tor-browser

ipred_tmpl.c (27732B)

---

/*
* Copyright © 2018, VideoLAN and dav1d authors
* Copyright © 2018, Two Orioles, LLC
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
*    list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
*    this list of conditions and the following disclaimer in the documentation
*    and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

#include "config.h"

#include <stdlib.h>
#include <string.h>

#include "common/attributes.h"
#include "common/intops.h"

#include "src/ipred.h"
#include "src/tables.h"

static NOINLINE void
splat_dc(pixel *dst, const ptrdiff_t stride,
        const int width, const int height, const int dc HIGHBD_DECL_SUFFIX)
{
#if BITDEPTH == 8
   assert(dc <= 0xff);
   if (width > 4) {
       const uint64_t dcN = dc * 0x0101010101010101ULL;
       for (int y = 0; y < height; y++) {
           for (int x = 0; x < width; x += sizeof(dcN))
               *((uint64_t *) &dst[x]) = dcN;
           dst += PXSTRIDE(stride);
       }
   } else {
       const unsigned dcN = dc * 0x01010101U;
       for (int y = 0; y < height; y++) {
           for (int x = 0; x < width; x += sizeof(dcN))
               *((unsigned *) &dst[x]) = dcN;
           dst += PXSTRIDE(stride);
       }
   }
#else
   assert(dc <= bitdepth_max);
   const uint64_t dcN = dc * 0x0001000100010001ULL;
   for (int y = 0; y < height; y++) {
       for (int x = 0; x < width; x += sizeof(dcN) >> 1)
           *((uint64_t *) &dst[x]) = dcN;
       dst += PXSTRIDE(stride);
   }
#endif
}

static NOINLINE void
cfl_pred(pixel *dst, const ptrdiff_t stride,
        const int width, const int height, const int dc,
        const int16_t *ac, const int alpha HIGHBD_DECL_SUFFIX)
{
   for (int y = 0; y < height; y++) {
       for (int x = 0; x < width; x++) {
           const int diff = alpha * ac[x];
           dst[x] = iclip_pixel(dc + apply_sign((abs(diff) + 32) >> 6, diff));
       }
       ac += width;
       dst += PXSTRIDE(stride);
   }
}

static unsigned dc_gen_top(const pixel *const topleft, const int width) {
   unsigned dc = width >> 1;
   for (int i = 0; i < width; i++)
      dc += topleft[1 + i];
   return dc >> ctz(width);
}

static void ipred_dc_top_c(pixel *dst, const ptrdiff_t stride,
                          const pixel *const topleft,
                          const int width, const int height, const int a,
                          const int max_width, const int max_height
                          HIGHBD_DECL_SUFFIX)
{
   splat_dc(dst, stride, width, height, dc_gen_top(topleft, width)
            HIGHBD_TAIL_SUFFIX);
}

static void ipred_cfl_top_c(pixel *dst, const ptrdiff_t stride,
                           const pixel *const topleft,
                           const int width, const int height,
                           const int16_t *ac, const int alpha
                           HIGHBD_DECL_SUFFIX)
{
   cfl_pred(dst, stride, width, height, dc_gen_top(topleft, width), ac, alpha
            HIGHBD_TAIL_SUFFIX);
}

static unsigned dc_gen_left(const pixel *const topleft, const int height) {
   unsigned dc = height >> 1;
   for (int i = 0; i < height; i++)
      dc += topleft[-(1 + i)];
   return dc >> ctz(height);
}

static void ipred_dc_left_c(pixel *dst, const ptrdiff_t stride,
                           const pixel *const topleft,
                           const int width, const int height, const int a,
                           const int max_width, const int max_height
                           HIGHBD_DECL_SUFFIX)
{
   splat_dc(dst, stride, width, height, dc_gen_left(topleft, height)
            HIGHBD_TAIL_SUFFIX);
}

static void ipred_cfl_left_c(pixel *dst, const ptrdiff_t stride,
                            const pixel *const topleft,
                            const int width, const int height,
                            const int16_t *ac, const int alpha
                            HIGHBD_DECL_SUFFIX)
{
   const unsigned dc = dc_gen_left(topleft, height);
   cfl_pred(dst, stride, width, height, dc, ac, alpha HIGHBD_TAIL_SUFFIX);
}

