av1/common/arm/convolve_scale_neon.h

/*
 * Copyright (c) 2024, 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.
 */

#ifndef AOM_AV1_COMMON_ARM_CONVOLVE_SCALE_NEON_H_
#define AOM_AV1_COMMON_ARM_CONVOLVE_SCALE_NEON_H_

#include <assert.h>
#include <arm_neon.h>

#include "config/aom_config.h"
#include "config/av1_rtcd.h"

#include "aom_dsp/arm/mem_neon.h"
#include "aom_dsp/arm/transpose_neon.h"

static inline int16x4_t compound_convolve8_4_v(
    const int16x4_t s0, const int16x4_t s1, const int16x4_t s2,
    const int16x4_t s3, const int16x4_t s4, const int16x4_t s5,
    const int16x4_t s6, const int16x4_t s7, const int16x8_t filter,
    const int32x4_t offset_const) {
  const int16x4_t filter_0_3 = vget_low_s16(filter);
  const int16x4_t filter_4_7 = vget_high_s16(filter);

  int32x4_t sum = offset_const;
  sum = vmlal_lane_s16(sum, s0, filter_0_3, 0);
  sum = vmlal_lane_s16(sum, s1, filter_0_3, 1);
  sum = vmlal_lane_s16(sum, s2, filter_0_3, 2);
  sum = vmlal_lane_s16(sum, s3, filter_0_3, 3);
  sum = vmlal_lane_s16(sum, s4, filter_4_7, 0);
  sum = vmlal_lane_s16(sum, s5, filter_4_7, 1);
  sum = vmlal_lane_s16(sum, s6, filter_4_7, 2);
  sum = vmlal_lane_s16(sum, s7, filter_4_7, 3);

  return vshrn_n_s32(sum, COMPOUND_ROUND1_BITS);
}

static inline int16x8_t compound_convolve8_8_v(
    const int16x8_t s0, const int16x8_t s1, const int16x8_t s2,
    const int16x8_t s3, const int16x8_t s4, const int16x8_t s5,
    const int16x8_t s6, const int16x8_t s7, const int16x8_t filter,
    const int32x4_t offset_const) {
  const int16x4_t filter_0_3 = vget_low_s16(filter);
  const int16x4_t filter_4_7 = vget_high_s16(filter);

  int32x4_t sum0 = offset_const;
  sum0 = vmlal_lane_s16(sum0, vget_low_s16(s0), filter_0_3, 0);
  sum0 = vmlal_lane_s16(sum0, vget_low_s16(s1), filter_0_3, 1);
  sum0 = vmlal_lane_s16(sum0, vget_low_s16(s2), filter_0_3, 2);
  sum0 = vmlal_lane_s16(sum0, vget_low_s16(s3), filter_0_3, 3);
  sum0 = vmlal_lane_s16(sum0, vget_low_s16(s4), filter_4_7, 0);
  sum0 = vmlal_lane_s16(sum0, vget_low_s16(s5), filter_4_7, 1);
  sum0 = vmlal_lane_s16(sum0, vget_low_s16(s6), filter_4_7, 2);
  sum0 = vmlal_lane_s16(sum0, vget_low_s16(s7), filter_4_7, 3);

  int32x4_t sum1 = offset_const;
  sum1 = vmlal_lane_s16(sum1, vget_high_s16(s0), filter_0_3, 0);
  sum1 = vmlal_lane_s16(sum1, vget_high_s16(s1), filter_0_3, 1);
  sum1 = vmlal_lane_s16(sum1, vget_high_s16(s2), filter_0_3, 2);
  sum1 = vmlal_lane_s16(sum1, vget_high_s16(s3), filter_0_3, 3);
  sum1 = vmlal_lane_s16(sum1, vget_high_s16(s4), filter_4_7, 0);
  sum1 = vmlal_lane_s16(sum1, vget_high_s16(s5), filter_4_7, 1);
  sum1 = vmlal_lane_s16(sum1, vget_high_s16(s6), filter_4_7, 2);
  sum1 = vmlal_lane_s16(sum1, vget_high_s16(s7), filter_4_7, 3);

  int16x4_t res0 = vshrn_n_s32(sum0, COMPOUND_ROUND1_BITS);
  int16x4_t res1 = vshrn_n_s32(sum1, COMPOUND_ROUND1_BITS);

  return vcombine_s16(res0, res1);
}

static inline void compound_convolve_vert_scale_8tap_neon(
    const int16_t *src, int src_stride, uint16_t *dst, int dst_stride, int w,
    int h, const int16_t *y_filter, int subpel_y_qn, int y_step_qn) {
  const int bd = 8;
  const int offset_bits = bd + 2 * FILTER_BITS - ROUND0_BITS;
  // A shim of 1 << (COMPOUND_ROUND1_BITS - 1) enables us to use
  // non-rounding shifts - which are generally faster than rounding shifts on
  // modern CPUs.
  const int32x4_t vert_offset =
      vdupq_n_s32((1 << offset_bits) + (1 << (COMPOUND_ROUND1_BITS - 1)));

  int y_qn = subpel_y_qn;

  if (w == 4) {
    do {
      const int16_t *s = &src[(y_qn >> SCALE_SUBPEL_BITS) * src_stride];

      const ptrdiff_t filter_offset =
          SUBPEL_TAPS * ((y_qn & SCALE_SUBPEL_MASK) >> SCALE_EXTRA_BITS);
      const int16x8_t filter = vld1q_s16(y_filter + filter_offset);

      int16x4_t s0, s1, s2, s3, s4, s5, s6, s7;
      load_s16_4x8(s, src_stride, &s0, &s1, &s2, &s3, &s4, &s5, &s6, &s7);

      int16x4_t d0 = compound_convolve8_4_v(s0, s1, s2, s3, s4, s5, s6, s7,
                                            filter, vert_offset);

      vst1_u16(dst, vreinterpret_u16_s16(d0));

