swscale_altivec_template.c

/*
  AltiVec-enhanced yuv2yuvX

    Copyright (C) 2004 Romain Dolbeau <[email protected]>
    based on the equivalent C code in "postproc/swscale.c"


    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program 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 General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

#ifdef CONFIG_DARWIN
#define AVV(x...) (x)
#else
#define AVV(x...) {x}
#endif

static const vector signed int vzero =
  (const vector signed int)AVV(0, 0, 0, 0);
static const vector unsigned int altivec_vectorShiftInt19 =
  (const vector unsigned int)AVV(19, 19, 19, 19);

static inline void
altivec_packIntArrayToCharArray(int *val, uint8_t* dest, int dstW) {
  register int i;
  if ((unsigned long)dest % 16) {
    /* badly aligned store, we force store alignement */
    /* and will handle load misalignement on val w/ vec_perm */
    for (i = 0 ; (i < dstW) &&
           (((unsigned long)dest + i) % 16) ; i++) {
      int t = val[i] >> 19;
      dest[i] = (t < 0) ? 0 : ((t > 255) ? 255 : t);
    }
    vector unsigned char perm1 = vec_lvsl(i << 2, val);
    vector signed int v1 = vec_ld(i << 2, val);
    for ( ; i < (dstW - 15); i+=16) {
      int offset = i << 2;
      vector signed int v2 = vec_ld(offset + 16, val);
      vector signed int v3 = vec_ld(offset + 32, val);
      vector signed int v4 = vec_ld(offset + 48, val);
      vector signed int v5 = vec_ld(offset + 64, val);
      vector signed int v12 = vec_perm(v1,v2,perm1);
      vector signed int v23 = vec_perm(v2,v3,perm1);
      vector signed int v34 = vec_perm(v3,v4,perm1);
      vector signed int v45 = vec_perm(v4,v5,perm1);
      
      vector signed int vA = vec_sra(v12, altivec_vectorShiftInt19);
      vector signed int vB = vec_sra(v23, altivec_vectorShiftInt19);
      vector signed int vC = vec_sra(v34, altivec_vectorShiftInt19);
      vector signed int vD = vec_sra(v45, altivec_vectorShiftInt19);
      vector unsigned short vs1 = vec_packsu(vA, vB);
      vector unsigned short vs2 = vec_packsu(vC, vD);
      vector unsigned char vf = vec_packsu(vs1, vs2);
      vec_st(vf, i, dest);
      v1 = v5;
    }
  } else { // dest is properly aligned, great
    for (i = 0; i < (dstW - 15); i+=16) {
      int offset = i << 2;
      vector signed int v1 = vec_ld(offset, val);
      vector signed int v2 = vec_ld(offset + 16, val);
      vector signed int v3 = vec_ld(offset + 32, val);
      vector signed int v4 = vec_ld(offset + 48, val);
      vector signed int v5 = vec_sra(v1, altivec_vectorShiftInt19);
      vector signed int v6 = vec_sra(v2, altivec_vectorShiftInt19);
      vector signed int v7 = vec_sra(v3, altivec_vectorShiftInt19);
      vector signed int v8 = vec_sra(v4, altivec_vectorShiftInt19);
      vector unsigned short vs1 = vec_packsu(v5, v6);
      vector unsigned short vs2 = vec_packsu(v7, v8);
      vector unsigned char vf = vec_packsu(vs1, vs2);
      vec_st(vf, i, dest);
    }
  }
  for ( ; i < dstW ; i++) {
    int t = val[i] >> 19;
    dest[i] = (t < 0) ? 0 : ((t > 255) ? 255 : t);
  }
}

static inline void
yuv2yuvX_altivec_real(int16_t *lumFilter, int16_t **lumSrc, int lumFilterSize,
                      int16_t *chrFilter, int16_t **chrSrc, int chrFilterSize,
                      uint8_t *dest, uint8_t *uDest, uint8_t *vDest, int dstW, int chrDstW)
{
  const vector signed int vini = {(1 << 18), (1 << 18), (1 << 18), (1 << 18)};
  register int i, j;
  {
    int __attribute__ ((aligned (16))) val[dstW];
    
