/*
 * 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 <emmintrin.h>  // SSE2

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

#include "aom_dsp/x86/synonyms.h"

#include "aom_ports/mem.h"

#include "./av1_rtcd.h"
#include "av1/common/filter.h"
#include "av1/common/onyxc_int.h"
#include "av1/common/reconinter.h"

typedef void (*getNxMvar_fn_t)(const unsigned char *src, int src_stride,
                               const unsigned char *ref, int ref_stride,
                               unsigned int *sse, int *sum);

unsigned int aom_get_mb_ss_sse2(const int16_t *src) {
  __m128i vsum = _mm_setzero_si128();
  int i;

  for (i = 0; i < 32; ++i) {
    const __m128i v = xx_loadu_128(src);
    vsum = _mm_add_epi32(vsum, _mm_madd_epi16(v, v));
    src += 8;
  }

  vsum = _mm_add_epi32(vsum, _mm_srli_si128(vsum, 8));
  vsum = _mm_add_epi32(vsum, _mm_srli_si128(vsum, 4));
  return _mm_cvtsi128_si32(vsum);
}

// Read 4 samples from each of row and row + 1. Interleave the two rows and
// zero-extend them to 16 bit samples stored in the lower half of an SSE
// register.
static __m128i read64(const uint8_t *p, int stride, int row) {
  __m128i row0 = xx_loadl_32(p + (row + 0) * stride);
  __m128i row1 = xx_loadl_32(p + (row + 1) * stride);
  return _mm_unpacklo_epi8(_mm_unpacklo_epi8(row0, row1), _mm_setzero_si128());
}

static void get4x4var_sse2(const uint8_t *src, int src_stride,
                           const uint8_t *ref, int ref_stride,
                           unsigned int *sse, int *sum) {
  const __m128i src0 = read64(src, src_stride, 0);
  const __m128i src1 = read64(src, src_stride, 2);
  const __m128i ref0 = read64(ref, ref_stride, 0);
  const __m128i ref1 = read64(ref, ref_stride, 2);
  const __m128i diff0 = _mm_sub_epi16(src0, ref0);
  const __m128i diff1 = _mm_sub_epi16(src1, ref1);

  // sum
  __m128i vsum = _mm_add_epi16(diff0, diff1);
  vsum = _mm_add_epi16(vsum, _mm_srli_si128(vsum, 8));
  vsum = _mm_add_epi16(vsum, _mm_srli_si128(vsum, 4));
  vsum = _mm_add_epi16(vsum, _mm_srli_si128(vsum, 2));
  *sum = (int16_t)_mm_extract_epi16(vsum, 0);

  // sse
  vsum =
      _mm_add_epi32(_mm_madd_epi16(diff0, diff0), _mm_madd_epi16(diff1, diff1));
  vsum = _mm_add_epi32(vsum, _mm_srli_si128(vsum, 8));
  vsum = _mm_add_epi32(vsum, _mm_srli_si128(vsum, 4));
  *sse = _mm_cvtsi128_si32(vsum);
}

void aom_get8x8var_sse2(const uint8_t *src, int src_stride, const uint8_t *ref,
                        int ref_stride, unsigned int *sse, int *sum) {
  const __m128i zero = _mm_setzero_si128();
  __m128i vsum = _mm_setzero_si128();
  __m128i vsse = _mm_setzero_si128();
  int i;

  for (i = 0; i < 8; i += 2) {
    const __m128i src0 =
        _mm_unpacklo_epi8(xx_loadl_64(src + i * src_stride), zero);
    const __m128i ref0 =
        _mm_unpacklo_epi8(xx_loadl_64(ref + i * ref_stride), zero);
    const __m128i diff0 = _mm_sub_epi16(src0, ref0);

    const __m128i src1 =
        _mm_unpacklo_epi8(xx_loadl_64(src + (i + 1) * src_stride), zero);
    const __m128i ref1 =
        _mm_unpacklo_epi8(xx_loadl_64(ref + (i + 1) * ref_stride), zero);
    const __m128i diff1 = _mm_sub_epi16(src1, ref1);

    vsum = _mm_add_epi16(vsum, diff0);
    vsum = _mm_add_epi16(vsum, diff1);
    vsse = _mm_add_epi32(vsse, _mm_madd_epi16(diff0, diff0));
    vsse = _mm_add_epi32(vsse, _mm_madd_epi16(diff1, diff1));
  }