      dst += dst_stride;
      y_qn += y_step_qn;
    } while (--h != 0);
  } else {
    do {
      const int16_t *s = &src[(y_qn >> SCALE_SUBPEL_BITS) * src_stride];

      const ptrdiff_t filter_offset =
          SUBPEL_TAPS * ((y_qn & SCALE_SUBPEL_MASK) >> SCALE_EXTRA_BITS);
      const int16x8_t filter = vld1q_s16(y_filter + filter_offset);

      int width = w;
      uint16_t *d = dst;

      do {
        int16x8_t s0, s1, s2, s3, s4, s5, s6, s7;
        load_s16_8x8(s, src_stride, &s0, &s1, &s2, &s3, &s4, &s5, &s6, &s7);

        int16x8_t d0 = compound_convolve8_8_v(s0, s1, s2, s3, s4, s5, s6, s7,
                                              filter, vert_offset);

        vst1q_u16(d, vreinterpretq_u16_s16(d0));

        s += 8;
        d += 8;
        width -= 8;
      } while (width != 0);

      dst += dst_stride;
      y_qn += y_step_qn;
    } while (--h != 0);
  }
}

static inline void compound_avg_convolve_vert_scale_8tap_neon(
    const int16_t *src, int src_stride, uint8_t *dst8, int dst8_stride,
    uint16_t *dst16, int dst16_stride, int w, int h, const int16_t *y_filter,
    int subpel_y_qn, int y_step_qn) {
  const int bd = 8;
  const int offset_bits = bd + 2 * FILTER_BITS - ROUND0_BITS;
  // A shim of 1 << (COMPOUND_ROUND1_BITS - 1) enables us to use
  // non-rounding shifts - which are generally faster than rounding shifts
  // on modern CPUs.
  const int32_t vert_offset_bits =
      (1 << offset_bits) + (1 << (COMPOUND_ROUND1_BITS - 1));
  // For the averaging code path substract round offset and convolve round.
  const int32_t avg_offset_bits = (1 << (offset_bits + 1)) + (1 << offset_bits);
  const int32x4_t vert_offset = vdupq_n_s32(vert_offset_bits - avg_offset_bits);

  int y_qn = subpel_y_qn;

  if (w == 4) {
    do {
      const int16_t *s = &src[(y_qn >> SCALE_SUBPEL_BITS) * src_stride];

      const ptrdiff_t filter_offset =
          SUBPEL_TAPS * ((y_qn & SCALE_SUBPEL_MASK) >> SCALE_EXTRA_BITS);
      const int16x8_t filter = vld1q_s16(y_filter + filter_offset);

      int16x4_t s0, s1, s2, s3, s4, s5, s6, s7;
      load_s16_4x8(s, src_stride, &s0, &s1, &s2, &s3, &s4, &s5, &s6, &s7);

      int16x4_t d0 = compound_convolve8_4_v(s0, s1, s2, s3, s4, s5, s6, s7,
                                            filter, vert_offset);

      int16x4_t dd0 = vreinterpret_s16_u16(vld1_u16(dst16));

      int16x4_t avg = vhadd_s16(dd0, d0);
      int16x8_t d0_s16 = vcombine_s16(avg, vdup_n_s16(0));

      uint8x8_t d0_u8 = vqrshrun_n_s16(
          d0_s16, 2 * FILTER_BITS - ROUND0_BITS - COMPOUND_ROUND1_BITS);

      store_u8_4x1(dst8, d0_u8);

      dst16 += dst16_stride;
      dst8 += dst8_stride;
      y_qn += y_step_qn;
    } while (--h != 0);
  } else {
    do {
      const int16_t *s = &src[(y_qn >> SCALE_SUBPEL_BITS) * src_stride];

      const ptrdiff_t filter_offset =
          SUBPEL_TAPS * ((y_qn & SCALE_SUBPEL_MASK) >> SCALE_EXTRA_BITS);
      const int16x8_t filter = vld1q_s16(y_filter + filter_offset);

      int width = w;
      uint8_t *dst8_ptr = dst8;
      uint16_t *dst16_ptr = dst16;

      do {
        int16x8_t s0, s1, s2, s3, s4, s5, s6, s7;
        load_s16_8x8(s, src_stride, &s0, &s1, &s2, &s3, &s4, &s5, &s6, &s7);

        int16x8_t d0 = compound_convolve8_8_v(s0, s1, s2, s3, s4, s5, s6, s7,
                                              filter, vert_offset);

        int16x8_t dd0 = vreinterpretq_s16_u16(vld1q_u16(dst16_ptr));

        int16x8_t avg = vhaddq_s16(dd0, d0);

        uint8x8_t d0_u8 = vqrshrun_n_s16(
            avg, 2 * FILTER_BITS - ROUND0_BITS - COMPOUND_ROUND1_BITS);

        vst1_u8(dst8_ptr, d0_u8);

        s += 8;
        dst8_ptr += 8;
        dst16_ptr += 8;
        width -= 8;
      } while (width != 0);

      dst16 += dst16_stride;
      dst8 += dst8_stride;
      y_qn += y_step_qn;
    } while (--h != 0);
  }
}

