av1/common/arm/av1_convolve_scale_neon_dotprod.c - aom - Git at Google

 /*
  * 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.
  */

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

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

 #include "aom_dsp/aom_dsp_common.h"
 #include "aom_dsp/aom_filter.h"
 #include "aom_dsp/arm/mem_neon.h"
 #include "aom_dsp/arm/transpose_neon.h"
 #include "aom_ports/mem.h"
 #include "av1/common/arm/convolve_scale_neon.h"
 #include "av1/common/convolve.h"
 #include "av1/common/enums.h"
 #include "av1/common/filter.h"

 // clang-format off
 DECLARE_ALIGNED(16, static const uint8_t, kScale2DotProdPermuteTbl[32]) = {
   0, 1, 2, 3, 2, 3, 4, 5, 4, 5,  6,  7,  6,  7,  8,  9,
   4, 5, 6, 7, 6, 7, 8, 9, 8, 9, 10, 11, 10, 11, 12, 13
 };
 // clang-format on

 static INLINE int16x4_t convolve8_4_h(const uint8x8_t s0, const uint8x8_t s1,
                                       const uint8x8_t s2, const uint8x8_t s3,
                                       const int8x8_t filter,
                                       const int32x4_t horiz_const) {
   const int8x16_t filters = vcombine_s8(filter, filter);

   uint8x16_t s01 = vcombine_u8(s0, s1);
   uint8x16_t s23 = vcombine_u8(s2, s3);

   // Transform sample range to [-128, 127] for 8-bit signed dot product.
   int8x16_t s01_128 = vreinterpretq_s8_u8(vsubq_u8(s01, vdupq_n_u8(128)));
   int8x16_t s23_128 = vreinterpretq_s8_u8(vsubq_u8(s23, vdupq_n_u8(128)));

   int32x4_t sum01 = vdotq_s32(horiz_const, s01_128, filters);
   int32x4_t sum23 = vdotq_s32(horiz_const, s23_128, filters);

   int32x4_t sum = vpaddq_s32(sum01, sum23);

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

 static INLINE int16x8_t convolve8_8_h(const uint8x8_t s0, const uint8x8_t s1,
                                       const uint8x8_t s2, const uint8x8_t s3,
                                       const uint8x8_t s4, const uint8x8_t s5,
                                       const uint8x8_t s6, const uint8x8_t s7,
                                       const int8x8_t filter,
                                       const int32x4_t horiz_const) {
   const int8x16_t filters = vcombine_s8(filter, filter);

   uint8x16_t s01 = vcombine_u8(s0, s1);
   uint8x16_t s23 = vcombine_u8(s2, s3);
   uint8x16_t s45 = vcombine_u8(s4, s5);
   uint8x16_t s67 = vcombine_u8(s6, s7);

   // Transform sample range to [-128, 127] for 8-bit signed dot product.
   int8x16_t s01_128 = vreinterpretq_s8_u8(vsubq_u8(s01, vdupq_n_u8(128)));
   int8x16_t s23_128 = vreinterpretq_s8_u8(vsubq_u8(s23, vdupq_n_u8(128)));
   int8x16_t s45_128 = vreinterpretq_s8_u8(vsubq_u8(s45, vdupq_n_u8(128)));
   int8x16_t s67_128 = vreinterpretq_s8_u8(vsubq_u8(s67, vdupq_n_u8(128)));

   int32x4_t sum01 = vdotq_s32(horiz_const, s01_128, filters);
   int32x4_t sum23 = vdotq_s32(horiz_const, s23_128, filters);
   int32x4_t sum45 = vdotq_s32(horiz_const, s45_128, filters);
   int32x4_t sum67 = vdotq_s32(horiz_const, s67_128, filters);

   int32x4_t sum0123 = vpaddq_s32(sum01, sum23);
   int32x4_t sum4567 = vpaddq_s32(sum45, sum67);

   // We halved the filter values so -1 from right shift.
   return vcombine_s16(vshrn_n_s32(sum0123, ROUND0_BITS - 1),
                       vshrn_n_s32(sum4567, ROUND0_BITS - 1));
 }

 static INLINE void convolve_horiz_scale_neon_dotprod(
     const uint8_t *src, int src_stride, int16_t *dst, int dst_stride, int w,
     int h, const int16_t *x_filter, const int subpel_x_qn,
     const int x_step_qn) {
   DECLARE_ALIGNED(16, int16_t, temp[8 * 8]);
   const int bd = 8;
   // A 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_offset =
       (1 << (bd + FILTER_BITS - 1)) + (1 << (ROUND0_BITS - 1));
   // The shim of 128 << FILTER_BITS is needed because we are subtracting 128
   // from every source value.
   const int32_t dotprod_offset = 128 << FILTER_BITS;
   // Divide the total by 4: we halved the filter values and will use a pairwise
   // add in the convolution kernel.
   const int32x4_t horiz_offset_vec =
       vdupq_n_s32((horiz_offset + dotprod_offset) >> 2);

   if (w == 4) {
     do {
       int x_qn = subpel_x_qn;