  // sum
  vsum = _mm_add_epi16(vsum, _mm_srli_si128(vsum, 8));
  vsum = _mm_add_epi16(vsum, _mm_srli_si128(vsum, 4));
  vsum = _mm_add_epi16(vsum, _mm_srli_si128(vsum, 2));
  *sum = (int16_t)_mm_extract_epi16(vsum, 0);

  // sse
  vsse = _mm_add_epi32(vsse, _mm_srli_si128(vsse, 8));
  vsse = _mm_add_epi32(vsse, _mm_srli_si128(vsse, 4));
  *sse = _mm_cvtsi128_si32(vsse);
}

void aom_get16x16var_sse2(const uint8_t *src, int src_stride,
                          const uint8_t *ref, int ref_stride, unsigned int *sse,
                          int *sum) {
  const __m128i zero = _mm_setzero_si128();
  __m128i vsum = _mm_setzero_si128();
  __m128i vsse = _mm_setzero_si128();
  int i;

  for (i = 0; i < 16; ++i) {
    const __m128i s = xx_loadu_128(src);
    const __m128i r = xx_loadu_128(ref);

    const __m128i src0 = _mm_unpacklo_epi8(s, zero);
    const __m128i ref0 = _mm_unpacklo_epi8(r, zero);
    const __m128i diff0 = _mm_sub_epi16(src0, ref0);

    const __m128i src1 = _mm_unpackhi_epi8(s, zero);
    const __m128i ref1 = _mm_unpackhi_epi8(r, zero);
    const __m128i diff1 = _mm_sub_epi16(src1, ref1);

    vsum = _mm_add_epi16(vsum, diff0);
    vsum = _mm_add_epi16(vsum, diff1);
    vsse = _mm_add_epi32(vsse, _mm_madd_epi16(diff0, diff0));
    vsse = _mm_add_epi32(vsse, _mm_madd_epi16(diff1, diff1));

    src += src_stride;
    ref += ref_stride;
  }

  // sum
  vsum = _mm_add_epi16(vsum, _mm_srli_si128(vsum, 8));
  vsum = _mm_add_epi16(vsum, _mm_srli_si128(vsum, 4));
  *sum =
      (int16_t)_mm_extract_epi16(vsum, 0) + (int16_t)_mm_extract_epi16(vsum, 1);

  // sse
  vsse = _mm_add_epi32(vsse, _mm_srli_si128(vsse, 8));
  vsse = _mm_add_epi32(vsse, _mm_srli_si128(vsse, 4));
  *sse = _mm_cvtsi128_si32(vsse);
}

static void variance_sse2(const unsigned char *src, int src_stride,
                          const unsigned char *ref, int ref_stride, int w,
                          int h, unsigned int *sse, int *sum,
                          getNxMvar_fn_t var_fn, int block_size) {
  int i, j;

  *sse = 0;
  *sum = 0;

  for (i = 0; i < h; i += block_size) {
    for (j = 0; j < w; j += block_size) {
      unsigned int sse0;
      int sum0;
      var_fn(src + src_stride * i + j, src_stride, ref + ref_stride * i + j,
             ref_stride, &sse0, &sum0);
      *sse += sse0;
      *sum += sum0;
    }
  }
}

unsigned int aom_variance4x4_sse2(const uint8_t *src, int src_stride,
                                  const uint8_t *ref, int ref_stride,
                                  unsigned int *sse) {
  int sum;
  get4x4var_sse2(src, src_stride, ref, ref_stride, sse, &sum);
  assert(sum <= 255 * 4 * 4);
  assert(sum >= -255 * 4 * 4);
  return *sse - ((sum * sum) >> 4);
}

unsigned int aom_variance8x4_sse2(const uint8_t *src, int src_stride,
                                  const uint8_t *ref, int ref_stride,
                                  unsigned int *sse) {
  int sum;
  variance_sse2(src, src_stride, ref, ref_stride, 8, 4, sse, &sum,
                get4x4var_sse2, 4);
  assert(sum <= 255 * 8 * 4);
  assert(sum >= -255 * 8 * 4);
  return *sse - ((sum * sum) >> 5);
}