static inline void compound_dist_wtd_convolve_vert_scale_8tap_neon(
    const int16_t *src, int src_stride, uint8_t *dst8, int dst8_stride,
    uint16_t *dst16, int dst16_stride, int w, int h, const int16_t *y_filter,
    ConvolveParams *conv_params, int subpel_y_qn, int y_step_qn) {
  const int bd = 8;
  const int offset_bits = bd + 2 * FILTER_BITS - ROUND0_BITS;
  int y_qn = subpel_y_qn;
  // A shim of 1 << (COMPOUND_ROUND1_BITS - 1) enables us to use
  // non-rounding shifts - which are generally faster than rounding shifts on
  // modern CPUs.
  const int32x4_t vert_offset =
      vdupq_n_s32((1 << offset_bits) + (1 << (COMPOUND_ROUND1_BITS - 1)));
  // For the weighted averaging code path we have to substract round offset and
  // convolve round. The shim of 1 << (2 * FILTER_BITS - ROUND0_BITS -
  // COMPOUND_ROUND1_BITS - 1) enables us to use non-rounding shifts. The
  // additional shift by DIST_PRECISION_BITS is needed in order to merge two
  // shift calculations into one.
  const int32x4_t dist_wtd_offset = vdupq_n_s32(
      (1 << (2 * FILTER_BITS - ROUND0_BITS - COMPOUND_ROUND1_BITS - 1 +
             DIST_PRECISION_BITS)) -
      (1 << (offset_bits - COMPOUND_ROUND1_BITS + DIST_PRECISION_BITS)) -
      (1 << (offset_bits - COMPOUND_ROUND1_BITS - 1 + DIST_PRECISION_BITS)));
  const int16x4_t bck_offset = vdup_n_s16(conv_params->bck_offset);
  const int16x4_t fwd_offset = vdup_n_s16(conv_params->fwd_offset);

  if (w == 4) {
    do {
      const int16_t *s = &src[(y_qn >> SCALE_SUBPEL_BITS) * src_stride];

      const ptrdiff_t filter_offset =
          SUBPEL_TAPS * ((y_qn & SCALE_SUBPEL_MASK) >> SCALE_EXTRA_BITS);
      const int16x8_t filter = vld1q_s16(y_filter + filter_offset);

      int16x4_t s0, s1, s2, s3, s4, s5, s6, s7;
      load_s16_4x8(s, src_stride, &s0, &s1, &s2, &s3, &s4, &s5, &s6, &s7);

      int16x4_t d0 = compound_convolve8_4_v(s0, s1, s2, s3, s4, s5, s6, s7,
                                            filter, vert_offset);

      int16x4_t dd0 = vreinterpret_s16_u16(vld1_u16(dst16));

      int32x4_t dst_wtd_avg = vmlal_s16(dist_wtd_offset, bck_offset, d0);
      dst_wtd_avg = vmlal_s16(dst_wtd_avg, fwd_offset, dd0);

      int16x4_t d0_s16 = vshrn_n_s32(
          dst_wtd_avg, 2 * FILTER_BITS - ROUND0_BITS - COMPOUND_ROUND1_BITS +
                           DIST_PRECISION_BITS);

      uint8x8_t d0_u8 = vqmovun_s16(vcombine_s16(d0_s16, vdup_n_s16(0)));

      store_u8_4x1(dst8, d0_u8);

      dst16 += dst16_stride;
      dst8 += dst8_stride;
      y_qn += y_step_qn;
    } while (--h != 0);
  } else {
    do {
      const int16_t *s = &src[(y_qn >> SCALE_SUBPEL_BITS) * src_stride];

      const ptrdiff_t filter_offset =
          SUBPEL_TAPS * ((y_qn & SCALE_SUBPEL_MASK) >> SCALE_EXTRA_BITS);
      const int16x8_t filter = vld1q_s16(y_filter + filter_offset);

      int width = w;
      uint8_t *dst8_ptr = dst8;
      uint16_t *dst16_ptr = dst16;

      do {
        int16x8_t s0, s1, s2, s3, s4, s5, s6, s7;
        load_s16_8x8(s, src_stride, &s0, &s1, &s2, &s3, &s4, &s5, &s6, &s7);

        int16x8_t d0 = compound_convolve8_8_v(s0, s1, s2, s3, s4, s5, s6, s7,
                                              filter, vert_offset);

        int16x8_t dd0 = vreinterpretq_s16_u16(vld1q_u16(dst16_ptr));

        int32x4_t dst_wtd_avg0 =
            vmlal_s16(dist_wtd_offset, bck_offset, vget_low_s16(d0));
        int32x4_t dst_wtd_avg1 =
            vmlal_s16(dist_wtd_offset, bck_offset, vget_high_s16(d0));

        dst_wtd_avg0 = vmlal_s16(dst_wtd_avg0, fwd_offset, vget_low_s16(dd0));
        dst_wtd_avg1 = vmlal_s16(dst_wtd_avg1, fwd_offset, vget_high_s16(dd0));

        int16x4_t d0_s16_0 = vshrn_n_s32(
            dst_wtd_avg0, 2 * FILTER_BITS - ROUND0_BITS - COMPOUND_ROUND1_BITS +
                              DIST_PRECISION_BITS);
        int16x4_t d0_s16_1 = vshrn_n_s32(
            dst_wtd_avg1, 2 * FILTER_BITS - ROUND0_BITS - COMPOUND_ROUND1_BITS +
                              DIST_PRECISION_BITS);

        uint8x8_t d0_u8 = vqmovun_s16(vcombine_s16(d0_s16_0, d0_s16_1));

        vst1_u8(dst8_ptr, d0_u8);

        s += 8;
        dst8_ptr += 8;
        dst16_ptr += 8;
        width -= 8;
      } while (width != 0);

      dst16 += dst16_stride;
      dst8 += dst8_stride;
      y_qn += y_step_qn;
    } while (--h != 0);
  }
}

static inline uint8x8_t convolve8_4_v(const int16x4_t s0, const int16x4_t s1,
                                      const int16x4_t s2, const int16x4_t s3,
                                      const int16x4_t s4, const int16x4_t s5,
                                      const int16x4_t s6, const int16x4_t s7,
                                      const int16x8_t filter,
                                      const int32x4_t offset_const) {
  const int16x4_t filter_0_3 = vget_low_s16(filter);
  const int16x4_t filter_4_7 = vget_high_s16(filter);

  int32x4_t sum = offset_const;
  sum = vmlal_lane_s16(sum, s0, filter_0_3, 0);
  sum = vmlal_lane_s16(sum, s1, filter_0_3, 1);
  sum = vmlal_lane_s16(sum, s2, filter_0_3, 2);
  sum = vmlal_lane_s16(sum, s3, filter_0_3, 3);
  sum = vmlal_lane_s16(sum, s4, filter_4_7, 0);
  sum = vmlal_lane_s16(sum, s5, filter_4_7, 1);
  sum = vmlal_lane_s16(sum, s6, filter_4_7, 2);
  sum = vmlal_lane_s16(sum, s7, filter_4_7, 3);

