/*
 * Copyright (c) 2016, Alliance for Open Media. All rights reserved
 *
 * This source code is subject to the terms of the BSD 2 Clause License and
 * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
 * was not distributed with this source code in the LICENSE file, you can
 * obtain it at www.aomedia.org/license/software. If the Alliance for Open
 * Media Patent License 1.0 was not distributed with this source code in the
 * PATENTS file, you can obtain it at www.aomedia.org/license/patent.
 */

#include <assert.h>
#include <math.h>

#include "./aom_config.h"
#include "./aom_dsp_rtcd.h"

#include "aom_dsp/aom_dsp_common.h"
#include "aom_dsp/intrapred_common.h"
#include "aom_mem/aom_mem.h"
#include "aom_ports/bitops.h"

#define DST(x, y) dst[(x) + (y)*stride]
#define AVG3(a, b, c) (((a) + 2 * (b) + (c) + 2) >> 2)
#define AVG2(a, b) (((a) + (b) + 1) >> 1)

static INLINE void d207e_predictor(uint8_t *dst, ptrdiff_t stride, int bw,
                                   int bh, const uint8_t *above,
                                   const uint8_t *left) {
  int r, c;
  (void)above;

  for (r = 0; r < bh; ++r) {
    for (c = 0; c < bw; ++c) {
      dst[c] = c & 1 ? AVG3(left[(c >> 1) + r], left[(c >> 1) + r + 1],
                            left[(c >> 1) + r + 2])
                     : AVG2(left[(c >> 1) + r], left[(c >> 1) + r + 1]);
    }
    dst += stride;
  }
}

static INLINE void d63e_predictor(uint8_t *dst, ptrdiff_t stride, int bw,
                                  int bh, const uint8_t *above,
                                  const uint8_t *left) {
  int r, c;
  (void)left;
  for (r = 0; r < bh; ++r) {
    for (c = 0; c < bw; ++c) {
      dst[c] = r & 1 ? AVG3(above[(r >> 1) + c], above[(r >> 1) + c + 1],
                            above[(r >> 1) + c + 2])
                     : AVG2(above[(r >> 1) + c], above[(r >> 1) + c + 1]);
    }
    dst += stride;
  }
}

static INLINE void d45e_predictor(uint8_t *dst, ptrdiff_t stride, int bw,
                                  int bh, const uint8_t *above,
                                  const uint8_t *left) {
  int r, c;
  (void)left;
  for (r = 0; r < bh; ++r) {
    for (c = 0; c < bw; ++c) {
      dst[c] = AVG3(above[r + c], above[r + c + 1],
                    above[r + c + 1 + (r + c + 2 < bw + bh)]);
    }
    dst += stride;
  }
}

static INLINE void d117_predictor(uint8_t *dst, ptrdiff_t stride, int bw,
                                  int bh, const uint8_t *above,
                                  const uint8_t *left) {
  int r, c;

  // first row
  for (c = 0; c < bw; c++) dst[c] = AVG2(above[c - 1], above[c]);
  dst += stride;

  // second row
  dst[0] = AVG3(left[0], above[-1], above[0]);
  for (c = 1; c < bw; c++) dst[c] = AVG3(above[c - 2], above[c - 1], above[c]);
  dst += stride;

  // the rest of first col
  dst[0] = AVG3(above[-1], left[0], left[1]);
  for (r = 3; r < bh; ++r)
    dst[(r - 2) * stride] = AVG3(left[r - 3], left[r - 2], left[r - 1]);

  // the rest of the block
  for (r = 2; r < bh; ++r) {
    for (c = 1; c < bw; c++) dst[c] = dst[-2 * stride + c - 1];
    dst += stride;
  }
}

static INLINE void d135_predictor(uint8_t *dst, ptrdiff_t stride, int bw,
                                  int bh, const uint8_t *above,
                                  const uint8_t *left) {
  int i;
#if defined(__GNUC__) && __GNUC__ == 4 && __GNUC_MINOR__ > 7
  // silence a spurious -Warray-bounds warning, possibly related to:
  // https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56273
  uint8_t border[133];
#else
  uint8_t border[64 + 64 - 1];  // outer border from bottom-left to top-right
#endif

  // dst(bh, bh - 2)[0], i.e., border starting at bottom-left
  for (i = 0; i < bh - 2; ++i) {
    border[i] = AVG3(left[bh - 3 - i], left[bh - 2 - i], left[bh - 1 - i]);
  }
  border[bh - 2] = AVG3(above[-1], left[0], left[1]);
  border[bh - 1] = AVG3(left[0], above[-1], above[0]);
  border[bh - 0] = AVG3(above[-1], above[0], above[1]);
  // dst[0][2, size), i.e., remaining top border ascending
  for (i = 0; i < bw - 2; ++i) {
    border[bh + 1 + i] = AVG3(above[i], above[i + 1], above[i + 2]);
  }

  for (i = 0; i < bh; ++i) {
    memcpy(dst + i * stride, border + bh - 1 - i, bw);
  }
}

static INLINE void d153_predictor(uint8_t *dst, ptrdiff_t stride, int bw,
                                  int bh, const uint8_t *above,
                                  const uint8_t *left) {
  int r, c;
  dst[0] = AVG2(above[-1], left[0]);
  for (r = 1; r < bh; r++) dst[r * stride] = AVG2(left[r - 1], left[r]);
  dst++;

  dst[0] = AVG3(left[0], above[-1], above[0]);
  dst[stride] = AVG3(above[-1], left[0], left[1]);
  for (r = 2; r < bh; r++)
    dst[r * stride] = AVG3(left[r - 2], left[r - 1], left[r]);
  dst++;

  for (c = 0; c < bw - 2; c++)
    dst[c] = AVG3(above[c - 1], above[c], above[c + 1]);
  dst += stride;

  for (r = 1; r < bh; ++r) {
    for (c = 0; c < bw - 2; c++) dst[c] = dst[-stride + c - 2];
    dst += stride;
  }
}

static INLINE void v_predictor(uint8_t *dst, ptrdiff_t stride, int bw, int bh,
                               const uint8_t *above, const uint8_t *left) {
  int r;
  (void)left;

  for (r = 0; r < bh; r++) {
    memcpy(dst, above, bw);
    dst += stride;
  }
}

static INLINE void h_predictor(uint8_t *dst, ptrdiff_t stride, int bw, int bh,
                               const uint8_t *above, const uint8_t *left) {
  int r;
  (void)above;

  for (r = 0; r < bh; r++) {
    memset(dst, left[r], bw);
    dst += stride;
  }
}

static INLINE int abs_diff(int a, int b) { return (a > b) ? a - b : b - a; }

static INLINE uint16_t paeth_predictor_single(uint16_t left, uint16_t top,
                                              uint16_t top_left) {
  const int base = top + left - top_left;
  const int p_left = abs_diff(base, left);
  const int p_top = abs_diff(base, top);
  const int p_top_left = abs_diff(base, top_left);

