mirror of
https://github.com/TomHarte/CLK.git
synced 2025-01-11 08:30:55 +00:00
Eliminate Ind[BXPlusSI/etc] in favour of specifying everything via a ScaleIndexBase.
This commit is contained in:
Thomas Harte
parent
546b4edbf1
commit
9e9e160c43
@ -429,37 +429,23 @@ std::pair<int, InstructionSet::x86::Instruction> Decoder::decode(const uint8_t *
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}
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};
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switch(mod) {
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case 0: {
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constexpr Source rm_table[8] = {
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Source::IndBXPlusSI, Source::IndBXPlusDI,
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Source::IndBPPlusSI, Source::IndBPPlusDI,
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Source::IndSI, Source::IndDI,
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Source::DirectAddress, Source::IndBX,
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};
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memreg = rm_table[rm];
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} break;
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default: {
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// TODO: switch to this table.
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// constexpr ScaleIndexBase rm_table[8] = {
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// ScaleIndexBase(0, Source::eBX, Source::eSI),
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// ScaleIndexBase(0, Source::eBX, Source::eDI),
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// ScaleIndexBase(0, Source::eBP, Source::eSI),
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// ScaleIndexBase(0, Source::eBP, Source::eDI),
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// ScaleIndexBase(0, Source::None, Source::eSI),
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// ScaleIndexBase(0, Source::None, Source::eDI),
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// ScaleIndexBase(0, Source::None, Source::eBP),
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// ScaleIndexBase(0, Source::None, Source::eBX),
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// };
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constexpr Source rm_table[8] = {
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Source::IndBXPlusSI, Source::IndBXPlusDI,
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Source::IndBPPlusSI, Source::IndBPPlusDI,
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Source::IndSI, Source::IndDI,
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Source::IndBP, Source::IndBX,
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};
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memreg = rm_table[rm];
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default:
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displacement_size_ = 1 + (mod == 2);
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[[fallthrough]];
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case 0: {
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constexpr ScaleIndexBase rm_table[8] = {
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ScaleIndexBase(0, Source::eBX, Source::eSI),
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ScaleIndexBase(0, Source::eBX, Source::eDI),
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ScaleIndexBase(0, Source::eBP, Source::eSI),
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ScaleIndexBase(0, Source::eBP, Source::eDI),
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ScaleIndexBase(0, Source::None, Source::eSI),
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ScaleIndexBase(0, Source::None, Source::eDI),
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ScaleIndexBase(0, Source::None, Source::eBP),
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ScaleIndexBase(0, Source::None, Source::eBX),
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};
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memreg = Source::Indirect;
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sib_ = rm_table[rm];
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} break;
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// Other operand is just a register.
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@ -710,6 +696,7 @@ std::pair<int, InstructionSet::x86::Instruction> Decoder::decode(const uint8_t *
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operation_,
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source_,
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destination_,
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sib_,
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lock_,
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segment_override_,
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repetition_,
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@ -168,6 +168,7 @@ class Decoder {
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repetition_ = Repetition::None;
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phase_ = Phase::Instruction;
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source_ = destination_ = Source::None;
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sib_ = 0;
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}
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};
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@ -329,28 +329,21 @@ enum class Source: uint8_t {
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// Legacy 8-bit registers that can't be described as e.g. 8-bit eAX.
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AH, BH, CH, DH,
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// Sources that are not a register.
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/// The address included within this instruction should be used as the source.
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DirectAddress,
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/// The immediate value included within this instruction should be used as the source.
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Immediate,
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/// The ScaleIndexBase associated with this source should be used.
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Indirect,
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// TODO: compact and replace with a reference to a SIB.
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IndBXPlusSI,
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IndBXPlusDI,
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IndBPPlusSI,
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IndBPPlusDI,
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IndSI,
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IndDI,
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IndBP,
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IndBX,
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/// @c None can be treated as a source that produces 0 when encountered;
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/// it is semantically valid to receive it with that meaning in some contexts —
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/// e.g. to indicate no index in indirect addressing.
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None,
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/// The ScaleIndexBase associated with this source should be used.
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Indirect = 0b11000,
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// Elsewhere, as an implementation detail, the low three bits of an indirect source
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// are reused.
