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// Copyright 2020 The libgav1 Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "src/dsp/arm/common_neon.h"
#include "src/dsp/super_res.h"
#include "src/utils/cpu.h"
#if LIBGAV1_ENABLE_NEON
#include <arm_neon.h>
#include "src/dsp/constants.h"
#include "src/dsp/dsp.h"
#include "src/utils/common.h"
#include "src/utils/constants.h"
namespace libgav1 {
namespace dsp {
namespace low_bitdepth {
namespace {
void SuperResCoefficients_NEON(const int upscaled_width,
const int initial_subpixel_x, const int step,
void* const coefficients) {
auto* dst = static_cast<uint8_t*>(coefficients);
int subpixel_x = initial_subpixel_x;
int x = RightShiftWithCeiling(upscaled_width, 3);
do {
uint8x8_t filter[8];
uint8x16_t d[kSuperResFilterTaps / 2];
for (int i = 0; i < 8; ++i, subpixel_x += step) {
filter[i] =
vld1_u8(kUpscaleFilterUnsigned[(subpixel_x & kSuperResScaleMask) >>
kSuperResExtraBits]);
}
Transpose8x8(filter, d);
vst1q_u8(dst, d[0]);
dst += 16;
vst1q_u8(dst, d[1]);
dst += 16;
vst1q_u8(dst, d[2]);
dst += 16;
vst1q_u8(dst, d[3]);
dst += 16;
} while (--x != 0);
}
// Maximum sum of positive taps: 171 = 7 + 86 + 71 + 7
// Maximum sum: 255*171 == 0xAA55
// The sum is clipped to [0, 255], so adding all positive and then
// subtracting all negative with saturation is sufficient.
// 0 1 2 3 4 5 6 7
// tap sign: - + - + + - + -
inline uint8x8_t SuperRes(const uint8x8_t src[kSuperResFilterTaps],
const uint8_t** coefficients) {
uint8x16_t f[kSuperResFilterTaps / 2];
for (int i = 0; i < kSuperResFilterTaps / 2; ++i, *coefficients += 16) {
f[i] = vld1q_u8(*coefficients);
}
uint16x8_t res = vmull_u8(src[1], vget_high_u8(f[0]));
res = vmlal_u8(res, src[3], vget_high_u8(f[1]));
res = vmlal_u8(res, src[4], vget_low_u8(f[2]));
res = vmlal_u8(res, src[6], vget_low_u8(f[3]));
uint16x8_t temp = vmull_u8(src[0], vget_low_u8(f[0]));
temp = vmlal_u8(temp, src[2], vget_low_u8(f[1]));
temp = vmlal_u8(temp, src[5], vget_high_u8(f[2]));
temp = vmlal_u8(temp, src[7], vget_high_u8(f[3]));
res = vqsubq_u16(res, temp);
return vqrshrn_n_u16(res, kFilterBits);
}
void SuperRes_NEON(const void* const coefficients, void* const source,
const ptrdiff_t stride, const int height,
const int downscaled_width, const int upscaled_width,
const int initial_subpixel_x, const int step,
void* const dest) {
auto* src = static_cast<uint8_t*>(source) - DivideBy2(kSuperResFilterTaps);
auto* dst = static_cast<uint8_t*>(dest);
int y = height;
do {
const auto* filter = static_cast<const uint8_t*>(coefficients);
uint8_t* dst_ptr = dst;
ExtendLine<uint8_t>(src + DivideBy2(kSuperResFilterTaps), downscaled_width,
kSuperResHorizontalBorder, kSuperResHorizontalBorder);
int subpixel_x = initial_subpixel_x;
uint8x8_t sr[8];
uint8x16_t s[8];
int x = RightShiftWithCeiling(upscaled_width, 4);
// The below code calculates up to 15 extra upscaled
// pixels which will over-read up to 15 downscaled pixels in the end of each
// row. kSuperResHorizontalBorder accounts for this.
do {
for (int i = 0; i < 8; ++i, subpixel_x += step) {
sr[i] = vld1_u8(&src[subpixel_x >> kSuperResScaleBits]);
}
for (int i = 0; i < 8; ++i, subpixel_x += step) {
const uint8x8_t s_hi = vld1_u8(&src[subpixel_x >> kSuperResScaleBits]);
s[i] = vcombine_u8(sr[i], s_hi);
}
Transpose8x16(s);
// Do not use loop for the following 8 instructions, since the compiler
// will generate redundant code.
sr[0] = vget_low_u8(s[0]);
sr[1] = vget_low_u8(s[1]);
sr[2] = vget_low_u8(s[2]);
sr[3] = vget_low_u8(s[3]);
sr[4] = vget_low_u8(s[4]);
sr[5] = vget_low_u8(s[5]);
sr[6] = vget_low_u8(s[6]);
sr[7] = vget_low_u8(s[7]);
const uint8x8_t d0 = SuperRes(sr, &filter);
// Do not use loop for the following 8 instructions, since the compiler
// will generate redundant code.
sr[0] = vget_high_u8(s[0]);
sr[1] = vget_high_u8(s[1]);
sr[2] = vget_high_u8(s[2]);
sr[3] = vget_high_u8(s[3]);
sr[4] = vget_high_u8(s[4]);
sr[5] = vget_high_u8(s[5]);
sr[6] = vget_high_u8(s[6]);
sr[7] = vget_high_u8(s[7]);
const uint8x8_t d1 = SuperRes(sr, &filter);
vst1q_u8(dst_ptr, vcombine_u8(d0, d1));
dst_ptr += 16;
} while (--x != 0);
src += stride;
dst += stride;
} while (--y != 0);
}
void Init8bpp() {
Dsp* dsp = dsp_internal::GetWritableDspTable(kBitdepth8);
dsp->super_res_coefficients = SuperResCoefficients_NEON;
dsp->super_res = SuperRes_NEON;
}
} // namespace
} // namespace low_bitdepth
void SuperResInit_NEON() { low_bitdepth::Init8bpp(); }
} // namespace dsp
} // namespace libgav1
#else // !LIBGAV1_ENABLE_NEON
namespace libgav1 {
namespace dsp {
void SuperResInit_NEON() {}
} // namespace dsp
} // namespace libgav1
#endif // LIBGAV1_ENABLE_NEON
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