unsigned int aom_variance4x8_sse2(const uint8_t *src, int src_stride,
                                  const uint8_t *ref, int ref_stride,
                                  unsigned int *sse) {
  int sum;
  variance_sse2(src, src_stride, ref, ref_stride, 4, 8, sse, &sum,
                get4x4var_sse2, 4);
  assert(sum <= 255 * 8 * 4);
  assert(sum >= -255 * 8 * 4);
  return *sse - ((sum * sum) >> 5);
}

unsigned int aom_variance8x8_sse2(const unsigned char *src, int src_stride,
                                  const unsigned char *ref, int ref_stride,
                                  unsigned int *sse) {
  int sum;
  aom_get8x8var_sse2(src, src_stride, ref, ref_stride, sse, &sum);
  assert(sum <= 255 * 8 * 8);
  assert(sum >= -255 * 8 * 8);
  return *sse - ((sum * sum) >> 6);
}

unsigned int aom_variance16x8_sse2(const unsigned char *src, int src_stride,
                                   const unsigned char *ref, int ref_stride,
                                   unsigned int *sse) {
  int sum;
  variance_sse2(src, src_stride, ref, ref_stride, 16, 8, sse, &sum,
                aom_get8x8var_sse2, 8);
  assert(sum <= 255 * 16 * 8);
  assert(sum >= -255 * 16 * 8);
  return *sse - ((sum * sum) >> 7);
}

unsigned int aom_variance8x16_sse2(const unsigned char *src, int src_stride,
                                   const unsigned char *ref, int ref_stride,
                                   unsigned int *sse) {
  int sum;
  variance_sse2(src, src_stride, ref, ref_stride, 8, 16, sse, &sum,
                aom_get8x8var_sse2, 8);
  assert(sum <= 255 * 16 * 8);
  assert(sum >= -255 * 16 * 8);
  return *sse - ((sum * sum) >> 7);
}

unsigned int aom_variance16x16_sse2(const unsigned char *src, int src_stride,
                                    const unsigned char *ref, int ref_stride,
                                    unsigned int *sse) {
  int sum;
  aom_get16x16var_sse2(src, src_stride, ref, ref_stride, sse, &sum);
  assert(sum <= 255 * 16 * 16);
  assert(sum >= -255 * 16 * 16);
  return *sse - ((uint32_t)((int64_t)sum * sum) >> 8);
}

#define AOM_VAR_16_SSE2(bw, bh, bits)                                         \
  unsigned int aom_variance##bw##x##bh##_sse2(                                \
      const uint8_t *src, int src_stride, const uint8_t *ref, int ref_stride, \
      unsigned int *sse) {                                                    \
    int sum;                                                                  \
    variance_sse2(src, src_stride, ref, ref_stride, bw, bh, sse, &sum,        \
                  aom_get16x16var_sse2, 16);                                  \
    assert(sum <= 255 * bw * bh);                                             \
    assert(sum >= -255 * bw * bh);                                            \
    return *sse - (uint32_t)(((int64_t)sum * sum) >> bits);                   \
  }

AOM_VAR_16_SSE2(32, 32, 10);
AOM_VAR_16_SSE2(32, 16, 9);
AOM_VAR_16_SSE2(16, 32, 9);
AOM_VAR_16_SSE2(64, 64, 12);
AOM_VAR_16_SSE2(64, 32, 11);
AOM_VAR_16_SSE2(32, 64, 11);
AOM_VAR_16_SSE2(128, 128, 14);
AOM_VAR_16_SSE2(128, 64, 13);
AOM_VAR_16_SSE2(64, 128, 13);

unsigned int aom_mse8x8_sse2(const uint8_t *src, int src_stride,
                             const uint8_t *ref, int ref_stride,
                             unsigned int *sse) {
  aom_variance8x8_sse2(src, src_stride, ref, ref_stride, sse);
  return *sse;
}

unsigned int aom_mse8x16_sse2(const uint8_t *src, int src_stride,
                              const uint8_t *ref, int ref_stride,
                              unsigned int *sse) {
  aom_variance8x16_sse2(src, src_stride, ref, ref_stride, sse);
  return *sse;
}

unsigned int aom_mse16x8_sse2(const uint8_t *src, int src_stride,
                              const uint8_t *ref, int ref_stride,
                              unsigned int *sse) {
  aom_variance16x8_sse2(src, src_stride, ref, ref_stride, sse);
  return *sse;
}

