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/*
* 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_AOM_DSP_FLOW_ESTIMATION_ARM_DISFLOW_NEON_H_
#define AOM_AOM_DSP_FLOW_ESTIMATION_ARM_DISFLOW_NEON_H_
#include "aom_dsp/flow_estimation/disflow.h"
#include <arm_neon.h>
#include <math.h>
#include "aom_dsp/arm/mem_neon.h"
#include "config/aom_config.h"
#include "config/aom_dsp_rtcd.h"
static inline void get_cubic_kernel_dbl(double x, double kernel[4]) {
// Check that the fractional position is in range.
//
// Note: x is calculated from, e.g., `u_frac = u - floor(u)`.
// Mathematically, this implies that 0 <= x < 1. However, in practice it is
// possible to have x == 1 due to floating point rounding. This is fine,
// and we still interpolate correctly if we allow x = 1.
assert(0 <= x && x <= 1);
double x2 = x * x;
double x3 = x2 * x;
kernel[0] = -0.5 * x + x2 - 0.5 * x3;
kernel[1] = 1.0 - 2.5 * x2 + 1.5 * x3;
kernel[2] = 0.5 * x + 2.0 * x2 - 1.5 * x3;
kernel[3] = -0.5 * x2 + 0.5 * x3;
}
static inline void get_cubic_kernel_int(double x, int kernel[4]) {
double kernel_dbl[4];
get_cubic_kernel_dbl(x, kernel_dbl);
kernel[0] = (int)rint(kernel_dbl[0] * (1 << DISFLOW_INTERP_BITS));
kernel[1] = (int)rint(kernel_dbl[1] * (1 << DISFLOW_INTERP_BITS));
kernel[2] = (int)rint(kernel_dbl[2] * (1 << DISFLOW_INTERP_BITS));
kernel[3] = (int)rint(kernel_dbl[3] * (1 << DISFLOW_INTERP_BITS));
}
static inline void sobel_filter_x(const uint8_t *src, int src_stride,
int16_t *dst, int dst_stride) {
int16_t tmp[DISFLOW_PATCH_SIZE * (DISFLOW_PATCH_SIZE + 2)];
// Horizontal filter, using kernel {1, 0, -1}.
const uint8_t *src_start = src - 1 * src_stride - 1;
for (int i = 0; i < DISFLOW_PATCH_SIZE + 2; i++) {
uint8x16_t s = vld1q_u8(src_start + i * src_stride);
uint8x8_t s0 = vget_low_u8(s);
uint8x8_t s2 = vget_low_u8(vextq_u8(s, s, 2));
// Given that the kernel is {1, 0, -1} the convolution is a simple
// subtraction.
int16x8_t diff = vreinterpretq_s16_u16(vsubl_u8(s0, s2));
vst1q_s16(tmp + i * DISFLOW_PATCH_SIZE, diff);
}
// Vertical filter, using kernel {1, 2, 1}.
// This kernel can be split into two 2-taps kernels of value {1, 1}.
// That way we need only 3 add operations to perform the convolution, one of
// which can be reused for the next line.
int16x8_t s0 = vld1q_s16(tmp);
int16x8_t s1 = vld1q_s16(tmp + DISFLOW_PATCH_SIZE);
int16x8_t sum01 = vaddq_s16(s0, s1);
for (int i = 0; i < DISFLOW_PATCH_SIZE; i++) {
int16x8_t s2 = vld1q_s16(tmp + (i + 2) * DISFLOW_PATCH_SIZE);
int16x8_t sum12 = vaddq_s16(s1, s2);
int16x8_t sum = vaddq_s16(sum01, sum12);
vst1q_s16(dst + i * dst_stride, sum);
sum01 = sum12;
s1 = s2;
}
}
static inline void sobel_filter_y(const uint8_t *src, int src_stride,
int16_t *dst, int dst_stride) {
int16_t tmp[DISFLOW_PATCH_SIZE * (DISFLOW_PATCH_SIZE + 2)];
// Horizontal filter, using kernel {1, 2, 1}.
// This kernel can be split into two 2-taps kernels of value {1, 1}.
// That way we need only 3 add operations to perform the convolution.
const uint8_t *src_start = src - 1 * src_stride - 1;
for (int i = 0; i < DISFLOW_PATCH_SIZE + 2; i++) {
uint8x16_t s = vld1q_u8(src_start + i * src_stride);
uint8x8_t s0 = vget_low_u8(s);
uint8x8_t s1 = vget_low_u8(vextq_u8(s, s, 1));
uint8x8_t s2 = vget_low_u8(vextq_u8(s, s, 2));
uint16x8_t sum01 = vaddl_u8(s0, s1);
uint16x8_t sum12 = vaddl_u8(s1, s2);
uint16x8_t sum = vaddq_u16(sum01, sum12);
vst1q_s16(tmp + i * DISFLOW_PATCH_SIZE, vreinterpretq_s16_u16(sum));
}
// Vertical filter, using kernel {1, 0, -1}.
// Load the whole block at once to avoid redundant loads during convolution.
int16x8_t t[10];
load_s16_8x10(tmp, DISFLOW_PATCH_SIZE, &t[0], &t[1], &t[2], &t[3], &t[4],
&t[5], &t[6], &t[7], &t[8], &t[9]);
for (int i = 0; i < DISFLOW_PATCH_SIZE; i++) {
// Given that the kernel is {1, 0, -1} the convolution is a simple
// subtraction.
int16x8_t diff = vsubq_s16(t[i], t[i + 2]);
vst1q_s16(dst + i * dst_stride, diff);
}
}
#endif // AOM_AOM_DSP_FLOW_ESTIMATION_ARM_DISFLOW_NEON_H_