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};
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enum class Repetition: uint8_t {
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@ -367,6 +360,8 @@ class ScaleIndexBase {
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constexpr ScaleIndexBase() noexcept {}
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constexpr ScaleIndexBase(uint8_t sib) noexcept : sib_(sib) {}
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constexpr ScaleIndexBase(int scale, Source index, Source base) noexcept : sib_(uint8_t(scale << 6 | (int(index != Source::None ? index : Source::eSI) << 3) | int(base))) {}
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constexpr ScaleIndexBase(Source index, Source base) noexcept : ScaleIndexBase(0, index, base) {}
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constexpr explicit ScaleIndexBase(Source base) noexcept : ScaleIndexBase(0, Source::None, base) {}
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/// @returns the power of two by which to multiply @c index() before adding it to @c base().
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constexpr int scale() const {
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@ -387,6 +382,18 @@ class ScaleIndexBase {
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return Source(sib_ & 0x7);
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}
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bool operator ==(const ScaleIndexBase &rhs) const {
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// Permit either exact equality or index and base being equal
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// but transposed with a scale of 1.
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return
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(sib_ == rhs.sib_) ||
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(
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!scale() && !rhs.scale() &&
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rhs.index() == base() &&
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rhs.base() == index()
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);
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}
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private:
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// Data is stored directly as an 80386 SIB byte.
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uint8_t sib_ = 0;
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@ -394,6 +401,20 @@ class ScaleIndexBase {
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static_assert(sizeof(ScaleIndexBase) == 1);
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static_assert(alignof(ScaleIndexBase) == 1);
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// TODO: improve the naming of SourceSIB.
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struct SourceSIB {
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SourceSIB(Source source) : source(source) {}
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SourceSIB(ScaleIndexBase sib) : sib(sib) {}
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SourceSIB(Source source, ScaleIndexBase sib) : source(source), sib(sib) {}
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bool operator ==(const SourceSIB &rhs) const {
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return source == rhs.source && (source != Source::Indirect || sib == rhs.sib);
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}
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Source source = Source::Indirect;
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ScaleIndexBase sib;
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};
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class Instruction {
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public:
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Operation operation = Operation::Invalid;
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@ -403,7 +424,8 @@ class Instruction {
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repetition_size_ == rhs.repetition_size_ &&
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sources_ == rhs.sources_ &&
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displacement_ == rhs.displacement_ &&
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operand_ == rhs.operand_;
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operand_ == rhs.operand_ &&
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sib_ == rhs.sib_;
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}
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private:
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@ -421,9 +443,12 @@ class Instruction {
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int16_t displacement_ = 0;
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uint16_t operand_ = 0; // ... or used to store a segment for far operations.
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// Fields yet to be properly incorporated...
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ScaleIndexBase sib_;
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public:
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Source source() const { return Source(sources_ & 0x3f); }
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Source destination() const { return Source((sources_ >> 6) & 0x3f); }
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SourceSIB source() const { return SourceSIB(Source(sources_ & 0x3f), sib_); }
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SourceSIB destination() const { return SourceSIB(Source((sources_ >> 6) & 0x3f), sib_); }
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bool lock() const { return sources_ & 0x8000; }
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Source segment_override() const { return Source((sources_ >> 12) & 7); }
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@ -441,6 +466,7 @@ class Instruction {
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Operation operation,
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Source source,
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Source destination,
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ScaleIndexBase sib,
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bool lock,
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Source segment_override,
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Repetition repetition,
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@ -456,10 +482,12 @@ class Instruction {
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(int(lock) << 15)
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)),
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displacement_(displacement),
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operand_(operand) {}
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operand_(operand),
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sib_(sib) {}
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};
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static_assert(sizeof(Instruction) <= 8);
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// TODO: repack.
