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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.
#include "lib/jxl/modular/transform/rct.h"
#undef HWY_TARGET_INCLUDE
#define HWY_TARGET_INCLUDE "lib/jxl/modular/transform/rct.cc"
#include <hwy/foreach_target.h>
#include <hwy/highway.h>
HWY_BEFORE_NAMESPACE();
namespace jxl {
namespace HWY_NAMESPACE {
// These templates are not found via ADL.
using hwy::HWY_NAMESPACE::Add;
using hwy::HWY_NAMESPACE::ShiftRight;
using hwy::HWY_NAMESPACE::Sub;
template <int transform_type>
void InvRCTRow(const pixel_type* in0, const pixel_type* in1,
const pixel_type* in2, pixel_type* out0, pixel_type* out1,
pixel_type* out2, size_t w) {
static_assert(transform_type >= 0 && transform_type < 7,
"Invalid transform type");
int second = transform_type >> 1;
int third = transform_type & 1;
size_t x = 0;
const HWY_FULL(pixel_type) d;
const size_t N = Lanes(d);
for (; x + N - 1 < w; x += N) {
if (transform_type == 6) {
auto Y = Load(d, in0 + x);
auto Co = Load(d, in1 + x);
auto Cg = Load(d, in2 + x);
Y = Sub(Y, ShiftRight<1>(Cg));
auto G = Add(Cg, Y);
Y = Sub(Y, ShiftRight<1>(Co));
auto R = Add(Y, Co);
Store(R, d, out0 + x);
Store(G, d, out1 + x);
Store(Y, d, out2 + x);
} else {
auto First = Load(d, in0 + x);
auto Second = Load(d, in1 + x);
auto Third = Load(d, in2 + x);
if (third) Third = Add(Third, First);
if (second == 1) {
Second = Add(Second, First);
} else if (second == 2) {
Second = Add(Second, ShiftRight<1>(Add(First, Third)));
}
Store(First, d, out0 + x);
Store(Second, d, out1 + x);
Store(Third, d, out2 + x);
}
}
for (; x < w; x++) {
if (transform_type == 6) {
pixel_type Y = in0[x];
pixel_type Co = in1[x];
pixel_type Cg = in2[x];
pixel_type tmp = PixelAdd(Y, -(Cg >> 1));
pixel_type G = PixelAdd(Cg, tmp);
pixel_type B = PixelAdd(tmp, -(Co >> 1));
pixel_type R = PixelAdd(B, Co);
out0[x] = R;
out1[x] = G;
out2[x] = B;
} else {
pixel_type First = in0[x];
pixel_type Second = in1[x];
pixel_type Third = in2[x];
if (third) Third = PixelAdd(Third, First);
if (second == 1) {
Second = PixelAdd(Second, First);
} else if (second == 2) {
Second = PixelAdd(Second, (PixelAdd(First, Third) >> 1));
}
out0[x] = First;
out1[x] = Second;
out2[x] = Third;
}
}
}
Status InvRCT(Image& input, size_t begin_c, size_t rct_type, ThreadPool* pool) {
JXL_RETURN_IF_ERROR(CheckEqualChannels(input, begin_c, begin_c + 2));
size_t m = begin_c;
Channel& c0 = input.channel[m + 0];
size_t w = c0.w;
size_t h = c0.h;
if (rct_type == 0) { // noop
return true;
}
// Permutation: 0=RGB, 1=GBR, 2=BRG, 3=RBG, 4=GRB, 5=BGR
int permutation = rct_type / 7;
JXL_ENSURE(permutation < 6);
// 0-5 values have the low bit corresponding to Third and the high bits
// corresponding to Second. 6 corresponds to YCoCg.
//
// Second: 0=nop, 1=SubtractFirst, 2=SubtractAvgFirstThird
//
// Third: 0=nop, 1=SubtractFirst
int custom = rct_type % 7;
// Special case: permute-only. Swap channels around.
if (custom == 0) {
Channel ch0 = std::move(input.channel[m]);
Channel ch1 = std::move(input.channel[m + 1]);
Channel ch2 = std::move(input.channel[m + 2]);
input.channel[m + (permutation % 3)] = std::move(ch0);
input.channel[m + ((permutation + 1 + permutation / 3) % 3)] =
std::move(ch1);
input.channel[m + ((permutation + 2 - permutation / 3) % 3)] =
std::move(ch2);
return true;
}
constexpr decltype(&InvRCTRow<0>) inv_rct_row[] = {
InvRCTRow<0>, InvRCTRow<1>, InvRCTRow<2>, InvRCTRow<3>,
InvRCTRow<4>, InvRCTRow<5>, InvRCTRow<6>};
const auto process_row = [&](const uint32_t task,
size_t /* thread */) -> Status {
const size_t y = task;
const pixel_type* in0 = input.channel[m].Row(y);
const pixel_type* in1 = input.channel[m + 1].Row(y);
const pixel_type* in2 = input.channel[m + 2].Row(y);
pixel_type* out0 = input.channel[m + (permutation % 3)].Row(y);
pixel_type* out1 =
input.channel[m + ((permutation + 1 + permutation / 3) % 3)].Row(y);
pixel_type* out2 =
input.channel[m + ((permutation + 2 - permutation / 3) % 3)].Row(y);
inv_rct_row[custom](in0, in1, in2, out0, out1, out2, w);
return true;
};
JXL_RETURN_IF_ERROR(
RunOnPool(pool, 0, h, ThreadPool::NoInit, process_row, "InvRCT"));
return true;
}
} // namespace HWY_NAMESPACE
} // namespace jxl
HWY_AFTER_NAMESPACE();
#if HWY_ONCE
namespace jxl {
HWY_EXPORT(InvRCT);
Status InvRCT(Image& input, size_t begin_c, size_t rct_type, ThreadPool* pool) {
return HWY_DYNAMIC_DISPATCH(InvRCT)(input, begin_c, rct_type, pool);
}
} // namespace jxl
#endif