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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
// Copyright (c) 2011-2016 Google Inc.
// Use of this source code is governed by a BSD-style license that can be
// found in the gfx/skia/LICENSE file.
#include "SkConvolver.h"
#include "mozilla/Attributes.h"
#include <arm_neon.h>
namespace skia {
static MOZ_ALWAYS_INLINE void AccumRemainder(
const unsigned char* pixelsLeft,
const SkConvolutionFilter1D::ConvolutionFixed* filterValues,
int32x4_t& accum, int r) {
int remainder[4] = {0};
for (int i = 0; i < r; i++) {
SkConvolutionFilter1D::ConvolutionFixed coeff = filterValues[i];
remainder[0] += coeff * pixelsLeft[i * 4 + 0];
remainder[1] += coeff * pixelsLeft[i * 4 + 1];
remainder[2] += coeff * pixelsLeft[i * 4 + 2];
remainder[3] += coeff * pixelsLeft[i * 4 + 3];
}
int32x4_t t = {remainder[0], remainder[1], remainder[2], remainder[3]};
accum += t;
}
// Convolves horizontally along a single row. The row data is given in
// |srcData| and continues for the numValues() of the filter.
void convolve_horizontally_neon(const unsigned char* srcData,
const SkConvolutionFilter1D& filter,
unsigned char* outRow, bool /*hasAlpha*/) {
// Loop over each pixel on this row in the output image.
int numValues = filter.numValues();
for (int outX = 0; outX < numValues; outX++) {
uint8x8_t coeff_mask0 = vcreate_u8(0x0100010001000100);
uint8x8_t coeff_mask1 = vcreate_u8(0x0302030203020302);
uint8x8_t coeff_mask2 = vcreate_u8(0x0504050405040504);
uint8x8_t coeff_mask3 = vcreate_u8(0x0706070607060706);
// Get the filter that determines the current output pixel.
int filterOffset, filterLength;
const SkConvolutionFilter1D::ConvolutionFixed* filterValues =
filter.FilterForValue(outX, &filterOffset, &filterLength);
// Compute the first pixel in this row that the filter affects. It will
// touch |filterLength| pixels (4 bytes each) after this.
const unsigned char* rowToFilter = &srcData[filterOffset * 4];
// Apply the filter to the row to get the destination pixel in |accum|.
int32x4_t accum = vdupq_n_s32(0);
for (int filterX = 0; filterX < filterLength >> 2; filterX++) {
// Load 4 coefficients
int16x4_t coeffs, coeff0, coeff1, coeff2, coeff3;
coeffs = vld1_s16(filterValues);
coeff0 = vreinterpret_s16_u8(
vtbl1_u8(vreinterpret_u8_s16(coeffs), coeff_mask0));
coeff1 = vreinterpret_s16_u8(
vtbl1_u8(vreinterpret_u8_s16(coeffs), coeff_mask1));
coeff2 = vreinterpret_s16_u8(
vtbl1_u8(vreinterpret_u8_s16(coeffs), coeff_mask2));
coeff3 = vreinterpret_s16_u8(
vtbl1_u8(vreinterpret_u8_s16(coeffs), coeff_mask3));
// Load pixels and calc
uint8x16_t pixels = vld1q_u8(rowToFilter);
int16x8_t p01_16 = vreinterpretq_s16_u16(vmovl_u8(vget_low_u8(pixels)));
int16x8_t p23_16 = vreinterpretq_s16_u16(vmovl_u8(vget_high_u8(pixels)));
int16x4_t p0_src = vget_low_s16(p01_16);
int16x4_t p1_src = vget_high_s16(p01_16);
int16x4_t p2_src = vget_low_s16(p23_16);
int16x4_t p3_src = vget_high_s16(p23_16);
int32x4_t p0 = vmull_s16(p0_src, coeff0);
int32x4_t p1 = vmull_s16(p1_src, coeff1);
int32x4_t p2 = vmull_s16(p2_src, coeff2);
int32x4_t p3 = vmull_s16(p3_src, coeff3);
accum += p0;
accum += p1;
accum += p2;
accum += p3;
// Advance the pointers
rowToFilter += 16;
filterValues += 4;
}
int r = filterLength & 3;
if (r) {
int remainder_offset = (filterOffset + filterLength - r) * 4;
AccumRemainder(srcData + remainder_offset, filterValues, accum, r);
}
// Bring this value back in range. All of the filter scaling factors
// are in fixed point with kShiftBits bits of fractional part.
accum = vshrq_n_s32(accum, SkConvolutionFilter1D::kShiftBits);
// Pack and store the new pixel.
int16x4_t accum16 = vqmovn_s32(accum);
uint8x8_t accum8 = vqmovun_s16(vcombine_s16(accum16, accum16));
vst1_lane_u32(reinterpret_cast<uint32_t*>(outRow),
vreinterpret_u32_u8(accum8), 0);
outRow += 4;
}
}
// Does vertical convolution to produce one output row. The filter values and
// length are given in the first two parameters. These are applied to each
// of the rows pointed to in the |sourceDataRows| array, with each row
// being |pixelWidth| wide.