  // Return nearest to base of left, top and top_left.
  return (p_left <= p_top && p_left <= p_top_left)
             ? left
             : (p_top <= p_top_left) ? top : top_left;
}

static INLINE void paeth_predictor(uint8_t *dst, ptrdiff_t stride, int bw,
                                   int bh, const uint8_t *above,
                                   const uint8_t *left) {
  int r, c;
  const uint8_t ytop_left = above[-1];

  for (r = 0; r < bh; r++) {
    for (c = 0; c < bw; c++)
      dst[c] = (uint8_t)paeth_predictor_single(left[r], above[c], ytop_left);
    dst += stride;
  }
}

// Some basic checks on weights for smooth predictor.
#define sm_weights_sanity_checks(weights_w, weights_h, weights_scale, \
                                 pred_scale)                          \
  assert(weights_w[0] < weights_scale);                               \
  assert(weights_h[0] < weights_scale);                               \
  assert(weights_scale - weights_w[bw - 1] < weights_scale);          \
  assert(weights_scale - weights_h[bh - 1] < weights_scale);          \
  assert(pred_scale < 31)  // ensures no overflow when calculating predictor.

#define divide_round(value, bits) (((value) + (1 << ((bits)-1))) >> (bits))

static INLINE void smooth_predictor(uint8_t *dst, ptrdiff_t stride, int bw,
                                    int bh, const uint8_t *above,
                                    const uint8_t *left) {
  const uint8_t below_pred = left[bh - 1];   // estimated by bottom-left pixel
  const uint8_t right_pred = above[bw - 1];  // estimated by top-right pixel
  const uint8_t *const sm_weights_w = sm_weight_arrays + bw;
  const uint8_t *const sm_weights_h = sm_weight_arrays + bh;
  // scale = 2 * 2^sm_weight_log2_scale
  const int log2_scale = 1 + sm_weight_log2_scale;
  const uint16_t scale = (1 << sm_weight_log2_scale);
  sm_weights_sanity_checks(sm_weights_w, sm_weights_h, scale,
                           log2_scale + sizeof(*dst));
  int r;
  for (r = 0; r < bh; ++r) {
    int c;
    for (c = 0; c < bw; ++c) {
      const uint8_t pixels[] = { above[c], below_pred, left[r], right_pred };
      const uint8_t weights[] = { sm_weights_h[r], scale - sm_weights_h[r],
                                  sm_weights_w[c], scale - sm_weights_w[c] };
      uint32_t this_pred = 0;
      int i;
      assert(scale >= sm_weights_h[r] && scale >= sm_weights_w[c]);
      for (i = 0; i < 4; ++i) {
        this_pred += weights[i] * pixels[i];
      }
      dst[c] = clip_pixel(divide_round(this_pred, log2_scale));
    }
    dst += stride;
  }
}

static INLINE void smooth_v_predictor(uint8_t *dst, ptrdiff_t stride, int bw,
                                      int bh, const uint8_t *above,
                                      const uint8_t *left) {
  const uint8_t below_pred = left[bh - 1];  // estimated by bottom-left pixel
  const uint8_t *const sm_weights = sm_weight_arrays + bh;
  // scale = 2^sm_weight_log2_scale
  const int log2_scale = sm_weight_log2_scale;
  const uint16_t scale = (1 << sm_weight_log2_scale);
  sm_weights_sanity_checks(sm_weights, sm_weights, scale,
                           log2_scale + sizeof(*dst));

  int r;
  for (r = 0; r < bh; r++) {
    int c;
    for (c = 0; c < bw; ++c) {
      const uint8_t pixels[] = { above[c], below_pred };
      const uint8_t weights[] = { sm_weights[r], scale - sm_weights[r] };
      uint32_t this_pred = 0;
      assert(scale >= sm_weights[r]);
      int i;
      for (i = 0; i < 2; ++i) {
        this_pred += weights[i] * pixels[i];
      }
      dst[c] = clip_pixel(divide_round(this_pred, log2_scale));
    }
    dst += stride;
  }
}

static INLINE void smooth_h_predictor(uint8_t *dst, ptrdiff_t stride, int bw,
                                      int bh, const uint8_t *above,
                                      const uint8_t *left) {
  const uint8_t right_pred = above[bw - 1];  // estimated by top-right pixel
  const uint8_t *const sm_weights = sm_weight_arrays + bw;
  // scale = 2^sm_weight_log2_scale
  const int log2_scale = sm_weight_log2_scale;
  const uint16_t scale = (1 << sm_weight_log2_scale);
  sm_weights_sanity_checks(sm_weights, sm_weights, scale,
                           log2_scale + sizeof(*dst));

  int r;
  for (r = 0; r < bh; r++) {
    int c;
    for (c = 0; c < bw; ++c) {
      const uint8_t pixels[] = { left[r], right_pred };
      const uint8_t weights[] = { sm_weights[c], scale - sm_weights[c] };
      uint32_t this_pred = 0;
      assert(scale >= sm_weights[c]);
      int i;
      for (i = 0; i < 2; ++i) {
        this_pred += weights[i] * pixels[i];
      }
      dst[c] = clip_pixel(divide_round(this_pred, log2_scale));
    }
    dst += stride;
  }
}

static INLINE void dc_128_predictor(uint8_t *dst, ptrdiff_t stride, int bw,
                                    int bh, const uint8_t *above,
                                    const uint8_t *left) {
  int r;
  (void)above;
  (void)left;