  int16x4_t res = vshrn_n_s32(sum, 2 * FILTER_BITS - ROUND0_BITS);

  return vqmovun_s16(vcombine_s16(res, vdup_n_s16(0)));
}

static inline uint8x8_t convolve8_8_v(const int16x8_t s0, const int16x8_t s1,
                                      const int16x8_t s2, const int16x8_t s3,
                                      const int16x8_t s4, const int16x8_t s5,
                                      const int16x8_t s6, const int16x8_t s7,
                                      const int16x8_t filter,
                                      const int32x4_t offset_const) {
  const int16x4_t filter_0_3 = vget_low_s16(filter);
  const int16x4_t filter_4_7 = vget_high_s16(filter);

  int32x4_t sum0 = offset_const;
  sum0 = vmlal_lane_s16(sum0, vget_low_s16(s0), filter_0_3, 0);
  sum0 = vmlal_lane_s16(sum0, vget_low_s16(s1), filter_0_3, 1);
  sum0 = vmlal_lane_s16(sum0, vget_low_s16(s2), filter_0_3, 2);
  sum0 = vmlal_lane_s16(sum0, vget_low_s16(s3), filter_0_3, 3);
  sum0 = vmlal_lane_s16(sum0, vget_low_s16(s4), filter_4_7, 0);
  sum0 = vmlal_lane_s16(sum0, vget_low_s16(s5), filter_4_7, 1);
  sum0 = vmlal_lane_s16(sum0, vget_low_s16(s6), filter_4_7, 2);
  sum0 = vmlal_lane_s16(sum0, vget_low_s16(s7), filter_4_7, 3);

  int32x4_t sum1 = offset_const;
  sum1 = vmlal_lane_s16(sum1, vget_high_s16(s0), filter_0_3, 0);
  sum1 = vmlal_lane_s16(sum1, vget_high_s16(s1), filter_0_3, 1);
  sum1 = vmlal_lane_s16(sum1, vget_high_s16(s2), filter_0_3, 2);
  sum1 = vmlal_lane_s16(sum1, vget_high_s16(s3), filter_0_3, 3);
  sum1 = vmlal_lane_s16(sum1, vget_high_s16(s4), filter_4_7, 0);
  sum1 = vmlal_lane_s16(sum1, vget_high_s16(s5), filter_4_7, 1);
  sum1 = vmlal_lane_s16(sum1, vget_high_s16(s6), filter_4_7, 2);
  sum1 = vmlal_lane_s16(sum1, vget_high_s16(s7), filter_4_7, 3);

  int16x4_t res0 = vshrn_n_s32(sum0, 2 * FILTER_BITS - ROUND0_BITS);
  int16x4_t res1 = vshrn_n_s32(sum1, 2 * FILTER_BITS - ROUND0_BITS);

  return vqmovun_s16(vcombine_s16(res0, res1));
}

static inline void convolve_vert_scale_8tap_neon(
    const int16_t *src, int src_stride, uint8_t *dst, int dst_stride, int w,
    int h, const int16_t *y_filter, int subpel_y_qn, int y_step_qn) {
  const int bd = 8;
  const int offset_bits = bd + 2 * FILTER_BITS - ROUND0_BITS;
  const int round_1 = 2 * FILTER_BITS - ROUND0_BITS;
  // The shim of 1 << (round_1 - 1) enables us to use non-rounding shifts.
  int32x4_t vert_offset =
      vdupq_n_s32((1 << (round_1 - 1)) - (1 << (offset_bits - 1)));

  int y_qn = subpel_y_qn;
  if (w == 4) {
    do {
      const int16_t *s = &src[(y_qn >> SCALE_SUBPEL_BITS) * src_stride];

      const ptrdiff_t filter_offset =
          SUBPEL_TAPS * ((y_qn & SCALE_SUBPEL_MASK) >> SCALE_EXTRA_BITS);
      const int16x8_t filter = vld1q_s16(y_filter + filter_offset);

      int16x4_t s0, s1, s2, s3, s4, s5, s6, s7;
      load_s16_4x8(s, src_stride, &s0, &s1, &s2, &s3, &s4, &s5, &s6, &s7);

      uint8x8_t d =
          convolve8_4_v(s0, s1, s2, s3, s4, s5, s6, s7, filter, vert_offset);

      store_u8_4x1(dst, d);

      dst += dst_stride;
      y_qn += y_step_qn;
    } while (--h != 0);
  } else if (w == 8) {
    do {
      const int16_t *s = &src[(y_qn >> SCALE_SUBPEL_BITS) * src_stride];

      const ptrdiff_t filter_offset =
          SUBPEL_TAPS * ((y_qn & SCALE_SUBPEL_MASK) >> SCALE_EXTRA_BITS);
      const int16x8_t filter = vld1q_s16(y_filter + filter_offset);

      int16x8_t s0, s1, s2, s3, s4, s5, s6, s7;
      load_s16_8x8(s, src_stride, &s0, &s1, &s2, &s3, &s4, &s5, &s6, &s7);

      uint8x8_t d =
          convolve8_8_v(s0, s1, s2, s3, s4, s5, s6, s7, filter, vert_offset);

      vst1_u8(dst, d);

      dst += dst_stride;
      y_qn += y_step_qn;
    } while (--h != 0);
  } else {
    do {
      const int16_t *s = &src[(y_qn >> SCALE_SUBPEL_BITS) * src_stride];
      uint8_t *d = dst;
      int width = w;

      const ptrdiff_t filter_offset =
          SUBPEL_TAPS * ((y_qn & SCALE_SUBPEL_MASK) >> SCALE_EXTRA_BITS);
      const int16x8_t filter = vld1q_s16(y_filter + filter_offset);

