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get immediate operand when opcode is ADC Immediate

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This commit is contained in:
Alex Weisberger 2014-10-01 18:40:58 -04:00
parent 3e2fecec8f
commit 3563f6362c
2 changed files with 10 additions and 8 deletions
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4
src/instruction.rs
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@ -48,7 +48,9 @@ pub enum Instruction
// NV BDIZC A X Y S PC M
//
// | outputs | inputs
{ ADC // ADd with Carry................ | NV ...ZC A = A + M + C
{
ADC(i8) // ADd with Carry................ | NV ...ZC A = A + M + C
, AND // logical AND (bitwise)......... | N. ...Z. A = A && M
, ASL // Arithmetic Shift Left......... | N. ...ZC A = M << 1
, BCC // Branch if Carry Clear......... | .. ..... PC = !C

14
src/machine.rs
View File

@ -50,27 +50,27 @@ impl Machine {
*self = Machine::new();
}
pub fn fetch_instruction(&mut self) -> u8 {
pub fn fetch_instruction(&mut self) -> i8 {
let instr = self.memory.get_byte(&self.registers.program_counter);
// Will need smarter logic to fetch the correct number of bytes
// for instruction
self.registers.program_counter = self.registers.program_counter + AddressDiff(1);
instr
}
instr as i8
}
pub fn decode_instruction(&mut self, raw_instruction: u8) -> Instruction {
pub fn decode_instruction(&mut self, raw_instruction: i8) -> Instruction {
match raw_instruction {
0x69 => ADC,
0x69 => ADC(self.fetch_instruction()),
_ => NOP
}
}
pub fn execute_instruction(&mut self, instruction: Instruction) {
match instruction {
ADC => {
ADC(immediate) => {
println!("executing add with carry");
self.add_with_carry(1);
self.add_with_carry(immediate);
},
NOP => {
println!("nop instr");