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Attempts to complete operand recognition.

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This commit is contained in:
Thomas Harte 2021-01-07 21:59:00 -05:00
parent 205649cac2
commit 30c2c0f050
2 changed files with 58 additions and 13 deletions
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55
Processors/Decoders/x86/x86.cpp
View File

@ -285,9 +285,9 @@ Instruction Decoder::decode(const uint8_t *source, size_t length) {
case 0xe7: AddrReg(OUT, AX, 2, 1); break;
case 0xe8: RegData(CALLD, None, 2); break;
case 0xe9: RegData(JMP, None, 2); break;
case 0xea: Far(JMP); break;
case 0xeb: Jump(JMP); break;
case 0xe9: RegData(JMPN, None, 2); break;
case 0xea: Far(JMPF); break;
case 0xeb: Jump(JMPN); break;
case 0xec: Complete(IN, DX, AL, 1); break;
case 0xed: Complete(IN, DX, AX, 1); break;
@ -306,14 +306,8 @@ Instruction Decoder::decode(const uint8_t *source, size_t length) {
case 0xfc: Complete(CLD, None, None, 1); break;
case 0xfd: Complete(STD, None, None, 1); break;
/*
Unimplemented (but should be):
0xfe, 0xff
[and consider which others are unused but seem to be
known to consume a second byte?]
*/
case 0xfe: MemRegReg(Invalid, MemRegINC_DEC, 1); break;
case 0xff: MemRegReg(Invalid, MemRegINC_to_PUSH, 1); break;
// Other prefix bytes.
case 0xf0: lock_ = true; break;
@ -444,6 +438,45 @@ Instruction Decoder::decode(const uint8_t *source, size_t length) {
}
break;
case ModRegRMFormat::MemRegINC_DEC:
source_ = destination_ = memreg;
switch(reg) {
default:
reset_parsing();
return Instruction(consumed_);
case 0: operation_ = Operation::INC; break;
case 1: operation_ = Operation::DEC; break;
}
break;
case ModRegRMFormat::MemRegINC_to_PUSH:
source_ = destination_ = memreg;
switch(reg) {
default:
reset_parsing();
return Instruction(consumed_);
case 0: operation_ = Operation::INC; break;
case 1: operation_ = Operation::DEC; break;
case 2: operation_ = Operation::CALLN; break;
case 3:
operation_ = Operation::CALLF;
operand_size_ = 4;
source_ = Source::Immediate;
break;
case 4: operation_ = Operation::JMPN; break;
case 5:
operation_ = Operation::JMPF;
operand_size_ = 4;
source_ = Source::Immediate;
break;
case 6: operation_ = Operation::PUSH; break;
}
break;
case ModRegRMFormat::MemRegPOP:
source_ = destination_ = memreg;

16
Processors/Decoders/x86/x86.hpp
View File

@ -41,7 +41,7 @@ enum class Operation: uint8_t {
CALLF,
/// Displacement call; followed by a 16-bit operand providing a call offset.
CALLD,
/* TODO: other CALLs */
CALLN,
/// Convert byte into word; source will be AL, destination will be AH.
CBW,
/// Clear carry flag; no source or destination provided.
@ -68,7 +68,9 @@ enum class Operation: uint8_t {
INC, INT, INT3, INTO, IRET,
JO, JNO, JB, JNB, JE, JNE, JBE, JNBE,
JS, JNS, JP, JNP, JL, JNL, JLE, JNLE,
JMP, JCXZ,
JMPN,
JMPF,
JCXZ,
LAHF, LDS, LEA,
LODS, LOOPE, LOOPNE, MOV, MOVS, MUL, NEG, NOP, NOT, OR, OUT,
POP, POPF, PUSH, PUSHF, RCL, RCR, REP, ROL, ROR, SAHF,
@ -210,6 +212,16 @@ struct Decoder {
// register based on the reg field.
SegReg,
// Parse for mode and register/memory fields, populating the
// source_ and destination_ fields with the result. Uses the
// 'register' field to pick INC or DEC.
MemRegINC_DEC,
// Parse for mode and register/memory fields, populating the
// source_ and destination_ fields with the result. Uses the
// 'register' field to pick from INC/DEC/CALL/JMP/PUSH, altering
// the source to ::Immediate and setting an operand size if necessary.
MemRegINC_to_PUSH,
} modregrm_format_ = ModRegRMFormat::MemReg_Reg;
// Ephemeral decoding state.