unsigned int aom_mse16x16_sse2(const uint8_t *src, int src_stride,
                               const uint8_t *ref, int ref_stride,
                               unsigned int *sse) {
  aom_variance16x16_sse2(src, src_stride, ref, ref_stride, sse);
  return *sse;
}

unsigned int aom_variance4x16_sse2(const uint8_t *src, int src_stride,
                                   const uint8_t *ref, int ref_stride,
                                   unsigned int *sse) {
  int sum;
  variance_sse2(src, src_stride, ref, ref_stride, 4, 16, sse, &sum,
                get4x4var_sse2, 4);
  assert(sum <= 255 * 4 * 16);
  assert(sum >= -255 * 4 * 16);
  return *sse - (unsigned int)(((int64_t)sum * sum) >> 6);
}

unsigned int aom_variance16x4_sse2(const uint8_t *src, int src_stride,
                                   const uint8_t *ref, int ref_stride,
                                   unsigned int *sse) {
  int sum;
  variance_sse2(src, src_stride, ref, ref_stride, 16, 4, sse, &sum,
                get4x4var_sse2, 4);
  assert(sum <= 255 * 16 * 4);
  assert(sum >= -255 * 16 * 4);
  return *sse - (unsigned int)(((int64_t)sum * sum) >> 6);
}

unsigned int aom_variance8x32_sse2(const uint8_t *src, int src_stride,
                                   const uint8_t *ref, int ref_stride,
                                   unsigned int *sse) {
  int sum;
  variance_sse2(src, src_stride, ref, ref_stride, 8, 32, sse, &sum,
                aom_get8x8var_sse2, 8);
  assert(sum <= 255 * 8 * 32);
  assert(sum >= -255 * 8 * 32);
  return *sse - (unsigned int)(((int64_t)sum * sum) >> 8);
}

unsigned int aom_variance32x8_sse2(const uint8_t *src, int src_stride,
                                   const uint8_t *ref, int ref_stride,
                                   unsigned int *sse) {
  int sum;
  variance_sse2(src, src_stride, ref, ref_stride, 32, 8, sse, &sum,
                aom_get8x8var_sse2, 8);
  assert(sum <= 255 * 32 * 8);
  assert(sum >= -255 * 32 * 8);
  return *sse - (unsigned int)(((int64_t)sum * sum) >> 8);
}

unsigned int aom_variance16x64_sse2(const uint8_t *src, int src_stride,
                                    const uint8_t *ref, int ref_stride,
                                    unsigned int *sse) {
  int sum;
  variance_sse2(src, src_stride, ref, ref_stride, 16, 64, sse, &sum,
                aom_get16x16var_sse2, 16);
  assert(sum <= 255 * 16 * 64);
  assert(sum >= -255 * 16 * 64);
  return *sse - (unsigned int)(((int64_t)sum * sum) >> 10);
}

unsigned int aom_variance64x16_sse2(const uint8_t *src, int src_stride,
                                    const uint8_t *ref, int ref_stride,
                                    unsigned int *sse) {
  int sum;
  variance_sse2(src, src_stride, ref, ref_stride, 64, 16, sse, &sum,
                aom_get16x16var_sse2, 16);
  assert(sum <= 255 * 64 * 16);
  assert(sum >= -255 * 64 * 16);
  return *sse - (unsigned int)(((int64_t)sum * sum) >> 10);
}

// The 2 unused parameters are place holders for PIC enabled build.
// These definitions are for functions defined in subpel_variance.asm
#define DECL(w, opt)                                                           \
  int aom_sub_pixel_variance##w##xh_##opt(                                     \
      const uint8_t *src, ptrdiff_t src_stride, int x_offset, int y_offset,    \
      const uint8_t *dst, ptrdiff_t dst_stride, int height, unsigned int *sse, \
      void *unused0, void *unused)
#define DECLS(opt) \
  DECL(4, opt);    \
  DECL(8, opt);    \
  DECL(16, opt)