    for (i = 0; i < (dstW -7); i+=4) {
      vec_st(vini, i << 2, val);
    }
    for (; i < dstW; i++) {
      val[i] = (1 << 18);
    }
    
    for (j = 0; j < lumFilterSize; j++) {
      vector signed short vLumFilter = vec_ld(j << 1, lumFilter);
      vector unsigned char perm0 = vec_lvsl(j << 1, lumFilter);
      vLumFilter = vec_perm(vLumFilter, vLumFilter, perm0);
      vLumFilter = vec_splat(vLumFilter, 0); // lumFilter[j] is loaded 8 times in vLumFilter
      
      vector unsigned char perm = vec_lvsl(0, lumSrc[j]);
      vector signed short l1 = vec_ld(0, lumSrc[j]);
      
      for (i = 0; i < (dstW - 7); i+=8) {
        int offset = i << 2;
        vector signed short l2 = vec_ld((i << 1) + 16, lumSrc[j]);
        
        vector signed int v1 = vec_ld(offset, val);
        vector signed int v2 = vec_ld(offset + 16, val);
        
        vector signed short ls = vec_perm(l1, l2, perm); // lumSrc[j][i] ... lumSrc[j][i+7]
        
        vector signed int i1 = vec_mule(vLumFilter, ls);
        vector signed int i2 = vec_mulo(vLumFilter, ls);
        
        vector signed int vf1 = vec_mergeh(i1, i2);
        vector signed int vf2 = vec_mergel(i1, i2); // lumSrc[j][i] * lumFilter[j] ... lumSrc[j][i+7] * lumFilter[j]
        
        vector signed int vo1 = vec_add(v1, vf1);
        vector signed int vo2 = vec_add(v2, vf2);
        
        vec_st(vo1, offset, val);
        vec_st(vo2, offset + 16, val);
        
        l1 = l2;
      }
      for ( ; i < dstW; i++) {
        val[i] += lumSrc[j][i] * lumFilter[j];
      }
    }
    altivec_packIntArrayToCharArray(val,dest,dstW);
  }
  if (uDest != 0) {
    int  __attribute__ ((aligned (16))) u[chrDstW];
    int  __attribute__ ((aligned (16))) v[chrDstW];

    for (i = 0; i < (chrDstW -7); i+=4) {
      vec_st(vini, i << 2, u);
      vec_st(vini, i << 2, v);
    }
    for (; i < chrDstW; i++) {
      u[i] = (1 << 18);
      v[i] = (1 << 18);
    }
    
    for (j = 0; j < chrFilterSize; j++) {
      vector signed short vChrFilter = vec_ld(j << 1, chrFilter);
      vector unsigned char perm0 = vec_lvsl(j << 1, chrFilter);
      vChrFilter = vec_perm(vChrFilter, vChrFilter, perm0);
      vChrFilter = vec_splat(vChrFilter, 0); // chrFilter[j] is loaded 8 times in vChrFilter
      
      vector unsigned char perm = vec_lvsl(0, chrSrc[j]);
      vector signed short l1 = vec_ld(0, chrSrc[j]);
      vector signed short l1_V = vec_ld(2048 << 1, chrSrc[j]);
      
      for (i = 0; i < (chrDstW - 7); i+=8) {
        int offset = i << 2;
        vector signed short l2 = vec_ld((i << 1) + 16, chrSrc[j]);
        vector signed short l2_V = vec_ld(((i + 2048) << 1) + 16, chrSrc[j]);
        
        vector signed int v1 = vec_ld(offset, u);
        vector signed int v2 = vec_ld(offset + 16, u);
        vector signed int v1_V = vec_ld(offset, v);
        vector signed int v2_V = vec_ld(offset + 16, v);
        
        vector signed short ls = vec_perm(l1, l2, perm); // chrSrc[j][i] ... chrSrc[j][i+7]
        vector signed short ls_V = vec_perm(l1_V, l2_V, perm); // chrSrc[j][i+2048] ... chrSrc[j][i+2055]
        
        vector signed int i1 = vec_mule(vChrFilter, ls);
        vector signed int i2 = vec_mulo(vChrFilter, ls);
        vector signed int i1_V = vec_mule(vChrFilter, ls_V);
        vector signed int i2_V = vec_mulo(vChrFilter, ls_V);
        
