/*
 * Copyright (c) 2023, 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 <arm_neon.h>
#include <assert.h>

#include "aom_dsp/arm/mem_neon.h"
#include "aom_dsp/arm/transpose_neon.h"
#include "av1/common/arm/compound_convolve_neon.h"
#include "av1/common/arm/convolve_neon_dotprod.h"
#include "config/aom_config.h"
#include "config/av1_rtcd.h"

static inline int16x4_t convolve4_4_2d_h(uint8x16_t samples,
                                         const int8x8_t x_filter,
                                         const int32x4_t correction,
                                         const uint8x16_t range_limit,
                                         const uint8x16_t permute_tbl) {
  // Clamp sample range to [-128, 127] for 8-bit signed dot product.
  int8x16_t clamped_samples =
      vreinterpretq_s8_u8(vsubq_u8(samples, range_limit));

  // Permute samples ready for dot product.
  // { 0,  1,  2,  3,  1,  2,  3,  4,  2,  3,  4,  5,  3,  4,  5,  6 }
  int8x16_t permuted_samples = vqtbl1q_s8(clamped_samples, permute_tbl);

  // Accumulate dot product into 'correction' to account for range clamp.
  int32x4_t sum = vdotq_lane_s32(correction, permuted_samples, x_filter, 0);

  // We halved the convolution filter values so -1 from the right shift.
  return vshrn_n_s32(sum, ROUND0_BITS - 1);
}

static inline int16x8_t convolve8_8_2d_h(uint8x16_t samples,
                                         const int8x8_t x_filter,
                                         const int32x4_t correction,
                                         const uint8x16_t range_limit,
                                         const uint8x16x3_t permute_tbl) {
  int8x16_t clamped_samples, permuted_samples[3];
  int32x4_t sum[2];

  // Clamp sample range to [-128, 127] for 8-bit signed dot product.
  clamped_samples = vreinterpretq_s8_u8(vsubq_u8(samples, range_limit));

  // Permute samples ready for dot product. */
  // { 0,  1,  2,  3,  1,  2,  3,  4,  2,  3,  4,  5,  3,  4,  5,  6 }
  permuted_samples[0] = vqtbl1q_s8(clamped_samples, permute_tbl.val[0]);
  // { 4,  5,  6,  7,  5,  6,  7,  8,  6,  7,  8,  9,  7,  8,  9, 10 }
  permuted_samples[1] = vqtbl1q_s8(clamped_samples, permute_tbl.val[1]);
  // { 8,  9, 10, 11,  9, 10, 11, 12, 10, 11, 12, 13, 11, 12, 13, 14 }
  permuted_samples[2] = vqtbl1q_s8(clamped_samples, permute_tbl.val[2]);

  // Accumulate dot product into 'correction' to account for range clamp.
  // First 4 output values.
  sum[0] = vdotq_lane_s32(correction, permuted_samples[0], x_filter, 0);
  sum[0] = vdotq_lane_s32(sum[0], permuted_samples[1], x_filter, 1);
  // Second 4 output values.
  sum[1] = vdotq_lane_s32(correction, permuted_samples[1], x_filter, 0);
  sum[1] = vdotq_lane_s32(sum[1], permuted_samples[2], x_filter, 1);

  // Narrow and re-pack.
  // We halved the convolution filter values so -1 from the right shift.
  return vcombine_s16(vshrn_n_s32(sum[0], ROUND0_BITS - 1),
                      vshrn_n_s32(sum[1], ROUND0_BITS - 1));
}

static inline void dist_wtd_convolve_2d_horiz_neon_dotprod(
    const uint8_t *src, int src_stride, int16_t *im_block, const int im_stride,
    const int16_t *x_filter_ptr, const int im_h, int w) {
  const int bd = 8;
  // Dot product constants and other shims.
  const int16x8_t x_filter_s16 = vld1q_s16(x_filter_ptr);
  // This shim of 1 << (ROUND0_BITS - 1) enables us to use non-rounding shifts
  // - which are generally faster than rounding shifts on modern CPUs.
  const int32_t horiz_const =
      ((1 << (bd + FILTER_BITS - 1)) + (1 << (ROUND0_BITS - 1)));
  // Halve the total because we will halve the filter values.
  const int32x4_t correction =
      vdupq_n_s32(((128 << FILTER_BITS) + horiz_const) / 2);
  const uint8x16_t range_limit = vdupq_n_u8(128);

  const uint8_t *src_ptr = src;
  int16_t *dst_ptr = im_block;
  int dst_stride = im_stride;
  int height = im_h;

  if (w == 4) {
    const uint8x16_t permute_tbl = vld1q_u8(kDotProdPermuteTbl);
    // 4-tap filters are used for blocks having width <= 4.
    // Filter values are even, so halve to reduce intermediate precision reqs.
    const int8x8_t x_filter =
        vshrn_n_s16(vcombine_s16(vld1_s16(x_filter_ptr + 2), vdup_n_s16(0)), 1);

    src_ptr += 2;

    do {
      uint8x16_t s0, s1, s2, s3;
      load_u8_16x4(src_ptr, src_stride, &s0, &s1, &s2, &s3);

      int16x4_t d0 =
          convolve4_4_2d_h(s0, x_filter, correction, range_limit, permute_tbl);
      int16x4_t d1 =
          convolve4_4_2d_h(s1, x_filter, correction, range_limit, permute_tbl);
      int16x4_t d2 =
          convolve4_4_2d_h(s2, x_filter, correction, range_limit, permute_tbl);
      int16x4_t d3 =
          convolve4_4_2d_h(s3, x_filter, correction, range_limit, permute_tbl);

      store_s16_4x4(dst_ptr, dst_stride, d0, d1, d2, d3);

      src_ptr += 4 * src_stride;
      dst_ptr += 4 * dst_stride;
      height -= 4;
    } while (height > 4);

    do {
      uint8x16_t s0 = vld1q_u8(src_ptr);

      int16x4_t d0 =
          convolve4_4_2d_h(s0, x_filter, correction, range_limit, permute_tbl);

      vst1_s16(dst_ptr, d0);

      src_ptr += src_stride;
      dst_ptr += dst_stride;
    } while (--height != 0);
  } else {
    const uint8x16x3_t permute_tbl = vld1q_u8_x3(kDotProdPermuteTbl);
    // Filter values are even, so halve to reduce intermediate precision reqs.
    const int8x8_t x_filter = vshrn_n_s16(x_filter_s16, 1);

    do {
      const uint8_t *s = src_ptr;
      int16_t *d = dst_ptr;
      int width = w;

      do {
        uint8x16_t s0, s1, s2, s3;
        load_u8_16x4(s, src_stride, &s0, &s1, &s2, &s3);

        int16x8_t d0 = convolve8_8_2d_h(s0, x_filter, correction, range_limit,
                                        permute_tbl);
        int16x8_t d1 = convolve8_8_2d_h(s1, x_filter, correction, range_limit,
                                        permute_tbl);
        int16x8_t d2 = convolve8_8_2d_h(s2, x_filter, correction, range_limit,
                                        permute_tbl);
        int16x8_t d3 = convolve8_8_2d_h(s3, x_filter, correction, range_limit,
                                        permute_tbl);

        store_s16_8x4(d, dst_stride, d0, d1, d2, d3);

        s += 8;
        d += 8;
        width -= 8;
      } while (width > 0);
      src_ptr += 4 * src_stride;
      dst_ptr += 4 * dst_stride;
      height -= 4;
    } while (height > 4);

    do {
      const uint8_t *s = src_ptr;
      int16_t *d = dst_ptr;
      int width = w;

      do {
        uint8x16_t s0 = vld1q_u8(s);

        int16x8_t d0 = convolve8_8_2d_h(s0, x_filter, correction, range_limit,
                                        permute_tbl);

        vst1q_s16(d, d0);

        s += 8;
        d += 8;
        width -= 8;
      } while (width > 0);
      src_ptr += src_stride;
      dst_ptr += dst_stride;
    } while (--height != 0);
  }
}

void av1_dist_wtd_convolve_2d_neon_dotprod(
    const uint8_t *src, int src_stride, uint8_t *dst8, int dst8_stride, int w,
    int h, const InterpFilterParams *filter_params_x,
    const InterpFilterParams *filter_params_y, const int subpel_x_qn,
    const int subpel_y_qn, ConvolveParams *conv_params) {
  assert(w % 4 == 0);
  assert(h % 4 == 0);

  DECLARE_ALIGNED(16, int16_t,
                  im_block[(MAX_SB_SIZE + SUBPEL_TAPS - 1) * MAX_SB_SIZE]);

  const int y_filter_taps = get_filter_tap(filter_params_y, subpel_y_qn);
  const int clamped_y_taps = y_filter_taps < 6 ? 6 : y_filter_taps;

  const int im_h = h + clamped_y_taps - 1;
  const int im_stride = MAX_SB_SIZE;
  const int vert_offset = clamped_y_taps / 2 - 1;
  const int horiz_offset = filter_params_x->taps / 2 - 1;
  const uint8_t *src_ptr = src - vert_offset * src_stride - horiz_offset;
  const int16_t *x_filter_ptr = av1_get_interp_filter_subpel_kernel(
      filter_params_x, subpel_x_qn & SUBPEL_MASK);
  const int16_t *y_filter_ptr = av1_get_interp_filter_subpel_kernel(
      filter_params_y, subpel_y_qn & SUBPEL_MASK);

  const int16x8_t y_filter = vld1q_s16(y_filter_ptr);

  dist_wtd_convolve_2d_horiz_neon_dotprod(src_ptr, src_stride, im_block,
                                          im_stride, x_filter_ptr, im_h, w);

  if (clamped_y_taps == 6) {
    if (conv_params->do_average) {
      if (UNLIKELY(conv_params->use_dist_wtd_comp_avg)) {
        dist_wtd_convolve_2d_vert_6tap_dist_wtd_avg_neon(
            im_block, im_stride, dst8, dst8_stride, conv_params, y_filter, h,
            w);
      } else {
        dist_wtd_convolve_2d_vert_6tap_avg_neon(im_block, im_stride, dst8,
                                                dst8_stride, conv_params,
                                                y_filter, h, w);
      }
    } else {
      dist_wtd_convolve_2d_vert_6tap_neon(im_block, im_stride, conv_params,
                                          y_filter, h, w);
    }
  } else {
    if (conv_params->do_average) {
      if (UNLIKELY(conv_params->use_dist_wtd_comp_avg)) {
        dist_wtd_convolve_2d_vert_8tap_dist_wtd_avg_neon(
            im_block, im_stride, dst8, dst8_stride, conv_params, y_filter, h,
            w);
      } else {
        dist_wtd_convolve_2d_vert_8tap_avg_neon(im_block, im_stride, dst8,
                                                dst8_stride, conv_params,
                                                y_filter, h, w);
      }
    } else {
      dist_wtd_convolve_2d_vert_8tap_neon(im_block, im_stride, conv_params,
                                          y_filter, h, w);
    }
  }
}

static inline uint16x4_t convolve4_4_x(uint8x16_t samples,
                                       const int8x8_t x_filter,
                                       const int32x4_t correction,
                                       const uint8x16_t range_limit,
                                       const uint8x16_t permute_tbl) {
  // Clamp sample range to [-128, 127] for 8-bit signed dot product.
  int8x16_t clamped_samples =
      vreinterpretq_s8_u8(vsubq_u8(samples, range_limit));

  // Permute samples ready for dot product.
  // { 0,  1,  2,  3,  1,  2,  3,  4,  2,  3,  4,  5,  3,  4,  5,  6 }
  int8x16_t permuted_samples = vqtbl1q_s8(clamped_samples, permute_tbl);

  // Accumulate dot product into 'correction' to account for range clamp.
  int32x4_t sum = vdotq_lane_s32(correction, permuted_samples, x_filter, 0);