       // Process a 4x4 tile.
       for (int r = 0; r < 4; r++) {
         const uint8_t *const s = &src[x_qn >> SCALE_SUBPEL_BITS];

         const ptrdiff_t filter_offset =
             SUBPEL_TAPS * ((x_qn & SCALE_SUBPEL_MASK) >> SCALE_EXTRA_BITS);
         // Filter values are all even so halve them to fit in int8_t.
         const int8x8_t filter =
             vshrn_n_s16(vld1q_s16(x_filter + filter_offset), 1);

         uint8x8_t t0, t1, t2, t3;
         load_u8_8x4(s, src_stride, &t0, &t1, &t2, &t3);

         int16x4_t d0 = convolve8_4_h(t0, t1, t2, t3, filter, horiz_offset_vec);

         vst1_s16(&temp[r * 4], d0);

         x_qn += x_step_qn;
       }

       // Transpose the 4x4 result tile and store.
       int16x4_t d0, d1, d2, d3;
       load_s16_4x4(temp, 4, &d0, &d1, &d2, &d3);

       transpose_elems_inplace_s16_4x4(&d0, &d1, &d2, &d3);

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

       dst += 4 * dst_stride;
       src += 4 * src_stride;
       h -= 4;
     } while (h > 0);
   } else {
     do {
       int x_qn = subpel_x_qn;
       int16_t *d = dst;
       int width = w;

       do {
         // Process an 8x8 tile.
         for (int r = 0; r < 8; r++) {
           const uint8_t *const s = &src[(x_qn >> SCALE_SUBPEL_BITS)];

           const ptrdiff_t filter_offset =
               SUBPEL_TAPS * ((x_qn & SCALE_SUBPEL_MASK) >> SCALE_EXTRA_BITS);
           // Filter values are all even so halve them to fit in int8_t.
           int8x8_t filter = vshrn_n_s16(vld1q_s16(x_filter + filter_offset), 1);

           uint8x8_t t0, t1, t2, t3, t4, t5, t6, t7;
           load_u8_8x8(s, src_stride, &t0, &t1, &t2, &t3, &t4, &t5, &t6, &t7);

           int16x8_t d0 = convolve8_8_h(t0, t1, t2, t3, t4, t5, t6, t7, filter,
                                        horiz_offset_vec);

           vst1q_s16(&temp[r * 8], d0);

           x_qn += x_step_qn;
         }

         // Transpose the 8x8 result tile and store.
         int16x8_t d0, d1, d2, d3, d4, d5, d6, d7;
         load_s16_8x8(temp, 8, &d0, &d1, &d2, &d3, &d4, &d5, &d6, &d7);

         transpose_elems_inplace_s16_8x8(&d0, &d1, &d2, &d3, &d4, &d5, &d6, &d7);

         store_s16_8x8(d, dst_stride, d0, d1, d2, d3, d4, d5, d6, d7);

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

       dst += 8 * dst_stride;
       src += 8 * src_stride;
       h -= 8;
     } while (h > 0);
   }
 }

 static INLINE int16x4_t convolve8_4_h_scale_2(uint8x16_t samples,
                                               const int8x8_t filters,
                                               const int32x4_t horiz_const,
                                               const uint8x16x2_t permute_tbl) {
   // Transform sample range to [-128, 127] for 8-bit signed dot product.
   int8x16_t samples_128 =
       vreinterpretq_s8_u8(vsubq_u8(samples, vdupq_n_u8(128)));

   // Permute samples ready for dot product.
   // { 0, 1, 2, 3, 2, 3, 4, 5, 4, 5,  6,  7,  6,  7,  8,  9 }
   // { 4, 5, 6, 7, 6, 7, 8, 9, 8, 9, 10, 11, 10, 11, 12, 13 }
   int8x16_t perm_samples[2] = { vqtbl1q_s8(samples_128, permute_tbl.val[0]),
                                 vqtbl1q_s8(samples_128, permute_tbl.val[1]) };

   int32x4_t sum = vdotq_lane_s32(horiz_const, perm_samples[0], filters, 0);
   sum = vdotq_lane_s32(sum, perm_samples[1], filters, 1);

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

 static INLINE int16x8_t convolve8_8_h_scale_2(uint8x16_t samples[2],
                                               const int8x8_t filters,
                                               const int32x4_t horiz_const,
                                               const uint8x16x2_t permute_tbl) {
   // Transform sample range to [-128, 127] for 8-bit signed dot product.
   int8x16_t samples0_128 =
       vreinterpretq_s8_u8(vsubq_u8(samples[0], vdupq_n_u8(128)));
   int8x16_t samples1_128 =
       vreinterpretq_s8_u8(vsubq_u8(samples[1], vdupq_n_u8(128)));