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//static_assert(sizeof(Instruction) <= 8);
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}
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}
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@ -17,6 +17,8 @@ namespace {
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using Instruction = InstructionSet::x86::Instruction;
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using Source = InstructionSet::x86::Source;
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using Size = InstructionSet::x86::Size;
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using ScaleIndexBase = InstructionSet::x86::ScaleIndexBase;
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using SourceSIB = InstructionSet::x86::SourceSIB;
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}
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@interface x86DecoderTests : XCTestCase
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@ -42,42 +44,42 @@ namespace {
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XCTAssertEqual(instruction.operation_size(), InstructionSet::x86::Size(size));
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}
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- (void)assert:(Instruction &)instruction operation:(Operation)operation size:(int)size source:(Source)source destination:(Source)destination displacement:(int16_t)displacement {
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- (void)assert:(Instruction &)instruction operation:(Operation)operation size:(int)size source:(SourceSIB)source destination:(SourceSIB)destination displacement:(int16_t)displacement {
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XCTAssertEqual(instruction.operation, operation);
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XCTAssertEqual(instruction.operation_size(), InstructionSet::x86::Size(size));
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XCTAssertEqual(instruction.source(), source);
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XCTAssertEqual(instruction.destination(), destination);
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XCTAssert(instruction.source() == source);
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XCTAssert(instruction.destination() == destination);
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XCTAssertEqual(instruction.displacement(), displacement);
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}
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- (void)assert:(Instruction &)instruction operation:(Operation)operation size:(int)size source:(Source)source destination:(Source)destination displacement:(int16_t)displacement operand:(uint16_t)operand {
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- (void)assert:(Instruction &)instruction operation:(Operation)operation size:(int)size source:(SourceSIB)source destination:(SourceSIB)destination displacement:(int16_t)displacement operand:(uint16_t)operand {
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[self assert:instruction operation:operation size:size source:source destination:destination displacement:displacement];
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XCTAssertEqual(instruction.operand(), operand);
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}
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- (void)assert:(Instruction &)instruction operation:(Operation)operation size:(int)size source:(Source)source destination:(Source)destination operand:(uint16_t)operand {
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- (void)assert:(Instruction &)instruction operation:(Operation)operation size:(int)size source:(SourceSIB)source destination:(SourceSIB)destination operand:(uint16_t)operand {
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[self assert:instruction operation:operation size:size source:source destination:destination displacement:0 operand:operand];
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}
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- (void)assert:(Instruction &)instruction operation:(Operation)operation size:(int)size source:(Source)source destination:(Source)destination {
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- (void)assert:(Instruction &)instruction operation:(Operation)operation size:(int)size source:(SourceSIB)source destination:(SourceSIB)destination {
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[self assert:instruction operation:operation size:size source:source destination:destination displacement:0];
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}
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- (void)assert:(Instruction &)instruction operation:(Operation)operation size:(int)size source:(Source)source {
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- (void)assert:(Instruction &)instruction operation:(Operation)operation size:(int)size source:(SourceSIB)source {
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XCTAssertEqual(instruction.operation, operation);
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XCTAssertEqual(instruction.operation_size(), InstructionSet::x86::Size(size));
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XCTAssertEqual(instruction.source(), source);
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XCTAssert(instruction.source() == source);
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}
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- (void)assert:(Instruction &)instruction operation:(Operation)operation size:(int)size destination:(Source)destination {
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- (void)assert:(Instruction &)instruction operation:(Operation)operation size:(int)size destination:(SourceSIB)destination {
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[self assert:instruction operation:operation size:size];
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XCTAssertEqual(instruction.destination(), destination);
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XCTAssert(instruction.destination() == destination);
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}
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- (void)assert:(Instruction &)instruction operation:(Operation)operation size:(int)size operand:(uint16_t)operand destination:(Source)destination {
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- (void)assert:(Instruction &)instruction operation:(Operation)operation size:(int)size operand:(uint16_t)operand destination:(SourceSIB)destination {
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[self assert:instruction operation:operation size:size];
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XCTAssertEqual(instruction.destination(), destination);
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XCTAssertEqual(instruction.source(), Source::Immediate);
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XCTAssert(instruction.destination() == destination);
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XCTAssert(instruction.source() == SourceSIB(Source::Immediate));
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XCTAssertEqual(instruction.operand(), operand);
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XCTAssertEqual(instruction.displacement(), 0);
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}
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@ -200,15 +202,15 @@ namespace {
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// adc %bh,0x3c(%bx)
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[self assert:instructions[14] operation:Operation::INC size:2 source:Source::eBX destination:Source::eBX];