        vector signed int vf1 = vec_mergeh(i1, i2);
        vector signed int vf2 = vec_mergel(i1, i2); // chrSrc[j][i] * chrFilter[j] ... chrSrc[j][i+7] * chrFilter[j]
        vector signed int vf1_V = vec_mergeh(i1_V, i2_V);
        vector signed int vf2_V = vec_mergel(i1_V, i2_V); // chrSrc[j][i] * chrFilter[j] ... chrSrc[j][i+7] * chrFilter[j]
        
        vector signed int vo1 = vec_add(v1, vf1);
        vector signed int vo2 = vec_add(v2, vf2);
        vector signed int vo1_V = vec_add(v1_V, vf1_V);
        vector signed int vo2_V = vec_add(v2_V, vf2_V);
        
        vec_st(vo1, offset, u);
        vec_st(vo2, offset + 16, u);
        vec_st(vo1_V, offset, v);
        vec_st(vo2_V, offset + 16, v);
        
        l1 = l2;
        l1_V = l2_V;
      }
      for ( ; i < chrDstW; i++) {
        u[i] += chrSrc[j][i] * chrFilter[j];
        v[i] += chrSrc[j][i + 2048] * chrFilter[j];
      } 
    }
    altivec_packIntArrayToCharArray(u,uDest,chrDstW);
    altivec_packIntArrayToCharArray(v,vDest,chrDstW);
  }
}

static inline void hScale_altivec_real(int16_t *dst, int dstW, uint8_t *src, int srcW, int xInc, int16_t *filter, int16_t *filterPos, int filterSize) {
  register int i;
  int __attribute__ ((aligned (16))) tempo[4];

  if (filterSize % 4) {
    for(i=0; i<dstW; i++) {
      register int j;
      register int srcPos = filterPos[i];
      register int val = 0;
      for(j=0; j<filterSize; j++) {
        val += ((int)src[srcPos + j])*filter[filterSize*i + j];
      }
      dst[i] = MIN(MAX(0, val>>7), (1<<15)-1);
    }
  }
  else
  switch (filterSize) {
  case 4:
    {
      for(i=0; i<dstW; i++) {
        register int j;
        register int srcPos = filterPos[i];

        vector unsigned char src_v0 = vec_ld(srcPos, src);
        vector unsigned char src_v1;
        if ((((int)src + srcPos)% 16) > 12) {
          src_v1 = vec_ld(srcPos + 16, src);
        }
        vector unsigned char src_vF = vec_perm(src_v0, src_v1, vec_lvsl(srcPos, src));

        vector signed short src_v = // vec_unpackh sign-extends...
          (vector signed short)(vec_mergeh((vector unsigned char)vzero, src_vF));
        // now put our elements in the even slots
        src_v = vec_mergeh(src_v, (vector signed short)vzero);

        vector signed short filter_v = vec_ld(i << 3, filter);
        // the 3 above is 2 (filterSize == 4) + 1 (sizeof(short) == 2)

        // the neat trick : we only care for half the elements,
        // high or low depending on (i<<3)%16 (it's 0 or 8 here),
        // and we're going to use vec_mule, so we chose
        // carefully how to "unpack" the elements into the even slots
        if ((i << 3) % 16)
          filter_v = vec_mergel(filter_v,(vector signed short)vzero);
        else
          filter_v = vec_mergeh(filter_v,(vector signed short)vzero);

        vector signed int val_vEven = vec_mule(src_v, filter_v);
        vector signed int val_s = vec_sums(val_vEven, vzero);
        vec_st(val_s, 0, tempo);
        dst[i] = MIN(MAX(0, tempo[3]>>7), (1<<15)-1);
      }
    }
    break;

  case 8:
    {
      for(i=0; i<dstW; i++) {
        register int srcPos = filterPos[i];

        vector unsigned char src_v0 = vec_ld(srcPos, src);
        vector unsigned char src_v1;
        if ((((int)src + srcPos)% 16) > 8) {
          src_v1 = vec_ld(srcPos + 16, src);
        }
        vector unsigned char src_vF = vec_perm(src_v0, src_v1, vec_lvsl(srcPos, src));