#if BITDEPTH == 8
#define MULTIPLIER_1x2 0x5556
#define MULTIPLIER_1x4 0x3334
#define BASE_SHIFT 16
#else
#define MULTIPLIER_1x2 0xAAAB
#define MULTIPLIER_1x4 0x6667
#define BASE_SHIFT 17
#endif

static unsigned dc_gen(const pixel *const topleft,
                      const int width, const int height)
{
   unsigned dc = (width + height) >> 1;
   for (int i = 0; i < width; i++)
      dc += topleft[i + 1];
   for (int i = 0; i < height; i++)
      dc += topleft[-(i + 1)];
   dc >>= ctz(width + height);

   if (width != height) {
       dc *= (width > height * 2 || height > width * 2) ? MULTIPLIER_1x4 :
                                                          MULTIPLIER_1x2;
       dc >>= BASE_SHIFT;
   }
   return dc;
}

static void ipred_dc_c(pixel *dst, const ptrdiff_t stride,
                      const pixel *const topleft,
                      const int width, const int height, const int a,
                      const int max_width, const int max_height
                      HIGHBD_DECL_SUFFIX)
{
   splat_dc(dst, stride, width, height, dc_gen(topleft, width, height)
            HIGHBD_TAIL_SUFFIX);
}

static void ipred_cfl_c(pixel *dst, const ptrdiff_t stride,
                       const pixel *const topleft,
                       const int width, const int height,
                       const int16_t *ac, const int alpha
                       HIGHBD_DECL_SUFFIX)
{
   unsigned dc = dc_gen(topleft, width, height);
   cfl_pred(dst, stride, width, height, dc, ac, alpha HIGHBD_TAIL_SUFFIX);
}

#undef MULTIPLIER_1x2
#undef MULTIPLIER_1x4
#undef BASE_SHIFT

static void ipred_dc_128_c(pixel *dst, const ptrdiff_t stride,
                          const pixel *const topleft,
                          const int width, const int height, const int a,
                          const int max_width, const int max_height
                          HIGHBD_DECL_SUFFIX)
{
#if BITDEPTH == 16
   const int dc = (bitdepth_max + 1) >> 1;
#else
   const int dc = 128;
#endif
   splat_dc(dst, stride, width, height, dc HIGHBD_TAIL_SUFFIX);
}

static void ipred_cfl_128_c(pixel *dst, const ptrdiff_t stride,
                           const pixel *const topleft,
                           const int width, const int height,
                           const int16_t *ac, const int alpha
                           HIGHBD_DECL_SUFFIX)
{
#if BITDEPTH == 16
   const int dc = (bitdepth_max + 1) >> 1;
#else
   const int dc = 128;
#endif
   cfl_pred(dst, stride, width, height, dc, ac, alpha HIGHBD_TAIL_SUFFIX);
}

static void ipred_v_c(pixel *dst, const ptrdiff_t stride,
                     const pixel *const topleft,
                     const int width, const int height, const int a,
                     const int max_width, const int max_height
                     HIGHBD_DECL_SUFFIX)
{
   for (int y = 0; y < height; y++) {
       pixel_copy(dst, topleft + 1, width);
       dst += PXSTRIDE(stride);
   }
}

static void ipred_h_c(pixel *dst, const ptrdiff_t stride,
                     const pixel *const topleft,
                     const int width, const int height, const int a,
                     const int max_width, const int max_height
                     HIGHBD_DECL_SUFFIX)
{
   for (int y = 0; y < height; y++) {
       pixel_set(dst, topleft[-(1 + y)], width);
       dst += PXSTRIDE(stride);
   }
}

static void ipred_paeth_c(pixel *dst, const ptrdiff_t stride,
                         const pixel *const tl_ptr,
                         const int width, const int height, const int a,
                         const int max_width, const int max_height
                         HIGHBD_DECL_SUFFIX)
{
   const int topleft = tl_ptr[0];
   for (int y = 0; y < height; y++) {
       const int left = tl_ptr[-(y + 1)];
       for (int x = 0; x < width; x++) {
           const int top = tl_ptr[1 + x];
           const int base = left + top - topleft;
           const int ldiff = abs(left - base);
           const int tdiff = abs(top - base);
           const int tldiff = abs(topleft - base);