   // Permute samples ready for dot product.
   // { 0, 1, 2, 3, 2, 3, 4, 5, 4, 5,  6,  7,  6,  7,  8,  9 }
   // { 4, 5, 6, 7, 6, 7, 8, 9, 8, 9, 10, 11, 10, 11, 12, 13 }
   int8x16_t perm_samples[4] = { vqtbl1q_s8(samples0_128, permute_tbl.val[0]),
                                 vqtbl1q_s8(samples0_128, permute_tbl.val[1]),
                                 vqtbl1q_s8(samples1_128, permute_tbl.val[0]),
                                 vqtbl1q_s8(samples1_128, permute_tbl.val[1]) };

   // First 4 output values.
   int32x4_t sum0123 = vdotq_lane_s32(horiz_const, perm_samples[0], filters, 0);
   sum0123 = vdotq_lane_s32(sum0123, perm_samples[1], filters, 1);
   // Second 4 output values.
   int32x4_t sum4567 = vdotq_lane_s32(horiz_const, perm_samples[2], filters, 0);
   sum4567 = vdotq_lane_s32(sum4567, perm_samples[3], filters, 1);

   // We halved the filter values so -1 from right shift.
   return vcombine_s16(vshrn_n_s32(sum0123, ROUND0_BITS - 1),
                       vshrn_n_s32(sum4567, ROUND0_BITS - 1));
 }

 static INLINE void convolve_horiz_scale_2_neon_dotprod(
     const uint8_t *src, int src_stride, int16_t *dst, int dst_stride, int w,
     int h, const int16_t *x_filter) {
   const int bd = 8;
   // A 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_offset =
       (1 << (bd + FILTER_BITS - 1)) + (1 << (ROUND0_BITS - 1));
   // The shim of 128 << FILTER_BITS is needed because we are subtracting 128
   // from every source value.
   const int32_t dotprod_offset = 128 << FILTER_BITS;
   // Divide the total by 2 because we halved the filter values.
   const int32x4_t horiz_offset_vec =
       vdupq_n_s32((horiz_offset + dotprod_offset) >> 1);

   const uint8x16x2_t permute_tbl = vld1q_u8_x2(kScale2DotProdPermuteTbl);
   // Filter values are all even so halve them to fit in int8_t.
   const int8x8_t filter = vshrn_n_s16(vld1q_s16(x_filter), 1);

   if (w == 4) {
     do {
       const uint8_t *s = src;
       int16_t *d = dst;
       int width = w;

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

         int16x4_t d0 =
             convolve8_4_h_scale_2(s0, filter, horiz_offset_vec, permute_tbl);
         int16x4_t d1 =
             convolve8_4_h_scale_2(s1, filter, horiz_offset_vec, permute_tbl);
         int16x4_t d2 =
             convolve8_4_h_scale_2(s2, filter, horiz_offset_vec, permute_tbl);
         int16x4_t d3 =
             convolve8_4_h_scale_2(s3, filter, horiz_offset_vec, permute_tbl);

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

         s += 8;
         d += 4;
         width -= 4;
       } while (width != 0);

       dst += 4 * dst_stride;
       src += 4 * src_stride;
       h -= 4;
     } while (h > 0);
   } else {
     do {
       const uint8_t *s = src;
       int16_t *d = dst;
       int width = w;

       do {
         uint8x16_t s0[2], s1[2], s2[2], s3[2];
         load_u8_16x4(s, src_stride, &s0[0], &s1[0], &s2[0], &s3[0]);
         load_u8_16x4(s + 8, src_stride, &s0[1], &s1[1], &s2[1], &s3[1]);

         int16x8_t d0 =
             convolve8_8_h_scale_2(s0, filter, horiz_offset_vec, permute_tbl);
         int16x8_t d1 =
             convolve8_8_h_scale_2(s1, filter, horiz_offset_vec, permute_tbl);
         int16x8_t d2 =
             convolve8_8_h_scale_2(s2, filter, horiz_offset_vec, permute_tbl);
         int16x8_t d3 =
             convolve8_8_h_scale_2(s3, filter, horiz_offset_vec, permute_tbl);

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

         s += 16;
         d += 8;
         width -= 8;
       } while (width != 0);

       dst += 4 * dst_stride;
       src += 4 * src_stride;
       h -= 4;
     } while (h > 0);
   }
 }

 void av1_convolve_2d_scale_neon_dotprod(
     const uint8_t *src, int src_stride, uint8_t *dst, int dst_stride, int w,
     int h, const InterpFilterParams *filter_params_x,
     const InterpFilterParams *filter_params_y, const int subpel_x_qn,
     const int x_step_qn, const int subpel_y_qn, const int y_step_qn,
     ConvolveParams *conv_params) {
   if (w < 4 || h < 4) {
     av1_convolve_2d_scale_c(src, src_stride, dst, dst_stride, w, h,
                             filter_params_x, filter_params_y, subpel_x_qn,
                             x_step_qn, subpel_y_qn, y_step_qn, conv_params);
     return;
   }