DECLS(sse2);
DECLS(ssse3);
#undef DECLS
#undef DECL

#define FN(w, h, wf, wlog2, hlog2, opt, cast_prod, cast)                       \
  unsigned int aom_sub_pixel_variance##w##x##h##_##opt(                        \
      const uint8_t *src, int src_stride, int x_offset, int y_offset,          \
      const uint8_t *dst, int dst_stride, unsigned int *sse_ptr) {             \
    unsigned int sse;                                                          \
    int se = aom_sub_pixel_variance##wf##xh_##opt(src, src_stride, x_offset,   \
                                                  y_offset, dst, dst_stride,   \
                                                  h, &sse, NULL, NULL);        \
    if (w > wf) {                                                              \
      unsigned int sse2;                                                       \
      int se2 = aom_sub_pixel_variance##wf##xh_##opt(                          \
          src + 16, src_stride, x_offset, y_offset, dst + 16, dst_stride, h,   \
          &sse2, NULL, NULL);                                                  \
      se += se2;                                                               \
      sse += sse2;                                                             \
      if (w > wf * 2) {                                                        \
        se2 = aom_sub_pixel_variance##wf##xh_##opt(                            \
            src + 32, src_stride, x_offset, y_offset, dst + 32, dst_stride, h, \
            &sse2, NULL, NULL);                                                \
        se += se2;                                                             \
        sse += sse2;                                                           \
        se2 = aom_sub_pixel_variance##wf##xh_##opt(                            \
            src + 48, src_stride, x_offset, y_offset, dst + 48, dst_stride, h, \
            &sse2, NULL, NULL);                                                \
        se += se2;                                                             \
        sse += sse2;                                                           \
      }                                                                        \
    }                                                                          \
    *sse_ptr = sse;                                                            \
    return sse - (unsigned int)(cast_prod(cast se * se) >> (wlog2 + hlog2));   \
  }

#define FNS(opt)                                    \
  FN(64, 64, 16, 6, 6, opt, (int64_t), (int64_t));  \
  FN(64, 32, 16, 6, 5, opt, (int64_t), (int64_t));  \
  FN(32, 64, 16, 5, 6, opt, (int64_t), (int64_t));  \
  FN(32, 32, 16, 5, 5, opt, (int64_t), (int64_t));  \
  FN(32, 16, 16, 5, 4, opt, (int64_t), (int64_t));  \
  FN(16, 32, 16, 4, 5, opt, (int64_t), (int64_t));  \
  FN(16, 16, 16, 4, 4, opt, (uint32_t), (int64_t)); \
  FN(16, 8, 16, 4, 3, opt, (int32_t), (int32_t));   \
  FN(8, 16, 8, 3, 4, opt, (int32_t), (int32_t));    \
  FN(8, 8, 8, 3, 3, opt, (int32_t), (int32_t));     \
  FN(8, 4, 8, 3, 2, opt, (int32_t), (int32_t));     \
  FN(4, 8, 4, 2, 3, opt, (int32_t), (int32_t));     \
  FN(4, 4, 4, 2, 2, opt, (int32_t), (int32_t));     \
  FN(4, 16, 4, 2, 4, opt, (int32_t), (int32_t));    \
  FN(16, 4, 16, 4, 2, opt, (int32_t), (int32_t));   \
  FN(8, 32, 8, 3, 5, opt, (uint32_t), (int64_t));   \
  FN(32, 8, 16, 5, 3, opt, (uint32_t), (int64_t));  \
  FN(16, 64, 16, 4, 6, opt, (int64_t), (int64_t));  \
  FN(64, 16, 16, 6, 4, opt, (int64_t), (int64_t))

FNS(sse2);
FNS(ssse3);

#undef FNS
#undef FN

// The 2 unused parameters are place holders for PIC enabled build.
#define DECL(w, opt)                                                        \
  int aom_sub_pixel_avg_variance##w##xh_##opt(                              \
      const uint8_t *src, ptrdiff_t src_stride, int x_offset, int y_offset, \
      const uint8_t *dst, ptrdiff_t dst_stride, const uint8_t *sec,         \
      ptrdiff_t sec_stride, int height, unsigned int *sse, void *unused0,   \
      void *unused)
#define DECLS(opt) \
  DECL(4, opt);    \
  DECL(8, opt);    \
  DECL(16, opt)