           dst[x] = ldiff <= tdiff && ldiff <= tldiff ? left :
                    tdiff <= tldiff ? top : topleft;
       }
       dst += PXSTRIDE(stride);
   }
}

static void ipred_smooth_c(pixel *dst, const ptrdiff_t stride,
                          const pixel *const topleft,
                          const int width, const int height, const int a,
                          const int max_width, const int max_height
                          HIGHBD_DECL_SUFFIX)
{
   const uint8_t *const weights_hor = &dav1d_sm_weights[width];
   const uint8_t *const weights_ver = &dav1d_sm_weights[height];
   const int right = topleft[width], bottom = topleft[-height];

   for (int y = 0; y < height; y++) {
       for (int x = 0; x < width; x++) {
           const int pred = weights_ver[y]  * topleft[1 + x] +
                     (256 - weights_ver[y]) * bottom +
                            weights_hor[x]  * topleft[-(1 + y)] +
                     (256 - weights_hor[x]) * right;
           dst[x] = (pred + 256) >> 9;
       }
       dst += PXSTRIDE(stride);
   }
}

static void ipred_smooth_v_c(pixel *dst, const ptrdiff_t stride,
                            const pixel *const topleft,
                            const int width, const int height, const int a,
                            const int max_width, const int max_height
                            HIGHBD_DECL_SUFFIX)
{
   const uint8_t *const weights_ver = &dav1d_sm_weights[height];
   const int bottom = topleft[-height];

   for (int y = 0; y < height; y++) {
       for (int x = 0; x < width; x++) {
           const int pred = weights_ver[y]  * topleft[1 + x] +
                     (256 - weights_ver[y]) * bottom;
           dst[x] = (pred + 128) >> 8;
       }
       dst += PXSTRIDE(stride);
   }
}

static void ipred_smooth_h_c(pixel *dst, const ptrdiff_t stride,
                            const pixel *const topleft,
                            const int width, const int height, const int a,
                            const int max_width, const int max_height
                            HIGHBD_DECL_SUFFIX)
{
   const uint8_t *const weights_hor = &dav1d_sm_weights[width];
   const int right = topleft[width];

   for (int y = 0; y < height; y++) {
       for (int x = 0; x < width; x++) {
           const int pred = weights_hor[x]  * topleft[-(y + 1)] +
                     (256 - weights_hor[x]) * right;
           dst[x] = (pred + 128) >> 8;
       }
       dst += PXSTRIDE(stride);
   }
}

static NOINLINE int get_filter_strength(const int wh, const int angle,
                                       const int is_sm)
{
   if (is_sm) {
       if (wh <= 8) {
           if (angle >= 64) return 2;
           if (angle >= 40) return 1;
       } else if (wh <= 16) {
           if (angle >= 48) return 2;
           if (angle >= 20) return 1;
       } else if (wh <= 24) {
           if (angle >=  4) return 3;
       } else {
           return 3;
       }
   } else {
       if (wh <= 8) {
           if (angle >= 56) return 1;
       } else if (wh <= 16) {
           if (angle >= 40) return 1;
       } else if (wh <= 24) {
           if (angle >= 32) return 3;
           if (angle >= 16) return 2;
           if (angle >=  8) return 1;
       } else if (wh <= 32) {
           if (angle >= 32) return 3;
           if (angle >=  4) return 2;
           return 1;
       } else {
           return 3;
       }
   }
   return 0;
}

static NOINLINE void filter_edge(pixel *const out, const int sz,
                                const int lim_from, const int lim_to,
                                const pixel *const in, const int from,
                                const int to, const int strength)
{
   static const uint8_t kernel[3][5] = {
       { 0, 4, 8, 4, 0 },
       { 0, 5, 6, 5, 0 },
       { 2, 4, 4, 4, 2 }
   };