   // For the interpolation 8-tap filters are used.
   assert(filter_params_y->taps <= 8 && filter_params_x->taps <= 8);

   DECLARE_ALIGNED(32, int16_t,
                   im_block[(2 * MAX_SB_SIZE + MAX_FILTER_TAP) * MAX_SB_SIZE]);
   int im_h = (((h - 1) * y_step_qn + subpel_y_qn) >> SCALE_SUBPEL_BITS) +
              filter_params_y->taps;
   int im_stride = MAX_SB_SIZE;
   CONV_BUF_TYPE *dst16 = conv_params->dst;
   const int dst16_stride = conv_params->dst_stride;

   // Account for needing filter_taps / 2 - 1 lines prior and filter_taps / 2
   // lines post both horizontally and vertically.
   const ptrdiff_t horiz_offset = filter_params_x->taps / 2 - 1;
   const ptrdiff_t vert_offset = (filter_params_y->taps / 2 - 1) * src_stride;

   // Horizontal filter
   if (x_step_qn != 2 * (1 << SCALE_SUBPEL_BITS)) {
     convolve_horiz_scale_neon_dotprod(
         src - horiz_offset - vert_offset, src_stride, im_block, im_stride, w,
         im_h, filter_params_x->filter_ptr, subpel_x_qn, x_step_qn);
   } else {
     assert(subpel_x_qn < (1 << SCALE_SUBPEL_BITS));
     // The filter index is calculated using the
     // ((subpel_x_qn + x * x_step_qn) & SCALE_SUBPEL_MASK) >> SCALE_EXTRA_BITS
     // equation, where the values of x are from 0 to w. If x_step_qn is a
     // multiple of SCALE_SUBPEL_MASK we can leave it out of the equation.
     const ptrdiff_t filter_offset =
         SUBPEL_TAPS * ((subpel_x_qn & SCALE_SUBPEL_MASK) >> SCALE_EXTRA_BITS);
     const int16_t *x_filter = filter_params_x->filter_ptr + filter_offset;

     // The source index is calculated using the (subpel_x_qn + x * x_step_qn) >>
     // SCALE_SUBPEL_BITS, where the values of x are from 0 to w. If subpel_x_qn
     // < (1 << SCALE_SUBPEL_BITS) and x_step_qn % (1 << SCALE_SUBPEL_BITS) == 0,
     // the source index can be determined using the value x * (x_step_qn /
     // (1 << SCALE_SUBPEL_BITS)).
     convolve_horiz_scale_2_neon_dotprod(src - horiz_offset - vert_offset,
                                         src_stride, im_block, im_stride, w,
                                         im_h, x_filter);
   }

   // Vertical filter
   if (filter_params_y->interp_filter == MULTITAP_SHARP) {
     if (UNLIKELY(conv_params->is_compound)) {
       if (conv_params->do_average) {
         if (conv_params->use_dist_wtd_comp_avg) {
           compound_dist_wtd_convolve_vert_scale_8tap_neon(
               im_block, im_stride, dst, dst_stride, dst16, dst16_stride, w, h,
               filter_params_y->filter_ptr, conv_params, subpel_y_qn, y_step_qn);
         } else {
           compound_avg_convolve_vert_scale_8tap_neon(
               im_block, im_stride, dst, dst_stride, dst16, dst16_stride, w, h,
               filter_params_y->filter_ptr, subpel_y_qn, y_step_qn);
         }
       } else {
         compound_convolve_vert_scale_8tap_neon(
             im_block, im_stride, dst16, dst16_stride, w, h,
             filter_params_y->filter_ptr, subpel_y_qn, y_step_qn);
       }
     } else {
       convolve_vert_scale_8tap_neon(im_block, im_stride, dst, dst_stride, w, h,
                                     filter_params_y->filter_ptr, subpel_y_qn,
                                     y_step_qn);
     }
   } else {
     if (UNLIKELY(conv_params->is_compound)) {
       if (conv_params->do_average) {
         if (conv_params->use_dist_wtd_comp_avg) {
           compound_dist_wtd_convolve_vert_scale_6tap_neon(
               im_block + im_stride, im_stride, dst, dst_stride, dst16,
               dst16_stride, w, h, filter_params_y->filter_ptr, conv_params,
               subpel_y_qn, y_step_qn);
         } else {
           compound_avg_convolve_vert_scale_6tap_neon(
               im_block + im_stride, im_stride, dst, dst_stride, dst16,
               dst16_stride, w, h, filter_params_y->filter_ptr, subpel_y_qn,
               y_step_qn);
         }
       } else {
         compound_convolve_vert_scale_6tap_neon(
             im_block + im_stride, im_stride, dst16, dst16_stride, w, h,
             filter_params_y->filter_ptr, subpel_y_qn, y_step_qn);
       }
     } else {
       convolve_vert_scale_6tap_neon(
           im_block + im_stride, im_stride, dst, dst_stride, w, h,
           filter_params_y->filter_ptr, subpel_y_qn, y_step_qn);
     }
   }
 }
	/*
	* 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.
	*/