//
// The output must have room for |pixelWidth * 4| bytes.
template <bool hasAlpha>
static void ConvolveVertically(
const SkConvolutionFilter1D::ConvolutionFixed* filterValues,
int filterLength, unsigned char* const* sourceDataRows, int pixelWidth,
unsigned char* outRow) {
int width = pixelWidth & ~3;
// Output four pixels per iteration (16 bytes).
for (int outX = 0; outX < width; outX += 4) {
// Accumulated result for each pixel. 32 bits per RGBA channel.
int32x4_t accum0 = vdupq_n_s32(0);
int32x4_t accum1 = vdupq_n_s32(0);
int32x4_t accum2 = vdupq_n_s32(0);
int32x4_t accum3 = vdupq_n_s32(0);
// Convolve with one filter coefficient per iteration.
for (int filterY = 0; filterY < filterLength; filterY++) {
// Duplicate the filter coefficient 4 times.
// [16] cj cj cj cj
int16x4_t coeff16 = vdup_n_s16(filterValues[filterY]);
// Load four pixels (16 bytes) together.
// [8] a3 b3 g3 r3 a2 b2 g2 r2 a1 b1 g1 r1 a0 b0 g0 r0
uint8x16_t src8 = vld1q_u8(&sourceDataRows[filterY][outX << 2]);
int16x8_t src16_01 = vreinterpretq_s16_u16(vmovl_u8(vget_low_u8(src8)));
int16x8_t src16_23 = vreinterpretq_s16_u16(vmovl_u8(vget_high_u8(src8)));
int16x4_t src16_0 = vget_low_s16(src16_01);
int16x4_t src16_1 = vget_high_s16(src16_01);
int16x4_t src16_2 = vget_low_s16(src16_23);
int16x4_t src16_3 = vget_high_s16(src16_23);
accum0 += vmull_s16(src16_0, coeff16);
accum1 += vmull_s16(src16_1, coeff16);
accum2 += vmull_s16(src16_2, coeff16);
accum3 += vmull_s16(src16_3, coeff16);
}
// Shift right for fixed point implementation.
accum0 = vshrq_n_s32(accum0, SkConvolutionFilter1D::kShiftBits);
accum1 = vshrq_n_s32(accum1, SkConvolutionFilter1D::kShiftBits);
accum2 = vshrq_n_s32(accum2, SkConvolutionFilter1D::kShiftBits);
accum3 = vshrq_n_s32(accum3, SkConvolutionFilter1D::kShiftBits);
// Packing 32 bits |accum| to 16 bits per channel (signed saturation).
// [16] a1 b1 g1 r1 a0 b0 g0 r0
int16x8_t accum16_0 = vcombine_s16(vqmovn_s32(accum0), vqmovn_s32(accum1));
// [16] a3 b3 g3 r3 a2 b2 g2 r2
int16x8_t accum16_1 = vcombine_s16(vqmovn_s32(accum2), vqmovn_s32(accum3));
// Packing 16 bits |accum| to 8 bits per channel (unsigned saturation).
// [8] a3 b3 g3 r3 a2 b2 g2 r2 a1 b1 g1 r1 a0 b0 g0 r0
uint8x16_t accum8 =
vcombine_u8(vqmovun_s16(accum16_0), vqmovun_s16(accum16_1));
if (hasAlpha) {
// Compute the max(ri, gi, bi) for each pixel.
// [8] xx a3 b3 g3 xx a2 b2 g2 xx a1 b1 g1 xx a0 b0 g0
uint8x16_t a =
vreinterpretq_u8_u32(vshrq_n_u32(vreinterpretq_u32_u8(accum8), 8));
// [8] xx xx xx max3 xx xx xx max2 xx xx xx max1 xx xx xx max0
uint8x16_t b = vmaxq_u8(a, accum8); // Max of r and g
// [8] xx xx a3 b3 xx xx a2 b2 xx xx a1 b1 xx xx a0 b0
a = vreinterpretq_u8_u32(vshrq_n_u32(vreinterpretq_u32_u8(accum8), 16));
// [8] xx xx xx max3 xx xx xx max2 xx xx xx max1 xx xx xx max0
b = vmaxq_u8(a, b); // Max of r and g and b.