  for (r = 0; r < bh; r++) {
    memset(dst, 128, bw);
    dst += stride;
  }
}

static INLINE void dc_left_predictor(uint8_t *dst, ptrdiff_t stride, int bw,
                                     int bh, const uint8_t *above,
                                     const uint8_t *left) {
  int i, r, expected_dc, sum = 0;
  (void)above;

  for (i = 0; i < bh; i++) sum += left[i];
  expected_dc = (sum + (bh >> 1)) / bh;

  for (r = 0; r < bh; r++) {
    memset(dst, expected_dc, bw);
    dst += stride;
  }
}

static INLINE void dc_top_predictor(uint8_t *dst, ptrdiff_t stride, int bw,
                                    int bh, const uint8_t *above,
                                    const uint8_t *left) {
  int i, r, expected_dc, sum = 0;
  (void)left;

  for (i = 0; i < bw; i++) sum += above[i];
  expected_dc = (sum + (bw >> 1)) / bw;

  for (r = 0; r < bh; r++) {
    memset(dst, expected_dc, bw);
    dst += stride;
  }
}

static INLINE void dc_predictor(uint8_t *dst, ptrdiff_t stride, int bw, int bh,
                                const uint8_t *above, const uint8_t *left) {
  int i, r, expected_dc, sum = 0;
  const int count = bw + bh;

  for (i = 0; i < bw; i++) {
    sum += above[i];
  }
  for (i = 0; i < bh; i++) {
    sum += left[i];
  }

  expected_dc = (sum + (count >> 1)) / count;

  for (r = 0; r < bh; r++) {
    memset(dst, expected_dc, bw);
    dst += stride;
  }
}

static INLINE void dc_predictor_rect(uint8_t *dst, ptrdiff_t stride, int bw,
                                     int bh, const uint8_t *above,
                                     const uint8_t *left, uint32_t multiplier,
                                     int shift) {
  int i, r, expected_dc, sum = 0;

  for (i = 0; i < bw; i++) {
    sum += above[i];
  }
  for (i = 0; i < bh; i++) {
    sum += left[i];
  }

  expected_dc = (int)(((uint64_t)sum * multiplier) >> shift);
  expected_dc = clip_pixel(expected_dc);

  for (r = 0; r < bh; r++) {
    memset(dst, expected_dc, bw);
    dst += stride;
  }
}

#define DC_MULTIPLIER_1X2 0xABU
#define DC_MULTIPLIER_1X4 0xCDU

void aom_dc_predictor_4x8_c(uint8_t *dst, ptrdiff_t stride,
                            const uint8_t *above, const uint8_t *left) {
  dc_predictor_rect(dst, stride, 4, 8, above, left, DC_MULTIPLIER_1X2, 11);
}

void aom_dc_predictor_8x4_c(uint8_t *dst, ptrdiff_t stride,
                            const uint8_t *above, const uint8_t *left) {
  dc_predictor_rect(dst, stride, 8, 4, above, left, DC_MULTIPLIER_1X2, 11);
}

void aom_dc_predictor_4x16_c(uint8_t *dst, ptrdiff_t stride,
                             const uint8_t *above, const uint8_t *left) {
  dc_predictor_rect(dst, stride, 4, 16, above, left, DC_MULTIPLIER_1X4, 12);
}

void aom_dc_predictor_16x4_c(uint8_t *dst, ptrdiff_t stride,
                             const uint8_t *above, const uint8_t *left) {
  dc_predictor_rect(dst, stride, 16, 4, above, left, DC_MULTIPLIER_1X4, 12);
}

void aom_dc_predictor_8x16_c(uint8_t *dst, ptrdiff_t stride,
                             const uint8_t *above, const uint8_t *left) {
  dc_predictor_rect(dst, stride, 8, 16, above, left, DC_MULTIPLIER_1X2, 12);
}

void aom_dc_predictor_16x8_c(uint8_t *dst, ptrdiff_t stride,
                             const uint8_t *above, const uint8_t *left) {
  dc_predictor_rect(dst, stride, 16, 8, above, left, DC_MULTIPLIER_1X2, 12);
}

void aom_dc_predictor_8x32_c(uint8_t *dst, ptrdiff_t stride,
                             const uint8_t *above, const uint8_t *left) {
  dc_predictor_rect(dst, stride, 8, 32, above, left, DC_MULTIPLIER_1X4, 13);
}

void aom_dc_predictor_32x8_c(uint8_t *dst, ptrdiff_t stride,
                             const uint8_t *above, const uint8_t *left) {
  dc_predictor_rect(dst, stride, 32, 8, above, left, DC_MULTIPLIER_1X4, 13);
}

void aom_dc_predictor_16x32_c(uint8_t *dst, ptrdiff_t stride,
                              const uint8_t *above, const uint8_t *left) {
  dc_predictor_rect(dst, stride, 16, 32, above, left, DC_MULTIPLIER_1X2, 13);
}

void aom_dc_predictor_32x16_c(uint8_t *dst, ptrdiff_t stride,
                              const uint8_t *above, const uint8_t *left) {
  dc_predictor_rect(dst, stride, 32, 16, above, left, DC_MULTIPLIER_1X2, 13);
}

void aom_dc_predictor_16x64_c(uint8_t *dst, ptrdiff_t stride,
                              const uint8_t *above, const uint8_t *left) {
  dc_predictor_rect(dst, stride, 16, 64, above, left, DC_MULTIPLIER_1X4, 14);
}

void aom_dc_predictor_64x16_c(uint8_t *dst, ptrdiff_t stride,
                              const uint8_t *above, const uint8_t *left) {
  dc_predictor_rect(dst, stride, 64, 16, above, left, DC_MULTIPLIER_1X4, 14);
}

void aom_dc_predictor_32x64_c(uint8_t *dst, ptrdiff_t stride,
                              const uint8_t *above, const uint8_t *left) {
  dc_predictor_rect(dst, stride, 32, 64, above, left, DC_MULTIPLIER_1X2, 14);
}

void aom_dc_predictor_64x32_c(uint8_t *dst, ptrdiff_t stride,
                              const uint8_t *above, const uint8_t *left) {
  dc_predictor_rect(dst, stride, 64, 32, above, left, DC_MULTIPLIER_1X2, 14);
}

void aom_d45e_predictor_2x2_c(uint8_t *dst, ptrdiff_t stride,
                              const uint8_t *above, const uint8_t *left) {
  const int A = above[0];
  const int B = above[1];
  const int C = above[2];
  const int D = above[3];
  (void)stride;
  (void)left;