  // We halved the convolution filter values so -1 from the right shift.
  return vreinterpret_u16_s16(vshrn_n_s32(sum, ROUND0_BITS - 1));
}

static inline uint16x8_t convolve8_8_x(uint8x16_t samples,
                                       const int8x8_t x_filter,
                                       const int32x4_t correction,
                                       const uint8x16_t range_limit,
                                       const uint8x16x3_t permute_tbl) {
  int8x16_t clamped_samples, permuted_samples[3];
  int32x4_t sum[2];

  // Clamp sample range to [-128, 127] for 8-bit signed dot product.
  clamped_samples = vreinterpretq_s8_u8(vsubq_u8(samples, range_limit));

  // Permute samples ready for dot product. */
  // { 0,  1,  2,  3,  1,  2,  3,  4,  2,  3,  4,  5,  3,  4,  5,  6 }
  permuted_samples[0] = vqtbl1q_s8(clamped_samples, permute_tbl.val[0]);
  // { 4,  5,  6,  7,  5,  6,  7,  8,  6,  7,  8,  9,  7,  8,  9, 10 }
  permuted_samples[1] = vqtbl1q_s8(clamped_samples, permute_tbl.val[1]);
  // { 8,  9, 10, 11,  9, 10, 11, 12, 10, 11, 12, 13, 11, 12, 13, 14 }
  permuted_samples[2] = vqtbl1q_s8(clamped_samples, permute_tbl.val[2]);

  // Accumulate dot product into 'correction' to account for range clamp.
  // First 4 output values.
  sum[0] = vdotq_lane_s32(correction, permuted_samples[0], x_filter, 0);
  sum[0] = vdotq_lane_s32(sum[0], permuted_samples[1], x_filter, 1);
  // Second 4 output values.
  sum[1] = vdotq_lane_s32(correction, permuted_samples[1], x_filter, 0);
  sum[1] = vdotq_lane_s32(sum[1], permuted_samples[2], x_filter, 1);

  // Narrow and re-pack.
  // We halved the convolution filter values so -1 from the right shift.
  int16x8_t res = vcombine_s16(vshrn_n_s32(sum[0], ROUND0_BITS - 1),
                               vshrn_n_s32(sum[1], ROUND0_BITS - 1));
  return vreinterpretq_u16_s16(res);
}

static inline void dist_wtd_convolve_x_dist_wtd_avg_neon_dotprod(
    const uint8_t *src, int src_stride, uint8_t *dst8, int dst8_stride, int w,
    int h, const InterpFilterParams *filter_params_x, const int subpel_x_qn,
    ConvolveParams *conv_params) {
  assert(w % 4 == 0);
  assert(h % 4 == 0);

  const int bd = 8;
  const int offset_bits = bd + 2 * FILTER_BITS - ROUND0_BITS;
  const int16_t round_offset = (1 << (offset_bits - COMPOUND_ROUND1_BITS)) +
                               (1 << (offset_bits - COMPOUND_ROUND1_BITS - 1));
  const int16x8_t round_offset_vec = vdupq_n_s16(round_offset);

  const uint16_t fwd_offset = conv_params->fwd_offset;
  const uint16_t bck_offset = conv_params->bck_offset;

  // Horizontal filter.
  const int16_t *x_filter_ptr = av1_get_interp_filter_subpel_kernel(
      filter_params_x, subpel_x_qn & SUBPEL_MASK);
  const int16x8_t x_filter_s16 = vld1q_s16(x_filter_ptr);

  // Dot-product constants and other shims.
  const uint8x16_t range_limit = vdupq_n_u8(128);
  // Fold round_offset into the dot-product filter correction constant. The
  // additional shim of 1 << (ROUND0_BITS - 1) enables us to use non-rounding
  // shifts - which are generally faster than rounding shifts on modern CPUs.
  // Halve the total because we will halve the filter values.
  int32x4_t correction =
      vdupq_n_s32(((128 << FILTER_BITS) + (round_offset << ROUND0_BITS) +
                   (1 << (ROUND0_BITS - 1))) /
                  2);

  const int horiz_offset = filter_params_x->taps / 2 - 1;
  const uint8_t *src_ptr = src - horiz_offset;
  CONV_BUF_TYPE *dst_ptr = conv_params->dst;
  uint8_t *dst8_ptr = dst8;
  int dst_stride = conv_params->dst_stride;
  int height = h;

  if (w == 4) {
    const uint8x16_t permute_tbl = vld1q_u8(kDotProdPermuteTbl);
    // 4-tap filters are used for blocks having width <= 4.
    // Filter values are even, so halve to reduce intermediate precision reqs.
    const int8x8_t x_filter =
        vshrn_n_s16(vcombine_s16(vld1_s16(x_filter_ptr + 2), vdup_n_s16(0)), 1);

    src_ptr += 2;

    do {
      uint8x16_t s0, s1, s2, s3;
      load_u8_16x4(src_ptr, src_stride, &s0, &s1, &s2, &s3);

      uint16x4_t d0 =
          convolve4_4_x(s0, x_filter, correction, range_limit, permute_tbl);
      uint16x4_t d1 =
          convolve4_4_x(s1, x_filter, correction, range_limit, permute_tbl);
      uint16x4_t d2 =
          convolve4_4_x(s2, x_filter, correction, range_limit, permute_tbl);
      uint16x4_t d3 =
          convolve4_4_x(s3, x_filter, correction, range_limit, permute_tbl);

      uint16x4_t dd0, dd1, dd2, dd3;
      load_u16_4x4(dst_ptr, dst_stride, &dd0, &dd1, &dd2, &dd3);

      uint8x8_t d01_u8, d23_u8;
      compute_dist_wtd_avg_4x4(dd0, dd1, dd2, dd3, d0, d1, d2, d3, fwd_offset,
                               bck_offset, round_offset_vec, &d01_u8, &d23_u8);

      store_u8x4_strided_x2(dst8_ptr + 0 * dst8_stride, dst8_stride, d01_u8);
      store_u8x4_strided_x2(dst8_ptr + 2 * dst8_stride, dst8_stride, d23_u8);

      src_ptr += 4 * src_stride;
      dst_ptr += 4 * dst_stride;
      dst8_ptr += 4 * dst8_stride;
      height -= 4;
    } while (height != 0);
  } else {
    const uint8x16x3_t permute_tbl = vld1q_u8_x3(kDotProdPermuteTbl);
    // Filter values are even, so halve to reduce intermediate precision reqs.
    const int8x8_t x_filter = vshrn_n_s16(x_filter_s16, 1);

    do {
      const uint8_t *s = src_ptr;
      CONV_BUF_TYPE *d = dst_ptr;
      uint8_t *d_u8 = dst8_ptr;
      int width = w;

      do {
        uint8x16_t s0, s1, s2, s3;
        load_u8_16x4(s, src_stride, &s0, &s1, &s2, &s3);

        uint16x8_t d0 =
            convolve8_8_x(s0, x_filter, correction, range_limit, permute_tbl);
        uint16x8_t d1 =
            convolve8_8_x(s1, x_filter, correction, range_limit, permute_tbl);
        uint16x8_t d2 =
            convolve8_8_x(s2, x_filter, correction, range_limit, permute_tbl);
        uint16x8_t d3 =
            convolve8_8_x(s3, x_filter, correction, range_limit, permute_tbl);

        uint16x8_t dd0, dd1, dd2, dd3;
        load_u16_8x4(d, dst_stride, &dd0, &dd1, &dd2, &dd3);

        uint8x8_t d0_u8, d1_u8, d2_u8, d3_u8;
        compute_dist_wtd_avg_8x4(dd0, dd1, dd2, dd3, d0, d1, d2, d3, fwd_offset,
                                 bck_offset, round_offset_vec, &d0_u8, &d1_u8,
                                 &d2_u8, &d3_u8);

        store_u8_8x4(d_u8, dst8_stride, d0_u8, d1_u8, d2_u8, d3_u8);

        s += 8;
        d += 8;
        d_u8 += 8;
        width -= 8;
      } while (width != 0);
      src_ptr += 4 * src_stride;
      dst_ptr += 4 * dst_stride;
      dst8_ptr += 4 * dst8_stride;
      height -= 4;
    } while (height != 0);
  }
}

static inline void dist_wtd_convolve_x_avg_neon_dotprod(
    const uint8_t *src, int src_stride, uint8_t *dst8, int dst8_stride, int w,
    int h, const InterpFilterParams *filter_params_x, const int subpel_x_qn,
    ConvolveParams *conv_params) {
  assert(w % 4 == 0);
  assert(h % 4 == 0);

  const int bd = 8;
  const int offset_bits = bd + 2 * FILTER_BITS - ROUND0_BITS;
  const int16_t round_offset = (1 << (offset_bits - COMPOUND_ROUND1_BITS)) +
                               (1 << (offset_bits - COMPOUND_ROUND1_BITS - 1));
  const int16x8_t round_offset_vec = vdupq_n_s16(round_offset);

  // Horizontal filter.
  const int16_t *x_filter_ptr = av1_get_interp_filter_subpel_kernel(
      filter_params_x, subpel_x_qn & SUBPEL_MASK);
  const int16x8_t x_filter_s16 = vld1q_s16(x_filter_ptr);

  // Dot-product constants and other shims.
  const uint8x16_t range_limit = vdupq_n_u8(128);
  // Fold round_offset into the dot-product filter correction constant. The
  // additional shim of 1 << (ROUND0_BITS - 1) enables us to use non-rounding
  // shifts - which are generally faster than rounding shifts on modern CPUs.
  // Halve the total because we will halve the filter values.
  int32x4_t correction =
      vdupq_n_s32(((128 << FILTER_BITS) + (round_offset << ROUND0_BITS) +
                   (1 << (ROUND0_BITS - 1))) /
                  2);

  const int horiz_offset = filter_params_x->taps / 2 - 1;
  const uint8_t *src_ptr = src - horiz_offset;
  CONV_BUF_TYPE *dst_ptr = conv_params->dst;
  uint8_t *dst8_ptr = dst8;
  int dst_stride = conv_params->dst_stride;
  int height = h;

  if (w == 4) {
    const uint8x16_t permute_tbl = vld1q_u8(kDotProdPermuteTbl);
    // 4-tap filters are used for blocks having width <= 4.
    // Filter values are even, so halve to reduce intermediate precision reqs.
    const int8x8_t x_filter =
        vshrn_n_s16(vcombine_s16(vld1_s16(x_filter_ptr + 2), vdup_n_s16(0)), 1);

    src_ptr += 2;

    do {
      uint8x16_t s0, s1, s2, s3;
      load_u8_16x4(src_ptr, src_stride, &s0, &s1, &s2, &s3);

      uint16x4_t d0 =
          convolve4_4_x(s0, x_filter, correction, range_limit, permute_tbl);
      uint16x4_t d1 =
          convolve4_4_x(s1, x_filter, correction, range_limit, permute_tbl);
      uint16x4_t d2 =
          convolve4_4_x(s2, x_filter, correction, range_limit, permute_tbl);
      uint16x4_t d3 =
          convolve4_4_x(s3, x_filter, correction, range_limit, permute_tbl);

      uint16x4_t dd0, dd1, dd2, dd3;
      load_u16_4x4(dst_ptr, dst_stride, &dd0, &dd1, &dd2, &dd3);

      uint8x8_t d01_u8, d23_u8;
      compute_basic_avg_4x4(dd0, dd1, dd2, dd3, d0, d1, d2, d3,
                            round_offset_vec, &d01_u8, &d23_u8);

      store_u8x4_strided_x2(dst8_ptr + 0 * dst8_stride, dst8_stride, d01_u8);
      store_u8x4_strided_x2(dst8_ptr + 2 * dst8_stride, dst8_stride, d23_u8);