      do {
        int16x8_t s0[2], s1[2], s2[2], s3[2], s4[2], s5[2], s6[2], s7[2];
        load_s16_8x8(s, src_stride, &s0[0], &s1[0], &s2[0], &s3[0], &s4[0],
                     &s5[0], &s6[0], &s7[0]);
        load_s16_8x8(s + 8, src_stride, &s0[1], &s1[1], &s2[1], &s3[1], &s4[1],
                     &s5[1], &s6[1], &s7[1]);

        uint8x8_t d0 = convolve8_8_v(s0[0], s1[0], s2[0], s3[0], s4[0], s5[0],
                                     s6[0], s7[0], filter, vert_offset);
        uint8x8_t d1 = convolve8_8_v(s0[1], s1[1], s2[1], s3[1], s4[1], s5[1],
                                     s6[1], s7[1], filter, vert_offset);

        vst1q_u8(d, vcombine_u8(d0, d1));

        s += 16;
        d += 16;
        width -= 16;
      } while (width != 0);

      dst += dst_stride;
      y_qn += y_step_qn;
    } while (--h != 0);
  }
}

static inline int16x4_t compound_convolve6_4_v(
    const int16x4_t s0, const int16x4_t s1, const int16x4_t s2,
    const int16x4_t s3, const int16x4_t s4, const int16x4_t s5,
    const int16x8_t filter, const int32x4_t offset_const) {
  const int16x4_t filter_0_3 = vget_low_s16(filter);
  const int16x4_t filter_4_7 = vget_high_s16(filter);

  int32x4_t sum = offset_const;
  // Filter values at indices 0 and 7 are 0.
  sum = vmlal_lane_s16(sum, s0, filter_0_3, 1);
  sum = vmlal_lane_s16(sum, s1, filter_0_3, 2);
  sum = vmlal_lane_s16(sum, s2, filter_0_3, 3);
  sum = vmlal_lane_s16(sum, s3, filter_4_7, 0);
  sum = vmlal_lane_s16(sum, s4, filter_4_7, 1);
  sum = vmlal_lane_s16(sum, s5, filter_4_7, 2);

  return vshrn_n_s32(sum, COMPOUND_ROUND1_BITS);
}

static inline int16x8_t compound_convolve6_8_v(
    const int16x8_t s0, const int16x8_t s1, const int16x8_t s2,
    const int16x8_t s3, const int16x8_t s4, const int16x8_t s5,
    const int16x8_t filter, const int32x4_t offset_const) {
  const int16x4_t filter_0_3 = vget_low_s16(filter);
  const int16x4_t filter_4_7 = vget_high_s16(filter);

  int32x4_t sum0 = offset_const;
  // Filter values at indices 0 and 7 are 0.
  sum0 = vmlal_lane_s16(sum0, vget_low_s16(s0), filter_0_3, 1);
  sum0 = vmlal_lane_s16(sum0, vget_low_s16(s1), filter_0_3, 2);
  sum0 = vmlal_lane_s16(sum0, vget_low_s16(s2), filter_0_3, 3);
  sum0 = vmlal_lane_s16(sum0, vget_low_s16(s3), filter_4_7, 0);
  sum0 = vmlal_lane_s16(sum0, vget_low_s16(s4), filter_4_7, 1);
  sum0 = vmlal_lane_s16(sum0, vget_low_s16(s5), filter_4_7, 2);

  int32x4_t sum1 = offset_const;
  sum1 = vmlal_lane_s16(sum1, vget_high_s16(s0), filter_0_3, 1);
  sum1 = vmlal_lane_s16(sum1, vget_high_s16(s1), filter_0_3, 2);
  sum1 = vmlal_lane_s16(sum1, vget_high_s16(s2), filter_0_3, 3);
  sum1 = vmlal_lane_s16(sum1, vget_high_s16(s3), filter_4_7, 0);
  sum1 = vmlal_lane_s16(sum1, vget_high_s16(s4), filter_4_7, 1);
  sum1 = vmlal_lane_s16(sum1, vget_high_s16(s5), filter_4_7, 2);

  int16x4_t res0 = vshrn_n_s32(sum0, COMPOUND_ROUND1_BITS);
  int16x4_t res1 = vshrn_n_s32(sum1, COMPOUND_ROUND1_BITS);

  return vcombine_s16(res0, res1);
}

static inline void compound_convolve_vert_scale_6tap_neon(
    const int16_t *src, int src_stride, uint16_t *dst, int dst_stride, int w,
    int h, const int16_t *y_filter, int subpel_y_qn, int y_step_qn) {
  const int bd = 8;
  const int offset_bits = bd + 2 * FILTER_BITS - ROUND0_BITS;
  // A shim of 1 << (COMPOUND_ROUND1_BITS - 1) enables us to use
  // non-rounding shifts - which are generally faster than rounding shifts on
  // modern CPUs.
  const int32x4_t vert_offset =
      vdupq_n_s32((1 << offset_bits) + (1 << (COMPOUND_ROUND1_BITS - 1)));

  int y_qn = subpel_y_qn;

  if (w == 4) {
    do {
      const int16_t *s = &src[(y_qn >> SCALE_SUBPEL_BITS) * src_stride];

      const ptrdiff_t filter_offset =
          SUBPEL_TAPS * ((y_qn & SCALE_SUBPEL_MASK) >> SCALE_EXTRA_BITS);
      const int16x8_t filter = vld1q_s16(y_filter + filter_offset);

      int16x4_t s0, s1, s2, s3, s4, s5;
      load_s16_4x6(s, src_stride, &s0, &s1, &s2, &s3, &s4, &s5);

      int16x4_t d0 =
          compound_convolve6_4_v(s0, s1, s2, s3, s4, s5, filter, vert_offset);

      vst1_u16(dst, vreinterpret_u16_s16(d0));

      dst += dst_stride;
      y_qn += y_step_qn;
    } while (--h != 0);
  } else {
    do {
      const int16_t *s = &src[(y_qn >> SCALE_SUBPEL_BITS) * src_stride];