  DST(0, 0) = AVG3(A, B, C);
  DST(1, 0) = DST(0, 1) = AVG3(B, C, D);
  DST(1, 1) = AVG3(C, D, D);
}

void aom_d117_predictor_2x2_c(uint8_t *dst, ptrdiff_t stride,
                              const uint8_t *above, const uint8_t *left) {
  const int I = left[0];
  const int X = above[-1];
  const int A = above[0];
  const int B = above[1];
  DST(0, 0) = AVG2(X, A);
  DST(1, 0) = AVG2(A, B);
  DST(0, 1) = AVG3(I, X, A);
  DST(1, 1) = AVG3(X, A, B);
}

void aom_d135_predictor_2x2_c(uint8_t *dst, ptrdiff_t stride,
                              const uint8_t *above, const uint8_t *left) {
  const int I = left[0];
  const int J = left[1];
  const int X = above[-1];
  const int A = above[0];
  const int B = above[1];
  (void)stride;
  DST(0, 1) = AVG3(X, I, J);
  DST(1, 1) = DST(0, 0) = AVG3(A, X, I);
  DST(1, 0) = AVG3(B, A, X);
}

void aom_d153_predictor_2x2_c(uint8_t *dst, ptrdiff_t stride,
                              const uint8_t *above, const uint8_t *left) {
  const int I = left[0];
  const int J = left[1];
  const int X = above[-1];
  const int A = above[0];

  DST(0, 0) = AVG2(I, X);
  DST(0, 1) = AVG2(J, I);
  DST(1, 0) = AVG3(I, X, A);
  DST(1, 1) = AVG3(J, I, X);
}

void aom_d45e_predictor_4x4_c(uint8_t *dst, ptrdiff_t stride,
                              const uint8_t *above, const uint8_t *left) {
  const int A = above[0];
  const int B = above[1];
  const int C = above[2];
  const int D = above[3];
  const int E = above[4];
  const int F = above[5];
  const int G = above[6];
  const int H = above[7];
  (void)stride;
  (void)left;
  DST(0, 0) = AVG3(A, B, C);
  DST(1, 0) = DST(0, 1) = AVG3(B, C, D);
  DST(2, 0) = DST(1, 1) = DST(0, 2) = AVG3(C, D, E);
  DST(3, 0) = DST(2, 1) = DST(1, 2) = DST(0, 3) = AVG3(D, E, F);
  DST(3, 1) = DST(2, 2) = DST(1, 3) = AVG3(E, F, G);
  DST(3, 2) = DST(2, 3) = AVG3(F, G, H);
  DST(3, 3) = AVG3(G, H, H);
}

void aom_d117_predictor_4x4_c(uint8_t *dst, ptrdiff_t stride,
                              const uint8_t *above, const uint8_t *left) {
  const int I = left[0];
  const int J = left[1];
  const int K = left[2];
  const int X = above[-1];
  const int A = above[0];
  const int B = above[1];
  const int C = above[2];
  const int D = above[3];
  DST(0, 0) = DST(1, 2) = AVG2(X, A);
  DST(1, 0) = DST(2, 2) = AVG2(A, B);
  DST(2, 0) = DST(3, 2) = AVG2(B, C);
  DST(3, 0) = AVG2(C, D);

  DST(0, 3) = AVG3(K, J, I);
  DST(0, 2) = AVG3(J, I, X);
  DST(0, 1) = DST(1, 3) = AVG3(I, X, A);
  DST(1, 1) = DST(2, 3) = AVG3(X, A, B);
  DST(2, 1) = DST(3, 3) = AVG3(A, B, C);
  DST(3, 1) = AVG3(B, C, D);
}

void aom_d135_predictor_4x4_c(uint8_t *dst, ptrdiff_t stride,
                              const uint8_t *above, const uint8_t *left) {
  const int I = left[0];
  const int J = left[1];
  const int K = left[2];
  const int L = left[3];
  const int X = above[-1];
  const int A = above[0];
  const int B = above[1];
  const int C = above[2];
  const int D = above[3];
  (void)stride;
  DST(0, 3) = AVG3(J, K, L);
  DST(1, 3) = DST(0, 2) = AVG3(I, J, K);
  DST(2, 3) = DST(1, 2) = DST(0, 1) = AVG3(X, I, J);
  DST(3, 3) = DST(2, 2) = DST(1, 1) = DST(0, 0) = AVG3(A, X, I);
  DST(3, 2) = DST(2, 1) = DST(1, 0) = AVG3(B, A, X);
  DST(3, 1) = DST(2, 0) = AVG3(C, B, A);
  DST(3, 0) = AVG3(D, C, B);
}

void aom_d153_predictor_4x4_c(uint8_t *dst, ptrdiff_t stride,
                              const uint8_t *above, const uint8_t *left) {
  const int I = left[0];
  const int J = left[1];
  const int K = left[2];
  const int L = left[3];
  const int X = above[-1];
  const int A = above[0];
  const int B = above[1];
  const int C = above[2];

  DST(0, 0) = DST(2, 1) = AVG2(I, X);
  DST(0, 1) = DST(2, 2) = AVG2(J, I);
  DST(0, 2) = DST(2, 3) = AVG2(K, J);
  DST(0, 3) = AVG2(L, K);

