public void cpu_OnJSR(Cpu cpu)
{
Debug.Assert(cpu.OpCode == 0x20); // JSR
// 6502 JSR semantics
StackByte jsrReturnAddrH = _stackBytes[StackPtr + 2];
StackByte jsrReturnAddrL = _stackBytes[StackPtr + 1];
JsrInfo info = new JsrInfo {
JsrOpcodeAddr = cpu.OpcodeRPC,
JsrTargetAddr = cpu.RPC,
StackPtrAfterJsr = StackPtr,
CyclesAfterJsr = cpu.Cycles,
JsrReturnAddrH = jsrReturnAddrH,
JsrReturnAddrL = jsrReturnAddrL,
CallDepthAtJsr = CallDepth,
};
// check integrity of JsrInfo (ReturnAddrOnStack is calculated property)
Debug.Assert((jsrReturnAddrL.Value | jsrReturnAddrH.Value << 8) == info.ReturnAddrOnStack);
_jsrInfoStack.Push(info);
jsrReturnAddrH.NotifyNewJsrInfo(info, AddressPart.High, cpu.Cycles);
jsrReturnAddrL.NotifyNewJsrInfo(info, AddressPart.Low, cpu.Cycles);
OnJSR?.Invoke(info);
}
public StackWrapper(MachineOperator mo)
{
_cpu = mo.Machine.Cpu;
_memory = mo.Machine.Memory;
for (int stackPtr = 0xff; stackPtr >= 0; stackPtr--)
{
_stackBytes[stackPtr] = new StackByte(_memory, stackPtr);
}
}
public void cpu_OnRTS(Cpu cpu)
{
Debug.Assert(cpu.OpCode == 0x60); // RTS
// RTS adds 1 to RPC, so return address needs to be one byte less than target RPC
// this how RTS is defined, so we can safely assert (6502 semantics, not StackWrapper semantics)
StackByte highRtsPart = _stackBytes[StackPtr];
StackByte lowRtsPart = _stackBytes[StackPtr - 1];
Debug.Assert(lowRtsPart.Value + (highRtsPart.Value << 8) + 1 == cpu.RPC);
if (StackPtr == TopStackPtrH)
{
// StackPtr is at the level where the matching JSR happened
JsrInfo info = PopJsrInfo(i => {
// TraceLine( $"<- RTS /{CallDepth} {cpu.RPC.ToHex()}" + (i.Retired ? $" (retired {i.JsrOpcodeAddr.ToHex()})" : "" ) );
});
AddRtsInfo(info);
OnRTS?.Invoke(info);
}
else
{
Debug.Assert(false, "UNTESTED");
if (StackPtr < TopStackPtrH)
{
// probably a RTS jump table
// nothing to do for us here
// we could probably assert that StackPtr is 2 below exectedStackPtr, but maybe caller wants to pass sth on the stack?
}
else
{
// probably an "exception", i.e. returning not to the caller but to the caller's caller
Debug.Assert(StackPtr > TopStackPtrH);
while (_jsrInfoStack.Count > 0 && StackPtr > TopStackPtrH)
{
JsrInfo info = PopJsrInfo(i => {
// TraceLine( $"<- ignored RTS /{CallDepth} {cpu.RPC.ToHex()}" + (i.Retired ? $" (retired {i.JsrOpcodeAddr.ToHex()})" : "") );
});
info.Ignored = true;
AddRtsInfo(info);
OnRTS?.Invoke(info);
}
}
}
}