DECLS(sse2);
DECLS(ssse3);
#undef DECL
#undef DECLS

#define FN(w, h, wf, wlog2, hlog2, opt, cast_prod, cast)                       \
  unsigned int aom_sub_pixel_avg_variance##w##x##h##_##opt(                    \
      const uint8_t *src, int src_stride, int x_offset, int y_offset,          \
      const uint8_t *dst, int dst_stride, unsigned int *sseptr,                \
      const uint8_t *sec) {                                                    \
    unsigned int sse;                                                          \
    int se = aom_sub_pixel_avg_variance##wf##xh_##opt(                         \
        src, src_stride, x_offset, y_offset, dst, dst_stride, sec, w, h, &sse, \
        NULL, NULL);                                                           \
    if (w > wf) {                                                              \
      unsigned int sse2;                                                       \
      int se2 = aom_sub_pixel_avg_variance##wf##xh_##opt(                      \
          src + 16, src_stride, x_offset, y_offset, dst + 16, dst_stride,      \
          sec + 16, w, h, &sse2, NULL, NULL);                                  \
      se += se2;                                                               \
      sse += sse2;                                                             \
      if (w > wf * 2) {                                                        \
        se2 = aom_sub_pixel_avg_variance##wf##xh_##opt(                        \
            src + 32, src_stride, x_offset, y_offset, dst + 32, dst_stride,    \
            sec + 32, w, h, &sse2, NULL, NULL);                                \
        se += se2;                                                             \
        sse += sse2;                                                           \
        se2 = aom_sub_pixel_avg_variance##wf##xh_##opt(                        \
            src + 48, src_stride, x_offset, y_offset, dst + 48, dst_stride,    \
            sec + 48, w, h, &sse2, NULL, NULL);                                \
        se += se2;                                                             \
        sse += sse2;                                                           \
      }                                                                        \
    }                                                                          \
    *sseptr = sse;                                                             \
    return sse - (unsigned int)(cast_prod(cast se * se) >> (wlog2 + hlog2));   \
  }

#define FNS(opt)                                    \
  FN(64, 64, 16, 6, 6, opt, (int64_t), (int64_t));  \
  FN(64, 32, 16, 6, 5, opt, (int64_t), (int64_t));  \
  FN(32, 64, 16, 5, 6, opt, (int64_t), (int64_t));  \
  FN(32, 32, 16, 5, 5, opt, (int64_t), (int64_t));  \
  FN(32, 16, 16, 5, 4, opt, (int64_t), (int64_t));  \
  FN(16, 32, 16, 4, 5, opt, (int64_t), (int64_t));  \
  FN(16, 16, 16, 4, 4, opt, (uint32_t), (int64_t)); \
  FN(16, 8, 16, 4, 3, opt, (uint32_t), (int32_t));  \
  FN(8, 16, 8, 3, 4, opt, (uint32_t), (int32_t));   \
  FN(8, 8, 8, 3, 3, opt, (uint32_t), (int32_t));    \
  FN(8, 4, 8, 3, 2, opt, (uint32_t), (int32_t));    \
  FN(4, 8, 4, 2, 3, opt, (uint32_t), (int32_t));    \
  FN(4, 4, 4, 2, 2, opt, (uint32_t), (int32_t));    \
  FN(4, 16, 4, 2, 4, opt, (int32_t), (int32_t));    \
  FN(16, 4, 16, 4, 2, opt, (int32_t), (int32_t));   \
  FN(8, 32, 8, 3, 5, opt, (uint32_t), (int64_t));   \
  FN(32, 8, 16, 5, 3, opt, (uint32_t), (int64_t));  \
  FN(16, 64, 16, 4, 6, opt, (int64_t), (int64_t));  \
  FN(64, 16, 16, 6, 4, opt, (int64_t), (int64_t))

FNS(sse2);
FNS(ssse3);

#undef FNS
#undef FN

void aom_upsampled_pred_sse2(MACROBLOCKD *xd, const struct AV1Common *const cm,
                             int mi_row, int mi_col, const MV *const mv,
                             uint8_t *comp_pred, int width, int height,
                             int subpel_x_q3, int subpel_y_q3,
                             const uint8_t *ref, int ref_stride) {
  // expect xd == NULL only in tests
  if (xd != NULL) {
    const MB_MODE_INFO *mi = xd->mi[0];
    const int ref_num = 0;
    const int is_intrabc = is_intrabc_block(mi);
    const struct scale_factors *const sf =
        is_intrabc ? &cm->sf_identity : &xd->block_refs[ref_num]->sf;
    const int is_scaled = av1_is_scaled(sf);

    if (is_scaled) {
      // Note: This is mostly a copy from the >=8X8 case in
      // build_inter_predictors() function, with some small tweaks.