      src_ptr += 4 * src_stride;
      dst_ptr += 4 * dst_stride;
      dst8_ptr += 4 * dst8_stride;
      height -= 4;
    } while (height != 0);
  } else {
    const uint8x16x3_t permute_tbl = vld1q_u8_x3(kDotProdPermuteTbl);
    // Filter values are even, so halve to reduce intermediate precision reqs.
    const int8x8_t x_filter = vshrn_n_s16(x_filter_s16, 1);

    do {
      const uint8_t *s = src_ptr;
      CONV_BUF_TYPE *d = dst_ptr;
      uint8_t *d_u8 = dst8_ptr;
      int width = w;

      do {
        uint8x16_t s0, s1, s2, s3;
        load_u8_16x4(s, src_stride, &s0, &s1, &s2, &s3);

        uint16x8_t d0 =
            convolve8_8_x(s0, x_filter, correction, range_limit, permute_tbl);
        uint16x8_t d1 =
            convolve8_8_x(s1, x_filter, correction, range_limit, permute_tbl);
        uint16x8_t d2 =
            convolve8_8_x(s2, x_filter, correction, range_limit, permute_tbl);
        uint16x8_t d3 =
            convolve8_8_x(s3, x_filter, correction, range_limit, permute_tbl);

        uint16x8_t dd0, dd1, dd2, dd3;
        load_u16_8x4(d, dst_stride, &dd0, &dd1, &dd2, &dd3);

        uint8x8_t d0_u8, d1_u8, d2_u8, d3_u8;
        compute_basic_avg_8x4(dd0, dd1, dd2, dd3, d0, d1, d2, d3,
                              round_offset_vec, &d0_u8, &d1_u8, &d2_u8, &d3_u8);

        store_u8_8x4(d_u8, dst8_stride, d0_u8, d1_u8, d2_u8, d3_u8);

        s += 8;
        d += 8;
        d_u8 += 8;
        width -= 8;
      } while (width != 0);
      src_ptr += 4 * src_stride;
      dst_ptr += 4 * dst_stride;
      dst8_ptr += 4 * dst8_stride;
      height -= 4;
    } while (height != 0);
  }
}

static inline void dist_wtd_convolve_x_neon_dotprod(
    const uint8_t *src, int src_stride, int w, int h,
    const InterpFilterParams *filter_params_x, const int subpel_x_qn,
    ConvolveParams *conv_params) {
  assert(w % 4 == 0);
  assert(h % 4 == 0);

  const int bd = 8;
  const int offset_bits = bd + 2 * FILTER_BITS - ROUND0_BITS;
  const int16_t round_offset = (1 << (offset_bits - COMPOUND_ROUND1_BITS)) +
                               (1 << (offset_bits - COMPOUND_ROUND1_BITS - 1));

  // Horizontal filter.
  const int16_t *x_filter_ptr = av1_get_interp_filter_subpel_kernel(
      filter_params_x, subpel_x_qn & SUBPEL_MASK);
  const int16x8_t x_filter_s16 = vld1q_s16(x_filter_ptr);

  // Dot-product constants and other shims.
  const uint8x16_t range_limit = vdupq_n_u8(128);
  // Fold round_offset into the dot-product filter correction constant. The
  // additional shim of 1 << (ROUND0_BITS - 1) enables us to use non-rounding
  // shifts - which are generally faster than rounding shifts on modern CPUs.
  // Halve the total because we will halve the vilter values.
  int32x4_t correction =
      vdupq_n_s32(((128 << FILTER_BITS) + (round_offset << ROUND0_BITS) +
                   (1 << (ROUND0_BITS - 1))) /
                  2);

  const int horiz_offset = filter_params_x->taps / 2 - 1;
  const uint8_t *src_ptr = src - horiz_offset;
  CONV_BUF_TYPE *dst_ptr = conv_params->dst;
  int dst_stride = conv_params->dst_stride;
  int height = h;

  if (w == 4) {
    const uint8x16_t permute_tbl = vld1q_u8(kDotProdPermuteTbl);
    // 4-tap filters are used for blocks having width <= 4.
    // Filter values are even, so halve to reduce intermediate precision reqs.
    const int8x8_t x_filter =
        vshrn_n_s16(vcombine_s16(vld1_s16(x_filter_ptr + 2), vdup_n_s16(0)), 1);

    src_ptr += 2;

    do {
      uint8x16_t s0, s1, s2, s3;
      load_u8_16x4(src_ptr, src_stride, &s0, &s1, &s2, &s3);

      uint16x4_t d0 =
          convolve4_4_x(s0, x_filter, correction, range_limit, permute_tbl);
      uint16x4_t d1 =
          convolve4_4_x(s1, x_filter, correction, range_limit, permute_tbl);
      uint16x4_t d2 =
          convolve4_4_x(s2, x_filter, correction, range_limit, permute_tbl);
      uint16x4_t d3 =
          convolve4_4_x(s3, x_filter, correction, range_limit, permute_tbl);

      store_u16_4x4(dst_ptr, dst_stride, d0, d1, d2, d3);

      src_ptr += 4 * src_stride;
      dst_ptr += 4 * dst_stride;
      height -= 4;
    } while (height != 0);
  } else {
    const uint8x16x3_t permute_tbl = vld1q_u8_x3(kDotProdPermuteTbl);
    // Filter values are even, so halve to reduce intermediate precision reqs.
    const int8x8_t x_filter = vshrn_n_s16(x_filter_s16, 1);

    do {
      const uint8_t *s = src_ptr;
      CONV_BUF_TYPE *d = dst_ptr;
      int width = w;

      do {
        uint8x16_t s0, s1, s2, s3;
        load_u8_16x4(s, src_stride, &s0, &s1, &s2, &s3);

        uint16x8_t d0 =
            convolve8_8_x(s0, x_filter, correction, range_limit, permute_tbl);
        uint16x8_t d1 =
            convolve8_8_x(s1, x_filter, correction, range_limit, permute_tbl);
        uint16x8_t d2 =
            convolve8_8_x(s2, x_filter, correction, range_limit, permute_tbl);
        uint16x8_t d3 =
            convolve8_8_x(s3, x_filter, correction, range_limit, permute_tbl);

        store_u16_8x4(d, dst_stride, d0, d1, d2, d3);

        s += 8;
        d += 8;
        width -= 8;
      } while (width != 0);
      src_ptr += 4 * src_stride;
      dst_ptr += 4 * dst_stride;
      height -= 4;
    } while (height != 0);
  }
}

void av1_dist_wtd_convolve_x_neon_dotprod(
    const uint8_t *src, int src_stride, uint8_t *dst8, int dst8_stride, int w,
    int h, const InterpFilterParams *filter_params_x, const int subpel_x_qn,
    ConvolveParams *conv_params) {
  if (conv_params->do_average) {
    if (UNLIKELY(conv_params->use_dist_wtd_comp_avg)) {
      dist_wtd_convolve_x_dist_wtd_avg_neon_dotprod(
          src, src_stride, dst8, dst8_stride, w, h, filter_params_x,
          subpel_x_qn, conv_params);
    } else {
      dist_wtd_convolve_x_avg_neon_dotprod(src, src_stride, dst8, dst8_stride,
                                           w, h, filter_params_x, subpel_x_qn,
                                           conv_params);
    }
  } else {
    dist_wtd_convolve_x_neon_dotprod(src, src_stride, w, h, filter_params_x,
                                     subpel_x_qn, conv_params);
  }
}

static inline int16x4_t convolve8_4_y(const int8x16_t s0, const int8x16_t s1,
                                      const int8x8_t filters) {
  // The sample range transform and permutation are performed by the caller.
  // Accumulate into 128 << FILTER_BITS to account for range transform.
  // (- 1 since we halved the filters.)
  const int32x4_t acc = vdupq_n_s32(128 << (FILTER_BITS - 1));
  int32x4_t sum = vdotq_lane_s32(acc, s0, filters, 0);
  sum = vdotq_lane_s32(sum, s1, filters, 1);

  // Further narrowing and packing is performed by the caller.
  return vmovn_s32(sum);
}

static inline uint16x8_t convolve8_8_y(const int8x16_t s0_lo,
                                       const int8x16_t s0_hi,
                                       const int8x16_t s1_lo,
                                       const int8x16_t s1_hi,
                                       const int8x8_t filters,
                                       const int16x8_t round_offset) {
  // The sample range transform and permutation are performed by the caller.
  // Accumulate into 128 << FILTER_BITS to account for range transform.
  // (- 1 since we halved the filters.)
  const int32x4_t acc = vdupq_n_s32(128 << (FILTER_BITS - 1));

  int32x4_t sum0123 = vdotq_lane_s32(acc, s0_lo, filters, 0);
  sum0123 = vdotq_lane_s32(sum0123, s1_lo, filters, 1);

  int32x4_t sum4567 = vdotq_lane_s32(acc, s0_hi, filters, 0);
  sum4567 = vdotq_lane_s32(sum4567, s1_hi, filters, 1);

  // Narrow and re-pack.
  int16x8_t sum = vcombine_s16(vmovn_s32(sum0123), vmovn_s32(sum4567));

  // We halved the filter values so -1 from right shift.
  return vreinterpretq_u16_s16(
      vrsraq_n_s16(round_offset, sum, ROUND0_BITS - 1));
}

static inline void dist_wtd_convolve_y_8tap_neon_dotprod(
    const uint8_t *src_ptr, int src_stride, int w, int h,
    const int16_t *y_filter_ptr, ConvolveParams *conv_params) {
  const int bd = 8;
  const int offset_bits = bd + 2 * FILTER_BITS - ROUND0_BITS;
  const int16_t round_offset = (1 << (offset_bits - COMPOUND_ROUND1_BITS)) +
                               (1 << (offset_bits - COMPOUND_ROUND1_BITS - 1));
  const int16x8_t round_offset_vec = vdupq_n_s16(round_offset);

  CONV_BUF_TYPE *dst_ptr = conv_params->dst;
  const int dst_stride = conv_params->dst_stride;

  // Filter values are even, so halve to reduce intermediate precision reqs.
  const int8x8_t filter = vshrn_n_s16(vld1q_s16(y_filter_ptr), 1);

  const uint8x16x3_t merge_block_tbl = vld1q_u8_x3(kDotProdMergeBlockTbl);

  if (w == 4) {
    uint8x8_t t0, t1, t2, t3, t4, t5, t6;
    load_u8_8x7(src_ptr, src_stride, &t0, &t1, &t2, &t3, &t4, &t5, &t6);
    src_ptr += 7 * src_stride;

    // Transform sample range to [-128, 127] for 8-bit signed dot product.
    int8x8_t s0 = vreinterpret_s8_u8(vsub_u8(t0, vdup_n_u8(128)));
    int8x8_t s1 = vreinterpret_s8_u8(vsub_u8(t1, vdup_n_u8(128)));
    int8x8_t s2 = vreinterpret_s8_u8(vsub_u8(t2, vdup_n_u8(128)));
    int8x8_t s3 = vreinterpret_s8_u8(vsub_u8(t3, vdup_n_u8(128)));
    int8x8_t s4 = vreinterpret_s8_u8(vsub_u8(t4, vdup_n_u8(128)));
    int8x8_t s5 = vreinterpret_s8_u8(vsub_u8(t5, vdup_n_u8(128)));
    int8x8_t s6 = vreinterpret_s8_u8(vsub_u8(t6, vdup_n_u8(128)));

    int8x16_t s0123, s1234, s2345, s3456;
    transpose_concat_elems_s8_4x4(s0, s1, s2, s3, &s0123);
    transpose_concat_elems_s8_4x4(s1, s2, s3, s4, &s1234);
    transpose_concat_elems_s8_4x4(s2, s3, s4, s5, &s2345);
    transpose_concat_elems_s8_4x4(s3, s4, s5, s6, &s3456);

    do {
      uint8x8_t t7, t8, t9, tA;
      load_u8_8x4(src_ptr, src_stride, &t7, &t8, &t9, &tA);

      int8x8_t s7 = vreinterpret_s8_u8(vsub_u8(t7, vdup_n_u8(128)));
      int8x8_t s8 = vreinterpret_s8_u8(vsub_u8(t8, vdup_n_u8(128)));
      int8x8_t s9 = vreinterpret_s8_u8(vsub_u8(t9, vdup_n_u8(128)));
      int8x8_t sA = vreinterpret_s8_u8(vsub_u8(tA, vdup_n_u8(128)));

      int8x16_t s4567, s5678, s6789, s789A;
      transpose_concat_elems_s8_4x4(s7, s8, s9, sA, &s789A);