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[self assert:instructions[15] operation:Operation::CMP size:1 operand:0x8e destination:Source::eAX];
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[self assert:instructions[16] operation:Operation::SBB size:1 source:Source::IndBXPlusSI destination:Source::BH displacement:0x45];
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[self assert:instructions[17] operation:Operation::ADC size:1 source:Source::BH destination:Source::IndBX displacement:0x3c];
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[self assert:instructions[16] operation:Operation::SBB size:1 source:ScaleIndexBase(Source::eBX, Source::eSI) destination:Source::BH displacement:0x45];
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[self assert:instructions[17] operation:Operation::ADC size:1 source:Source::BH destination:ScaleIndexBase(Source::eBX) displacement:0x3c];
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// sbb %bx,0x16(%bp,%si)
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// xor %sp,0x2c(%si)
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// out %ax,$0xc6
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// jge 0xffffffe0
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[self assert:instructions[18] operation:Operation::SBB size:2 source:Source::eBX destination:Source::IndBPPlusSI displacement:0x16];
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[self assert:instructions[19] operation:Operation::XOR size:2 source:Source::eSP destination:Source::IndSI displacement:0x2c];
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[self assert:instructions[18] operation:Operation::SBB size:2 source:Source::eBX destination:ScaleIndexBase(Source::eBP, Source::eSI) displacement:0x16];
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[self assert:instructions[19] operation:Operation::XOR size:2 source:Source::eSP destination:ScaleIndexBase(Source::eSI) displacement:0x2c];
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[self assert:instructions[20] operation:Operation::OUT size:2 source:Source::eAX destination:Source::DirectAddress operand:0xc6];
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[self assert:instructions[21] operation:Operation::JNL displacement:0xffb0];
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@ -228,7 +230,7 @@ namespace {
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// in $0xc9,%ax
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[self assert:instructions[26] operation:Operation::PUSH size:2 source:Source::eAX];
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[self assert:instructions[27] operation:Operation::JS displacement:0x3d];
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[self assert:instructions[28] operation:Operation::ADD size:2 source:Source::IndDI destination:Source::eBX];
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[self assert:instructions[28] operation:Operation::ADD size:2 source:ScaleIndexBase(Source::eDI) destination:Source::eBX];
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[self assert:instructions[29] operation:Operation::IN size:2 source:Source::DirectAddress destination:Source::eAX operand:0xc9];
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// xchg %ax,%di
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@ -274,7 +276,7 @@ namespace {
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// adc $0xb8c3,%ax
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// lods %ds:(%si),%ax
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[self assert:instructions[46] operation:Operation::XCHG size:2 source:Source::eAX destination:Source::eDX];
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[self assert:instructions[47] operation:Operation::CMP size:2 source:Source::eBX destination:Source::IndDI displacement:0xff90];
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[self assert:instructions[47] operation:Operation::CMP size:2 source:Source::eBX destination:ScaleIndexBase(Source::eDI) displacement:0xff90];
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[self assert:instructions[48] operation:Operation::ADC size:2 operand:0xb8c3 destination:Source::eAX];
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[self assert:instructions[49] operation:Operation::LODS size:2];
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@ -300,10 +302,10 @@ namespace {
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// sub %dl,%dl
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// negw 0x18(%bx)
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// xchg %dl,0x6425(%bx,%si)
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[self assert:instructions[58] operation:Operation::AND size:2 source:Source::IndBPPlusSI destination:Source::eBP displacement:0x5b2c];
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[self assert:instructions[58] operation:Operation::AND size:2 source:ScaleIndexBase(Source::eBP, Source::eSI) destination:Source::eBP displacement:0x5b2c];
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[self assert:instructions[59] operation:Operation::SUB size:1 source:Source::eDX destination:Source::eDX];
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[self assert:instructions[60] operation:Operation::NEG size:2 source:Source::IndBX destination:Source::IndBX displacement:0x18];
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[self assert:instructions[61] operation:Operation::XCHG size:1 source:Source::IndBXPlusSI destination:Source::eDX displacement:0x6425];
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[self assert:instructions[60] operation:Operation::NEG size:2 source:ScaleIndexBase(Source::eBX) destination:ScaleIndexBase(Source::eBX) displacement:0x18];
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[self assert:instructions[61] operation:Operation::XCHG size:1 source:ScaleIndexBase(Source::eBX, Source::eSI) destination:Source::eDX displacement:0x6425];
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// mov $0xc3,%bh
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[self assert:instructions[62] operation:Operation::MOV size:1 operand:0xc3 destination:Source::BH];
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@ -317,9 +319,9 @@ namespace {
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}];
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XCTAssertEqual(instructions.size(), 3);
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[self assert:instructions[0] operation:Operation::ADC size:2 source:Source::Immediate destination:Source::IndBXPlusSI operand:0xff80];
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[self assert:instructions[1] operation:Operation::CMP size:2 source:Source::Immediate destination:Source::IndBPPlusDI operand:0x4];
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[self assert:instructions[2] operation:Operation::SUB size:2 source:Source::Immediate destination:Source::IndBX operand:0x9];
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[self assert:instructions[0] operation:Operation::ADC size:2 source:Source::Immediate destination:ScaleIndexBase(Source::eBX, Source::eSI) operand:0xff80];
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[self assert:instructions[1] operation:Operation::CMP size:2 source:Source::Immediate destination:ScaleIndexBase(Source::eBP, Source::eDI) operand:0x4];
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[self assert:instructions[2] operation:Operation::SUB size:2 source:Source::Immediate destination:ScaleIndexBase(Source::eBX) operand:0x9];
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}
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- (void)testFar {
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