// [8] max3 00 00 00 max2 00 00 00 max1 00 00 00 max0 00 00 00
b = vreinterpretq_u8_u32(vshlq_n_u32(vreinterpretq_u32_u8(b), 24));
// Make sure the value of alpha channel is always larger than maximum
// value of color channels.
accum8 = vmaxq_u8(b, accum8);
} else {
// Set value of alpha channels to 0xFF.
accum8 = vreinterpretq_u8_u32(vreinterpretq_u32_u8(accum8) |
vdupq_n_u32(0xFF000000));
}
// Store the convolution result (16 bytes) and advance the pixel pointers.
vst1q_u8(outRow, accum8);
outRow += 16;
}
// Process the leftovers when the width of the output is not divisible
// by 4, that is at most 3 pixels.
int r = pixelWidth & 3;
if (r) {
int32x4_t accum0 = vdupq_n_s32(0);
int32x4_t accum1 = vdupq_n_s32(0);
int32x4_t accum2 = vdupq_n_s32(0);
for (int filterY = 0; filterY < filterLength; ++filterY) {
int16x4_t coeff16 = vdup_n_s16(filterValues[filterY]);
// [8] a3 b3 g3 r3 a2 b2 g2 r2 a1 b1 g1 r1 a0 b0 g0 r0
uint8x16_t src8 = vld1q_u8(&sourceDataRows[filterY][width << 2]);
int16x8_t src16_01 = vreinterpretq_s16_u16(vmovl_u8(vget_low_u8(src8)));
int16x8_t src16_23 = vreinterpretq_s16_u16(vmovl_u8(vget_high_u8(src8)));
int16x4_t src16_0 = vget_low_s16(src16_01);
int16x4_t src16_1 = vget_high_s16(src16_01);
int16x4_t src16_2 = vget_low_s16(src16_23);
accum0 += vmull_s16(src16_0, coeff16);
accum1 += vmull_s16(src16_1, coeff16);
accum2 += vmull_s16(src16_2, coeff16);
}
accum0 = vshrq_n_s32(accum0, SkConvolutionFilter1D::kShiftBits);
accum1 = vshrq_n_s32(accum1, SkConvolutionFilter1D::kShiftBits);
accum2 = vshrq_n_s32(accum2, SkConvolutionFilter1D::kShiftBits);
int16x8_t accum16_0 = vcombine_s16(vqmovn_s32(accum0), vqmovn_s32(accum1));
int16x8_t accum16_1 = vcombine_s16(vqmovn_s32(accum2), vqmovn_s32(accum2));
uint8x16_t accum8 =
vcombine_u8(vqmovun_s16(accum16_0), vqmovun_s16(accum16_1));
if (hasAlpha) {
// Compute the max(ri, gi, bi) for each pixel.
// [8] xx a3 b3 g3 xx a2 b2 g2 xx a1 b1 g1 xx a0 b0 g0
uint8x16_t a =
vreinterpretq_u8_u32(vshrq_n_u32(vreinterpretq_u32_u8(accum8), 8));
// [8] xx xx xx max3 xx xx xx max2 xx xx xx max1 xx xx xx max0
uint8x16_t b = vmaxq_u8(a, accum8); // Max of r and g
// [8] xx xx a3 b3 xx xx a2 b2 xx xx a1 b1 xx xx a0 b0
a = vreinterpretq_u8_u32(vshrq_n_u32(vreinterpretq_u32_u8(accum8), 16));
// [8] xx xx xx max3 xx xx xx max2 xx xx xx max1 xx xx xx max0
b = vmaxq_u8(a, b); // Max of r and g and b.
// [8] max3 00 00 00 max2 00 00 00 max1 00 00 00 max0 00 00 00
b = vreinterpretq_u8_u32(vshlq_n_u32(vreinterpretq_u32_u8(b), 24));
// Make sure the value of alpha channel is always larger than maximum
// value of color channels.
accum8 = vmaxq_u8(b, accum8);
} else {
// Set value of alpha channels to 0xFF.
accum8 = vreinterpretq_u8_u32(vreinterpretq_u32_u8(accum8) |
vdupq_n_u32(0xFF000000));
}
switch (r) {
case 1:
vst1q_lane_u32(reinterpret_cast<uint32_t*>(outRow),
vreinterpretq_u32_u8(accum8), 0);
break;
case 2:
vst1_u32(reinterpret_cast<uint32_t*>(outRow),
vreinterpret_u32_u8(vget_low_u8(accum8)));
break;
case 3:
vst1_u32(reinterpret_cast<uint32_t*>(outRow),
vreinterpret_u32_u8(vget_low_u8(accum8)));
vst1q_lane_u32(reinterpret_cast<uint32_t*>(outRow + 8),
vreinterpretq_u32_u8(accum8), 2);
break;
}
}
}
void convolve_vertically_neon(
const SkConvolutionFilter1D::ConvolutionFixed* filterValues,
int filterLength, unsigned char* const* sourceDataRows, int pixelWidth,
unsigned char* outRow, bool hasAlpha) {
if (hasAlpha) {
ConvolveVertically<true>(filterValues, filterLength, sourceDataRows,
pixelWidth, outRow);
} else {
ConvolveVertically<false>(filterValues, filterLength, sourceDataRows,
pixelWidth, outRow);
}
}
} // namespace skia