      // Merge new data into block from previous iteration.
      int8x16x2_t samples_LUT = { { s3456, s789A } };
      s4567 = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[0]);
      s5678 = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[1]);
      s6789 = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[2]);

      int16x4_t d0 = convolve8_4_y(s0123, s4567, filter);
      int16x4_t d1 = convolve8_4_y(s1234, s5678, filter);
      int16x4_t d2 = convolve8_4_y(s2345, s6789, filter);
      int16x4_t d3 = convolve8_4_y(s3456, s789A, filter);

      // We halved the filter values so -1 from right shift.
      int16x8_t d01 =
          vrsraq_n_s16(round_offset_vec, vcombine_s16(d0, d1), ROUND0_BITS - 1);
      int16x8_t d23 =
          vrsraq_n_s16(round_offset_vec, vcombine_s16(d2, d3), ROUND0_BITS - 1);

      store_u16x4_strided_x2(dst_ptr + 0 * dst_stride, dst_stride,
                             vreinterpretq_u16_s16(d01));
      store_u16x4_strided_x2(dst_ptr + 2 * dst_stride, dst_stride,
                             vreinterpretq_u16_s16(d23));

      // Prepare block for next iteration - re-using as much as possible.
      // Shuffle everything up four rows.
      s0123 = s4567;
      s1234 = s5678;
      s2345 = s6789;
      s3456 = s789A;

      src_ptr += 4 * src_stride;
      dst_ptr += 4 * dst_stride;
      h -= 4;
    } while (h != 0);
  } else {
    do {
      int height = h;
      const uint8_t *s = src_ptr;
      CONV_BUF_TYPE *d = dst_ptr;

      uint8x8_t t0, t1, t2, t3, t4, t5, t6;
      load_u8_8x7(s, src_stride, &t0, &t1, &t2, &t3, &t4, &t5, &t6);
      s += 7 * src_stride;

      // Transform sample range to [-128, 127] for 8-bit signed dot product.
      int8x8_t s0 = vreinterpret_s8_u8(vsub_u8(t0, vdup_n_u8(128)));
      int8x8_t s1 = vreinterpret_s8_u8(vsub_u8(t1, vdup_n_u8(128)));
      int8x8_t s2 = vreinterpret_s8_u8(vsub_u8(t2, vdup_n_u8(128)));
      int8x8_t s3 = vreinterpret_s8_u8(vsub_u8(t3, vdup_n_u8(128)));
      int8x8_t s4 = vreinterpret_s8_u8(vsub_u8(t4, vdup_n_u8(128)));
      int8x8_t s5 = vreinterpret_s8_u8(vsub_u8(t5, vdup_n_u8(128)));
      int8x8_t s6 = vreinterpret_s8_u8(vsub_u8(t6, vdup_n_u8(128)));

      // This operation combines a conventional transpose and the sample
      // permute (see horizontal case) required before computing the dot
      // product.
      int8x16_t s0123_lo, s0123_hi, s1234_lo, s1234_hi, s2345_lo, s2345_hi,
          s3456_lo, s3456_hi;
      transpose_concat_elems_s8_8x4(s0, s1, s2, s3, &s0123_lo, &s0123_hi);
      transpose_concat_elems_s8_8x4(s1, s2, s3, s4, &s1234_lo, &s1234_hi);
      transpose_concat_elems_s8_8x4(s2, s3, s4, s5, &s2345_lo, &s2345_hi);
      transpose_concat_elems_s8_8x4(s3, s4, s5, s6, &s3456_lo, &s3456_hi);

      do {
        uint8x8_t t7, t8, t9, tA;
        load_u8_8x4(s, src_stride, &t7, &t8, &t9, &tA);

        int8x8_t s7 = vreinterpret_s8_u8(vsub_u8(t7, vdup_n_u8(128)));
        int8x8_t s8 = vreinterpret_s8_u8(vsub_u8(t8, vdup_n_u8(128)));
        int8x8_t s9 = vreinterpret_s8_u8(vsub_u8(t9, vdup_n_u8(128)));
        int8x8_t sA = vreinterpret_s8_u8(vsub_u8(tA, vdup_n_u8(128)));

        int8x16_t s4567_lo, s4567_hi, s5678_lo, s5678_hi, s6789_lo, s6789_hi,
            s789A_lo, s789A_hi;
        transpose_concat_elems_s8_8x4(s7, s8, s9, sA, &s789A_lo, &s789A_hi);

        // Merge new data into block from previous iteration.
        int8x16x2_t samples_LUT_lo = { { s3456_lo, s789A_lo } };
        s4567_lo = vqtbl2q_s8(samples_LUT_lo, merge_block_tbl.val[0]);
        s5678_lo = vqtbl2q_s8(samples_LUT_lo, merge_block_tbl.val[1]);
        s6789_lo = vqtbl2q_s8(samples_LUT_lo, merge_block_tbl.val[2]);

        int8x16x2_t samples_LUT_hi = { { s3456_hi, s789A_hi } };
        s4567_hi = vqtbl2q_s8(samples_LUT_hi, merge_block_tbl.val[0]);
        s5678_hi = vqtbl2q_s8(samples_LUT_hi, merge_block_tbl.val[1]);
        s6789_hi = vqtbl2q_s8(samples_LUT_hi, merge_block_tbl.val[2]);

        uint16x8_t d0 = convolve8_8_y(s0123_lo, s0123_hi, s4567_lo, s4567_hi,
                                      filter, round_offset_vec);
        uint16x8_t d1 = convolve8_8_y(s1234_lo, s1234_hi, s5678_lo, s5678_hi,
                                      filter, round_offset_vec);
        uint16x8_t d2 = convolve8_8_y(s2345_lo, s2345_hi, s6789_lo, s6789_hi,
                                      filter, round_offset_vec);
        uint16x8_t d3 = convolve8_8_y(s3456_lo, s3456_hi, s789A_lo, s789A_hi,
                                      filter, round_offset_vec);

        store_u16_8x4(d, dst_stride, d0, d1, d2, d3);

        // Prepare block for next iteration - re-using as much as possible.
        // Shuffle everything up four rows.
        s0123_lo = s4567_lo;
        s0123_hi = s4567_hi;
        s1234_lo = s5678_lo;
        s1234_hi = s5678_hi;
        s2345_lo = s6789_lo;
        s2345_hi = s6789_hi;
        s3456_lo = s789A_lo;
        s3456_hi = s789A_hi;

        s += 4 * src_stride;
        d += 4 * dst_stride;
        height -= 4;
      } while (height != 0);
      src_ptr += 8;
      dst_ptr += 8;
      w -= 8;
    } while (w != 0);
  }
}

static inline void dist_wtd_convolve_y_8tap_dist_wtd_avg_neon_dotprod(
    const uint8_t *src_ptr, int src_stride, uint8_t *dst8_ptr,
    const int dst8_stride, int w, int h, const int16_t *y_filter_ptr,
    ConvolveParams *conv_params) {
  const int bd = 8;
  const int offset_bits = bd + 2 * FILTER_BITS - ROUND0_BITS;
  const int16_t round_offset = (1 << (offset_bits - COMPOUND_ROUND1_BITS)) +
                               (1 << (offset_bits - COMPOUND_ROUND1_BITS - 1));
  const int16x8_t round_offset_vec = vdupq_n_s16(round_offset);

  const uint16_t fwd_offset = conv_params->fwd_offset;
  const uint16_t bck_offset = conv_params->bck_offset;

  CONV_BUF_TYPE *dst_ptr = conv_params->dst;
  const int dst_stride = conv_params->dst_stride;

  // Filter values are even, so halve to reduce intermediate precision reqs.
  const int8x8_t filter = vshrn_n_s16(vld1q_s16(y_filter_ptr), 1);

  const uint8x16x3_t merge_block_tbl = vld1q_u8_x3(kDotProdMergeBlockTbl);

  if (w == 4) {
    uint8x8_t t0, t1, t2, t3, t4, t5, t6;
    load_u8_8x7(src_ptr, src_stride, &t0, &t1, &t2, &t3, &t4, &t5, &t6);
    src_ptr += 7 * src_stride;

    // Transform sample range to [-128, 127] for 8-bit signed dot product.
    int8x8_t s0 = vreinterpret_s8_u8(vsub_u8(t0, vdup_n_u8(128)));
    int8x8_t s1 = vreinterpret_s8_u8(vsub_u8(t1, vdup_n_u8(128)));
    int8x8_t s2 = vreinterpret_s8_u8(vsub_u8(t2, vdup_n_u8(128)));
    int8x8_t s3 = vreinterpret_s8_u8(vsub_u8(t3, vdup_n_u8(128)));
    int8x8_t s4 = vreinterpret_s8_u8(vsub_u8(t4, vdup_n_u8(128)));
    int8x8_t s5 = vreinterpret_s8_u8(vsub_u8(t5, vdup_n_u8(128)));
    int8x8_t s6 = vreinterpret_s8_u8(vsub_u8(t6, vdup_n_u8(128)));

    int8x16_t s0123, s1234, s2345, s3456;
    transpose_concat_elems_s8_4x4(s0, s1, s2, s3, &s0123);
    transpose_concat_elems_s8_4x4(s1, s2, s3, s4, &s1234);
    transpose_concat_elems_s8_4x4(s2, s3, s4, s5, &s2345);
    transpose_concat_elems_s8_4x4(s3, s4, s5, s6, &s3456);

    do {
      uint8x8_t t7, t8, t9, tA;
      load_u8_8x4(src_ptr, src_stride, &t7, &t8, &t9, &tA);

      int8x8_t s7 = vreinterpret_s8_u8(vsub_u8(t7, vdup_n_u8(128)));
      int8x8_t s8 = vreinterpret_s8_u8(vsub_u8(t8, vdup_n_u8(128)));
      int8x8_t s9 = vreinterpret_s8_u8(vsub_u8(t9, vdup_n_u8(128)));
      int8x8_t sA = vreinterpret_s8_u8(vsub_u8(tA, vdup_n_u8(128)));

      int8x16_t s4567, s5678, s6789, s789A;
      transpose_concat_elems_s8_4x4(s7, s8, s9, sA, &s789A);

      // Merge new data into block from previous iteration.
      int8x16x2_t samples_LUT = { { s3456, s789A } };
      s4567 = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[0]);
      s5678 = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[1]);
      s6789 = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[2]);

      int16x4_t d0 = convolve8_4_y(s0123, s4567, filter);
      int16x4_t d1 = convolve8_4_y(s1234, s5678, filter);
      int16x4_t d2 = convolve8_4_y(s2345, s6789, filter);
      int16x4_t d3 = convolve8_4_y(s3456, s789A, filter);

