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// Copyright (c) the JPEG XL Project Authors. All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
#if defined(LIB_JXL_FAST_DCT_INL_H_) == defined(HWY_TARGET_TOGGLE)
#ifdef LIB_JXL_FAST_DCT_INL_H_
#undef LIB_JXL_FAST_DCT_INL_H_
#else
#define LIB_JXL_FAST_DCT_INL_H_
#endif
#include <cmath>
#include <hwy/aligned_allocator.h>
#include <hwy/highway.h>
#include "lib/jxl/base/status.h"
HWY_BEFORE_NAMESPACE();
namespace jxl {
namespace HWY_NAMESPACE {
namespace {
#if HWY_TARGET == HWY_NEON
HWY_NOINLINE void FastTransposeBlock(const int16_t* JXL_RESTRICT data_in,
size_t stride_in, size_t N, size_t M,
int16_t* JXL_RESTRICT data_out,
size_t stride_out) {
JXL_DASSERT(N % 8 == 0);
JXL_DASSERT(M % 8 == 0);
for (size_t i = 0; i < N; i += 8) {
for (size_t j = 0; j < M; j += 8) {
// TODO(veluca): one could optimize the M==8, stride_in==8 case further
// with vld4.
// This code is about 40% faster for N == M == stride_in ==
// stride_out == 8
// Using loads + stores to reshuffle things to be able to
// use vld4 doesn't help.
/*
auto a0 = vld4q_s16(data_in); auto a1 = vld4q_s16(data_in + 32);
int16x8x4_t out0;
int16x8x4_t out1;
out0.val[0] = vuzp1q_s16(a0.val[0], a1.val[0]);
out0.val[1] = vuzp1q_s16(a0.val[1], a1.val[1]);
out0.val[2] = vuzp1q_s16(a0.val[2], a1.val[2]);
out0.val[3] = vuzp1q_s16(a0.val[3], a1.val[3]);
out1.val[0] = vuzp2q_s16(a0.val[0], a1.val[0]);
out1.val[1] = vuzp2q_s16(a0.val[1], a1.val[1]);
out1.val[2] = vuzp2q_s16(a0.val[2], a1.val[2]);
out1.val[3] = vuzp2q_s16(a0.val[3], a1.val[3]);
vst1q_s16_x4(data_out, out0);
vst1q_s16_x4(data_out + 32, out1);
*/
auto a0 = vld1q_s16(data_in + i * stride_in + j);
auto a1 = vld1q_s16(data_in + (i + 1) * stride_in + j);
auto a2 = vld1q_s16(data_in + (i + 2) * stride_in + j);
auto a3 = vld1q_s16(data_in + (i + 3) * stride_in + j);
auto a01 = vtrnq_s16(a0, a1);
auto a23 = vtrnq_s16(a2, a3);
auto four0 = vtrnq_s32(vreinterpretq_s32_s16(a01.val[0]),
vreinterpretq_s32_s16(a23.val[0]));
auto four1 = vtrnq_s32(vreinterpretq_s32_s16(a01.val[1]),
vreinterpretq_s32_s16(a23.val[1]));
auto a4 = vld1q_s16(data_in + (i + 4) * stride_in + j);
auto a5 = vld1q_s16(data_in + (i + 5) * stride_in + j);
auto a6 = vld1q_s16(data_in + (i + 6) * stride_in + j);
auto a7 = vld1q_s16(data_in + (i + 7) * stride_in + j);
auto a45 = vtrnq_s16(a4, a5);
auto a67 = vtrnq_s16(a6, a7);
auto four2 = vtrnq_s32(vreinterpretq_s32_s16(a45.val[0]),
vreinterpretq_s32_s16(a67.val[0]));
auto four3 = vtrnq_s32(vreinterpretq_s32_s16(a45.val[1]),
vreinterpretq_s32_s16(a67.val[1]));
auto out0 =
vcombine_s32(vget_low_s32(four0.val[0]), vget_low_s32(four2.val[0]));
auto out1 =
vcombine_s32(vget_low_s32(four1.val[0]), vget_low_s32(four3.val[0]));
auto out2 =
vcombine_s32(vget_low_s32(four0.val[1]), vget_low_s32(four2.val[1]));
auto out3 =
vcombine_s32(vget_low_s32(four1.val[1]), vget_low_s32(four3.val[1]));
auto out4 = vcombine_s32(vget_high_s32(four0.val[0]),
vget_high_s32(four2.val[0]));
auto out5 = vcombine_s32(vget_high_s32(four1.val[0]),
vget_high_s32(four3.val[0]));
auto out6 = vcombine_s32(vget_high_s32(four0.val[1]),
vget_high_s32(four2.val[1]));
auto out7 = vcombine_s32(vget_high_s32(four1.val[1]),
vget_high_s32(four3.val[1]));
vst1q_s16(data_out + j * stride_out + i, vreinterpretq_s16_s32(out0));
vst1q_s16(data_out + (j + 1) * stride_out + i,
vreinterpretq_s16_s32(out1));
vst1q_s16(data_out + (j + 2) * stride_out + i,
vreinterpretq_s16_s32(out2));
vst1q_s16(data_out + (j + 3) * stride_out + i,
vreinterpretq_s16_s32(out3));
vst1q_s16(data_out + (j + 4) * stride_out + i,
vreinterpretq_s16_s32(out4));
vst1q_s16(data_out + (j + 5) * stride_out + i,
vreinterpretq_s16_s32(out5));
vst1q_s16(data_out + (j + 6) * stride_out + i,
vreinterpretq_s16_s32(out6));
vst1q_s16(data_out + (j + 7) * stride_out + i,
vreinterpretq_s16_s32(out7));
}
}
}
template <size_t N>
struct FastDCTTag {};
#include "lib/jxl/fast_dct128-inl.h"
#include "lib/jxl/fast_dct16-inl.h"
#include "lib/jxl/fast_dct256-inl.h"
#include "lib/jxl/fast_dct32-inl.h"
#include "lib/jxl/fast_dct64-inl.h"
#include "lib/jxl/fast_dct8-inl.h"
template <size_t ROWS, size_t COLS>
struct ComputeFastScaledIDCT {
// scratch_space must be aligned, and should have space for ROWS*COLS
// int16_ts.