  DST(3, 0) = AVG3(A, B, C);
  DST(2, 0) = AVG3(X, A, B);
  DST(1, 0) = DST(3, 1) = AVG3(I, X, A);
  DST(1, 1) = DST(3, 2) = AVG3(J, I, X);
  DST(1, 2) = DST(3, 3) = AVG3(K, J, I);
  DST(1, 3) = AVG3(L, K, J);
}

static INLINE void highbd_d207e_predictor(uint16_t *dst, ptrdiff_t stride,
                                          int bw, int bh, const uint16_t *above,
                                          const uint16_t *left, int bd) {
  int r, c;
  (void)above;
  (void)bd;

  for (r = 0; r < bh; ++r) {
    for (c = 0; c < bw; ++c) {
      dst[c] = c & 1 ? AVG3(left[(c >> 1) + r], left[(c >> 1) + r + 1],
                            left[(c >> 1) + r + 2])
                     : AVG2(left[(c >> 1) + r], left[(c >> 1) + r + 1]);
    }
    dst += stride;
  }
}

static INLINE void highbd_d63e_predictor(uint16_t *dst, ptrdiff_t stride,
                                         int bw, int bh, const uint16_t *above,
                                         const uint16_t *left, int bd) {
  int r, c;
  (void)left;
  (void)bd;
  for (r = 0; r < bh; ++r) {
    for (c = 0; c < bw; ++c) {
      dst[c] = r & 1 ? AVG3(above[(r >> 1) + c], above[(r >> 1) + c + 1],
                            above[(r >> 1) + c + 2])
                     : AVG2(above[(r >> 1) + c], above[(r >> 1) + c + 1]);
    }
    dst += stride;
  }
}

static INLINE void highbd_d45e_predictor(uint16_t *dst, ptrdiff_t stride,
                                         int bw, int bh, const uint16_t *above,
                                         const uint16_t *left, int bd) {
  int r, c;
  (void)left;
  (void)bd;
  for (r = 0; r < bh; ++r) {
    for (c = 0; c < bw; ++c) {
      dst[c] = AVG3(above[r + c], above[r + c + 1],
                    above[r + c + 1 + (r + c + 2 < bw + bh)]);
    }
    dst += stride;
  }
}

static INLINE void highbd_d117_predictor(uint16_t *dst, ptrdiff_t stride,
                                         int bw, int bh, const uint16_t *above,
                                         const uint16_t *left, int bd) {
  int r, c;
  (void)bd;

  // first row
  for (c = 0; c < bw; c++) dst[c] = AVG2(above[c - 1], above[c]);
  dst += stride;

  // second row
  dst[0] = AVG3(left[0], above[-1], above[0]);
  for (c = 1; c < bw; c++) dst[c] = AVG3(above[c - 2], above[c - 1], above[c]);
  dst += stride;

  // the rest of first col
  dst[0] = AVG3(above[-1], left[0], left[1]);
  for (r = 3; r < bh; ++r)
    dst[(r - 2) * stride] = AVG3(left[r - 3], left[r - 2], left[r - 1]);

  // the rest of the block
  for (r = 2; r < bh; ++r) {
    for (c = 1; c < bw; c++) dst[c] = dst[-2 * stride + c - 1];
    dst += stride;
  }
}

static INLINE void highbd_d135_predictor(uint16_t *dst, ptrdiff_t stride,
                                         int bw, int bh, const uint16_t *above,
                                         const uint16_t *left, int bd) {
  int r, c;
  (void)bd;
  dst[0] = AVG3(left[0], above[-1], above[0]);
  for (c = 1; c < bw; c++) dst[c] = AVG3(above[c - 2], above[c - 1], above[c]);

  dst[stride] = AVG3(above[-1], left[0], left[1]);
  for (r = 2; r < bh; ++r)
    dst[r * stride] = AVG3(left[r - 2], left[r - 1], left[r]);

  dst += stride;
  for (r = 1; r < bh; ++r) {
    for (c = 1; c < bw; c++) dst[c] = dst[-stride + c - 1];
    dst += stride;
  }
}

static INLINE void highbd_d153_predictor(uint16_t *dst, ptrdiff_t stride,
                                         int bw, int bh, const uint16_t *above,
                                         const uint16_t *left, int bd) {
  int r, c;
  (void)bd;
  dst[0] = AVG2(above[-1], left[0]);
  for (r = 1; r < bh; r++) dst[r * stride] = AVG2(left[r - 1], left[r]);
  dst++;

  dst[0] = AVG3(left[0], above[-1], above[0]);
  dst[stride] = AVG3(above[-1], left[0], left[1]);
  for (r = 2; r < bh; r++)
    dst[r * stride] = AVG3(left[r - 2], left[r - 1], left[r]);
  dst++;

  for (c = 0; c < bw - 2; c++)
    dst[c] = AVG3(above[c - 1], above[c], above[c + 1]);
  dst += stride;

  for (r = 1; r < bh; ++r) {
    for (c = 0; c < bw - 2; c++) dst[c] = dst[-stride + c - 2];
    dst += stride;
  }
}

static INLINE void highbd_v_predictor(uint16_t *dst, ptrdiff_t stride, int bw,
                                      int bh, const uint16_t *above,
                                      const uint16_t *left, int bd) {
  int r;
  (void)left;
  (void)bd;
  for (r = 0; r < bh; r++) {
    memcpy(dst, above, bw * sizeof(uint16_t));
    dst += stride;
  }
}

static INLINE void highbd_h_predictor(uint16_t *dst, ptrdiff_t stride, int bw,
                                      int bh, const uint16_t *above,
                                      const uint16_t *left, int bd) {
  int r;
  (void)above;
  (void)bd;
  for (r = 0; r < bh; r++) {
    aom_memset16(dst, left[r], bw);
    dst += stride;
  }
}

void aom_highbd_d207_predictor_2x2_c(uint16_t *dst, ptrdiff_t stride,
                                     const uint16_t *above,
                                     const uint16_t *left, int bd) {
  const int I = left[0];
  const int J = left[1];
  const int K = left[2];
  const int L = left[3];
  (void)above;
  (void)bd;
  DST(0, 0) = AVG2(I, J);
  DST(0, 1) = AVG2(J, K);
  DST(1, 0) = AVG3(I, J, K);
  DST(1, 1) = AVG3(J, K, L);
}

void aom_highbd_d63_predictor_2x2_c(uint16_t *dst, ptrdiff_t stride,
                                    const uint16_t *above, const uint16_t *left,
                                    int bd) {
  const int A = above[0];
  const int B = above[1];
  const int C = above[2];
  const int D = above[3];
  (void)left;
  (void)bd;
  DST(0, 0) = AVG2(A, B);
  DST(1, 0) = AVG2(B, C);
  DST(0, 1) = AVG3(A, B, C);
  DST(1, 1) = AVG3(B, C, D);
}

