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common/bitfield: make it endianness-aware
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src
@ -34,6 +34,7 @@
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#include <limits>
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#include <type_traits>
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#include "common/common_funcs.h"
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#include "common/swap.h"
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/*
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* Abstract bitfield class
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@ -108,7 +109,7 @@
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* symptoms.
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*/
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#pragma pack(1)
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template <std::size_t Position, std::size_t Bits, typename T>
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template <std::size_t Position, std::size_t Bits, typename T, typename EndianTag = LETag>
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struct BitField {
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private:
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// UnderlyingType is T for non-enum types and the underlying type of T if
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@ -121,6 +122,8 @@ private:
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// We store the value as the unsigned type to avoid undefined behaviour on value shifting
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using StorageType = std::make_unsigned_t<UnderlyingType>;
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using StorageTypeWithEndian = typename AddEndian<StorageType, EndianTag>::type;
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public:
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BitField& operator=(const BitField&) = default;
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@ -168,7 +171,7 @@ public:
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}
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FORCE_INLINE void Assign(const T& value) {
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storage = (storage & ~mask) | FormatValue(value);
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storage = (static_cast<StorageType>(storage) & ~mask) | FormatValue(value);
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}
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FORCE_INLINE T Value() const {
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@ -180,7 +183,7 @@ public:
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}
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private:
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StorageType storage;
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StorageTypeWithEndian storage;
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static_assert(bits + position <= 8 * sizeof(T), "Bitfield out of range");
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@ -196,3 +199,6 @@ private:
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static_assert(std::is_trivially_copyable<BitField<0, 1, unsigned>>::value,
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"BitField must be trivially copyable");
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#endif
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template <std::size_t Position, std::size_t Bits, typename T>
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using BitFieldBE = BitField<Position, Bits, T, BETag>;
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@ -1,4 +1,5 @@
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add_executable(tests
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common/bit_field.cpp
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common/param_package.cpp
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core/arm/arm_test_common.cpp
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core/arm/arm_test_common.h
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90
src/tests/common/bit_field.cpp
Normal file
90
src/tests/common/bit_field.cpp
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@ -0,0 +1,90 @@
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// Copyright 2019 Citra Emulator Project
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// Licensed under GPLv2 or any later version
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// Refer to the license.txt file included.
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#include <array>
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#include <cstring>
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#include <type_traits>
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#include <catch2/catch.hpp>
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#include "common/bit_field.h"
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TEST_CASE("BitField", "[common]") {
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enum class TestEnum : u32 {
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A = 0b10111101,
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B = 0b10101110,
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C = 0b00001111,
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};
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union LEBitField {
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u32_le raw;
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BitField<0, 6, u32> a;
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BitField<6, 4, s32> b;
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BitField<10, 8, TestEnum> c;
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BitField<18, 14, u32> d;
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} le_bitfield;
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union BEBitField {
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u32_be raw;
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BitFieldBE<0, 6, u32> a;
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BitFieldBE<6, 4, s32> b;
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BitFieldBE<10, 8, TestEnum> c;
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BitFieldBE<18, 14, u32> d;
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} be_bitfield;
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static_assert(sizeof(LEBitField) == sizeof(u32));
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static_assert(sizeof(BEBitField) == sizeof(u32));
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static_assert(std::is_trivially_copyable_v<LEBitField>);
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static_assert(std::is_trivially_copyable_v<BEBitField>);
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std::array<u8, 4> raw{{
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0b01101100,
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0b11110110,
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0b10111010,
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0b11101100,
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}};
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std::memcpy(&le_bitfield, &raw, sizeof(raw));
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std::memcpy(&be_bitfield, &raw, sizeof(raw));
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// bit fields: 11101100101110'10111101'1001'101100
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REQUIRE(le_bitfield.raw == 0b11101100'10111010'11110110'01101100);
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REQUIRE(le_bitfield.a == 0b101100);
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REQUIRE(le_bitfield.b == -7); // 1001 as two's complement
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REQUIRE(le_bitfield.c == TestEnum::A);
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REQUIRE(le_bitfield.d == 0b11101100101110);
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le_bitfield.a.Assign(0b000111);
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le_bitfield.b.Assign(-1);
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le_bitfield.c.Assign(TestEnum::C);
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le_bitfield.d.Assign(0b01010101010101);
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std::memcpy(&raw, &le_bitfield, sizeof(raw));
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// bit fields: 01010101010101'00001111'1111'000111
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REQUIRE(le_bitfield.raw == 0b01010101'01010100'00111111'11000111);
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REQUIRE(raw == std::array<u8, 4>{{
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0b11000111,
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0b00111111,
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0b01010100,
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0b01010101,
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}});
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// bit fields: 01101100111101'10101110'1011'101100
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REQUIRE(be_bitfield.raw == 0b01101100'11110110'10111010'11101100);
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REQUIRE(be_bitfield.a == 0b101100);
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REQUIRE(be_bitfield.b == -5); // 1011 as two's complement
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REQUIRE(be_bitfield.c == TestEnum::B);
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REQUIRE(be_bitfield.d == 0b01101100111101);
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be_bitfield.a.Assign(0b000111);
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be_bitfield.b.Assign(-1);
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be_bitfield.c.Assign(TestEnum::C);
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be_bitfield.d.Assign(0b01010101010101);
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std::memcpy(&raw, &be_bitfield, sizeof(raw));
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// bit fields: 01010101010101'00001111'1111'000111
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REQUIRE(be_bitfield.raw == 0b01010101'01010100'00111111'11000111);
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REQUIRE(raw == std::array<u8, 4>{{
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0b01010101,
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0b01010100,
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0b00111111,
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0b11000111,
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}});
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}
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