      // We halved the filter values so -1 from right shift.
      uint16x8_t d01 = vreinterpretq_u16_s16(vrsraq_n_s16(
          round_offset_vec, vcombine_s16(d0, d1), ROUND0_BITS - 1));
      uint16x8_t d23 = vreinterpretq_u16_s16(vrsraq_n_s16(
          round_offset_vec, vcombine_s16(d2, d3), ROUND0_BITS - 1));

      uint16x4_t dd0, dd1, dd2, dd3;
      load_u16_4x4(dst_ptr, dst_stride, &dd0, &dd1, &dd2, &dd3);

      uint8x8_t d0_u8, d1_u8;
      compute_dist_wtd_avg_8x2(vcombine_u16(dd0, dd1), vcombine_u16(dd2, dd3),
                               d01, d23, fwd_offset, bck_offset,
                               round_offset_vec, &d0_u8, &d1_u8);

      store_u8x4_strided_x2(dst8_ptr + 0 * dst8_stride, dst8_stride, d0_u8);
      store_u8x4_strided_x2(dst8_ptr + 2 * dst8_stride, dst8_stride, d1_u8);

      // Prepare block for next iteration - re-using as much as possible.
      // Shuffle everything up four rows.
      s0123 = s4567;
      s1234 = s5678;
      s2345 = s6789;
      s3456 = s789A;

      src_ptr += 4 * src_stride;
      dst_ptr += 4 * dst_stride;
      dst8_ptr += 4 * dst8_stride;
      h -= 4;
    } while (h != 0);
  } else {
    do {
      int height = h;
      const uint8_t *s = src_ptr;
      CONV_BUF_TYPE *d = dst_ptr;
      uint8_t *d_u8 = dst8_ptr;

      uint8x8_t t0, t1, t2, t3, t4, t5, t6;
      load_u8_8x7(s, src_stride, &t0, &t1, &t2, &t3, &t4, &t5, &t6);
      s += 7 * src_stride;

      // Transform sample range to [-128, 127] for 8-bit signed dot product.
      int8x8_t s0 = vreinterpret_s8_u8(vsub_u8(t0, vdup_n_u8(128)));
      int8x8_t s1 = vreinterpret_s8_u8(vsub_u8(t1, vdup_n_u8(128)));
      int8x8_t s2 = vreinterpret_s8_u8(vsub_u8(t2, vdup_n_u8(128)));
      int8x8_t s3 = vreinterpret_s8_u8(vsub_u8(t3, vdup_n_u8(128)));
      int8x8_t s4 = vreinterpret_s8_u8(vsub_u8(t4, vdup_n_u8(128)));
      int8x8_t s5 = vreinterpret_s8_u8(vsub_u8(t5, vdup_n_u8(128)));
      int8x8_t s6 = vreinterpret_s8_u8(vsub_u8(t6, vdup_n_u8(128)));

      // This operation combines a conventional transpose and the sample
      // permute (see horizontal case) required before computing the dot
      // product.
      int8x16_t s0123_lo, s0123_hi, s1234_lo, s1234_hi, s2345_lo, s2345_hi,
          s3456_lo, s3456_hi;
      transpose_concat_elems_s8_8x4(s0, s1, s2, s3, &s0123_lo, &s0123_hi);
      transpose_concat_elems_s8_8x4(s1, s2, s3, s4, &s1234_lo, &s1234_hi);
      transpose_concat_elems_s8_8x4(s2, s3, s4, s5, &s2345_lo, &s2345_hi);
      transpose_concat_elems_s8_8x4(s3, s4, s5, s6, &s3456_lo, &s3456_hi);

      do {
        uint8x8_t t7, t8, t9, tA;
        load_u8_8x4(s, src_stride, &t7, &t8, &t9, &tA);

        int8x8_t s7 = vreinterpret_s8_u8(vsub_u8(t7, vdup_n_u8(128)));
        int8x8_t s8 = vreinterpret_s8_u8(vsub_u8(t8, vdup_n_u8(128)));
        int8x8_t s9 = vreinterpret_s8_u8(vsub_u8(t9, vdup_n_u8(128)));
        int8x8_t sA = vreinterpret_s8_u8(vsub_u8(tA, vdup_n_u8(128)));

        int8x16_t s4567_lo, s4567_hi, s5678_lo, s5678_hi, s6789_lo, s6789_hi,
            s789A_lo, s789A_hi;
        transpose_concat_elems_s8_8x4(s7, s8, s9, sA, &s789A_lo, &s789A_hi);

        // Merge new data into block from previous iteration.
        int8x16x2_t samples_LUT_lo = { { s3456_lo, s789A_lo } };
        s4567_lo = vqtbl2q_s8(samples_LUT_lo, merge_block_tbl.val[0]);
        s5678_lo = vqtbl2q_s8(samples_LUT_lo, merge_block_tbl.val[1]);
        s6789_lo = vqtbl2q_s8(samples_LUT_lo, merge_block_tbl.val[2]);

        int8x16x2_t samples_LUT_hi = { { s3456_hi, s789A_hi } };
        s4567_hi = vqtbl2q_s8(samples_LUT_hi, merge_block_tbl.val[0]);
        s5678_hi = vqtbl2q_s8(samples_LUT_hi, merge_block_tbl.val[1]);
        s6789_hi = vqtbl2q_s8(samples_LUT_hi, merge_block_tbl.val[2]);

        uint16x8_t d0 = convolve8_8_y(s0123_lo, s0123_hi, s4567_lo, s4567_hi,
                                      filter, round_offset_vec);
        uint16x8_t d1 = convolve8_8_y(s1234_lo, s1234_hi, s5678_lo, s5678_hi,
                                      filter, round_offset_vec);
        uint16x8_t d2 = convolve8_8_y(s2345_lo, s2345_hi, s6789_lo, s6789_hi,
                                      filter, round_offset_vec);
        uint16x8_t d3 = convolve8_8_y(s3456_lo, s3456_hi, s789A_lo, s789A_hi,
                                      filter, round_offset_vec);

        uint16x8_t dd0, dd1, dd2, dd3;
        load_u16_8x4(d, dst_stride, &dd0, &dd1, &dd2, &dd3);

        uint8x8_t d0_u8, d1_u8, d2_u8, d3_u8;
        compute_dist_wtd_avg_8x4(dd0, dd1, dd2, dd3, d0, d1, d2, d3, fwd_offset,
                                 bck_offset, round_offset_vec, &d0_u8, &d1_u8,
                                 &d2_u8, &d3_u8);

        store_u8_8x4(d_u8, dst8_stride, d0_u8, d1_u8, d2_u8, d3_u8);

        // Prepare block for next iteration - re-using as much as possible.
        // Shuffle everything up four rows.
        s0123_lo = s4567_lo;
        s0123_hi = s4567_hi;
        s1234_lo = s5678_lo;
        s1234_hi = s5678_hi;
        s2345_lo = s6789_lo;
        s2345_hi = s6789_hi;
        s3456_lo = s789A_lo;
        s3456_hi = s789A_hi;

        s += 4 * src_stride;
        d += 4 * dst_stride;
        d_u8 += 4 * dst8_stride;
        height -= 4;
      } while (height != 0);
      src_ptr += 8;
      dst_ptr += 8;
      dst8_ptr += 8;
      w -= 8;
    } while (w != 0);
  }
}

static inline void dist_wtd_convolve_y_8tap_avg_neon_dotprod(
    const uint8_t *src_ptr, int src_stride, uint8_t *dst8_ptr,
    const int dst8_stride, int w, int h, const int16_t *y_filter_ptr,
    ConvolveParams *conv_params) {
  const int bd = 8;
  const int offset_bits = bd + 2 * FILTER_BITS - ROUND0_BITS;
  const int16_t round_offset = (1 << (offset_bits - COMPOUND_ROUND1_BITS)) +
                               (1 << (offset_bits - COMPOUND_ROUND1_BITS - 1));
  const int16x8_t round_offset_vec = vdupq_n_s16(round_offset);

  CONV_BUF_TYPE *dst_ptr = conv_params->dst;
  const int dst_stride = conv_params->dst_stride;

  // Filter values are even, so halve to reduce intermediate precision reqs.
  const int8x8_t filter = vshrn_n_s16(vld1q_s16(y_filter_ptr), 1);

  const uint8x16x3_t merge_block_tbl = vld1q_u8_x3(kDotProdMergeBlockTbl);

  if (w == 4) {
    uint8x8_t t0, t1, t2, t3, t4, t5, t6;
    load_u8_8x7(src_ptr, src_stride, &t0, &t1, &t2, &t3, &t4, &t5, &t6);
    src_ptr += 7 * src_stride;

    // Transform sample range to [-128, 127] for 8-bit signed dot product.
    int8x8_t s0 = vreinterpret_s8_u8(vsub_u8(t0, vdup_n_u8(128)));
    int8x8_t s1 = vreinterpret_s8_u8(vsub_u8(t1, vdup_n_u8(128)));
    int8x8_t s2 = vreinterpret_s8_u8(vsub_u8(t2, vdup_n_u8(128)));
    int8x8_t s3 = vreinterpret_s8_u8(vsub_u8(t3, vdup_n_u8(128)));
    int8x8_t s4 = vreinterpret_s8_u8(vsub_u8(t4, vdup_n_u8(128)));
    int8x8_t s5 = vreinterpret_s8_u8(vsub_u8(t5, vdup_n_u8(128)));
    int8x8_t s6 = vreinterpret_s8_u8(vsub_u8(t6, vdup_n_u8(128)));

    int8x16_t s0123, s1234, s2345, s3456;
    transpose_concat_elems_s8_4x4(s0, s1, s2, s3, &s0123);
    transpose_concat_elems_s8_4x4(s1, s2, s3, s4, &s1234);
    transpose_concat_elems_s8_4x4(s2, s3, s4, s5, &s2345);
    transpose_concat_elems_s8_4x4(s3, s4, s5, s6, &s3456);

    do {
      uint8x8_t t7, t8, t9, tA;
      load_u8_8x4(src_ptr, src_stride, &t7, &t8, &t9, &tA);

      int8x8_t s7 = vreinterpret_s8_u8(vsub_u8(t7, vdup_n_u8(128)));
      int8x8_t s8 = vreinterpret_s8_u8(vsub_u8(t8, vdup_n_u8(128)));
      int8x8_t s9 = vreinterpret_s8_u8(vsub_u8(t9, vdup_n_u8(128)));
      int8x8_t sA = vreinterpret_s8_u8(vsub_u8(tA, vdup_n_u8(128)));

      int8x16_t s4567, s5678, s6789, s789A;
      transpose_concat_elems_s8_4x4(s7, s8, s9, sA, &s789A);

      // Merge new data into block from previous iteration.
      int8x16x2_t samples_LUT = { { s3456, s789A } };
      s4567 = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[0]);
      s5678 = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[1]);
      s6789 = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[2]);

      int16x4_t d0 = convolve8_4_y(s0123, s4567, filter);
      int16x4_t d1 = convolve8_4_y(s1234, s5678, filter);
      int16x4_t d2 = convolve8_4_y(s2345, s6789, filter);
      int16x4_t d3 = convolve8_4_y(s3456, s789A, filter);

      // We halved the filter values so -1 from right shift.
      uint16x8_t d01 = vreinterpretq_u16_s16(vrsraq_n_s16(
          round_offset_vec, vcombine_s16(d0, d1), ROUND0_BITS - 1));
      uint16x8_t d23 = vreinterpretq_u16_s16(vrsraq_n_s16(
          round_offset_vec, vcombine_s16(d2, d3), ROUND0_BITS - 1));

      uint16x4_t dd0, dd1, dd2, dd3;
      load_u16_4x4(dst_ptr, dst_stride, &dd0, &dd1, &dd2, &dd3);

      uint8x8_t d0_u8, d1_u8;
      compute_basic_avg_8x2(vcombine_u16(dd0, dd1), vcombine_u16(dd2, dd3), d01,
                            d23, round_offset_vec, &d0_u8, &d1_u8);

      store_u8x4_strided_x2(dst8_ptr + 0 * dst8_stride, dst8_stride, d0_u8);
      store_u8x4_strided_x2(dst8_ptr + 2 * dst8_stride, dst8_stride, d1_u8);

