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Finally runs into the wall of trying to merge operands and offsets.

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This commit is contained in:
Thomas Harte 2021-01-03 20:08:13 -05:00
parent a8738b533a
commit 38bca5f0f0
2 changed files with 25 additions and 14 deletions
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33
Processors/Decoders/x86/x86.cpp
View File

@ -16,8 +16,8 @@ using namespace CPU::Decoder::x86;
// Only 8086 is suppoted for now.
Decoder::Decoder(Model) {}
Instruction Decoder::decode(uint8_t *source, size_t length) {
uint8_t *const end = source + length;
Instruction Decoder::decode(const uint8_t *source, size_t length) {
const uint8_t *const end = source + length;
#define MapPartial(value, op, lrg, fmt, phs) \
case value: \
@ -49,10 +49,15 @@ Instruction Decoder::decode(uint8_t *source, size_t length) {
// Retain the instruction byte, in case additional decoding is deferred
// to the ModRM byte.
instr_ = *source;
++source;
++consumed_;
switch(instr_) {
default:
default: {
const Instruction instruction(consumed_);
reset_parsing();
return Instruction();
return instruction;
}
#define PartialBlock(start, operation) \
MapPartial(start + 0x00, operation, false, MemReg_Reg, ModRM); \
@ -115,7 +120,7 @@ Instruction Decoder::decode(uint8_t *source, size_t length) {
/* 0x60–0x6f: not used. */
#define MapJump(value, operation) MapPartial(value, operation, false, Disp, AwaitingOperands);
#define MapJump(value, operation) MapPartial(value, operation, false, Immediate, AwaitingOperands);
MapJump(0x70, JO);
MapJump(0x71, JNO);
MapJump(0x72, JB);
@ -164,7 +169,7 @@ Instruction Decoder::decode(uint8_t *source, size_t length) {
MapComplete(0x98, CBW, None, None);
MapComplete(0x99, CWD, None, None);
MapPartial(0x9a, CALL, true, Addr, AwaitingOperands);
MapPartial(0x9a, CALL, true, Immediate, AwaitingOperands);
MapComplete(0x9b, WAIT, None, None);
MapComplete(0x9c, PUSHF, None, None);
MapComplete(0x9d, POPF, None, None);
@ -182,18 +187,24 @@ Instruction Decoder::decode(uint8_t *source, size_t length) {
MapRegData(0xbc, MOV, true, SP); MapRegData(0xbd, MOV, true, BP);
MapRegData(0xbe, MOV, true, SI); MapRegData(0xbf, MOV, true, DI);
MapPartial(0xc2, RETIntra, true, Disp, AwaitingOperands);
MapPartial(0xc2, RETIntra, true, Immediate, AwaitingOperands);
MapComplete(0xc3, RETIntra, None, None);
MapPartial(0xca, RETInter, true, Disp, AwaitingOperands);
MapPartial(0xca, RETInter, true, Immediate, AwaitingOperands);
MapComplete(0xcb, RETInter, None, None);
MapPartial(0xd4, AAM, false, Immediate, AwaitingOperands);
MapPartial(0xd5, AAD, false, Immediate, AwaitingOperands);
// MapPartial(0xe4, IN, false, Immediate, AwaitingOperands);
MapComplete(0xec, IN, DX, AL); MapComplete(0xed, IN, DX, AX);
MapComplete(0xee, OUT, AL, DX); MapComplete(0xef, OUT, AX, DX);
// Other prefix bytes.
case 0xf0: lock_ = true; break;
case 0xf2: repetition_ = Repetition::RepNE; break;
case 0xf3: repetition_ = Repetition::RepE; break;
}
++source;
++consumed_;
}
#undef MapInstr
@ -283,7 +294,7 @@ Instruction Decoder::decode(uint8_t *source, size_t length) {
result = Instruction(operation_, large_operand_ ? Size::Word : Size::Byte, source_, destination_, consumed_);
break;
case Format::Disp:
case Format::Immediate:
result = Instruction(operation_, Size::Byte, Source::Immediate, Source::None, consumed_);
break;

6
Processors/Decoders/x86/x86.hpp
View File

@ -114,7 +114,7 @@ struct Decoder {
instruction in response, and the decoder may still not be able to complete decoding
even if given that number of bytes.
*/
Instruction decode(uint8_t *source, size_t length);
Instruction decode(const uint8_t *source, size_t length);
private:
enum class Phase {
@ -151,8 +151,8 @@ struct Decoder {
Addr_Reg,
SegReg_MemReg,
Disp,
Addr
Immediate,
} format_ = Format::MemReg_Reg;
// TODO: figure out which Formats can be folded together,
// and which are improperly elided.