HWY_MAYBE_UNUSED void operator()(int16_t* JXL_RESTRICT from, int16_t* to,
size_t to_stride,
int16_t* JXL_RESTRICT scratch_space) {
// Reverse the steps done in ComputeScaledDCT.
if (ROWS < COLS) {
FastTransposeBlock(from, COLS, ROWS, COLS, scratch_space, ROWS);
FastIDCT(FastDCTTag<COLS>(), scratch_space, ROWS, from, ROWS, ROWS);
FastTransposeBlock(from, ROWS, COLS, ROWS, scratch_space, COLS);
FastIDCT(FastDCTTag<ROWS>(), scratch_space, COLS, to, to_stride, COLS);
} else {
FastIDCT(FastDCTTag<COLS>(), from, ROWS, scratch_space, ROWS, ROWS);
FastTransposeBlock(scratch_space, ROWS, COLS, ROWS, from, COLS);
FastIDCT(FastDCTTag<ROWS>(), from, COLS, to, to_stride, COLS);
}
}
};
#endif
template <size_t N, size_t M>
HWY_NOINLINE void TestFastIDCT() {
#if HWY_TARGET == HWY_NEON
auto pixels_mem = hwy::AllocateAligned<float>(N * M);
float* pixels = pixels_mem.get();
auto dct_mem = hwy::AllocateAligned<float>(N * M);
float* dct = dct_mem.get();
auto dct_i_mem = hwy::AllocateAligned<int16_t>(N * M);
int16_t* dct_i = dct_i_mem.get();
auto dct_in_mem = hwy::AllocateAligned<int16_t>(N * M);
int16_t* dct_in = dct_in_mem.get();
auto idct_mem = hwy::AllocateAligned<int16_t>(N * M);
int16_t* idct = idct_mem.get();
auto scratch_space_mem = hwy::AllocateAligned<float>(N * M * 2);
float* scratch_space = scratch_space_mem.get();
auto scratch_space_i_mem = hwy::AllocateAligned<int16_t>(N * M * 2);
int16_t* scratch_space_i = scratch_space_i_mem.get();
Rng rng(0);
for (size_t i = 0; i < N * M; i++) {
pixels[i] = rng.UniformF(-1, 1);
}
ComputeScaledDCT<M, N>()(DCTFrom(pixels, N), dct, scratch_space);
size_t integer_bits = std::max(FastIDCTIntegerBits(FastDCTTag<N>()),
FastIDCTIntegerBits(FastDCTTag<M>()));
// Enough range for [-2, 2] output values.
JXL_ASSERT(integer_bits <= 14);
float scale = (1 << (14 - integer_bits));
for (size_t i = 0; i < N * M; i++) {
dct_i[i] = std::round(dct[i] * scale);
}
for (size_t j = 0; j < 40000000 / (M * N); j++) {
memcpy(dct_in, dct_i, sizeof(*dct_i) * N * M);
ComputeFastScaledIDCT<M, N>()(dct_in, idct, N, scratch_space_i);
}
float max_error = 0;
for (size_t i = 0; i < M * N; i++) {
float err = std::abs(idct[i] * (1.0f / scale) - pixels[i]);
if (std::abs(err) > max_error) {
max_error = std::abs(err);
}
}
printf("max error: %f mantissa bits: %d\n", max_error,
14 - (int)integer_bits);
#endif
}
template <size_t N, size_t M>
HWY_NOINLINE void TestFloatIDCT() {
auto pixels_mem = hwy::AllocateAligned<float>(N * M);
float* pixels = pixels_mem.get();
auto dct_mem = hwy::AllocateAligned<float>(N * M);
float* dct = dct_mem.get();
auto idct_mem = hwy::AllocateAligned<float>(N * M);
float* idct = idct_mem.get();
auto dct_in_mem = hwy::AllocateAligned<float>(N * M);
float* dct_in = dct_mem.get();
auto scratch_space_mem = hwy::AllocateAligned<float>(N * M * 2);
float* scratch_space = scratch_space_mem.get();
Rng rng(0);
for (size_t i = 0; i < N * M; i++) {
pixels[i] = rng.UniformF(-1, 1);
}
ComputeScaledDCT<M, N>()(DCTFrom(pixels, N), dct, scratch_space);
for (size_t j = 0; j < 40000000 / (M * N); j++) {
memcpy(dct_in, dct, sizeof(*dct) * N * M);
ComputeScaledIDCT<M, N>()(dct_in, DCTTo(idct, N), scratch_space);
}
float max_error = 0;
for (size_t i = 0; i < M * N; i++) {
float err = std::abs(idct[i] - pixels[i]);
if (std::abs(err) > max_error) {
max_error = std::abs(err);
}
}
printf("max error: %e\n", max_error);
}
} // namespace
// NOLINTNEXTLINE(google-readability-namespace-comments)
} // namespace HWY_NAMESPACE
} // namespace jxl
HWY_AFTER_NAMESPACE();
#endif // LIB_JXL_FAST_DCT_INL_H_
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