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Decodes 8e.

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This commit is contained in:
Thomas Harte
2021-01-07 21:36:05 -05:00
parent fd49b72e31
commit 205649cac2
2 changed files with 22 additions and 2 deletions
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19
Processors/Decoders/x86/x86.cpp
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@@ -176,7 +176,7 @@ Instruction Decoder::decode(const uint8_t *source, size_t length) {
case 0x8b: MemRegReg(MOV, Reg_MemReg, 2); break; case 0x8b: MemRegReg(MOV, Reg_MemReg, 2); break;
// 0x8c: not used. // 0x8c: not used.
case 0x8d: MemRegReg(LEA, Reg_MemReg, 2); break; case 0x8d: MemRegReg(LEA, Reg_MemReg, 2); break;
// case 0x84: MemRegReg(0x8e, MOV, SegReg_MemReg, 1); // TODO: SegReg_MemReg case 0x8e: MemRegReg(MOV, SegReg, 2); break;
case 0x8f: MemRegReg(POP, MemRegPOP, 2); break; case 0x8f: MemRegReg(POP, MemRegPOP, 2); break;
case 0x90: Complete(NOP, None, None, 0); break; // Or XCHG AX, AX? case 0x90: Complete(NOP, None, None, 0); break; // Or XCHG AX, AX?
@@ -309,7 +309,6 @@ Instruction Decoder::decode(const uint8_t *source, size_t length) {
/* /*
Unimplemented (but should be): Unimplemented (but should be):
0x8e,
0xfe, 0xff 0xfe, 0xff
[and consider which others are unused but seem to be [and consider which others are unused but seem to be
@@ -411,6 +410,22 @@ Instruction Decoder::decode(const uint8_t *source, size_t length) {
} }
break; break;
case ModRegRMFormat::SegReg: {
source_ = memreg;
constexpr Source seg_table[4] = {
Source::ES, Source::CS,
Source::SS, Source::DS,
};
if(reg & 4) {
reset_parsing();
return Instruction(consumed_);
}
destination_ = seg_table[reg];
} break;
case ModRegRMFormat::MemRegROL_to_SAR: case ModRegRMFormat::MemRegROL_to_SAR:
destination_ = memreg; destination_ = memreg;

5
Processors/Decoders/x86/x86.hpp
View File

@@ -205,6 +205,11 @@ struct Decoder {
// to pick an operation from the ROL/ROR/RCL/RCR/SAL/SHR/SAR group. // to pick an operation from the ROL/ROR/RCL/RCR/SAL/SHR/SAR group.
MemRegROL_to_SAR, MemRegROL_to_SAR,
// Parse for mode and register/memory fields, populating the
// source_ field with the result. Fills destination_ with a segment
// register based on the reg field.
SegReg,
} modregrm_format_ = ModRegRMFormat::MemReg_Reg; } modregrm_format_ = ModRegRMFormat::MemReg_Reg;
// Ephemeral decoding state. // Ephemeral decoding state.