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Marks intent for operand/displacement.

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This commit is contained in:
Thomas Harte 2021-01-08 22:45:27 -05:00
parent 97a64db5e0
commit 68fe16a092
1 changed files with 17 additions and 10 deletions
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27
Processors/Decoders/x86/x86.cpp
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@ -254,7 +254,7 @@ std::pair<int, Instruction> Decoder::decode(const uint8_t *source, size_t length
modregrm_format_ = ModRegRMFormat::MemRegROL_to_SAR;
operation_size_ = 1 + (instr_ & 1);
source_ = Source::Immediate;
// TODO: set operand to 1.
operand_ = 1;
break;
case 0xd2: case 0xd3:
phase_ = Phase::ModRegRM;
@ -512,19 +512,26 @@ std::pair<int, Instruction> Decoder::decode(const uint8_t *source, size_t length
// MARK: - Displacement and operand.
if(phase_ == Phase::AwaitingDisplacementOrOperand && source != end) {
// TODO: calculate number of expected operands.
const int required_bytes = displacement_size_ + operand_size_;
const int outstanding_bytes = required_bytes - operand_bytes_;
const int bytes_to_consume = std::min(int(end - source), outstanding_bytes);
source += bytes_to_consume;
consumed_ += bytes_to_consume;
operand_bytes_ += bytes_to_consume;
if(bytes_to_consume == outstanding_bytes) {
if(!required_bytes) {
phase_ = Phase::ReadyToPost;
} else {
// Provide a genuine measure of further bytes required.
return std::make_pair(-(outstanding_bytes - bytes_to_consume), Instruction());
const int outstanding_bytes = required_bytes - operand_bytes_;
const int bytes_to_consume = std::min(int(end - source), outstanding_bytes);
// TODO: fill displacement_ and operand_ here... efficiently?
source += bytes_to_consume;
consumed_ += bytes_to_consume;
operand_bytes_ += bytes_to_consume;
if(bytes_to_consume == outstanding_bytes) {
phase_ = Phase::ReadyToPost;
} else {
// Provide a genuine measure of further bytes required.
return std::make_pair(-(outstanding_bytes - bytes_to_consume), Instruction());
}
}
}