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

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

	#include "aom_dsp/aom_dsp_common.h"
	#include "aom_dsp/aom_filter.h"
	#include "aom_dsp/arm/mem_neon.h"
	#include "aom_dsp/arm/transpose_neon.h"
	#include "aom_ports/mem.h"
	#include "av1/common/arm/convolve_scale_neon.h"
	#include "av1/common/convolve.h"
	#include "av1/common/enums.h"
	#include "av1/common/filter.h"

	// clang-format off
	DECLARE_ALIGNED(16, static const uint8_t, kScale2DotProdPermuteTbl[32]) = {
	0, 1, 2, 3, 2, 3, 4, 5, 4, 5, 6, 7, 6, 7, 8, 9,
	4, 5, 6, 7, 6, 7, 8, 9, 8, 9, 10, 11, 10, 11, 12, 13
	};
	// clang-format on

	static INLINE int16x4_t convolve8_4_h(const uint8x8_t s0, const uint8x8_t s1,
	const uint8x8_t s2, const uint8x8_t s3,
	const int8x8_t filter,
	const int32x4_t horiz_const) {
	const int8x16_t filters = vcombine_s8(filter, filter);

	uint8x16_t s01 = vcombine_u8(s0, s1);
	uint8x16_t s23 = vcombine_u8(s2, s3);

	// Transform sample range to [-128, 127] for 8-bit signed dot product.
	int8x16_t s01_128 = vreinterpretq_s8_u8(vsubq_u8(s01, vdupq_n_u8(128)));
	int8x16_t s23_128 = vreinterpretq_s8_u8(vsubq_u8(s23, vdupq_n_u8(128)));

	int32x4_t sum01 = vdotq_s32(horiz_const, s01_128, filters);
	int32x4_t sum23 = vdotq_s32(horiz_const, s23_128, filters);

	int32x4_t sum = vpaddq_s32(sum01, sum23);

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

	static INLINE int16x8_t convolve8_8_h(const uint8x8_t s0, const uint8x8_t s1,
	const uint8x8_t s2, const uint8x8_t s3,
	const uint8x8_t s4, const uint8x8_t s5,
	const uint8x8_t s6, const uint8x8_t s7,
	const int8x8_t filter,
	const int32x4_t horiz_const) {
	const int8x16_t filters = vcombine_s8(filter, filter);

	uint8x16_t s01 = vcombine_u8(s0, s1);
	uint8x16_t s23 = vcombine_u8(s2, s3);
	uint8x16_t s45 = vcombine_u8(s4, s5);
	uint8x16_t s67 = vcombine_u8(s6, s7);

	// Transform sample range to [-128, 127] for 8-bit signed dot product.
	int8x16_t s01_128 = vreinterpretq_s8_u8(vsubq_u8(s01, vdupq_n_u8(128)));
	int8x16_t s23_128 = vreinterpretq_s8_u8(vsubq_u8(s23, vdupq_n_u8(128)));
	int8x16_t s45_128 = vreinterpretq_s8_u8(vsubq_u8(s45, vdupq_n_u8(128)));
	int8x16_t s67_128 = vreinterpretq_s8_u8(vsubq_u8(s67, vdupq_n_u8(128)));

	int32x4_t sum01 = vdotq_s32(horiz_const, s01_128, filters);
	int32x4_t sum23 = vdotq_s32(horiz_const, s23_128, filters);
	int32x4_t sum45 = vdotq_s32(horiz_const, s45_128, filters);
	int32x4_t sum67 = vdotq_s32(horiz_const, s67_128, filters);

	int32x4_t sum0123 = vpaddq_s32(sum01, sum23);
	int32x4_t sum4567 = vpaddq_s32(sum45, sum67);

	// We halved the filter values so -1 from right shift.
	return vcombine_s16(vshrn_n_s32(sum0123, ROUND0_BITS - 1),
	vshrn_n_s32(sum4567, ROUND0_BITS - 1));
	}

	static INLINE void convolve_horiz_scale_neon_dotprod(
	const uint8_t src, int src_stride, int16_t dst, int dst_stride, int w,
	int h, const int16_t *x_filter, const int subpel_x_qn,
	const int x_step_qn) {
	DECLARE_ALIGNED(16, int16_t, temp[8 * 8]);
	const int bd = 8;
	// A 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_offset =
	(1 << (bd + FILTER_BITS - 1)) + (1 << (ROUND0_BITS - 1));
	// The shim of 128 << FILTER_BITS is needed because we are subtracting 128
	// from every source value.
	const int32_t dotprod_offset = 128 << FILTER_BITS;
	// Divide the total by 4: we halved the filter values and will use a pairwise
	// add in the convolution kernel.
	const int32x4_t horiz_offset_vec =
	vdupq_n_s32((horiz_offset + dotprod_offset) >> 2);

	if (w == 4) {
	do {
	int x_qn = subpel_x_qn;

