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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.
// SIMDified inverse-move-to-front transform.
#if defined(LIB_JXL_INVERSE_MTF_INL_H_) == defined(HWY_TARGET_TOGGLE)
#ifdef LIB_JXL_INVERSE_MTF_INL_H_
#undef LIB_JXL_INVERSE_MTF_INL_H_
#else
#define LIB_JXL_INVERSE_MTF_INL_H_
#endif
#include <hwy/highway.h>
#include "lib/jxl/base/sanitizers.h"
HWY_BEFORE_NAMESPACE();
namespace jxl {
namespace HWY_NAMESPACE {
// These templates are not found via ADL.
using hwy::HWY_NAMESPACE::FirstN;
using hwy::HWY_NAMESPACE::IfThenElse;
using hwy::HWY_NAMESPACE::Load;
using hwy::HWY_NAMESPACE::LoadU;
using hwy::HWY_NAMESPACE::StoreU;
inline void MoveToFront(uint8_t* v, uint8_t index) {
uint8_t value = v[index];
uint8_t i = index;
if (i < 4) {
for (; i; --i) v[i] = v[i - 1];
} else {
const HWY_CAPPED(uint8_t, 64) d;
int tail = i & (Lanes(d) - 1);
if (tail) {
i -= tail;
const auto vec = Load(d, v + i);
const auto prev = LoadU(d, v + i + 1);
StoreU(IfThenElse(FirstN(d, tail), vec, prev), d, v + i + 1);
}
while (i) {
i -= Lanes(d);
const auto vec = Load(d, v + i);
StoreU(vec, d, v + i + 1);
}
}
v[0] = value;
}
inline void InverseMoveToFrontTransform(uint8_t* v, int v_len) {
HWY_ALIGN uint8_t mtf[256 + 64];
int i;
for (i = 0; i < 256; ++i) {
mtf[i] = static_cast<uint8_t>(i);
}
#if JXL_MEMORY_SANITIZER
const HWY_CAPPED(uint8_t, 64) d;
for (size_t j = 0; j < Lanes(d); ++j) {
mtf[256 + j] = 0;
}
#endif // JXL_MEMORY_SANITIZER
for (i = 0; i < v_len; ++i) {
uint8_t index = v[i];
v[i] = mtf[index];
if (index) MoveToFront(mtf, index);
}
}
// NOLINTNEXTLINE(google-readability-namespace-comments)
} // namespace HWY_NAMESPACE
} // namespace jxl
HWY_AFTER_NAMESPACE();
#endif // LIB_JXL_INVERSE_MTF_INL_H_
#if HWY_ONCE
#ifndef INVERSE_MTF_ONCE
#define INVERSE_MTF_ONCE
namespace jxl {
inline void InverseMoveToFrontTransform(uint8_t* v, int v_len) {
HWY_STATIC_DISPATCH(InverseMoveToFrontTransform)(v, v_len);
}
} // namespace jxl
#endif // INVERSE_MTF_ONCE
#endif // HWY_ONCE