        vector signed short src_v = // vec_unpackh sign-extends...
          (vector signed short)(vec_mergeh((vector unsigned char)vzero, src_vF));
        vector signed short filter_v = vec_ld(i << 4, filter);
        // the 4 above is 3 (filterSize == 8) + 1 (sizeof(short) == 2)

        vector signed int val_v = vec_msums(src_v, filter_v, (vector signed int)vzero);
        vector signed int val_s = vec_sums(val_v, vzero);
        vec_st(val_s, 0, tempo);
        dst[i] = MIN(MAX(0, tempo[3]>>7), (1<<15)-1);
      }
    }
    break;

  case 16:
    {
      for(i=0; i<dstW; i++) {
        register int srcPos = filterPos[i];

        vector unsigned char src_v0 = vec_ld(srcPos, src);
        vector unsigned char src_v1 = vec_ld(srcPos + 16, src);
        vector unsigned char src_vF = vec_perm(src_v0, src_v1, vec_lvsl(srcPos, src));

        vector signed short src_vA = // vec_unpackh sign-extends...
          (vector signed short)(vec_mergeh((vector unsigned char)vzero, src_vF));
        vector signed short src_vB = // vec_unpackh sign-extends...
          (vector signed short)(vec_mergel((vector unsigned char)vzero, src_vF));

        vector signed short filter_v0 = vec_ld(i << 5, filter);
        vector signed short filter_v1 = vec_ld((i << 5) + 16, filter);
        // the 5 above are 4 (filterSize == 16) + 1 (sizeof(short) == 2)

        vector signed int val_acc = vec_msums(src_vA, filter_v0, (vector signed int)vzero);
        vector signed int val_v = vec_msums(src_vB, filter_v1, val_acc);

        vector signed int val_s = vec_sums(val_v, vzero);

        vec_st(val_s, 0, tempo);
        dst[i] = MIN(MAX(0, tempo[3]>>7), (1<<15)-1);
      }
    }
    break;
    
  default:
    {
      for(i=0; i<dstW; i++) {
        register int j;
        register int srcPos = filterPos[i];

        vector signed int val_v = (vector signed int)vzero;
        vector signed short filter_v0R = vec_ld(i * 2 * filterSize, filter);
        vector unsigned char permF = vec_lvsl((i * 2 * filterSize), filter);

        vector unsigned char src_v0 = vec_ld(srcPos, src);
        vector unsigned char permS = vec_lvsl(srcPos, src);

        for (j = 0 ; j < filterSize - 15; j += 16) {
          vector unsigned char src_v1 = vec_ld(srcPos + j + 16, src);
          vector unsigned char src_vF = vec_perm(src_v0, src_v1, permS);
          
          vector signed short src_vA = // vec_unpackh sign-extends...
            (vector signed short)(vec_mergeh((vector unsigned char)vzero, src_vF));
          vector signed short src_vB = // vec_unpackh sign-extends...
            (vector signed short)(vec_mergel((vector unsigned char)vzero, src_vF));
          
          vector signed short filter_v1R = vec_ld((i * 2 * filterSize) + (j * 2) + 16, filter);
          vector signed short filter_v2R = vec_ld((i * 2 * filterSize) + (j * 2) + 32, filter);
          vector signed short filter_v0 = vec_perm(filter_v0R, filter_v1R, permF);
          vector signed short filter_v1 = vec_perm(filter_v1R, filter_v2R, permF);
          
          vector signed int val_acc = vec_msums(src_vA, filter_v0, val_v);
          val_v = vec_msums(src_vB, filter_v1, val_acc);

          filter_v0R = filter_v2R;
          src_v0 = src_v1;
        }

        if (j < (filterSize-7)) {
          // loading src_v0 is useless, it's already done above
          //vector unsigned char src_v0 = vec_ld(srcPos + j, src);
          vector unsigned char src_v1;
          if ((((int)src + srcPos)% 16) > 8) {
            src_v1 = vec_ld(srcPos + j + 16, src);
          }
          vector unsigned char src_vF = vec_perm(src_v0, src_v1, permS);
          
          vector signed short src_v = // vec_unpackh sign-extends...
            (vector signed short)(vec_mergeh((vector unsigned char)vzero, src_vF));
          // loading filter_v0R is useless, it's already done above
          //vector signed short filter_v0R = vec_ld((i * 2 * filterSize) + j, filter);
          vector signed short filter_v1R = vec_ld((i * 2 * filterSize) + (j * 2) + 16, filter);
          vector signed short filter_v = vec_perm(filter_v0R, filter_v1R, permF);
          
          val_v = vec_msums(src_v, filter_v, val_v);
        }

        vector signed int val_s = vec_sums(val_v, vzero);
          
        vec_st(val_s, 0, tempo);
        dst[i] = MIN(MAX(0, tempo[3]>>7), (1<<15)-1);        
      }
      