void aom_highbd_d45e_predictor_2x2_c(uint16_t *dst, ptrdiff_t stride,
                                     const uint16_t *above,
                                     const uint16_t *left, int bd) {
  const int A = above[0];
  const int B = above[1];
  const int C = above[2];
  const int D = above[3];
  (void)stride;
  (void)left;
  (void)bd;
  DST(0, 0) = AVG3(A, B, C);
  DST(1, 0) = DST(0, 1) = AVG3(B, C, D);
  DST(1, 1) = AVG3(C, D, D);
}

void aom_highbd_d117_predictor_2x2_c(uint16_t *dst, ptrdiff_t stride,
                                     const uint16_t *above,
                                     const uint16_t *left, int bd) {
  const int I = left[0];
  const int X = above[-1];
  const int A = above[0];
  const int B = above[1];
  (void)bd;
  DST(0, 0) = AVG2(X, A);
  DST(1, 0) = AVG2(A, B);
  DST(0, 1) = AVG3(I, X, A);
  DST(1, 1) = AVG3(X, A, B);
}

void aom_highbd_d135_predictor_2x2_c(uint16_t *dst, ptrdiff_t stride,
                                     const uint16_t *above,
                                     const uint16_t *left, int bd) {
  const int I = left[0];
  const int J = left[1];
  const int X = above[-1];
  const int A = above[0];
  const int B = above[1];
  (void)bd;
  DST(0, 1) = AVG3(X, I, J);
  DST(1, 1) = DST(0, 0) = AVG3(A, X, I);
  DST(1, 0) = AVG3(B, A, X);
}

void aom_highbd_d153_predictor_2x2_c(uint16_t *dst, ptrdiff_t stride,
                                     const uint16_t *above,
                                     const uint16_t *left, int bd) {
  const int I = left[0];
  const int J = left[1];
  const int X = above[-1];
  const int A = above[0];
  (void)bd;
  DST(0, 0) = AVG2(I, X);
  DST(0, 1) = AVG2(J, I);
  DST(1, 0) = AVG3(I, X, A);
  DST(1, 1) = AVG3(J, I, X);
}

static INLINE void highbd_paeth_predictor(uint16_t *dst, ptrdiff_t stride,
                                          int bw, int bh, const uint16_t *above,
                                          const uint16_t *left, int bd) {
  int r, c;
  const uint16_t ytop_left = above[-1];
  (void)bd;

  for (r = 0; r < bh; r++) {
    for (c = 0; c < bw; c++)
      dst[c] = paeth_predictor_single(left[r], above[c], ytop_left);
    dst += stride;
  }
}

static INLINE void highbd_smooth_predictor(uint16_t *dst, ptrdiff_t stride,
                                           int bw, int bh,
                                           const uint16_t *above,
                                           const uint16_t *left, int bd) {
  const uint16_t below_pred = left[bh - 1];   // estimated by bottom-left pixel
  const uint16_t right_pred = above[bw - 1];  // estimated by top-right pixel
  const uint8_t *const sm_weights_w = sm_weight_arrays + bw;
  const uint8_t *const sm_weights_h = sm_weight_arrays + bh;
  // scale = 2 * 2^sm_weight_log2_scale
  const int log2_scale = 1 + sm_weight_log2_scale;
  const uint16_t scale = (1 << sm_weight_log2_scale);
  sm_weights_sanity_checks(sm_weights_w, sm_weights_h, scale,
                           log2_scale + sizeof(*dst));
  int r;
  for (r = 0; r < bh; ++r) {
    int c;
    for (c = 0; c < bw; ++c) {
      const uint16_t pixels[] = { above[c], below_pred, left[r], right_pred };
      const uint8_t weights[] = { sm_weights_h[r], scale - sm_weights_h[r],
                                  sm_weights_w[c], scale - sm_weights_w[c] };
      uint32_t this_pred = 0;
      int i;
      assert(scale >= sm_weights_h[r] && scale >= sm_weights_w[c]);
      for (i = 0; i < 4; ++i) {
        this_pred += weights[i] * pixels[i];
      }
      dst[c] = clip_pixel_highbd(divide_round(this_pred, log2_scale), bd);
    }
    dst += stride;
  }
}

static INLINE void highbd_smooth_v_predictor(uint16_t *dst, ptrdiff_t stride,
                                             int bw, int bh,
                                             const uint16_t *above,
                                             const uint16_t *left, int bd) {
  const uint16_t below_pred = left[bh - 1];  // estimated by bottom-left pixel
  const uint8_t *const sm_weights = sm_weight_arrays + bh;
  // scale = 2^sm_weight_log2_scale
  const int log2_scale = sm_weight_log2_scale;
  const uint16_t scale = (1 << sm_weight_log2_scale);
  sm_weights_sanity_checks(sm_weights, sm_weights, scale,
                           log2_scale + sizeof(*dst));

  int r;
  for (r = 0; r < bh; r++) {
    int c;
    for (c = 0; c < bw; ++c) {
      const uint16_t pixels[] = { above[c], below_pred };
      const uint8_t weights[] = { sm_weights[r], scale - sm_weights[r] };
      uint32_t this_pred = 0;
      assert(scale >= sm_weights[r]);
      int i;
      for (i = 0; i < 2; ++i) {
        this_pred += weights[i] * pixels[i];
      }
      dst[c] = clip_pixel_highbd(divide_round(this_pred, log2_scale), bd);
    }
    dst += stride;
  }
}

static INLINE void highbd_smooth_h_predictor(uint16_t *dst, ptrdiff_t stride,
                                             int bw, int bh,
                                             const uint16_t *above,
                                             const uint16_t *left, int bd) {
  const uint16_t right_pred = above[bw - 1];  // estimated by top-right pixel
  const uint8_t *const sm_weights = sm_weight_arrays + bw;
  // scale = 2^sm_weight_log2_scale
  const int log2_scale = sm_weight_log2_scale;
  const uint16_t scale = (1 << sm_weight_log2_scale);
  sm_weights_sanity_checks(sm_weights, sm_weights, scale,
                           log2_scale + sizeof(*dst));

