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Added PC hack to the various branch/jump instructions

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This commit is contained in:
transistor 2022-09-18 17:24:37 -07:00
parent f5a548ac90
commit 267ef488ab
1 changed files with 24 additions and 6 deletions
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30
src/cpus/m68k/execute.rs
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@ -309,17 +309,26 @@ impl M68k {
Instruction::Bcc(cond, offset) => {
let should_branch = self.get_current_condition(cond);
if should_branch {
self.set_pc((self.decoder.start + 2).wrapping_add(offset as u32))?;
if let Err(err) = self.set_pc((self.decoder.start + 2).wrapping_add(offset as u32)) {
self.state.pc -= 2;
return Err(err);
}
}
},
Instruction::BRA(offset) => {
self.set_pc((self.decoder.start + 2).wrapping_add(offset as u32))?;
if let Err(err) = self.set_pc((self.decoder.start + 2).wrapping_add(offset as u32)) {
self.state.pc -= 2;
return Err(err);
}
},
Instruction::BSR(offset) => {
self.push_long(self.state.pc)?;
let sp = *self.get_stack_pointer_mut();
self.debugger.stack_tracer.push_return(sp);
self.set_pc((self.decoder.start + 2).wrapping_add(offset as u32))?;
if let Err(err) = self.set_pc((self.decoder.start + 2).wrapping_add(offset as u32)) {
self.state.pc -= 2;
return Err(err);
}
},
Instruction::BCHG(bitnum, target, size) => {
let bitnum = self.get_target_value(bitnum, Size::Byte, Used::Once)?;
@ -450,7 +459,10 @@ impl M68k {
let next = ((get_value_sized(self.state.d_reg[reg as usize], Size::Word) as u16) as i16).wrapping_sub(1);
set_value_sized(&mut self.state.d_reg[reg as usize], next as u32, Size::Word);
if next != -1 {
self.set_pc((self.decoder.start + 2).wrapping_add(offset as u32))?;
if let Err(err) = self.set_pc((self.decoder.start + 2).wrapping_add(offset as u32)) {
self.state.pc -= 2;
return Err(err);
}
}
}
},
@ -559,12 +571,18 @@ impl M68k {
},
Instruction::JMP(target) => {
let addr = self.get_target_address(target)?;
self.set_pc(addr)?;
if let Err(err) = self.set_pc(addr) {
self.state.pc -= 2;
return Err(err);
}
},
Instruction::JSR(target) => {
let previous_pc = self.state.pc;
let addr = self.get_target_address(target)?;
self.set_pc(addr)?;
if let Err(err) = self.set_pc(addr) {
self.state.pc -= 2;
return Err(err);
}
// If the address is good, then push the old PC onto the stack
self.push_long(previous_pc)?;