      const ptrdiff_t filter_offset =
          SUBPEL_TAPS * ((y_qn & SCALE_SUBPEL_MASK) >> SCALE_EXTRA_BITS);
      const int16x8_t filter = vld1q_s16(y_filter + filter_offset);

      int width = w;
      uint16_t *d = dst;

      do {
        int16x8_t s0, s1, s2, s3, s4, s5;
        load_s16_8x6(s, src_stride, &s0, &s1, &s2, &s3, &s4, &s5);

        int16x8_t d0 =
            compound_convolve6_8_v(s0, s1, s2, s3, s4, s5, filter, vert_offset);

        vst1q_u16(d, vreinterpretq_u16_s16(d0));

        s += 8;
        d += 8;
        width -= 8;
      } while (width != 0);

      dst += dst_stride;
      y_qn += y_step_qn;
    } while (--h != 0);
  }
}

static inline void compound_avg_convolve_vert_scale_6tap_neon(
    const int16_t *src, int src_stride, uint8_t *dst8, int dst8_stride,
    uint16_t *dst16, int dst16_stride, int w, int h, const int16_t *y_filter,
    int subpel_y_qn, int y_step_qn) {
  const int bd = 8;
  const int offset_bits = bd + 2 * FILTER_BITS - ROUND0_BITS;
  // A shim of 1 << (COMPOUND_ROUND1_BITS - 1) enables us to use
  // non-rounding shifts - which are generally faster than rounding shifts
  // on modern CPUs.
  const int32_t vert_offset_bits =
      (1 << offset_bits) + (1 << (COMPOUND_ROUND1_BITS - 1));
  // For the averaging code path substract round offset and convolve round.
  const int32_t avg_offset_bits = (1 << (offset_bits + 1)) + (1 << offset_bits);
  const int32x4_t vert_offset = vdupq_n_s32(vert_offset_bits - avg_offset_bits);

  int y_qn = subpel_y_qn;

  if (w == 4) {
    do {
      const int16_t *s = &src[(y_qn >> SCALE_SUBPEL_BITS) * src_stride];

      const ptrdiff_t filter_offset =
          SUBPEL_TAPS * ((y_qn & SCALE_SUBPEL_MASK) >> SCALE_EXTRA_BITS);
      const int16x8_t filter = vld1q_s16(y_filter + filter_offset);

      int16x4_t s0, s1, s2, s3, s4, s5;
      load_s16_4x6(s, src_stride, &s0, &s1, &s2, &s3, &s4, &s5);

      int16x4_t d0 =
          compound_convolve6_4_v(s0, s1, s2, s3, s4, s5, filter, vert_offset);

      int16x4_t dd0 = vreinterpret_s16_u16(vld1_u16(dst16));

      int16x4_t avg = vhadd_s16(dd0, d0);
      int16x8_t d0_s16 = vcombine_s16(avg, vdup_n_s16(0));

      uint8x8_t d0_u8 = vqrshrun_n_s16(
          d0_s16, 2 * FILTER_BITS - ROUND0_BITS - COMPOUND_ROUND1_BITS);

      store_u8_4x1(dst8, d0_u8);

      dst16 += dst16_stride;
      dst8 += dst8_stride;
      y_qn += y_step_qn;
    } while (--h != 0);
  } else {
    do {
      const int16_t *s = &src[(y_qn >> SCALE_SUBPEL_BITS) * src_stride];

      const ptrdiff_t filter_offset =
          SUBPEL_TAPS * ((y_qn & SCALE_SUBPEL_MASK) >> SCALE_EXTRA_BITS);
      const int16x8_t filter = vld1q_s16(y_filter + filter_offset);

      int width = w;
      uint8_t *dst8_ptr = dst8;
      uint16_t *dst16_ptr = dst16;

      do {
        int16x8_t s0, s1, s2, s3, s4, s5;
        load_s16_8x6(s, src_stride, &s0, &s1, &s2, &s3, &s4, &s5);

        int16x8_t d0 =
            compound_convolve6_8_v(s0, s1, s2, s3, s4, s5, filter, vert_offset);

        int16x8_t dd0 = vreinterpretq_s16_u16(vld1q_u16(dst16_ptr));

        int16x8_t avg = vhaddq_s16(dd0, d0);

        uint8x8_t d0_u8 = vqrshrun_n_s16(
            avg, 2 * FILTER_BITS - ROUND0_BITS - COMPOUND_ROUND1_BITS);

        vst1_u8(dst8_ptr, d0_u8);

        s += 8;
        dst8_ptr += 8;
        dst16_ptr += 8;
        width -= 8;
      } while (width != 0);

      dst16 += dst16_stride;
      dst8 += dst8_stride;
      y_qn += y_step_qn;
    } while (--h != 0);
  }
}

static inline void compound_dist_wtd_convolve_vert_scale_6tap_neon(
    const int16_t *src, int src_stride, uint8_t *dst8, int dst8_stride,
    uint16_t *dst16, int dst16_stride, int w, int h, const int16_t *y_filter,
    ConvolveParams *conv_params, int subpel_y_qn, int y_step_qn) {
  const int bd = 8;
  const int offset_bits = bd + 2 * FILTER_BITS - ROUND0_BITS;
  int y_qn = subpel_y_qn;
  // A shim of 1 << (COMPOUND_ROUND1_BITS - 1) enables us to use
  // non-rounding shifts - which are generally faster than rounding shifts on
  // modern CPUs.
  const int32x4_t vert_offset =
      vdupq_n_s32((1 << offset_bits) + (1 << (COMPOUND_ROUND1_BITS - 1)));
  // For the weighted averaging code path we have to substract round offset and
  // convolve round. The shim of 1 << (2 * FILTER_BITS - ROUND0_BITS -
  // COMPOUND_ROUND1_BITS - 1) enables us to use non-rounding shifts. The
  // additional shift by DIST_PRECISION_BITS is needed in order to merge two
  // shift calculations into one.
  const int32x4_t dist_wtd_offset = vdupq_n_s32(
      (1 << (2 * FILTER_BITS - ROUND0_BITS - COMPOUND_ROUND1_BITS - 1 +
             DIST_PRECISION_BITS)) -
      (1 << (offset_bits - COMPOUND_ROUND1_BITS + DIST_PRECISION_BITS)) -
      (1 << (offset_bits - COMPOUND_ROUND1_BITS - 1 + DIST_PRECISION_BITS)));
  const int16x4_t bck_offset = vdup_n_s16(conv_params->bck_offset);
  const int16x4_t fwd_offset = vdup_n_s16(conv_params->fwd_offset);