      // Prepare block for next iteration - re-using as much as possible.
      // Shuffle everything up four rows.
      s0123 = s4567;
      s1234 = s5678;
      s2345 = s6789;
      s3456 = s789A;

      src_ptr += 4 * src_stride;
      dst_ptr += 4 * dst_stride;
      dst8_ptr += 4 * dst8_stride;
      h -= 4;
    } while (h != 0);
  } else {
    do {
      int height = h;
      const uint8_t *s = src_ptr;
      CONV_BUF_TYPE *d = dst_ptr;
      uint8_t *d_u8 = dst8_ptr;

      uint8x8_t t0, t1, t2, t3, t4, t5, t6;
      load_u8_8x7(s, src_stride, &t0, &t1, &t2, &t3, &t4, &t5, &t6);
      s += 7 * src_stride;

      // Transform sample range to [-128, 127] for 8-bit signed dot product.
      int8x8_t s0 = vreinterpret_s8_u8(vsub_u8(t0, vdup_n_u8(128)));
      int8x8_t s1 = vreinterpret_s8_u8(vsub_u8(t1, vdup_n_u8(128)));
      int8x8_t s2 = vreinterpret_s8_u8(vsub_u8(t2, vdup_n_u8(128)));
      int8x8_t s3 = vreinterpret_s8_u8(vsub_u8(t3, vdup_n_u8(128)));
      int8x8_t s4 = vreinterpret_s8_u8(vsub_u8(t4, vdup_n_u8(128)));
      int8x8_t s5 = vreinterpret_s8_u8(vsub_u8(t5, vdup_n_u8(128)));
      int8x8_t s6 = vreinterpret_s8_u8(vsub_u8(t6, vdup_n_u8(128)));

      // This operation combines a conventional transpose and the sample
      // permute (see horizontal case) required before computing the dot
      // product.
      int8x16_t s0123_lo, s0123_hi, s1234_lo, s1234_hi, s2345_lo, s2345_hi,
          s3456_lo, s3456_hi;
      transpose_concat_elems_s8_8x4(s0, s1, s2, s3, &s0123_lo, &s0123_hi);
      transpose_concat_elems_s8_8x4(s1, s2, s3, s4, &s1234_lo, &s1234_hi);
      transpose_concat_elems_s8_8x4(s2, s3, s4, s5, &s2345_lo, &s2345_hi);
      transpose_concat_elems_s8_8x4(s3, s4, s5, s6, &s3456_lo, &s3456_hi);

      do {
        uint8x8_t t7, t8, t9, tA;
        load_u8_8x4(s, src_stride, &t7, &t8, &t9, &tA);

        int8x8_t s7 = vreinterpret_s8_u8(vsub_u8(t7, vdup_n_u8(128)));
        int8x8_t s8 = vreinterpret_s8_u8(vsub_u8(t8, vdup_n_u8(128)));
        int8x8_t s9 = vreinterpret_s8_u8(vsub_u8(t9, vdup_n_u8(128)));
        int8x8_t sA = vreinterpret_s8_u8(vsub_u8(tA, vdup_n_u8(128)));

        int8x16_t s4567_lo, s4567_hi, s5678_lo, s5678_hi, s6789_lo, s6789_hi,
            s789A_lo, s789A_hi;
        transpose_concat_elems_s8_8x4(s7, s8, s9, sA, &s789A_lo, &s789A_hi);

        // Merge new data into block from previous iteration.
        int8x16x2_t samples_LUT_lo = { { s3456_lo, s789A_lo } };
        s4567_lo = vqtbl2q_s8(samples_LUT_lo, merge_block_tbl.val[0]);
        s5678_lo = vqtbl2q_s8(samples_LUT_lo, merge_block_tbl.val[1]);
        s6789_lo = vqtbl2q_s8(samples_LUT_lo, merge_block_tbl.val[2]);

        int8x16x2_t samples_LUT_hi = { { s3456_hi, s789A_hi } };
        s4567_hi = vqtbl2q_s8(samples_LUT_hi, merge_block_tbl.val[0]);
        s5678_hi = vqtbl2q_s8(samples_LUT_hi, merge_block_tbl.val[1]);
        s6789_hi = vqtbl2q_s8(samples_LUT_hi, merge_block_tbl.val[2]);

        uint16x8_t d0 = convolve8_8_y(s0123_lo, s0123_hi, s4567_lo, s4567_hi,
                                      filter, round_offset_vec);
        uint16x8_t d1 = convolve8_8_y(s1234_lo, s1234_hi, s5678_lo, s5678_hi,
                                      filter, round_offset_vec);
        uint16x8_t d2 = convolve8_8_y(s2345_lo, s2345_hi, s6789_lo, s6789_hi,
                                      filter, round_offset_vec);
        uint16x8_t d3 = convolve8_8_y(s3456_lo, s3456_hi, s789A_lo, s789A_hi,
                                      filter, round_offset_vec);

        uint16x8_t dd0, dd1, dd2, dd3;
        load_u16_8x4(d, dst_stride, &dd0, &dd1, &dd2, &dd3);

        uint8x8_t d0_u8, d1_u8, d2_u8, d3_u8;
        compute_basic_avg_8x4(dd0, dd1, dd2, dd3, d0, d1, d2, d3,
                              round_offset_vec, &d0_u8, &d1_u8, &d2_u8, &d3_u8);

        store_u8_8x4(d_u8, dst8_stride, d0_u8, d1_u8, d2_u8, d3_u8);

        // Prepare block for next iteration - re-using as much as possible.
        // Shuffle everything up four rows.
        s0123_lo = s4567_lo;
        s0123_hi = s4567_hi;
        s1234_lo = s5678_lo;
        s1234_hi = s5678_hi;
        s2345_lo = s6789_lo;
        s2345_hi = s6789_hi;
        s3456_lo = s789A_lo;
        s3456_hi = s789A_hi;

        s += 4 * src_stride;
        d += 4 * dst_stride;
        d_u8 += 4 * dst8_stride;
        height -= 4;
      } while (height != 0);
      src_ptr += 8;
      dst_ptr += 8;
      dst8_ptr += 8;
      w -= 8;
    } while (w != 0);
  }
}

static inline int16x4_t convolve4_4_y(const int8x16_t s0,
                                      const int8x8_t filters) {
  // The sample range transform and permutation are performed by the caller.
  // Accumulate into 128 << FILTER_BITS to account for range transform.
  // (- 1 since we halved the filters.)
  const int32x4_t acc = vdupq_n_s32(128 << (FILTER_BITS - 1));

  int32x4_t sum = vdotq_lane_s32(acc, s0, filters, 0);

  // Further narrowing and packing is performed by the caller.
  return vmovn_s32(sum);
}

static inline uint16x8_t convolve4_8_y(const int8x16_t s0, const int8x16_t s1,
                                       const int8x8_t filters,
                                       const int16x8_t round_offset) {
  // The sample range transform and permutation are performed by the caller.
  // Accumulate into 128 << FILTER_BITS to account for range transform.
  // (- 1 since we halved the filters.)
  const int32x4_t acc = vdupq_n_s32(128 << (FILTER_BITS - 1));

  int32x4_t sum0123 = vdotq_lane_s32(acc, s0, filters, 0);
  int32x4_t sum4567 = vdotq_lane_s32(acc, s1, filters, 0);

  // Narrow and re-pack.
  int16x8_t sum = vcombine_s16(vmovn_s32(sum0123), vmovn_s32(sum4567));

  // We halved the filter values so -1 from right shift.
  return vreinterpretq_u16_s16(
      vrsraq_n_s16(round_offset, sum, ROUND0_BITS - 1));
}

static inline void dist_wtd_convolve_y_4tap_neon_dotprod(
    const uint8_t *src_ptr, int src_stride, int w, int h,
    const int16_t *y_filter_ptr, ConvolveParams *conv_params) {
  const int bd = 8;
  const int offset_bits = bd + 2 * FILTER_BITS - ROUND0_BITS;
  const int16_t round_offset = (1 << (offset_bits - COMPOUND_ROUND1_BITS)) +
                               (1 << (offset_bits - COMPOUND_ROUND1_BITS - 1));
  const int16x8_t round_offset_vec = vdupq_n_s16(round_offset);

  CONV_BUF_TYPE *dst_ptr = conv_params->dst;
  const int dst_stride = conv_params->dst_stride;

  // Filter values are even, so halve to reduce intermediate precision reqs.
  const int16x8_t filter_s16 =
      vcombine_s16(vld1_s16(y_filter_ptr + 2), vdup_n_s16(0));
  const int8x8_t filter = vshrn_n_s16(filter_s16, 1);
  const uint8x16x3_t merge_block_tbl = vld1q_u8_x3(kDotProdMergeBlockTbl);
  int8x16x2_t samples_LUT;

  if (w == 4) {
    uint8x8_t t0, t1, t2, t3;
    load_u8_8x4(src_ptr, src_stride, &t0, &t1, &t2, &t3);
    src_ptr += 4 * src_stride;

    // Transform sample range to [-128, 127] for 8-bit signed dot product.
    int8x8_t s0 = vreinterpret_s8_u8(vsub_u8(t0, vdup_n_u8(128)));
    int8x8_t s1 = vreinterpret_s8_u8(vsub_u8(t1, vdup_n_u8(128)));
    int8x8_t s2 = vreinterpret_s8_u8(vsub_u8(t2, vdup_n_u8(128)));
    int8x8_t s3 = vreinterpret_s8_u8(vsub_u8(t3, vdup_n_u8(128)));

    // This operation combines a conventional transpose and the sample permute
    // required before computing the dot product.
    int8x16_t s0123;
    transpose_concat_elems_s8_4x4(s0, s1, s2, s3, &s0123);

    do {
      uint8x8_t t4, t5, t6, t7;
      load_u8_8x4(src_ptr, src_stride, &t4, &t5, &t6, &t7);

      int8x8_t s4 = vreinterpret_s8_u8(vsub_u8(t4, vdup_n_u8(128)));
      int8x8_t s5 = vreinterpret_s8_u8(vsub_u8(t5, vdup_n_u8(128)));
      int8x8_t s6 = vreinterpret_s8_u8(vsub_u8(t6, vdup_n_u8(128)));
      int8x8_t s7 = vreinterpret_s8_u8(vsub_u8(t7, vdup_n_u8(128)));

      int8x16_t s4567;
      transpose_concat_elems_s8_4x4(s4, s5, s6, s7, &s4567);

      // Merge new data into block from previous iteration.
      samples_LUT.val[0] = s0123;
      samples_LUT.val[1] = s4567;
      int8x16_t s1234 = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[0]);
      int8x16_t s2345 = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[1]);
      int8x16_t s3456 = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[2]);

      int16x4_t d0 = convolve4_4_y(s0123, filter);
      int16x4_t d1 = convolve4_4_y(s1234, filter);
      int16x4_t d2 = convolve4_4_y(s2345, filter);
      int16x4_t d3 = convolve4_4_y(s3456, filter);

      // We halved the filter values so -1 from right shift.
      int16x8_t d01 =
          vrsraq_n_s16(round_offset_vec, vcombine_s16(d0, d1), ROUND0_BITS - 1);
      int16x8_t d23 =
          vrsraq_n_s16(round_offset_vec, vcombine_s16(d2, d3), ROUND0_BITS - 1);

      store_u16x4_strided_x2(dst_ptr + 0 * dst_stride, dst_stride,
                             vreinterpretq_u16_s16(d01));
      store_u16x4_strided_x2(dst_ptr + 2 * dst_stride, dst_stride,
                             vreinterpretq_u16_s16(d23));