      // Some assumptions.
      const int plane = 0;

      // Get pre-requisites.
      const struct macroblockd_plane *const pd = &xd->plane[plane];
      const int ssx = pd->subsampling_x;
      const int ssy = pd->subsampling_y;
      assert(ssx == 0 && ssy == 0);
      const struct buf_2d *const dst_buf = &pd->dst;
      const struct buf_2d *const pre_buf =
          is_intrabc ? dst_buf : &pd->pre[ref_num];
      const int mi_x = mi_col * MI_SIZE;
      const int mi_y = mi_row * MI_SIZE;

      // Calculate subpel_x/y and x/y_step.
      const int row_start = 0;  // Because ss_y is 0.
      const int col_start = 0;  // Because ss_x is 0.
      const int pre_x = (mi_x + MI_SIZE * col_start) >> ssx;
      const int pre_y = (mi_y + MI_SIZE * row_start) >> ssy;
      int orig_pos_y = pre_y << SUBPEL_BITS;
      orig_pos_y += mv->row * (1 << (1 - ssy));
      int orig_pos_x = pre_x << SUBPEL_BITS;
      orig_pos_x += mv->col * (1 << (1 - ssx));
      int pos_y = sf->scale_value_y(orig_pos_y, sf);
      int pos_x = sf->scale_value_x(orig_pos_x, sf);
      pos_x += SCALE_EXTRA_OFF;
      pos_y += SCALE_EXTRA_OFF;

      const int top = -AOM_LEFT_TOP_MARGIN_SCALED(ssy);
      const int left = -AOM_LEFT_TOP_MARGIN_SCALED(ssx);
      const int bottom = (pre_buf->height + AOM_INTERP_EXTEND)
                         << SCALE_SUBPEL_BITS;
      const int right = (pre_buf->width + AOM_INTERP_EXTEND)
                        << SCALE_SUBPEL_BITS;
      pos_y = clamp(pos_y, top, bottom);
      pos_x = clamp(pos_x, left, right);

      const uint8_t *const pre =
          pre_buf->buf0 + (pos_y >> SCALE_SUBPEL_BITS) * pre_buf->stride +
          (pos_x >> SCALE_SUBPEL_BITS);
      const int subpel_x = pos_x & SCALE_SUBPEL_MASK;
      const int subpel_y = pos_y & SCALE_SUBPEL_MASK;
      const int xs = sf->x_step_q4;
      const int ys = sf->y_step_q4;

      // Get warp types.
      const WarpedMotionParams *const wm =
          &xd->global_motion[mi->ref_frame[ref_num]];
      const int is_global = is_global_mv_block(mi, wm->wmtype);
      WarpTypesAllowed warp_types;
      warp_types.global_warp_allowed = is_global;
      warp_types.local_warp_allowed = mi->motion_mode == WARPED_CAUSAL;

      // Get convolve parameters.
      ConvolveParams conv_params = get_conv_params(ref_num, 0, plane, xd->bd);
      const InterpFilters filters =
          av1_broadcast_interp_filter(EIGHTTAP_REGULAR);

      // Get the inter predictor.
      const int build_for_obmc = 0;
      av1_make_inter_predictor(
          pre, pre_buf->stride, comp_pred, width, subpel_x, subpel_y, sf, width,
          height, &conv_params, filters, &warp_types, mi_x >> pd->subsampling_x,
          mi_y >> pd->subsampling_y, plane, ref_num, mi, build_for_obmc, xs, ys,
          xd, cm->allow_warped_motion);

      return;
    }
  }

  const InterpFilterParams filter =
      av1_get_interp_filter_params_with_block_size(EIGHTTAP_REGULAR, 8);