  if (w == 4) {
    do {
      const int16_t *s = &src[(y_qn >> SCALE_SUBPEL_BITS) * src_stride];

      const ptrdiff_t filter_offset =
          SUBPEL_TAPS * ((y_qn & SCALE_SUBPEL_MASK) >> SCALE_EXTRA_BITS);
      const int16x8_t filter = vld1q_s16(y_filter + filter_offset);

      int16x4_t s0, s1, s2, s3, s4, s5;
      load_s16_4x6(s, src_stride, &s0, &s1, &s2, &s3, &s4, &s5);

      int16x4_t d0 =
          compound_convolve6_4_v(s0, s1, s2, s3, s4, s5, filter, vert_offset);

      int16x4_t dd0 = vreinterpret_s16_u16(vld1_u16(dst16));

      int32x4_t dst_wtd_avg = vmlal_s16(dist_wtd_offset, bck_offset, d0);
      dst_wtd_avg = vmlal_s16(dst_wtd_avg, fwd_offset, dd0);

      int16x4_t d0_s16 = vshrn_n_s32(
          dst_wtd_avg, 2 * FILTER_BITS - ROUND0_BITS - COMPOUND_ROUND1_BITS +
                           DIST_PRECISION_BITS);

      uint8x8_t d0_u8 = vqmovun_s16(vcombine_s16(d0_s16, vdup_n_s16(0)));

      store_u8_4x1(dst8, d0_u8);

      dst16 += dst16_stride;
      dst8 += dst8_stride;
      y_qn += y_step_qn;
    } while (--h != 0);
  } else {
    do {
      const int16_t *s = &src[(y_qn >> SCALE_SUBPEL_BITS) * src_stride];

      const ptrdiff_t filter_offset =
          SUBPEL_TAPS * ((y_qn & SCALE_SUBPEL_MASK) >> SCALE_EXTRA_BITS);
      const int16x8_t filter = vld1q_s16(y_filter + filter_offset);

      int width = w;
      uint8_t *dst8_ptr = dst8;
      uint16_t *dst16_ptr = dst16;

      do {
        int16x8_t s0, s1, s2, s3, s4, s5;
        load_s16_8x6(s, src_stride, &s0, &s1, &s2, &s3, &s4, &s5);

        int16x8_t d0 =
            compound_convolve6_8_v(s0, s1, s2, s3, s4, s5, filter, vert_offset);

        int16x8_t dd0 = vreinterpretq_s16_u16(vld1q_u16(dst16_ptr));

        int32x4_t dst_wtd_avg0 =
            vmlal_s16(dist_wtd_offset, bck_offset, vget_low_s16(d0));
        int32x4_t dst_wtd_avg1 =
            vmlal_s16(dist_wtd_offset, bck_offset, vget_high_s16(d0));

        dst_wtd_avg0 = vmlal_s16(dst_wtd_avg0, fwd_offset, vget_low_s16(dd0));
        dst_wtd_avg1 = vmlal_s16(dst_wtd_avg1, fwd_offset, vget_high_s16(dd0));

        int16x4_t d0_s16_0 = vshrn_n_s32(
            dst_wtd_avg0, 2 * FILTER_BITS - ROUND0_BITS - COMPOUND_ROUND1_BITS +
                              DIST_PRECISION_BITS);
        int16x4_t d0_s16_1 = vshrn_n_s32(
            dst_wtd_avg1, 2 * FILTER_BITS - ROUND0_BITS - COMPOUND_ROUND1_BITS +
                              DIST_PRECISION_BITS);

        uint8x8_t d0_u8 = vqmovun_s16(vcombine_s16(d0_s16_0, d0_s16_1));

        vst1_u8(dst8_ptr, d0_u8);

        s += 8;
        dst8_ptr += 8;
        dst16_ptr += 8;
        width -= 8;
      } while (width != 0);

      dst16 += dst16_stride;
      dst8 += dst8_stride;
      y_qn += y_step_qn;
    } while (--h != 0);
  }
}

static inline uint8x8_t convolve6_4_v(const int16x4_t s0, const int16x4_t s1,
                                      const int16x4_t s2, const int16x4_t s3,
                                      const int16x4_t s4, const int16x4_t s5,
                                      const int16x8_t filter,
                                      const int32x4_t offset_const) {
  const int16x4_t filter_0_3 = vget_low_s16(filter);
  const int16x4_t filter_4_7 = vget_high_s16(filter);

  int32x4_t sum = offset_const;
  // Filter values at indices 0 and 7 are 0.
  sum = vmlal_lane_s16(sum, s0, filter_0_3, 1);
  sum = vmlal_lane_s16(sum, s1, filter_0_3, 2);
  sum = vmlal_lane_s16(sum, s2, filter_0_3, 3);
  sum = vmlal_lane_s16(sum, s3, filter_4_7, 0);
  sum = vmlal_lane_s16(sum, s4, filter_4_7, 1);
  sum = vmlal_lane_s16(sum, s5, filter_4_7, 2);

  int16x4_t res = vshrn_n_s32(sum, 2 * FILTER_BITS - ROUND0_BITS);

