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// SPDX-FileCopyrightText: Copyright 2021 yuzu Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later
#include <algorithm>
#include <array>
#include <bit>
#include <memory>
#include "common/common_types.h"
#include "shader_recompiler/exception.h"
#include "shader_recompiler/frontend/maxwell/decode.h"
#include "shader_recompiler/frontend/maxwell/opcodes.h"
namespace Shader::Maxwell {
namespace {
struct MaskValue {
u64 mask;
u64 value;
};
constexpr MaskValue MaskValueFromEncoding(const char* encoding) {
u64 mask{};
u64 value{};
u64 bit{u64(1) << 63};
while (*encoding) {
switch (*encoding) {
case '0':
mask |= bit;
break;
case '1':
mask |= bit;
value |= bit;
break;
case '-':
break;
case ' ':
break;
default:
throw LogicError("Invalid encoding character '{}'", *encoding);
}
++encoding;
if (*encoding != ' ') {
bit >>= 1;
}
}
return MaskValue{.mask = mask, .value = value};
}
struct InstEncoding {
MaskValue mask_value;
Opcode opcode;
};
constexpr std::array UNORDERED_ENCODINGS{
#define INST(name, cute, encode) \
InstEncoding{ \
.mask_value{MaskValueFromEncoding(encode)}, \
.opcode = Opcode::name, \
},
#include "maxwell.inc"
#undef INST
};
constexpr auto SortedEncodings() {
std::array encodings{UNORDERED_ENCODINGS};
std::ranges::sort(encodings, [](const InstEncoding& lhs, const InstEncoding& rhs) {
return std::popcount(lhs.mask_value.mask) > std::popcount(rhs.mask_value.mask);
});
return encodings;
}
constexpr auto ENCODINGS{SortedEncodings()};
constexpr int WidestLeftBits() {
int bits{64};
for (const InstEncoding& encoding : ENCODINGS) {
bits = std::min(bits, std::countr_zero(encoding.mask_value.mask));
}
return 64 - bits;
}
constexpr int WIDEST_LEFT_BITS{WidestLeftBits()};
constexpr int MASK_SHIFT{64 - WIDEST_LEFT_BITS};
constexpr size_t ToFastLookupIndex(u64 value) {
return static_cast<size_t>(value >> MASK_SHIFT);
}
constexpr size_t FastLookupSize() {
size_t max_width{};
for (const InstEncoding& encoding : ENCODINGS) {
max_width = std::max(max_width, ToFastLookupIndex(encoding.mask_value.mask));
}
return max_width + 1;
}
constexpr size_t FAST_LOOKUP_SIZE{FastLookupSize()};
struct InstInfo {
[[nodiscard]] u64 Mask() const noexcept {
return static_cast<u64>(high_mask) << MASK_SHIFT;
}
[[nodiscard]] u64 Value() const noexcept {
return static_cast<u64>(high_value) << MASK_SHIFT;
}
u16 high_mask;
u16 high_value;
Opcode opcode;
};
constexpr auto MakeFastLookupTableIndex(size_t index) {
std::array<InstInfo, 2> encodings{};
size_t element{};
for (const auto& encoding : ENCODINGS) {
const size_t mask{ToFastLookupIndex(encoding.mask_value.mask)};
const size_t value{ToFastLookupIndex(encoding.mask_value.value)};
if ((index & mask) == value) {
encodings.at(element) = InstInfo{
.high_mask = static_cast<u16>(encoding.mask_value.mask >> MASK_SHIFT),
.high_value = static_cast<u16>(encoding.mask_value.value >> MASK_SHIFT),
.opcode = encoding.opcode,
};
++element;
}
}
return encodings;
}
/*constexpr*/ auto MakeFastLookupTable() {
auto encodings{std::make_unique<std::array<std::array<InstInfo, 2>, FAST_LOOKUP_SIZE>>()};
for (size_t index = 0; index < FAST_LOOKUP_SIZE; ++index) {
(*encodings)[index] = MakeFastLookupTableIndex(index);
}
return encodings;
}
const auto FAST_LOOKUP_TABLE{MakeFastLookupTable()};
} // Anonymous namespace
Opcode Decode(u64 insn) {
const auto& table{(*FAST_LOOKUP_TABLE)[ToFastLookupIndex(insn)]};
const auto it{std::ranges::find_if(
table, [insn](const InstInfo& info) { return (insn & info.Mask()) == info.Value(); })};
if (it == table.end()) {
throw NotImplementedException("Instruction 0x{:016x} is unknown / unimplemented", insn);
}
return it->opcode;
}
} // namespace Shader::Maxwell
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