  if (!subpel_x_q3 && !subpel_y_q3) {
    if (width >= 16) {
      int i;
      assert(!(width & 15));
      /*Read 16 pixels one row at a time.*/
      for (i = 0; i < height; i++) {
        int j;
        for (j = 0; j < width; j += 16) {
          xx_storeu_128(comp_pred, xx_loadu_128(ref));
          comp_pred += 16;
          ref += 16;
        }
        ref += ref_stride - width;
      }
    } else if (width >= 8) {
      int i;
      assert(!(width & 7));
      assert(!(height & 1));
      /*Read 8 pixels two rows at a time.*/
      for (i = 0; i < height; i += 2) {
        __m128i s0 = xx_loadl_64(ref + 0 * ref_stride);
        __m128i s1 = xx_loadl_64(ref + 1 * ref_stride);
        xx_storeu_128(comp_pred, _mm_unpacklo_epi64(s0, s1));
        comp_pred += 16;
        ref += 2 * ref_stride;
      }
    } else {
      int i;
      assert(!(width & 3));
      assert(!(height & 3));
      /*Read 4 pixels four rows at a time.*/
      for (i = 0; i < height; i++) {
        const __m128i row0 = xx_loadl_64(ref + 0 * ref_stride);
        const __m128i row1 = xx_loadl_64(ref + 1 * ref_stride);
        const __m128i row2 = xx_loadl_64(ref + 2 * ref_stride);
        const __m128i row3 = xx_loadl_64(ref + 3 * ref_stride);
        const __m128i reg = _mm_unpacklo_epi64(_mm_unpacklo_epi32(row0, row1),
                                               _mm_unpacklo_epi32(row2, row3));
        xx_storeu_128(comp_pred, reg);
        comp_pred += 16;
        ref += 4 * ref_stride;
      }
    }
  } else if (!subpel_y_q3) {
    const int16_t *const kernel =
        av1_get_interp_filter_subpel_kernel(filter, subpel_x_q3 << 1);
    aom_convolve8_horiz(ref, ref_stride, comp_pred, width, kernel, 16, NULL, -1,
                        width, height);
  } else if (!subpel_x_q3) {
    const int16_t *const kernel =
        av1_get_interp_filter_subpel_kernel(filter, subpel_y_q3 << 1);
    aom_convolve8_vert(ref, ref_stride, comp_pred, width, NULL, -1, kernel, 16,
                       width, height);
  } else {
    DECLARE_ALIGNED(16, uint8_t,
                    temp[((MAX_SB_SIZE * 2 + 16) + 16) * MAX_SB_SIZE]);
    const int16_t *const kernel_x =
        av1_get_interp_filter_subpel_kernel(filter, subpel_x_q3 << 1);
    const int16_t *const kernel_y =
        av1_get_interp_filter_subpel_kernel(filter, subpel_y_q3 << 1);
    const int intermediate_height =
        (((height - 1) * 8 + subpel_y_q3) >> 3) + filter.taps;
    assert(intermediate_height <= (MAX_SB_SIZE * 2 + 16) + 16);
    aom_convolve8_horiz(ref - ref_stride * ((filter.taps >> 1) - 1), ref_stride,
                        temp, MAX_SB_SIZE, kernel_x, 16, NULL, -1, width,
                        intermediate_height);
    aom_convolve8_vert(temp + MAX_SB_SIZE * ((filter.taps >> 1) - 1),
                       MAX_SB_SIZE, comp_pred, width, NULL, -1, kernel_y, 16,
                       width, height);
  }
}

void aom_comp_avg_upsampled_pred_sse2(
    MACROBLOCKD *xd, const struct AV1Common *const cm, int mi_row, int mi_col,
    const MV *const mv, uint8_t *comp_pred, const uint8_t *pred, int width,
    int height, int subpel_x_q3, int subpel_y_q3, const uint8_t *ref,
    int ref_stride) {
  int n;
  int i;
  aom_upsampled_pred(xd, cm, mi_row, mi_col, mv, comp_pred, width, height,
                     subpel_x_q3, subpel_y_q3, ref, ref_stride);
  /*The total number of pixels must be a multiple of 16 (e.g., 4x4).*/
  assert(!(width * height & 15));
  n = width * height >> 4;
  for (i = 0; i < n; i++) {
    __m128i s0 = xx_loadu_128(comp_pred);
    __m128i p0 = xx_loadu_128(pred);
    xx_storeu_128(comp_pred, _mm_avg_epu8(s0, p0));
    comp_pred += 16;
    pred += 16;
  }
}