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UserspaceEmulator: Convert the XOR instruction to inline assembly

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This commit is contained in:
Andreas Kling 2020-07-11 15:55:00 +02:00
parent 9db588daf1
commit 76b9fb258d
2 changed files with 31 additions and 6 deletions
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31
DevTools/UserspaceEmulator/SoftCPU.cpp
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@ -139,12 +139,31 @@ u32 SoftCPU::pop32()
template<typename Destination, typename Source>
static typename TypeDoubler<Destination>::type op_xor(SoftCPU& cpu, const Destination& dest, const Source& src)
{
auto result = dest ^ src;
cpu.set_zf(dest == 0);
cpu.set_sf(dest & 0x80000000);
// FIXME: set_pf
cpu.set_of(false);
cpu.set_cf(false);
Destination result = 0;
u32 new_flags = 0;
if constexpr (sizeof(Destination) == 4) {
asm volatile("xorl %%ecx, %%eax\n"
: "=a"(result)
: "a"(dest), "c"(src));
} else if constexpr (sizeof(Destination) == 2) {
asm volatile("xor %%cx, %%ax\n"
: "=a"(result)
: "a"(dest), "c"(src));
} else if constexpr (sizeof(Destination) == 1) {
asm volatile("xorb %%cl, %%al\n"
: "=a"(result)
: "a"(dest), "c"(src));
} else {
ASSERT_NOT_REACHED();
}
asm volatile(
"pushf\n"
"pop %%ebx"
: "=b"(new_flags));
cpu.set_flags_oszpc(new_flags);
return result;
}

6
DevTools/UserspaceEmulator/SoftCPU.h
View file

@ -213,6 +213,12 @@ public:
m_eflags |= new_flags & (Flags::OF | Flags::SF | Flags::ZF | Flags::AF | Flags::PF);
}
void set_flags_oszpc(u32 new_flags)
{
m_eflags &= ~(Flags::OF | Flags::SF | Flags::ZF | Flags::PF | Flags::CF);
m_eflags |= new_flags & (Flags::OF | Flags::SF | Flags::ZF | Flags::PF | Flags::CF);
}
u16 cs() const { return m_segment[(int)X86::SegmentRegister::CS]; }
u16 ds() const { return m_segment[(int)X86::SegmentRegister::DS]; }
u16 es() const { return m_segment[(int)X86::SegmentRegister::ES]; }