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UserspaceEmulator: Add helpers for making loop instructions generic

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Use them to implement CMPSB/CMPSW/CMPSD.
This commit is contained in:
Andreas Kling 2020-07-18 00:10:21 +02:00
parent 28b6ba56aa
commit 485d1faf09
2 changed files with 138 additions and 22 deletions
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48
DevTools/UserspaceEmulator/SoftCPU.cpp
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@ -195,23 +195,9 @@ void SoftCPU::do_once_or_repeat(const X86::Instruction& insn, Callback callback)
if (!insn.has_rep_prefix())
return callback();
if (insn.has_address_size_override_prefix()) {
while (cx()) {
callback();
set_cx(cx() - 1);
if constexpr (check_zf) {
if (insn.rep_prefix() == X86::Prefix::REPZ && !zf())
break;
if (insn.rep_prefix() == X86::Prefix::REPNZ && zf())
break;
}
}
return;
}
while (ecx()) {
while (loop_index(insn.a32())) {
callback();
set_ecx(ecx() - 1);
decrement_loop_index(insn.a32());
if constexpr (check_zf) {
if (insn.rep_prefix() == X86::Prefix::REPZ && !zf())
break;
@ -1057,9 +1043,33 @@ void SoftCPU::CMOVcc_reg32_RM32(const X86::Instruction& insn)
gpr32(insn.reg32()) = insn.modrm().read32(*this, insn);
}
void SoftCPU::CMPSB(const X86::Instruction&) { TODO(); }
void SoftCPU::CMPSD(const X86::Instruction&) { TODO(); }
void SoftCPU::CMPSW(const X86::Instruction&) { TODO(); }
template<typename T>
ALWAYS_INLINE static void do_cmps(SoftCPU& cpu, const X86::Instruction& insn)
{
auto src_segment = cpu.segment(insn.segment_prefix().value_or(X86::SegmentRegister::DS));
cpu.do_once_or_repeat<true>(insn, [&] {
auto src = cpu.read_memory<T>({ src_segment, cpu.source_index(insn.a32()) });
auto dest = cpu.read_memory<T>({ cpu.es(), cpu.destination_index(insn.a32()) });
op_sub(cpu, dest, src);
cpu.step_source_index(insn.a32(), sizeof(T));
cpu.step_destination_index(insn.a32(), sizeof(T));
});
}
void SoftCPU::CMPSB(const X86::Instruction& insn)
{
do_cmps<u8>(*this, insn);
}
void SoftCPU::CMPSD(const X86::Instruction& insn)
{
do_cmps<u32>(*this, insn);
}
void SoftCPU::CMPSW(const X86::Instruction& insn)
{
do_cmps<u16>(*this, insn);
}
void SoftCPU::CMPXCHG_RM16_reg16(const X86::Instruction& insn)
{