  int r;
  for (r = 0; r < bh; r++) {
    int c;
    for (c = 0; c < bw; ++c) {
      const uint16_t pixels[] = { left[r], right_pred };
      const uint8_t weights[] = { sm_weights[c], scale - sm_weights[c] };
      uint32_t this_pred = 0;
      assert(scale >= sm_weights[c]);
      int i;
      for (i = 0; i < 2; ++i) {
        this_pred += weights[i] * pixels[i];
      }
      dst[c] = clip_pixel_highbd(divide_round(this_pred, log2_scale), bd);
    }
    dst += stride;
  }
}

static INLINE void highbd_dc_128_predictor(uint16_t *dst, ptrdiff_t stride,
                                           int bw, int bh,
                                           const uint16_t *above,
                                           const uint16_t *left, int bd) {
  int r;
  (void)above;
  (void)left;

  for (r = 0; r < bh; r++) {
    aom_memset16(dst, 128 << (bd - 8), bw);
    dst += stride;
  }
}

static INLINE void highbd_dc_left_predictor(uint16_t *dst, ptrdiff_t stride,
                                            int bw, int bh,
                                            const uint16_t *above,
                                            const uint16_t *left, int bd) {
  int i, r, expected_dc, sum = 0;
  (void)above;
  (void)bd;

  for (i = 0; i < bh; i++) sum += left[i];
  expected_dc = (sum + (bh >> 1)) / bh;

  for (r = 0; r < bh; r++) {
    aom_memset16(dst, expected_dc, bw);
    dst += stride;
  }
}

static INLINE void highbd_dc_top_predictor(uint16_t *dst, ptrdiff_t stride,
                                           int bw, int bh,
                                           const uint16_t *above,
                                           const uint16_t *left, int bd) {
  int i, r, expected_dc, sum = 0;
  (void)left;
  (void)bd;

  for (i = 0; i < bw; i++) sum += above[i];
  expected_dc = (sum + (bw >> 1)) / bw;

  for (r = 0; r < bh; r++) {
    aom_memset16(dst, expected_dc, bw);
    dst += stride;
  }
}

static INLINE void highbd_dc_predictor(uint16_t *dst, ptrdiff_t stride, int bw,
                                       int bh, const uint16_t *above,
                                       const uint16_t *left, int bd) {
  int i, r, expected_dc, sum = 0;
  const int count = bw + bh;
  (void)bd;

  for (i = 0; i < bw; i++) {
    sum += above[i];
  }
  for (i = 0; i < bh; i++) {
    sum += left[i];
  }

  expected_dc = (sum + (count >> 1)) / count;

  for (r = 0; r < bh; r++) {
    aom_memset16(dst, expected_dc, bw);
    dst += stride;
  }
}

static INLINE void highbd_dc_predictor_rect(uint16_t *dst, ptrdiff_t stride,
                                            int bw, int bh,
                                            const uint16_t *above,
                                            const uint16_t *left, int bd,
                                            uint32_t multiplier, int shift) {
  int i, r, expected_dc, sum = 0;

  for (i = 0; i < bw; i++) {
    sum += above[i];
  }
  for (i = 0; i < bh; i++) {
    sum += left[i];
  }

  expected_dc = (int)(((uint64_t)sum * multiplier) >> shift);
  expected_dc = clip_pixel_highbd(expected_dc, bd);

  for (r = 0; r < bh; r++) {
    aom_memset16(dst, expected_dc, bw);
    dst += stride;
  }
}

void aom_highbd_dc_predictor_4x8_c(uint16_t *dst, ptrdiff_t stride,
                                   const uint16_t *above, const uint16_t *left,
                                   int bd) {
  highbd_dc_predictor_rect(dst, stride, 4, 8, above, left, bd,
                           DC_MULTIPLIER_1X2, 11);
}

void aom_highbd_dc_predictor_8x4_c(uint16_t *dst, ptrdiff_t stride,
                                   const uint16_t *above, const uint16_t *left,
                                   int bd) {
  highbd_dc_predictor_rect(dst, stride, 8, 4, above, left, bd,
                           DC_MULTIPLIER_1X2, 11);
}

void aom_highbd_dc_predictor_4x16_c(uint16_t *dst, ptrdiff_t stride,
                                    const uint16_t *above, const uint16_t *left,
                                    int bd) {
  highbd_dc_predictor_rect(dst, stride, 4, 16, above, left, bd,
                           DC_MULTIPLIER_1X4, 12);
}

void aom_highbd_dc_predictor_16x4_c(uint16_t *dst, ptrdiff_t stride,
                                    const uint16_t *above, const uint16_t *left,
                                    int bd) {
  highbd_dc_predictor_rect(dst, stride, 16, 4, above, left, bd,
                           DC_MULTIPLIER_1X4, 12);
}

void aom_highbd_dc_predictor_8x16_c(uint16_t *dst, ptrdiff_t stride,
                                    const uint16_t *above, const uint16_t *left,
                                    int bd) {
  highbd_dc_predictor_rect(dst, stride, 8, 16, above, left, bd,
                           DC_MULTIPLIER_1X2, 12);
}

void aom_highbd_dc_predictor_16x8_c(uint16_t *dst, ptrdiff_t stride,
                                    const uint16_t *above, const uint16_t *left,
                                    int bd) {
  highbd_dc_predictor_rect(dst, stride, 16, 8, above, left, bd,
                           DC_MULTIPLIER_1X2, 12);
}

void aom_highbd_dc_predictor_8x32_c(uint16_t *dst, ptrdiff_t stride,
                                    const uint16_t *above, const uint16_t *left,
                                    int bd) {
  highbd_dc_predictor_rect(dst, stride, 8, 32, above, left, bd,
                           DC_MULTIPLIER_1X4, 13);
}

void aom_highbd_dc_predictor_32x8_c(uint16_t *dst, ptrdiff_t stride,
                                    const uint16_t *above, const uint16_t *left,
                                    int bd) {
  highbd_dc_predictor_rect(dst, stride, 32, 8, above, left, bd,
                           DC_MULTIPLIER_1X4, 13);
}

void aom_highbd_dc_predictor_16x32_c(uint16_t *dst, ptrdiff_t stride,
                                     const uint16_t *above,
                                     const uint16_t *left, int bd) {
  highbd_dc_predictor_rect(dst, stride, 16, 32, above, left, bd,
                           DC_MULTIPLIER_1X2, 13);
}