  return vqmovun_s16(vcombine_s16(res, vdup_n_s16(0)));
}

static inline uint8x8_t convolve6_8_v(const int16x8_t s0, const int16x8_t s1,
                                      const int16x8_t s2, const int16x8_t s3,
                                      const int16x8_t s4, const int16x8_t s5,
                                      const int16x8_t filter,
                                      const int32x4_t offset_const) {
  const int16x4_t filter_0_3 = vget_low_s16(filter);
  const int16x4_t filter_4_7 = vget_high_s16(filter);

  int32x4_t sum0 = offset_const;
  // Filter values at indices 0 and 7 are 0.
  sum0 = vmlal_lane_s16(sum0, vget_low_s16(s0), filter_0_3, 1);
  sum0 = vmlal_lane_s16(sum0, vget_low_s16(s1), filter_0_3, 2);
  sum0 = vmlal_lane_s16(sum0, vget_low_s16(s2), filter_0_3, 3);
  sum0 = vmlal_lane_s16(sum0, vget_low_s16(s3), filter_4_7, 0);
  sum0 = vmlal_lane_s16(sum0, vget_low_s16(s4), filter_4_7, 1);
  sum0 = vmlal_lane_s16(sum0, vget_low_s16(s5), filter_4_7, 2);

  int32x4_t sum1 = offset_const;
  sum1 = vmlal_lane_s16(sum1, vget_high_s16(s0), filter_0_3, 1);
  sum1 = vmlal_lane_s16(sum1, vget_high_s16(s1), filter_0_3, 2);
  sum1 = vmlal_lane_s16(sum1, vget_high_s16(s2), filter_0_3, 3);
  sum1 = vmlal_lane_s16(sum1, vget_high_s16(s3), filter_4_7, 0);
  sum1 = vmlal_lane_s16(sum1, vget_high_s16(s4), filter_4_7, 1);
  sum1 = vmlal_lane_s16(sum1, vget_high_s16(s5), filter_4_7, 2);

  int16x4_t res0 = vshrn_n_s32(sum0, 2 * FILTER_BITS - ROUND0_BITS);
  int16x4_t res1 = vshrn_n_s32(sum1, 2 * FILTER_BITS - ROUND0_BITS);

  return vqmovun_s16(vcombine_s16(res0, res1));
}

static inline void convolve_vert_scale_6tap_neon(
    const int16_t *src, int src_stride, uint8_t *dst, int dst_stride, int w,
    int h, const int16_t *y_filter, int subpel_y_qn, int y_step_qn) {
  const int bd = 8;
  const int offset_bits = bd + 2 * FILTER_BITS - ROUND0_BITS;
  const int round_1 = 2 * FILTER_BITS - ROUND0_BITS;
  // The shim of 1 << (round_1 - 1) enables us to use non-rounding shifts.
  int32x4_t vert_offset =
      vdupq_n_s32((1 << (round_1 - 1)) - (1 << (offset_bits - 1)));

  int y_qn = subpel_y_qn;
  if (w == 4) {
    do {
      const int16_t *s = &src[(y_qn >> SCALE_SUBPEL_BITS) * src_stride];

      const ptrdiff_t filter_offset =
          SUBPEL_TAPS * ((y_qn & SCALE_SUBPEL_MASK) >> SCALE_EXTRA_BITS);
      const int16x8_t filter = vld1q_s16(y_filter + filter_offset);

      int16x4_t s0, s1, s2, s3, s4, s5;
      load_s16_4x6(s, src_stride, &s0, &s1, &s2, &s3, &s4, &s5);

      uint8x8_t d = convolve6_4_v(s0, s1, s2, s3, s4, s5, filter, vert_offset);

      store_u8_4x1(dst, d);

      dst += dst_stride;
      y_qn += y_step_qn;
    } while (--h != 0);
  } else if (w == 8) {
    do {
      const int16_t *s = &src[(y_qn >> SCALE_SUBPEL_BITS) * src_stride];

      const ptrdiff_t filter_offset =
          SUBPEL_TAPS * ((y_qn & SCALE_SUBPEL_MASK) >> SCALE_EXTRA_BITS);
      const int16x8_t filter = vld1q_s16(y_filter + filter_offset);

      int16x8_t s0, s1, s2, s3, s4, s5;
      load_s16_8x6(s, src_stride, &s0, &s1, &s2, &s3, &s4, &s5);

      uint8x8_t d = convolve6_8_v(s0, s1, s2, s3, s4, s5, filter, vert_offset);

      vst1_u8(dst, d);

      dst += dst_stride;
      y_qn += y_step_qn;
    } while (--h != 0);
  } else {
    do {
      const int16_t *s = &src[(y_qn >> SCALE_SUBPEL_BITS) * src_stride];
      uint8_t *d = dst;
      int width = w;

      const ptrdiff_t filter_offset =
          SUBPEL_TAPS * ((y_qn & SCALE_SUBPEL_MASK) >> SCALE_EXTRA_BITS);
      const int16x8_t filter = vld1q_s16(y_filter + filter_offset);

      do {
        int16x8_t s0[2], s1[2], s2[2], s3[2], s4[2], s5[2];
        load_s16_8x6(s, src_stride, &s0[0], &s1[0], &s2[0], &s3[0], &s4[0],
                     &s5[0]);
        load_s16_8x6(s + 8, src_stride, &s0[1], &s1[1], &s2[1], &s3[1], &s4[1],
                     &s5[1]);

        uint8x8_t d0 = convolve6_8_v(s0[0], s1[0], s2[0], s3[0], s4[0], s5[0],
                                     filter, vert_offset);
        uint8x8_t d1 = convolve6_8_v(s0[1], s1[1], s2[1], s3[1], s4[1], s5[1],
                                     filter, vert_offset);

        vst1q_u8(d, vcombine_u8(d0, d1));

        s += 16;
        d += 16;
        width -= 16;
      } while (width != 0);

      dst += dst_stride;
      y_qn += y_step_qn;
    } while (--h != 0);
  }
}

#endif  // AOM_AV1_COMMON_ARM_CONVOLVE_SCALE_NEON_H_