	// Process a 4x4 tile.
	for (int r = 0; r < 4; r++) {
	const uint8_t *const s = &src[x_qn >> SCALE_SUBPEL_BITS];

	const ptrdiff_t filter_offset =
	SUBPEL_TAPS * ((x_qn & SCALE_SUBPEL_MASK) >> SCALE_EXTRA_BITS);
	// Filter values are all even so halve them to fit in int8_t.
	const int8x8_t filter =
	vshrn_n_s16(vld1q_s16(x_filter + filter_offset), 1);

	uint8x8_t t0, t1, t2, t3;
	load_u8_8x4(s, src_stride, &t0, &t1, &t2, &t3);

	int16x4_t d0 = convolve8_4_h(t0, t1, t2, t3, filter, horiz_offset_vec);

	vst1_s16(&temp[r * 4], d0);

	x_qn += x_step_qn;
	}

	// Transpose the 4x4 result tile and store.
	int16x4_t d0, d1, d2, d3;
	load_s16_4x4(temp, 4, &d0, &d1, &d2, &d3);

	transpose_elems_inplace_s16_4x4(&d0, &d1, &d2, &d3);

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

	dst += 4 * dst_stride;
	src += 4 * src_stride;
	h -= 4;
	} while (h > 0);
	} else {
	do {
	int x_qn = subpel_x_qn;
	int16_t *d = dst;
	int width = w;

	do {
	// Process an 8x8 tile.
	for (int r = 0; r < 8; r++) {
	const uint8_t *const s = &src[(x_qn >> SCALE_SUBPEL_BITS)];

	const ptrdiff_t filter_offset =
	SUBPEL_TAPS * ((x_qn & SCALE_SUBPEL_MASK) >> SCALE_EXTRA_BITS);
	// Filter values are all even so halve them to fit in int8_t.
	int8x8_t filter = vshrn_n_s16(vld1q_s16(x_filter + filter_offset), 1);

	uint8x8_t t0, t1, t2, t3, t4, t5, t6, t7;
	load_u8_8x8(s, src_stride, &t0, &t1, &t2, &t3, &t4, &t5, &t6, &t7);

	int16x8_t d0 = convolve8_8_h(t0, t1, t2, t3, t4, t5, t6, t7, filter,
	horiz_offset_vec);

	vst1q_s16(&temp[r * 8], d0);

	x_qn += x_step_qn;
	}

	// Transpose the 8x8 result tile and store.
	int16x8_t d0, d1, d2, d3, d4, d5, d6, d7;
	load_s16_8x8(temp, 8, &d0, &d1, &d2, &d3, &d4, &d5, &d6, &d7);

	transpose_elems_inplace_s16_8x8(&d0, &d1, &d2, &d3, &d4, &d5, &d6, &d7);

	store_s16_8x8(d, dst_stride, d0, d1, d2, d3, d4, d5, d6, d7);

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

	dst += 8 * dst_stride;
	src += 8 * src_stride;
	h -= 8;
	} while (h > 0);
	}
	}

	static INLINE int16x4_t convolve8_4_h_scale_2(uint8x16_t samples,
	const int8x8_t filters,
	const int32x4_t horiz_const,
	const uint8x16x2_t permute_tbl) {
	// Transform sample range to [-128, 127] for 8-bit signed dot product.
	int8x16_t samples_128 =
	vreinterpretq_s8_u8(vsubq_u8(samples, vdupq_n_u8(128)));

	// Permute samples ready for dot product.
	// { 0, 1, 2, 3, 2, 3, 4, 5, 4, 5, 6, 7, 6, 7, 8, 9 }
	// { 4, 5, 6, 7, 6, 7, 8, 9, 8, 9, 10, 11, 10, 11, 12, 13 }
	int8x16_t perm_samples[2] = { vqtbl1q_s8(samples_128, permute_tbl.val[0]),
	vqtbl1q_s8(samples_128, permute_tbl.val[1]) };

	int32x4_t sum = vdotq_lane_s32(horiz_const, perm_samples[0], filters, 0);
	sum = vdotq_lane_s32(sum, perm_samples[1], filters, 1);

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

	static INLINE int16x8_t convolve8_8_h_scale_2(uint8x16_t samples[2],
	const int8x8_t filters,
	const int32x4_t horiz_const,
	const uint8x16x2_t permute_tbl) {
	// Transform sample range to [-128, 127] for 8-bit signed dot product.
	int8x16_t samples0_128 =
	vreinterpretq_s8_u8(vsubq_u8(samples[0], vdupq_n_u8(128)));
	int8x16_t samples1_128 =
	vreinterpretq_s8_u8(vsubq_u8(samples[1], vdupq_n_u8(128)));

