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mre-mos6502
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simpler/more obvious way to select for different implementations on derivatives

This commit is contained in:
Sam M W 2024-04-24 12:13:13 +01:00
parent 4847744518
commit 309ad50374
1 changed files with 13 additions and 25 deletions
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38
src/instruction.rs
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@ -455,24 +455,15 @@ pub struct Ricoh2a03;
impl crate::Variant for Ricoh2a03 {
fn decode(opcode: u8) -> Option<(Instruction, AddressingMode)> {
match opcode {
0x61 => Some((Instruction::ADCnd, AddressingMode::IndexedIndirectX)),
0x65 => Some((Instruction::ADCnd, AddressingMode::ZeroPage)),
0x69 => Some((Instruction::ADCnd, AddressingMode::Immediate)),
0x6d => Some((Instruction::ADCnd, AddressingMode::Absolute)),
0x71 => Some((Instruction::ADCnd, AddressingMode::IndirectIndexedY)),
0x75 => Some((Instruction::ADCnd, AddressingMode::ZeroPageX)),
0x79 => Some((Instruction::ADCnd, AddressingMode::AbsoluteY)),
0x7d => Some((Instruction::ADCnd, AddressingMode::AbsoluteX)),
0xe1 => Some((Instruction::SBCnd, AddressingMode::IndexedIndirectX)),
0xe5 => Some((Instruction::SBCnd, AddressingMode::ZeroPage)),
0xe9 => Some((Instruction::SBCnd, AddressingMode::Immediate)),
0xed => Some((Instruction::SBCnd, AddressingMode::Absolute)),
0xf1 => Some((Instruction::SBCnd, AddressingMode::IndirectIndexedY)),
0xf5 => Some((Instruction::SBCnd, AddressingMode::ZeroPageX)),
0xf9 => Some((Instruction::SBCnd, AddressingMode::AbsoluteY)),
0xfd => Some((Instruction::SBCnd, AddressingMode::AbsoluteX)),
_ => Nmos6502::decode(opcode),
// It's the same as on NMOS, but doesn't support decimal mode.
match Nmos6502::decode(opcode) {
Some((Instruction::ADC, addressing_mode)) => {
Some((Instruction::ADCnd, addressing_mode))
}
Some((Instruction::SBC, addressing_mode)) => {
Some((Instruction::SBCnd, addressing_mode))
}
something_else => something_else,
}
}
}
@ -483,13 +474,10 @@ pub struct RevisionA;
impl crate::Variant for RevisionA {
fn decode(opcode: u8) -> Option<(Instruction, AddressingMode)> {
match opcode {
0x66 => None,
0x6a => None,
0x6e => None,
0x76 => None,
0x7e => None,
_ => Nmos6502::decode(opcode),
// It's the same as on NMOS, but has no ROR instruction.
match Nmos6502::decode(opcode) {
Some((Instruction::ROR, _)) => None,
something_else => something_else,
}
}
}