[stride*2] + 32 - r) >> 6;
  
      case 2: // 1/2 shift
  
          return (-src[-stride] + 9*src[0] + 9*src[stride] - src[stride*2] + 8 - r) >> 4;
  
      case 3: // 3/4 shift
  
          return (-3*src[-stride] + 18*src[0] + 53*src[stride] - 4*src[stride*2] + 32 - r) >> 6;
  
      }
  
      return 0; //should not occur
  
  }
  