   assert(strength > 0);
   int i = 0;
   for (; i < imin(sz, lim_from); i++)
       out[i] = in[iclip(i, from, to - 1)];
   for (; i < imin(lim_to, sz); i++) {
       int s = 0;
       for (int j = 0; j < 5; j++)
           s += in[iclip(i - 2 + j, from, to - 1)] * kernel[strength - 1][j];
       out[i] = (s + 8) >> 4;
   }
   for (; i < sz; i++)
       out[i] = in[iclip(i, from, to - 1)];
}

static inline int get_upsample(const int wh, const int angle, const int is_sm) {
   return angle < 40 && wh <= 16 >> is_sm;
}

static NOINLINE void upsample_edge(pixel *const out, const int hsz,
                                  const pixel *const in, const int from,
                                  const int to HIGHBD_DECL_SUFFIX)
{
   static const int8_t kernel[4] = { -1, 9, 9, -1 };
   int i;
   for (i = 0; i < hsz - 1; i++) {
       out[i * 2] = in[iclip(i, from, to - 1)];

       int s = 0;
       for (int j = 0; j < 4; j++)
           s += in[iclip(i + j - 1, from, to - 1)] * kernel[j];
       out[i * 2 + 1] = iclip_pixel((s + 8) >> 4);
   }
   out[i * 2] = in[iclip(i, from, to - 1)];
}

static void ipred_z1_c(pixel *dst, const ptrdiff_t stride,
                      const pixel *const topleft_in,
                      const int width, const int height, int angle,
                      const int max_width, const int max_height
                      HIGHBD_DECL_SUFFIX)
{
   const int is_sm = (angle >> 9) & 0x1;
   const int enable_intra_edge_filter = angle >> 10;
   angle &= 511;
   assert(angle < 90);
   int dx = dav1d_dr_intra_derivative[angle >> 1];
   pixel top_out[64 + 64];
   const pixel *top;
   int max_base_x;
   const int upsample_above = enable_intra_edge_filter ?
       get_upsample(width + height, 90 - angle, is_sm) : 0;
   if (upsample_above) {
       upsample_edge(top_out, width + height, &topleft_in[1], -1,
                     width + imin(width, height) HIGHBD_TAIL_SUFFIX);
       top = top_out;
       max_base_x = 2 * (width + height) - 2;
       dx <<= 1;
   } else {
       const int filter_strength = enable_intra_edge_filter ?
           get_filter_strength(width + height, 90 - angle, is_sm) : 0;
       if (filter_strength) {
           filter_edge(top_out, width + height, 0, width + height,
                       &topleft_in[1], -1, width + imin(width, height),
                       filter_strength);
           top = top_out;
           max_base_x = width + height - 1;
       } else {
           top = &topleft_in[1];
           max_base_x = width + imin(width, height) - 1;
       }
   }
   const int base_inc = 1 + upsample_above;
   for (int y = 0, xpos = dx; y < height;
        y++, dst += PXSTRIDE(stride), xpos += dx)
   {
       const int frac = xpos & 0x3E;

       for (int x = 0, base = xpos >> 6; x < width; x++, base += base_inc) {
           if (base < max_base_x) {
               const int v = top[base] * (64 - frac) + top[base + 1] * frac;
               dst[x] = (v + 32) >> 6;
           } else {
               pixel_set(&dst[x], top[max_base_x], width - x);
               break;
           }
       }
   }
}

static void ipred_z2_c(pixel *dst, const ptrdiff_t stride,
                      const pixel *const topleft_in,
                      const int width, const int height, int angle,
                      const int max_width, const int max_height
                      HIGHBD_DECL_SUFFIX)
{
   const int is_sm = (angle >> 9) & 0x1;
   const int enable_intra_edge_filter = angle >> 10;
   angle &= 511;
   assert(angle > 90 && angle < 180);
   int dy = dav1d_dr_intra_derivative[(angle - 90) >> 1];
   int dx = dav1d_dr_intra_derivative[(180 - angle) >> 1];
   const int upsample_left = enable_intra_edge_filter ?
       get_upsample(width + height, 180 - angle, is_sm) : 0;
   const int upsample_above = enable_intra_edge_filter ?
       get_upsample(width + height, angle - 90, is_sm) : 0;
   pixel edge[64 + 64 + 1];
   pixel *const topleft = &edge[64];