    }
  }
}

static inline int yv12toyuy2_unscaled_altivec(SwsContext *c, uint8_t* src[], int srcStride[], int srcSliceY,
     int srcSliceH, uint8_t* dstParam[], int dstStride_a[]) {
  uint8_t *dst=dstParam[0] + dstStride_a[0]*srcSliceY;
  // yv12toyuy2( src[0],src[1],src[2],dst,c->srcW,srcSliceH,srcStride[0],srcStride[1],dstStride[0] );
  uint8_t *ysrc = src[0];
  uint8_t *usrc = src[1];
  uint8_t *vsrc = src[2];
  const int width = c->srcW;
  const int height = srcSliceH;
  const int lumStride = srcStride[0];
  const int chromStride = srcStride[1];
  const int dstStride = dstStride_a[0];
  const vector unsigned char yperm = vec_lvsl(0, ysrc);
  const int vertLumPerChroma = 2;  
  register unsigned int y;

  /* this code assume:

  1) dst is 16 bytes-aligned
  2) dstStride is a multiple of 16
  3) width is a multiple of 16
  4) lum&chrom stride are multiple of 8
  */
  
  for(y=0; y<height; y++)
    {
      int i;
      for (i = 0; i < width - 31; i+= 32) {
        const unsigned int j = i >> 1;
        vector unsigned char v_yA = vec_ld(i, ysrc);
        vector unsigned char v_yB = vec_ld(i + 16, ysrc);
        vector unsigned char v_yC = vec_ld(i + 32, ysrc);
        vector unsigned char v_y1 = vec_perm(v_yA, v_yB, yperm);
        vector unsigned char v_y2 = vec_perm(v_yB, v_yC, yperm);
        vector unsigned char v_uA = vec_ld(j, usrc);
        vector unsigned char v_uB = vec_ld(j + 16, usrc);
        vector unsigned char v_u = vec_perm(v_uA, v_uB, vec_lvsl(j, usrc));
        vector unsigned char v_vA = vec_ld(j, vsrc);
        vector unsigned char v_vB = vec_ld(j + 16, vsrc);
        vector unsigned char v_v = vec_perm(v_vA, v_vB, vec_lvsl(j, vsrc));
        vector unsigned char v_uv_a = vec_mergeh(v_u, v_v);
        vector unsigned char v_uv_b = vec_mergel(v_u, v_v);
        vector unsigned char v_yuy2_0 = vec_mergeh(v_y1, v_uv_a);
        vector unsigned char v_yuy2_1 = vec_mergel(v_y1, v_uv_a);
        vector unsigned char v_yuy2_2 = vec_mergeh(v_y2, v_uv_b);
        vector unsigned char v_yuy2_3 = vec_mergel(v_y2, v_uv_b);
        vec_st(v_yuy2_0, (i << 1), dst);
        vec_st(v_yuy2_1, (i << 1) + 16, dst);
        vec_st(v_yuy2_2, (i << 1) + 32, dst);
        vec_st(v_yuy2_3, (i << 1) + 48, dst);
      }
      if (i < width) {
        const unsigned int j = i >> 1;
        vector unsigned char v_y1 = vec_ld(i, ysrc);
        vector unsigned char v_u = vec_ld(j, usrc);
        vector unsigned char v_v = vec_ld(j, vsrc);
        vector unsigned char v_uv_a = vec_mergeh(v_u, v_v);
        vector unsigned char v_yuy2_0 = vec_mergeh(v_y1, v_uv_a);
        vector unsigned char v_yuy2_1 = vec_mergel(v_y1, v_uv_a);
        vec_st(v_yuy2_0, (i << 1), dst);
        vec_st(v_yuy2_1, (i << 1) + 16, dst);
      }
      if((y&(vertLumPerChroma-1))==(vertLumPerChroma-1) )
        {
          usrc += chromStride;
          vsrc += chromStride;
        }
      ysrc += lumStride;
      dst += dstStride;
    }
  