void aom_highbd_dc_predictor_32x16_c(uint16_t *dst, ptrdiff_t stride,
                                     const uint16_t *above,
                                     const uint16_t *left, int bd) {
  highbd_dc_predictor_rect(dst, stride, 32, 16, above, left, bd,
                           DC_MULTIPLIER_1X2, 13);
}

void aom_highbd_dc_predictor_16x64_c(uint16_t *dst, ptrdiff_t stride,
                                     const uint16_t *above,
                                     const uint16_t *left, int bd) {
  highbd_dc_predictor_rect(dst, stride, 16, 64, above, left, bd,
                           DC_MULTIPLIER_1X4, 14);
}

void aom_highbd_dc_predictor_64x16_c(uint16_t *dst, ptrdiff_t stride,
                                     const uint16_t *above,
                                     const uint16_t *left, int bd) {
  highbd_dc_predictor_rect(dst, stride, 64, 16, above, left, bd,
                           DC_MULTIPLIER_1X4, 14);
}

void aom_highbd_dc_predictor_32x64_c(uint16_t *dst, ptrdiff_t stride,
                                     const uint16_t *above,
                                     const uint16_t *left, int bd) {
  highbd_dc_predictor_rect(dst, stride, 32, 64, above, left, bd,
                           DC_MULTIPLIER_1X2, 14);
}

void aom_highbd_dc_predictor_64x32_c(uint16_t *dst, ptrdiff_t stride,
                                     const uint16_t *above,
                                     const uint16_t *left, int bd) {
  highbd_dc_predictor_rect(dst, stride, 64, 32, above, left, bd,
                           DC_MULTIPLIER_1X2, 14);
}

// This serves as a wrapper function, so that all the prediction functions
// can be unified and accessed as a pointer array. Note that the boundary
// above and left are not necessarily used all the time.
#define intra_pred_sized(type, width, height)                  \
  void aom_##type##_predictor_##width##x##height##_c(          \
      uint8_t *dst, ptrdiff_t stride, const uint8_t *above,    \
      const uint8_t *left) {                                   \
    type##_predictor(dst, stride, width, height, above, left); \
  }

#define intra_pred_highbd_sized(type, width, height)                        \
  void aom_highbd_##type##_predictor_##width##x##height##_c(                \
      uint16_t *dst, ptrdiff_t stride, const uint16_t *above,               \
      const uint16_t *left, int bd) {                                       \
    highbd_##type##_predictor(dst, stride, width, height, above, left, bd); \
  }

/* clang-format off */
#define intra_pred_rectangular(type) \
  intra_pred_sized(type, 4, 8) \
  intra_pred_sized(type, 8, 4) \
  intra_pred_sized(type, 8, 16) \
  intra_pred_sized(type, 16, 8) \
  intra_pred_sized(type, 16, 32) \
  intra_pred_sized(type, 32, 16) \
  intra_pred_sized(type, 32, 64) \
  intra_pred_sized(type, 64, 32) \
  intra_pred_sized(type, 4, 16) \
  intra_pred_sized(type, 16, 4) \
  intra_pred_sized(type, 8, 32) \
  intra_pred_sized(type, 32, 8) \
  intra_pred_sized(type, 16, 64) \
  intra_pred_sized(type, 64, 16) \
  intra_pred_highbd_sized(type, 4, 8) \
  intra_pred_highbd_sized(type, 8, 4) \
  intra_pred_highbd_sized(type, 8, 16) \
  intra_pred_highbd_sized(type, 16, 8) \
  intra_pred_highbd_sized(type, 16, 32) \
  intra_pred_highbd_sized(type, 32, 16) \
  intra_pred_highbd_sized(type, 32, 64) \
  intra_pred_highbd_sized(type, 64, 32) \
  intra_pred_highbd_sized(type, 4, 16) \
  intra_pred_highbd_sized(type, 16, 4) \
  intra_pred_highbd_sized(type, 8, 32) \
  intra_pred_highbd_sized(type, 32, 8) \
  intra_pred_highbd_sized(type, 16, 64) \
  intra_pred_highbd_sized(type, 64, 16)
#define intra_pred_above_4x4(type) \
  intra_pred_sized(type, 8, 8) \
  intra_pred_sized(type, 16, 16) \
  intra_pred_sized(type, 32, 32) \
  intra_pred_sized(type, 64, 64) \
  intra_pred_highbd_sized(type, 4, 4) \
  intra_pred_highbd_sized(type, 8, 8) \
  intra_pred_highbd_sized(type, 16, 16) \
  intra_pred_highbd_sized(type, 32, 32) \
  intra_pred_highbd_sized(type, 64, 64) \
  intra_pred_rectangular(type)
#define intra_pred_allsizes(type) \
  intra_pred_sized(type, 2, 2) \
  intra_pred_sized(type, 4, 4) \
  intra_pred_highbd_sized(type, 2, 2) \
  intra_pred_above_4x4(type)
#define intra_pred_square(type) \
  intra_pred_sized(type, 2, 2) \
  intra_pred_sized(type, 4, 4) \
  intra_pred_sized(type, 8, 8) \
  intra_pred_sized(type, 16, 16) \
  intra_pred_sized(type, 32, 32) \
  intra_pred_sized(type, 64, 64) \
  intra_pred_highbd_sized(type, 2, 2) \
  intra_pred_highbd_sized(type, 4, 4) \
  intra_pred_highbd_sized(type, 8, 8) \
  intra_pred_highbd_sized(type, 16, 16) \
  intra_pred_highbd_sized(type, 32, 32) \
  intra_pred_highbd_sized(type, 64, 64)

intra_pred_allsizes(d207e)
intra_pred_allsizes(d63e)
intra_pred_above_4x4(d45e)
intra_pred_above_4x4(d117)
intra_pred_above_4x4(d135)
intra_pred_above_4x4(d153)
intra_pred_allsizes(v)
intra_pred_allsizes(h)
intra_pred_allsizes(smooth)
intra_pred_allsizes(smooth_v)
intra_pred_allsizes(smooth_h)
intra_pred_allsizes(paeth)
intra_pred_allsizes(dc_128)
intra_pred_allsizes(dc_left)
intra_pred_allsizes(dc_top)
intra_pred_square(dc)
/* clang-format on */
#undef intra_pred_allsizes