   if (upsample_above) {
       upsample_edge(topleft, width + 1, topleft_in, 0, width + 1
                     HIGHBD_TAIL_SUFFIX);
       dx <<= 1;
   } else {
       const int filter_strength = enable_intra_edge_filter ?
           get_filter_strength(width + height, angle - 90, is_sm) : 0;

       if (filter_strength) {
           filter_edge(&topleft[1], width, 0, max_width,
                       &topleft_in[1], -1, width,
                       filter_strength);
       } else {
           pixel_copy(&topleft[1], &topleft_in[1], width);
       }
   }
   if (upsample_left) {
       upsample_edge(&topleft[-height * 2], height + 1, &topleft_in[-height],
                     0, height + 1 HIGHBD_TAIL_SUFFIX);
       dy <<= 1;
   } else {
       const int filter_strength = enable_intra_edge_filter ?
           get_filter_strength(width + height, 180 - angle, is_sm) : 0;

       if (filter_strength) {
           filter_edge(&topleft[-height], height, height - max_height, height,
                       &topleft_in[-height],
                       0, height + 1, filter_strength);
       } else {
           pixel_copy(&topleft[-height], &topleft_in[-height], height);
       }
   }
   *topleft = *topleft_in;

   const int base_inc_x = 1 + upsample_above;
   const pixel *const left = &topleft[-(1 + upsample_left)];
   for (int y = 0, xpos = ((1 + upsample_above) << 6) - dx; y < height;
        y++, xpos -= dx, dst += PXSTRIDE(stride))
   {
       int base_x = xpos >> 6;
       const int frac_x = xpos & 0x3E;

       for (int x = 0, ypos = (y << (6 + upsample_left)) - dy; x < width;
            x++, base_x += base_inc_x, ypos -= dy)
       {
           int v;
           if (base_x >= 0) {
               v = topleft[base_x] * (64 - frac_x) +
                   topleft[base_x + 1] * frac_x;
           } else {
               const int base_y = ypos >> 6;
               assert(base_y >= -(1 + upsample_left));
               const int frac_y = ypos & 0x3E;
               v = left[-base_y] * (64 - frac_y) +
                   left[-(base_y + 1)] * frac_y;
           }
           dst[x] = (v + 32) >> 6;
       }
   }
}

static void ipred_z3_c(pixel *dst, const ptrdiff_t stride,
                      const pixel *const topleft_in,
                      const int width, const int height, int angle,
                      const int max_width, const int max_height
                      HIGHBD_DECL_SUFFIX)
{
   const int is_sm = (angle >> 9) & 0x1;
   const int enable_intra_edge_filter = angle >> 10;
   angle &= 511;
   assert(angle > 180);
   int dy = dav1d_dr_intra_derivative[(270 - angle) >> 1];
   pixel left_out[64 + 64];
   const pixel *left;
   int max_base_y;
   const int upsample_left = enable_intra_edge_filter ?
       get_upsample(width + height, angle - 180, is_sm) : 0;
   if (upsample_left) {
       upsample_edge(left_out, width + height,
                     &topleft_in[-(width + height)],
                     imax(width - height, 0), width + height + 1
                     HIGHBD_TAIL_SUFFIX);
       left = &left_out[2 * (width + height) - 2];
       max_base_y = 2 * (width + height) - 2;
       dy <<= 1;
   } else {
       const int filter_strength = enable_intra_edge_filter ?
           get_filter_strength(width + height, angle - 180, is_sm) : 0;

       if (filter_strength) {
           filter_edge(left_out, width + height, 0, width + height,
                       &topleft_in[-(width + height)],
                       imax(width - height, 0), width + height + 1,
                       filter_strength);
           left = &left_out[width + height - 1];
           max_base_y = width + height - 1;
       } else {
           left = &topleft_in[-1];
           max_base_y = height + imin(width, height) - 1;
       }
   }
   const int base_inc = 1 + upsample_left;
   for (int x = 0, ypos = dy; x < width; x++, ypos += dy) {
       const int frac = ypos & 0x3E;

       for (int y = 0, base = ypos >> 6; y < height; y++, base += base_inc) {
           if (base < max_base_y) {
               const int v = left[-base] * (64 - frac) +
                             left[-(base + 1)] * frac;
               dst[y * PXSTRIDE(stride) + x] = (v + 32) >> 6;
           } else {
               do {
                   dst[y * PXSTRIDE(stride) + x] = left[-max_base_y];
               } while (++y < height);
               break;
           }
       }
   }
}