  return srcSliceH;
}

static inline int yv12touyvy_unscaled_altivec(SwsContext *c, uint8_t* src[], int srcStride[], int srcSliceY,
     int srcSliceH, uint8_t* dstParam[], int dstStride_a[]) {
  uint8_t *dst=dstParam[0] + dstStride_a[0]*srcSliceY;
  // yv12toyuy2( src[0],src[1],src[2],dst,c->srcW,srcSliceH,srcStride[0],srcStride[1],dstStride[0] );
  uint8_t *ysrc = src[0];
  uint8_t *usrc = src[1];
  uint8_t *vsrc = src[2];
  const int width = c->srcW;
  const int height = srcSliceH;
  const int lumStride = srcStride[0];
  const int chromStride = srcStride[1];
  const int dstStride = dstStride_a[0];
  const int vertLumPerChroma = 2;
  const vector unsigned char yperm = vec_lvsl(0, ysrc);
  register unsigned int y;

  /* this code assume:

  1) dst is 16 bytes-aligned
  2) dstStride is a multiple of 16
  3) width is a multiple of 16
  4) lum&chrom stride are multiple of 8
  */
  
  for(y=0; y<height; y++)
    {
      int i;
      for (i = 0; i < width - 31; i+= 32) {
        const unsigned int j = i >> 1;
        vector unsigned char v_yA = vec_ld(i, ysrc);
        vector unsigned char v_yB = vec_ld(i + 16, ysrc);
        vector unsigned char v_yC = vec_ld(i + 32, ysrc);
        vector unsigned char v_y1 = vec_perm(v_yA, v_yB, yperm);
        vector unsigned char v_y2 = vec_perm(v_yB, v_yC, yperm);
        vector unsigned char v_uA = vec_ld(j, usrc);
        vector unsigned char v_uB = vec_ld(j + 16, usrc);
        vector unsigned char v_u = vec_perm(v_uA, v_uB, vec_lvsl(j, usrc));
        vector unsigned char v_vA = vec_ld(j, vsrc);
        vector unsigned char v_vB = vec_ld(j + 16, vsrc);
        vector unsigned char v_v = vec_perm(v_vA, v_vB, vec_lvsl(j, vsrc));
        vector unsigned char v_uv_a = vec_mergeh(v_u, v_v);
        vector unsigned char v_uv_b = vec_mergel(v_u, v_v);
        vector unsigned char v_uyvy_0 = vec_mergeh(v_uv_a, v_y1);
        vector unsigned char v_uyvy_1 = vec_mergel(v_uv_a, v_y1);
        vector unsigned char v_uyvy_2 = vec_mergeh(v_uv_b, v_y2);
        vector unsigned char v_uyvy_3 = vec_mergel(v_uv_b, v_y2);
        vec_st(v_uyvy_0, (i << 1), dst);
        vec_st(v_uyvy_1, (i << 1) + 16, dst);
        vec_st(v_uyvy_2, (i << 1) + 32, dst);
        vec_st(v_uyvy_3, (i << 1) + 48, dst);
      }
      if (i < width) {
        const unsigned int j = i >> 1;
        vector unsigned char v_y1 = vec_ld(i, ysrc);
        vector unsigned char v_u = vec_ld(j, usrc);
        vector unsigned char v_v = vec_ld(j, vsrc);
        vector unsigned char v_uv_a = vec_mergeh(v_u, v_v);
        vector unsigned char v_uyvy_0 = vec_mergeh(v_uv_a, v_y1);
        vector unsigned char v_uyvy_1 = vec_mergel(v_uv_a, v_y1);
        vec_st(v_uyvy_0, (i << 1), dst);
        vec_st(v_uyvy_1, (i << 1) + 16, dst);
      }
      if((y&(vertLumPerChroma-1))==(vertLumPerChroma-1) )
        {
          usrc += chromStride;
          vsrc += chromStride;
        }
      ysrc += lumStride;
      dst += dstStride;
    }
  return srcSliceH;
}

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