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Formally prepare for one- and two-operand instructions.

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This commit is contained in:
Thomas Harte 2022-04-12 09:14:46 -04:00
parent e7f6cc598d
commit 9aeb6ee532
2 changed files with 30 additions and 20 deletions
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4
InstructionSets/68k/Decoder.cpp
View File

@ -114,6 +114,10 @@ template <Operation operation> Preinstruction Predecoder::decode(uint16_t instru
AddressingMode::DataRegisterDirect, data_register);
}
//
// MARK: MOVEfromSR, NBCD.
//
//
// MARK: MULU, MULS, DIVU, DIVS.
//

46
InstructionSets/68k/Instruction.hpp
View File

@ -182,35 +182,41 @@ class Preinstruction {
public:
Operation operation = Operation::Undefined;
// First operand.
AddressingMode source_mode() {
return AddressingMode(source_ & 0x1f);
}
int source() {
return source_ >> 5;
}
// Instructions come with 0, 1 or 2 operands;
// the getters below act to provide a list of operands
// that is terminated by an AddressingMode::None.
//
// For two-operand instructions, argument 0 is a source
// and argument 1 is a destination.
//
// For one-operand instructions, only argument 0 will
// be provided, and will be a source and/or destination as
// per the semantics of the operation.
// Second operand.
AddressingMode destination_mode() {
return AddressingMode(destination_ & 0x1f);
template <int index> AddressingMode mode() {
if constexpr (index > 1) {
return AddressingMode::None;
}
return AddressingMode(operands_[index] & 0x1f);
}
int destination() {
return destination_ >> 5;
template <int index> int reg() {
if constexpr (index > 1) {
return 0;
}
return operands_[index] >> 5;
}
private:
uint8_t source_ = 0;
uint8_t destination_ = 0;
uint8_t operands_[2] = { uint8_t(AddressingMode::None), uint8_t(AddressingMode::None)};
public:
Preinstruction(
Operation operation,
AddressingMode source_mode,
int source,
AddressingMode destination_mode,
int destination) : operation(operation) {
source_ = uint8_t(source_mode) | uint8_t(source << 5);
destination_ = uint8_t(destination_mode) | uint8_t(destination << 5);
AddressingMode op1_mode, int op1_reg,
AddressingMode op2_mode, int op2_reg) : operation(operation)
{
operands_[0] = uint8_t(op1_mode) | uint8_t(op1_reg << 5);
operands_[1] = uint8_t(op2_mode) | uint8_t(op2_reg << 5);
}
Preinstruction() {}