#if ARCH_X86
#define FILTER(flt_ptr, p0, p1, p2, p3, p4, p5, p6) \
   flt_ptr[ 0] * p0 + flt_ptr[ 1] * p1 +           \
   flt_ptr[16] * p2 + flt_ptr[17] * p3 +           \
   flt_ptr[32] * p4 + flt_ptr[33] * p5 +           \
   flt_ptr[48] * p6
#define FLT_INCR 2
#else
#define FILTER(flt_ptr, p0, p1, p2, p3, p4, p5, p6) \
   flt_ptr[ 0] * p0 + flt_ptr[ 8] * p1 +           \
   flt_ptr[16] * p2 + flt_ptr[24] * p3 +           \
   flt_ptr[32] * p4 + flt_ptr[40] * p5 +           \
   flt_ptr[48] * p6
#define FLT_INCR 1
#endif

/* Up to 32x32 only */
static void ipred_filter_c(pixel *dst, const ptrdiff_t stride,
                          const pixel *const topleft_in,
                          const int width, const int height, int filt_idx,
                          const int max_width, const int max_height
                          HIGHBD_DECL_SUFFIX)
{
   filt_idx &= 511;
   assert(filt_idx < 5);

   const int8_t *const filter = dav1d_filter_intra_taps[filt_idx];
   const pixel *top = &topleft_in[1];
   for (int y = 0; y < height; y += 2) {
       const pixel *topleft = &topleft_in[-y];
       const pixel *left = &topleft[-1];
       ptrdiff_t left_stride = -1;
       for (int x = 0; x < width; x += 4) {
           const int p0 = *topleft;
           const int p1 = top[0], p2 = top[1], p3 = top[2], p4 = top[3];
           const int p5 = left[0 * left_stride], p6 = left[1 * left_stride];
           pixel *ptr = &dst[x];
           const int8_t *flt_ptr = filter;

           for (int yy = 0; yy < 2; yy++) {
               for (int xx = 0; xx < 4; xx++, flt_ptr += FLT_INCR) {
                   const int acc = FILTER(flt_ptr, p0, p1, p2, p3, p4, p5, p6);
                   ptr[xx] = iclip_pixel((acc + 8) >> 4);
               }
               ptr += PXSTRIDE(stride);
           }
           left = &dst[x + 4 - 1];
           left_stride = PXSTRIDE(stride);
           top += 4;
           topleft = &top[-1];
       }
       top = &dst[PXSTRIDE(stride)];
       dst = &dst[PXSTRIDE(stride) * 2];
   }
}

static NOINLINE void
cfl_ac_c(int16_t *ac, const pixel *ypx, const ptrdiff_t stride,
        const int w_pad, const int h_pad, const int width, const int height,
        const int ss_hor, const int ss_ver)
{
   int y, x;
   int16_t *const ac_orig = ac;

   assert(w_pad >= 0 && w_pad * 4 < width);
   assert(h_pad >= 0 && h_pad * 4 < height);

   for (y = 0; y < height - 4 * h_pad; y++) {
       for (x = 0; x < width - 4 * w_pad; x++) {
           int ac_sum = ypx[x << ss_hor];
           if (ss_hor) ac_sum += ypx[x * 2 + 1];
           if (ss_ver) {
               ac_sum += ypx[(x << ss_hor) + PXSTRIDE(stride)];
               if (ss_hor) ac_sum += ypx[x * 2 + 1 + PXSTRIDE(stride)];
           }
           ac[x] = ac_sum << (1 + !ss_ver + !ss_hor);
       }
       for (; x < width; x++)
           ac[x] = ac[x - 1];
       ac += width;
       ypx += PXSTRIDE(stride) << ss_ver;
   }
   for (; y < height; y++) {
       memcpy(ac, &ac[-width], width * sizeof(*ac));
       ac += width;
   }

   const int log2sz = ctz(width) + ctz(height);
   int sum = (1 << log2sz) >> 1;
   for (ac = ac_orig, y = 0; y < height; y++) {
       for (x = 0; x < width; x++)
           sum += ac[x];
       ac += width;
   }
   sum >>= log2sz;