	// Permute samples ready for dot product.
	// { 0, 1, 2, 3, 2, 3, 4, 5, 4, 5, 6, 7, 6, 7, 8, 9 }
	// { 4, 5, 6, 7, 6, 7, 8, 9, 8, 9, 10, 11, 10, 11, 12, 13 }
	int8x16_t perm_samples[4] = { vqtbl1q_s8(samples0_128, permute_tbl.val[0]),
	vqtbl1q_s8(samples0_128, permute_tbl.val[1]),
	vqtbl1q_s8(samples1_128, permute_tbl.val[0]),
	vqtbl1q_s8(samples1_128, permute_tbl.val[1]) };

	// First 4 output values.
	int32x4_t sum0123 = vdotq_lane_s32(horiz_const, perm_samples[0], filters, 0);
	sum0123 = vdotq_lane_s32(sum0123, perm_samples[1], filters, 1);
	// Second 4 output values.
	int32x4_t sum4567 = vdotq_lane_s32(horiz_const, perm_samples[2], filters, 0);
	sum4567 = vdotq_lane_s32(sum4567, perm_samples[3], filters, 1);

	// We halved the filter values so -1 from right shift.
	return vcombine_s16(vshrn_n_s32(sum0123, ROUND0_BITS - 1),
	vshrn_n_s32(sum4567, ROUND0_BITS - 1));
	}

	static INLINE void convolve_horiz_scale_2_neon_dotprod(
	const uint8_t src, int src_stride, int16_t dst, int dst_stride, int w,
	int h, const int16_t *x_filter) {
	const int bd = 8;
	// A 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_offset =
	(1 << (bd + FILTER_BITS - 1)) + (1 << (ROUND0_BITS - 1));
	// The shim of 128 << FILTER_BITS is needed because we are subtracting 128
	// from every source value.
	const int32_t dotprod_offset = 128 << FILTER_BITS;
	// Divide the total by 2 because we halved the filter values.
	const int32x4_t horiz_offset_vec =
	vdupq_n_s32((horiz_offset + dotprod_offset) >> 1);

	const uint8x16x2_t permute_tbl = vld1q_u8_x2(kScale2DotProdPermuteTbl);
	// Filter values are all even so halve them to fit in int8_t.
	const int8x8_t filter = vshrn_n_s16(vld1q_s16(x_filter), 1);

	if (w == 4) {
	do {
	const uint8_t *s = src;
	int16_t *d = dst;
	int width = w;

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

	int16x4_t d0 =
	convolve8_4_h_scale_2(s0, filter, horiz_offset_vec, permute_tbl);
	int16x4_t d1 =
	convolve8_4_h_scale_2(s1, filter, horiz_offset_vec, permute_tbl);
	int16x4_t d2 =
	convolve8_4_h_scale_2(s2, filter, horiz_offset_vec, permute_tbl);
	int16x4_t d3 =
	convolve8_4_h_scale_2(s3, filter, horiz_offset_vec, permute_tbl);

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

	s += 8;
	d += 4;
	width -= 4;
	} while (width != 0);

	dst += 4 * dst_stride;
	src += 4 * src_stride;
	h -= 4;
	} while (h > 0);
	} else {
	do {
	const uint8_t *s = src;
	int16_t *d = dst;
	int width = w;

	do {
	uint8x16_t s0[2], s1[2], s2[2], s3[2];
	load_u8_16x4(s, src_stride, &s0[0], &s1[0], &s2[0], &s3[0]);
	load_u8_16x4(s + 8, src_stride, &s0[1], &s1[1], &s2[1], &s3[1]);

	int16x8_t d0 =
	convolve8_8_h_scale_2(s0, filter, horiz_offset_vec, permute_tbl);
	int16x8_t d1 =
	convolve8_8_h_scale_2(s1, filter, horiz_offset_vec, permute_tbl);
	int16x8_t d2 =
	convolve8_8_h_scale_2(s2, filter, horiz_offset_vec, permute_tbl);
	int16x8_t d3 =
	convolve8_8_h_scale_2(s3, filter, horiz_offset_vec, permute_tbl);

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

	s += 16;
	d += 8;
	width -= 8;
	} while (width != 0);

	dst += 4 * dst_stride;
	src += 4 * src_stride;
	h -= 4;
	} while (h > 0);
	}
	}

	void av1_convolve_2d_scale_neon_dotprod(
	const uint8_t src, int src_stride, uint8_t dst, int dst_stride, int w,
	int h, const InterpFilterParams *filter_params_x,
	const InterpFilterParams *filter_params_y, const int subpel_x_qn,
	const int x_step_qn, const int subpel_y_qn, const int y_step_qn,
	ConvolveParams *conv_params) {
	if (w < 4 \|\| h < 4) {
	av1_convolve_2d_scale_c(src, src_stride, dst, dst_stride, w, h,
	filter_params_x, filter_params_y, subpel_x_qn,
	x_step_qn, subpel_y_qn, y_step_qn, conv_params);
	return;
	}

