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// Copyright 2018 yuzu Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.
#pragma once
#include <bit>
#include "common/common_types.h"
namespace Tegra::Texture::ASTC {
enum class IntegerEncoding { JustBits, Quint, Trit };
struct IntegerEncodedValue {
constexpr IntegerEncodedValue() = default;
constexpr IntegerEncodedValue(IntegerEncoding encoding_, u32 num_bits_)
: encoding{encoding_}, num_bits{num_bits_} {}
constexpr bool MatchesEncoding(const IntegerEncodedValue& other) const {
return encoding == other.encoding && num_bits == other.num_bits;
}
// Returns the number of bits required to encode num_vals values.
u32 GetBitLength(u32 num_vals) const {
u32 total_bits = num_bits * num_vals;
if (encoding == IntegerEncoding::Trit) {
total_bits += (num_vals * 8 + 4) / 5;
} else if (encoding == IntegerEncoding::Quint) {
total_bits += (num_vals * 7 + 2) / 3;
}
return total_bits;
}
IntegerEncoding encoding{};
u32 num_bits = 0;
u32 bit_value = 0;
union {
u32 quint_value = 0;
u32 trit_value;
};
};
// Returns a new instance of this struct that corresponds to the
// can take no more than mav_value values
constexpr IntegerEncodedValue CreateEncoding(u32 mav_value) {
while (mav_value > 0) {
u32 check = mav_value + 1;
// Is mav_value a power of two?
if (!(check & (check - 1))) {
return IntegerEncodedValue(IntegerEncoding::JustBits, std::popcount(mav_value));
}
// Is mav_value of the type 3*2^n - 1?
if ((check % 3 == 0) && !((check / 3) & ((check / 3) - 1))) {
return IntegerEncodedValue(IntegerEncoding::Trit, std::popcount(check / 3 - 1));
}
// Is mav_value of the type 5*2^n - 1?
if ((check % 5 == 0) && !((check / 5) & ((check / 5) - 1))) {
return IntegerEncodedValue(IntegerEncoding::Quint, std::popcount(check / 5 - 1));
}
// Apparently it can't be represented with a bounded integer sequence...
// just iterate.
mav_value--;
}
return IntegerEncodedValue(IntegerEncoding::JustBits, 0);
}
constexpr std::array<IntegerEncodedValue, 256> MakeEncodedValues() {
std::array<IntegerEncodedValue, 256> encodings{};
for (std::size_t i = 0; i < encodings.size(); ++i) {
encodings[i] = CreateEncoding(static_cast<u32>(i));
}
return encodings;
}
constexpr std::array<IntegerEncodedValue, 256> ASTC_ENCODINGS_VALUES = MakeEncodedValues();
void Decompress(std::span<const uint8_t> data, uint32_t width, uint32_t height, uint32_t depth,
uint32_t block_width, uint32_t block_height, std::span<uint8_t> output);
} // namespace Tegra::Texture::ASTC
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