   // subtract DC
   for (ac = ac_orig, y = 0; y < height; y++) {
       for (x = 0; x < width; x++)
           ac[x] -= sum;
       ac += width;
   }
}

#define cfl_ac_fn(fmt, ss_hor, ss_ver) \
static void cfl_ac_##fmt##_c(int16_t *const ac, const pixel *const ypx, \
                            const ptrdiff_t stride, const int w_pad, \
                            const int h_pad, const int cw, const int ch) \
{ \
   cfl_ac_c(ac, ypx, stride, w_pad, h_pad, cw, ch, ss_hor, ss_ver); \
}

cfl_ac_fn(420, 1, 1)
cfl_ac_fn(422, 1, 0)
cfl_ac_fn(444, 0, 0)

static void pal_pred_c(pixel *dst, const ptrdiff_t stride,
                      const pixel *const pal, const uint8_t *idx,
                      const int w, const int h)
{
   for (int y = 0; y < h; y++) {
       for (int x = 0; x < w; x += 2) {
           const int i = *idx++;
           assert(!(i & 0x88));
           dst[x + 0] = pal[i & 7];
           dst[x + 1] = pal[i >> 4];
       }
       dst += PXSTRIDE(stride);
   }
}

#if HAVE_ASM
#if ARCH_AARCH64 || ARCH_ARM
#include "src/arm/ipred.h"
#elif ARCH_RISCV
#include "src/riscv/ipred.h"
#elif ARCH_X86
#include "src/x86/ipred.h"
#elif ARCH_LOONGARCH64
#include "src/loongarch/ipred.h"
#endif
#endif

COLD void bitfn(dav1d_intra_pred_dsp_init)(Dav1dIntraPredDSPContext *const c) {
   c->intra_pred[DC_PRED      ] = ipred_dc_c;
   c->intra_pred[DC_128_PRED  ] = ipred_dc_128_c;
   c->intra_pred[TOP_DC_PRED  ] = ipred_dc_top_c;
   c->intra_pred[LEFT_DC_PRED ] = ipred_dc_left_c;
   c->intra_pred[HOR_PRED     ] = ipred_h_c;
   c->intra_pred[VERT_PRED    ] = ipred_v_c;
   c->intra_pred[PAETH_PRED   ] = ipred_paeth_c;
   c->intra_pred[SMOOTH_PRED  ] = ipred_smooth_c;
   c->intra_pred[SMOOTH_V_PRED] = ipred_smooth_v_c;
   c->intra_pred[SMOOTH_H_PRED] = ipred_smooth_h_c;
   c->intra_pred[Z1_PRED      ] = ipred_z1_c;
   c->intra_pred[Z2_PRED      ] = ipred_z2_c;
   c->intra_pred[Z3_PRED      ] = ipred_z3_c;
   c->intra_pred[FILTER_PRED  ] = ipred_filter_c;

   c->cfl_ac[DAV1D_PIXEL_LAYOUT_I420 - 1] = cfl_ac_420_c;
   c->cfl_ac[DAV1D_PIXEL_LAYOUT_I422 - 1] = cfl_ac_422_c;
   c->cfl_ac[DAV1D_PIXEL_LAYOUT_I444 - 1] = cfl_ac_444_c;

   c->cfl_pred[DC_PRED     ] = ipred_cfl_c;
   c->cfl_pred[DC_128_PRED ] = ipred_cfl_128_c;
   c->cfl_pred[TOP_DC_PRED ] = ipred_cfl_top_c;
   c->cfl_pred[LEFT_DC_PRED] = ipred_cfl_left_c;

   c->pal_pred = pal_pred_c;

#if HAVE_ASM
#if ARCH_AARCH64 || ARCH_ARM
   intra_pred_dsp_init_arm(c);
#elif ARCH_RISCV
   intra_pred_dsp_init_riscv(c);
#elif ARCH_X86
   intra_pred_dsp_init_x86(c);
#elif ARCH_LOONGARCH64
   intra_pred_dsp_init_loongarch(c);
#endif
#endif
}