      // Prepare block for next iteration - re-using as much as possible.
      // Shuffle everything up four rows.
      s0123 = s4567;

      src_ptr += 4 * src_stride;
      dst_ptr += 4 * dst_stride;
      h -= 4;
    } while (h != 0);
  } else {
    do {
      int height = h;
      const uint8_t *s = src_ptr;
      CONV_BUF_TYPE *d = dst_ptr;

      uint8x8_t t0, t1, t2, t3;
      load_u8_8x4(s, src_stride, &t0, &t1, &t2, &t3);
      s += 4 * src_stride;

      // Transform sample range to [-128, 127] for 8-bit signed dot product.
      int8x8_t s0 = vreinterpret_s8_u8(vsub_u8(t0, vdup_n_u8(128)));
      int8x8_t s1 = vreinterpret_s8_u8(vsub_u8(t1, vdup_n_u8(128)));
      int8x8_t s2 = vreinterpret_s8_u8(vsub_u8(t2, vdup_n_u8(128)));
      int8x8_t s3 = vreinterpret_s8_u8(vsub_u8(t3, vdup_n_u8(128)));

      // This operation combines a conventional transpose and the sample permute
      // required before computing the dot product.
      int8x16_t s0123_lo, s0123_hi;
      transpose_concat_elems_s8_8x4(s0, s1, s2, s3, &s0123_lo, &s0123_hi);

      do {
        uint8x8_t t4, t5, t6, t7;
        load_u8_8x4(s, src_stride, &t4, &t5, &t6, &t7);

        int8x8_t s4 = vreinterpret_s8_u8(vsub_u8(t4, vdup_n_u8(128)));
        int8x8_t s5 = vreinterpret_s8_u8(vsub_u8(t5, vdup_n_u8(128)));
        int8x8_t s6 = vreinterpret_s8_u8(vsub_u8(t6, vdup_n_u8(128)));
        int8x8_t s7 = vreinterpret_s8_u8(vsub_u8(t7, vdup_n_u8(128)));

        int8x16_t s4567_lo, s4567_hi;
        transpose_concat_elems_s8_8x4(s4, s5, s6, s7, &s4567_lo, &s4567_hi);

        // Merge new data into block from previous iteration.
        samples_LUT.val[0] = s0123_lo;
        samples_LUT.val[1] = s4567_lo;
        int8x16_t s1234_lo = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[0]);
        int8x16_t s2345_lo = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[1]);
        int8x16_t s3456_lo = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[2]);

        samples_LUT.val[0] = s0123_hi;
        samples_LUT.val[1] = s4567_hi;
        int8x16_t s1234_hi = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[0]);
        int8x16_t s2345_hi = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[1]);
        int8x16_t s3456_hi = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[2]);

        uint16x8_t d0 =
            convolve4_8_y(s0123_lo, s0123_hi, filter, round_offset_vec);
        uint16x8_t d1 =
            convolve4_8_y(s1234_lo, s1234_hi, filter, round_offset_vec);
        uint16x8_t d2 =
            convolve4_8_y(s2345_lo, s2345_hi, filter, round_offset_vec);
        uint16x8_t d3 =
            convolve4_8_y(s3456_lo, s3456_hi, filter, round_offset_vec);

        store_u16_8x4(d, dst_stride, d0, d1, d2, d3);

        // Prepare block for next iteration - re-using as much as possible.
        // Shuffle everything up four rows.
        s0123_lo = s4567_lo;
        s0123_hi = s4567_hi;

        s += 4 * src_stride;
        d += 4 * dst_stride;
        height -= 4;
      } while (height != 0);
      src_ptr += 8;
      dst_ptr += 8;
      w -= 8;
    } while (w != 0);
  }
}

static inline void dist_wtd_convolve_y_4tap_avg_neon_dotprod(
    const uint8_t *src_ptr, int src_stride, uint8_t *dst8_ptr,
    const int dst8_stride, int w, int h, const int16_t *y_filter_ptr,
    ConvolveParams *conv_params) {
  const int bd = 8;
  const int offset_bits = bd + 2 * FILTER_BITS - ROUND0_BITS;
  const int16_t round_offset = (1 << (offset_bits - COMPOUND_ROUND1_BITS)) +
                               (1 << (offset_bits - COMPOUND_ROUND1_BITS - 1));
  const int16x8_t round_offset_vec = vdupq_n_s16(round_offset);

  CONV_BUF_TYPE *dst_ptr = conv_params->dst;
  const int dst_stride = conv_params->dst_stride;

  // Filter values are even, so halve to reduce intermediate precision reqs.
  const int16x8_t filter_s16 =
      vcombine_s16(vld1_s16(y_filter_ptr + 2), vdup_n_s16(0));
  const int8x8_t filter = vshrn_n_s16(filter_s16, 1);
  const uint8x16x3_t merge_block_tbl = vld1q_u8_x3(kDotProdMergeBlockTbl);
  int8x16x2_t samples_LUT;

  if (w == 4) {
    uint8x8_t t0, t1, t2, t3;
    load_u8_8x4(src_ptr, src_stride, &t0, &t1, &t2, &t3);
    src_ptr += 4 * src_stride;

    // Transform sample range to [-128, 127] for 8-bit signed dot product.
    int8x8_t s0 = vreinterpret_s8_u8(vsub_u8(t0, vdup_n_u8(128)));
    int8x8_t s1 = vreinterpret_s8_u8(vsub_u8(t1, vdup_n_u8(128)));
    int8x8_t s2 = vreinterpret_s8_u8(vsub_u8(t2, vdup_n_u8(128)));
    int8x8_t s3 = vreinterpret_s8_u8(vsub_u8(t3, vdup_n_u8(128)));

    // This operation combines a conventional transpose and the sample permute
    // required before computing the dot product.
    int8x16_t s0123;
    transpose_concat_elems_s8_4x4(s0, s1, s2, s3, &s0123);

    do {
      uint8x8_t t4, t5, t6, t7;
      load_u8_8x4(src_ptr, src_stride, &t4, &t5, &t6, &t7);

      int8x8_t s4 = vreinterpret_s8_u8(vsub_u8(t4, vdup_n_u8(128)));
      int8x8_t s5 = vreinterpret_s8_u8(vsub_u8(t5, vdup_n_u8(128)));
      int8x8_t s6 = vreinterpret_s8_u8(vsub_u8(t6, vdup_n_u8(128)));
      int8x8_t s7 = vreinterpret_s8_u8(vsub_u8(t7, vdup_n_u8(128)));

      int8x16_t s4567;
      transpose_concat_elems_s8_4x4(s4, s5, s6, s7, &s4567);

      // Merge new data into block from previous iteration.
      samples_LUT.val[0] = s0123;
      samples_LUT.val[1] = s4567;
      int8x16_t s1234 = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[0]);
      int8x16_t s2345 = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[1]);
      int8x16_t s3456 = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[2]);

      int16x4_t d0 = convolve4_4_y(s0123, filter);
      int16x4_t d1 = convolve4_4_y(s1234, filter);
      int16x4_t d2 = convolve4_4_y(s2345, filter);
      int16x4_t d3 = convolve4_4_y(s3456, filter);

      // We halved the filter values so -1 from right shift.
      uint16x8_t d01 = vreinterpretq_u16_s16(vrsraq_n_s16(
          round_offset_vec, vcombine_s16(d0, d1), ROUND0_BITS - 1));
      uint16x8_t d23 = vreinterpretq_u16_s16(vrsraq_n_s16(
          round_offset_vec, vcombine_s16(d2, d3), ROUND0_BITS - 1));

      uint16x4_t dd0, dd1, dd2, dd3;
      load_u16_4x4(dst_ptr, dst_stride, &dd0, &dd1, &dd2, &dd3);

      uint8x8_t d0_u8, d1_u8;
      compute_basic_avg_8x2(vcombine_u16(dd0, dd1), vcombine_u16(dd2, dd3), d01,
                            d23, round_offset_vec, &d0_u8, &d1_u8);

      store_u8x4_strided_x2(dst8_ptr + 0 * dst8_stride, dst8_stride, d0_u8);
      store_u8x4_strided_x2(dst8_ptr + 2 * dst8_stride, dst8_stride, d1_u8);

      // Prepare block for next iteration - re-using as much as possible.
      // Shuffle everything up four rows.
      s0123 = s4567;

      src_ptr += 4 * src_stride;
      dst_ptr += 4 * dst_stride;
      dst8_ptr += 4 * dst8_stride;
      h -= 4;
    } while (h != 0);
  } else {
    do {
      int height = h;
      const uint8_t *s = src_ptr;
      CONV_BUF_TYPE *d = dst_ptr;
      uint8_t *d_u8 = dst8_ptr;

      uint8x8_t t0, t1, t2, t3;
      load_u8_8x4(s, src_stride, &t0, &t1, &t2, &t3);
      s += 4 * src_stride;

      // Transform sample range to [-128, 127] for 8-bit signed dot product.
      int8x8_t s0 = vreinterpret_s8_u8(vsub_u8(t0, vdup_n_u8(128)));
      int8x8_t s1 = vreinterpret_s8_u8(vsub_u8(t1, vdup_n_u8(128)));
      int8x8_t s2 = vreinterpret_s8_u8(vsub_u8(t2, vdup_n_u8(128)));
      int8x8_t s3 = vreinterpret_s8_u8(vsub_u8(t3, vdup_n_u8(128)));

      // This operation combines a conventional transpose and the sample permute
      // required before computing the dot product.
      int8x16_t s0123_lo, s0123_hi;
      transpose_concat_elems_s8_8x4(s0, s1, s2, s3, &s0123_lo, &s0123_hi);

      do {
        uint8x8_t t4, t5, t6, t7;
        load_u8_8x4(s, src_stride, &t4, &t5, &t6, &t7);

        int8x8_t s4 = vreinterpret_s8_u8(vsub_u8(t4, vdup_n_u8(128)));
        int8x8_t s5 = vreinterpret_s8_u8(vsub_u8(t5, vdup_n_u8(128)));
        int8x8_t s6 = vreinterpret_s8_u8(vsub_u8(t6, vdup_n_u8(128)));
        int8x8_t s7 = vreinterpret_s8_u8(vsub_u8(t7, vdup_n_u8(128)));

        int8x16_t s4567_lo, s4567_hi;
        transpose_concat_elems_s8_8x4(s4, s5, s6, s7, &s4567_lo, &s4567_hi);

        // Merge new data into block from previous iteration.
        samples_LUT.val[0] = s0123_lo;
        samples_LUT.val[1] = s4567_lo;
        int8x16_t s1234_lo = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[0]);
        int8x16_t s2345_lo = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[1]);
        int8x16_t s3456_lo = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[2]);

        samples_LUT.val[0] = s0123_hi;
        samples_LUT.val[1] = s4567_hi;
        int8x16_t s1234_hi = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[0]);
        int8x16_t s2345_hi = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[1]);
        int8x16_t s3456_hi = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[2]);

        uint16x8_t d0 =
            convolve4_8_y(s0123_lo, s0123_hi, filter, round_offset_vec);
        uint16x8_t d1 =
            convolve4_8_y(s1234_lo, s1234_hi, filter, round_offset_vec);
        uint16x8_t d2 =
            convolve4_8_y(s2345_lo, s2345_hi, filter, round_offset_vec);
        uint16x8_t d3 =
            convolve4_8_y(s3456_lo, s3456_hi, filter, round_offset_vec);

        uint16x8_t dd0, dd1, dd2, dd3;
        load_u16_8x4(d, dst_stride, &dd0, &dd1, &dd2, &dd3);

        uint8x8_t d0_u8, d1_u8, d2_u8, d3_u8;
        compute_basic_avg_8x4(dd0, dd1, dd2, dd3, d0, d1, d2, d3,
                              round_offset_vec, &d0_u8, &d1_u8, &d2_u8, &d3_u8);

        store_u8_8x4(d_u8, dst8_stride, d0_u8, d1_u8, d2_u8, d3_u8);