	// For the interpolation 8-tap filters are used.
	assert(filter_params_y->taps <= 8 && filter_params_x->taps <= 8);

	DECLARE_ALIGNED(32, int16_t,
	im_block[(2 * MAX_SB_SIZE + MAX_FILTER_TAP) * MAX_SB_SIZE]);
	int im_h = (((h - 1) * y_step_qn + subpel_y_qn) >> SCALE_SUBPEL_BITS) +
	filter_params_y->taps;
	int im_stride = MAX_SB_SIZE;
	CONV_BUF_TYPE *dst16 = conv_params->dst;
	const int dst16_stride = conv_params->dst_stride;

	// Account for needing filter_taps / 2 - 1 lines prior and filter_taps / 2
	// lines post both horizontally and vertically.
	const ptrdiff_t horiz_offset = filter_params_x->taps / 2 - 1;
	const ptrdiff_t vert_offset = (filter_params_y->taps / 2 - 1) * src_stride;

	// Horizontal filter
	if (x_step_qn != 2 * (1 << SCALE_SUBPEL_BITS)) {
	convolve_horiz_scale_neon_dotprod(
	src - horiz_offset - vert_offset, src_stride, im_block, im_stride, w,
	im_h, filter_params_x->filter_ptr, subpel_x_qn, x_step_qn);
	} else {
	assert(subpel_x_qn < (1 << SCALE_SUBPEL_BITS));
	// The filter index is calculated using the
	// ((subpel_x_qn + x * x_step_qn) & SCALE_SUBPEL_MASK) >> SCALE_EXTRA_BITS
	// equation, where the values of x are from 0 to w. If x_step_qn is a
	// multiple of SCALE_SUBPEL_MASK we can leave it out of the equation.
	const ptrdiff_t filter_offset =
	SUBPEL_TAPS * ((subpel_x_qn & SCALE_SUBPEL_MASK) >> SCALE_EXTRA_BITS);
	const int16_t *x_filter = filter_params_x->filter_ptr + filter_offset;

	// The source index is calculated using the (subpel_x_qn + x * x_step_qn) >>
	// SCALE_SUBPEL_BITS, where the values of x are from 0 to w. If subpel_x_qn
	// < (1 << SCALE_SUBPEL_BITS) and x_step_qn % (1 << SCALE_SUBPEL_BITS) == 0,
	// the source index can be determined using the value x * (x_step_qn /
	// (1 << SCALE_SUBPEL_BITS)).
	convolve_horiz_scale_2_neon_dotprod(src - horiz_offset - vert_offset,
	src_stride, im_block, im_stride, w,
	im_h, x_filter);
	}

	// Vertical filter
	if (filter_params_y->interp_filter == MULTITAP_SHARP) {
	if (UNLIKELY(conv_params->is_compound)) {
	if (conv_params->do_average) {
	if (conv_params->use_dist_wtd_comp_avg) {
	compound_dist_wtd_convolve_vert_scale_8tap_neon(
	im_block, im_stride, dst, dst_stride, dst16, dst16_stride, w, h,
	filter_params_y->filter_ptr, conv_params, subpel_y_qn, y_step_qn);
	} else {
	compound_avg_convolve_vert_scale_8tap_neon(
	im_block, im_stride, dst, dst_stride, dst16, dst16_stride, w, h,
	filter_params_y->filter_ptr, subpel_y_qn, y_step_qn);
	}
	} else {
	compound_convolve_vert_scale_8tap_neon(
	im_block, im_stride, dst16, dst16_stride, w, h,
	filter_params_y->filter_ptr, subpel_y_qn, y_step_qn);
	}
	} else {
	convolve_vert_scale_8tap_neon(im_block, im_stride, dst, dst_stride, w, h,
	filter_params_y->filter_ptr, subpel_y_qn,
	y_step_qn);
	}
	} else {
	if (UNLIKELY(conv_params->is_compound)) {
	if (conv_params->do_average) {
	if (conv_params->use_dist_wtd_comp_avg) {
	compound_dist_wtd_convolve_vert_scale_6tap_neon(
	im_block + im_stride, im_stride, dst, dst_stride, dst16,
	dst16_stride, w, h, filter_params_y->filter_ptr, conv_params,
	subpel_y_qn, y_step_qn);
	} else {
	compound_avg_convolve_vert_scale_6tap_neon(
	im_block + im_stride, im_stride, dst, dst_stride, dst16,
	dst16_stride, w, h, filter_params_y->filter_ptr, subpel_y_qn,
	y_step_qn);
	}
	} else {
	compound_convolve_vert_scale_6tap_neon(
	im_block + im_stride, im_stride, dst16, dst16_stride, w, h,
	filter_params_y->filter_ptr, subpel_y_qn, y_step_qn);
	}
	} else {
	convolve_vert_scale_6tap_neon(
	im_block + im_stride, im_stride, dst, dst_stride, w, h,
	filter_params_y->filter_ptr, subpel_y_qn, y_step_qn);
	}
	}
	}