        // Prepare block for next iteration - re-using as much as possible.
        // Shuffle everything up four rows.
        s0123_lo = s4567_lo;
        s0123_hi = s4567_hi;

        s += 4 * src_stride;
        d += 4 * dst_stride;
        d_u8 += 4 * dst8_stride;
        height -= 4;
      } while (height != 0);
      src_ptr += 8;
      dst_ptr += 8;
      dst8_ptr += 8;
      w -= 8;
    } while (w != 0);
  }
}

static inline void dist_wtd_convolve_y_4tap_dist_wtd_avg_neon_dotprod(
    const uint8_t *src_ptr, int src_stride, uint8_t *dst8_ptr,
    const int dst8_stride, int w, int h, const int16_t *y_filter_ptr,
    ConvolveParams *conv_params) {
  const int bd = 8;
  const int offset_bits = bd + 2 * FILTER_BITS - ROUND0_BITS;
  const int16_t round_offset = (1 << (offset_bits - COMPOUND_ROUND1_BITS)) +
                               (1 << (offset_bits - COMPOUND_ROUND1_BITS - 1));
  const int16x8_t round_offset_vec = vdupq_n_s16(round_offset);

  const uint16_t fwd_offset = conv_params->fwd_offset;
  const uint16_t bck_offset = conv_params->bck_offset;

  CONV_BUF_TYPE *dst_ptr = conv_params->dst;
  const int dst_stride = conv_params->dst_stride;

  // Filter values are even, so halve to reduce intermediate precision reqs.
  const int16x8_t filter_s16 =
      vcombine_s16(vld1_s16(y_filter_ptr + 2), vdup_n_s16(0));
  const int8x8_t filter = vshrn_n_s16(filter_s16, 1);
  const uint8x16x3_t merge_block_tbl = vld1q_u8_x3(kDotProdMergeBlockTbl);
  int8x16x2_t samples_LUT;

  if (w == 4) {
    uint8x8_t t0, t1, t2, t3;
    load_u8_8x4(src_ptr, src_stride, &t0, &t1, &t2, &t3);
    src_ptr += 4 * src_stride;

    // Transform sample range to [-128, 127] for 8-bit signed dot product.
    int8x8_t s0 = vreinterpret_s8_u8(vsub_u8(t0, vdup_n_u8(128)));
    int8x8_t s1 = vreinterpret_s8_u8(vsub_u8(t1, vdup_n_u8(128)));
    int8x8_t s2 = vreinterpret_s8_u8(vsub_u8(t2, vdup_n_u8(128)));
    int8x8_t s3 = vreinterpret_s8_u8(vsub_u8(t3, vdup_n_u8(128)));

    // This operation combines a conventional transpose and the sample permute
    // required before computing the dot product.
    int8x16_t s0123;
    transpose_concat_elems_s8_4x4(s0, s1, s2, s3, &s0123);

    do {
      uint8x8_t t4, t5, t6, t7;
      load_u8_8x4(src_ptr, src_stride, &t4, &t5, &t6, &t7);

      int8x8_t s4 = vreinterpret_s8_u8(vsub_u8(t4, vdup_n_u8(128)));
      int8x8_t s5 = vreinterpret_s8_u8(vsub_u8(t5, vdup_n_u8(128)));
      int8x8_t s6 = vreinterpret_s8_u8(vsub_u8(t6, vdup_n_u8(128)));
      int8x8_t s7 = vreinterpret_s8_u8(vsub_u8(t7, vdup_n_u8(128)));

      int8x16_t s4567;
      transpose_concat_elems_s8_4x4(s4, s5, s6, s7, &s4567);

      // Merge new data into block from previous iteration.
      samples_LUT.val[0] = s0123;
      samples_LUT.val[1] = s4567;
      int8x16_t s1234 = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[0]);
      int8x16_t s2345 = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[1]);
      int8x16_t s3456 = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[2]);

      int16x4_t d0 = convolve4_4_y(s0123, filter);
      int16x4_t d1 = convolve4_4_y(s1234, filter);
      int16x4_t d2 = convolve4_4_y(s2345, filter);
      int16x4_t d3 = convolve4_4_y(s3456, filter);

      // We halved the filter values so -1 from right shift.
      uint16x8_t d01 = vreinterpretq_u16_s16(vrsraq_n_s16(
          round_offset_vec, vcombine_s16(d0, d1), ROUND0_BITS - 1));
      uint16x8_t d23 = vreinterpretq_u16_s16(vrsraq_n_s16(
          round_offset_vec, vcombine_s16(d2, d3), ROUND0_BITS - 1));

      uint16x4_t dd0, dd1, dd2, dd3;
      load_u16_4x4(dst_ptr, dst_stride, &dd0, &dd1, &dd2, &dd3);

      uint8x8_t d0_u8, d1_u8;
      compute_dist_wtd_avg_8x2(vcombine_u16(dd0, dd1), vcombine_u16(dd2, dd3),
                               d01, d23, fwd_offset, bck_offset,
                               round_offset_vec, &d0_u8, &d1_u8);

      store_u8x4_strided_x2(dst8_ptr + 0 * dst8_stride, dst8_stride, d0_u8);
      store_u8x4_strided_x2(dst8_ptr + 2 * dst8_stride, dst8_stride, d1_u8);

      // Prepare block for next iteration - re-using as much as possible.
      // Shuffle everything up four rows.
      s0123 = s4567;

      src_ptr += 4 * src_stride;
      dst_ptr += 4 * dst_stride;
      dst8_ptr += 4 * dst8_stride;
      h -= 4;
    } while (h != 0);
  } else {
    do {
      int height = h;
      const uint8_t *s = src_ptr;
      CONV_BUF_TYPE *d = dst_ptr;
      uint8_t *d_u8 = dst8_ptr;

      uint8x8_t t0, t1, t2, t3;
      load_u8_8x4(s, src_stride, &t0, &t1, &t2, &t3);
      s += 4 * src_stride;

      // Transform sample range to [-128, 127] for 8-bit signed dot product.
      int8x8_t s0 = vreinterpret_s8_u8(vsub_u8(t0, vdup_n_u8(128)));
      int8x8_t s1 = vreinterpret_s8_u8(vsub_u8(t1, vdup_n_u8(128)));
      int8x8_t s2 = vreinterpret_s8_u8(vsub_u8(t2, vdup_n_u8(128)));
      int8x8_t s3 = vreinterpret_s8_u8(vsub_u8(t3, vdup_n_u8(128)));

      // This operation combines a conventional transpose and the sample permute
      // required before computing the dot product.
      int8x16_t s0123_lo, s0123_hi;
      transpose_concat_elems_s8_8x4(s0, s1, s2, s3, &s0123_lo, &s0123_hi);

      do {
        uint8x8_t t4, t5, t6, t7;
        load_u8_8x4(s, src_stride, &t4, &t5, &t6, &t7);

        int8x8_t s4 = vreinterpret_s8_u8(vsub_u8(t4, vdup_n_u8(128)));
        int8x8_t s5 = vreinterpret_s8_u8(vsub_u8(t5, vdup_n_u8(128)));
        int8x8_t s6 = vreinterpret_s8_u8(vsub_u8(t6, vdup_n_u8(128)));
        int8x8_t s7 = vreinterpret_s8_u8(vsub_u8(t7, vdup_n_u8(128)));

        int8x16_t s4567_lo, s4567_hi;
        transpose_concat_elems_s8_8x4(s4, s5, s6, s7, &s4567_lo, &s4567_hi);

        // Merge new data into block from previous iteration.
        samples_LUT.val[0] = s0123_lo;
        samples_LUT.val[1] = s4567_lo;
        int8x16_t s1234_lo = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[0]);
        int8x16_t s2345_lo = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[1]);
        int8x16_t s3456_lo = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[2]);

        samples_LUT.val[0] = s0123_hi;
        samples_LUT.val[1] = s4567_hi;
        int8x16_t s1234_hi = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[0]);
        int8x16_t s2345_hi = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[1]);
        int8x16_t s3456_hi = vqtbl2q_s8(samples_LUT, merge_block_tbl.val[2]);

        uint16x8_t d0 =
            convolve4_8_y(s0123_lo, s0123_hi, filter, round_offset_vec);
        uint16x8_t d1 =
            convolve4_8_y(s1234_lo, s1234_hi, filter, round_offset_vec);
        uint16x8_t d2 =
            convolve4_8_y(s2345_lo, s2345_hi, filter, round_offset_vec);
        uint16x8_t d3 =
            convolve4_8_y(s3456_lo, s3456_hi, filter, round_offset_vec);

        uint16x8_t dd0, dd1, dd2, dd3;
        load_u16_8x4(d, dst_stride, &dd0, &dd1, &dd2, &dd3);

        uint8x8_t d0_u8, d1_u8, d2_u8, d3_u8;
        compute_dist_wtd_avg_8x4(dd0, dd1, dd2, dd3, d0, d1, d2, d3, fwd_offset,
                                 bck_offset, round_offset_vec, &d0_u8, &d1_u8,
                                 &d2_u8, &d3_u8);

        store_u8_8x4(d_u8, dst8_stride, d0_u8, d1_u8, d2_u8, d3_u8);

        // Prepare block for next iteration - re-using as much as possible.
        // Shuffle everything up four rows.
        s0123_lo = s4567_lo;
        s0123_hi = s4567_hi;

        s += 4 * src_stride;
        d += 4 * dst_stride;
        d_u8 += 4 * dst8_stride;
        height -= 4;
      } while (height != 0);
      src_ptr += 8;
      dst_ptr += 8;
      dst8_ptr += 8;
      w -= 8;
    } while (w != 0);
  }
}

void av1_dist_wtd_convolve_y_neon_dotprod(
    const uint8_t *src, int src_stride, uint8_t *dst8, int dst8_stride, int w,
    int h, const InterpFilterParams *filter_params_y, const int subpel_y_qn,
    ConvolveParams *conv_params) {
  assert(w % 4 == 0);
  assert(h % 4 == 0);

  const int16_t *y_filter_ptr = av1_get_interp_filter_subpel_kernel(
      filter_params_y, subpel_y_qn & SUBPEL_MASK);

  if (get_filter_tap(filter_params_y, subpel_y_qn) <= 4) {
    if (conv_params->do_average) {
      if (UNLIKELY(conv_params->use_dist_wtd_comp_avg)) {
        dist_wtd_convolve_y_4tap_dist_wtd_avg_neon_dotprod(
            src - src_stride, src_stride, dst8, dst8_stride, w, h, y_filter_ptr,
            conv_params);
      } else {
        dist_wtd_convolve_y_4tap_avg_neon_dotprod(src - src_stride, src_stride,
                                                  dst8, dst8_stride, w, h,
                                                  y_filter_ptr, conv_params);
      }
    } else {
      dist_wtd_convolve_y_4tap_neon_dotprod(src - src_stride, src_stride, w, h,
                                            y_filter_ptr, conv_params);
    }
  } else {  // filter tap >= 6
    if (conv_params->do_average) {
      if (UNLIKELY(conv_params->use_dist_wtd_comp_avg)) {
        dist_wtd_convolve_y_8tap_dist_wtd_avg_neon_dotprod(
            src - 3 * src_stride, src_stride, dst8, dst8_stride, w, h,
            y_filter_ptr, conv_params);
      } else {
        dist_wtd_convolve_y_8tap_avg_neon_dotprod(
            src - 3 * src_stride, src_stride, dst8, dst8_stride, w, h,
            y_filter_ptr, conv_params);
      }
    } else {
      dist_wtd_convolve_y_8tap_neon_dotprod(src - 3 * src_stride, src_stride, w,
                                            h, y_filter_ptr, conv_params);
    }
  }
}