/// @brief Execute a PASM instruction in this cog.
/// @returns TRUE if it is the opportunity to trigger a breakpoint, or FALSE if not.
override public bool DoInstruction()
{
switch (State)
{
// Delay State
case CogRunState.WAIT_CYCLES:
if (--StateCount == 1)
{
WriteBackResult();
}
return(true);
// Clocked, but not executed
case CogRunState.WAIT_PREWAIT:
if (--StateCount == 1)
{
State = NextState;
}
return(true);
// Execute State
case CogRunState.STATE_EXECUTE:
break;
case CogRunState.WAIT_PNE:
{
uint maskedIn = (Carry ? Hub.INB : Hub.INA) & SourceValue;
if (maskedIn != DestinationValue)
{
DataResult = maskedIn;
Zero = (maskedIn == 0);
// TODO: DETERMINE CARRY
WriteBackResult();
}
return(true);
}
case CogRunState.WAIT_PEQ:
{
uint maskedIn = (Carry ? Hub.INB : Hub.INA) & SourceValue;
if (maskedIn == DestinationValue)
{
DataResult = maskedIn;
Zero = (maskedIn == 0);
// TODO: DETERMINE CARRY
WriteBackResult();
return(true);
}
return(true);
}
case CogRunState.WAIT_CNT:
{
long target = Hub.Counter;
if (DestinationValue == target)
{
target += SourceValue;
DataResult = (uint)target;
CarryResult = target > 0xFFFFFFFF;
ZeroResult = (DataResult == 0);
WriteBackResult();
return(true);
}
return(true);
}
case CogRunState.WAIT_VID:
if (Video.Ready)
{
Video.Feed(DestinationValue, SourceValue);
// TODO: Determine carry, zero, and result
WriteBackResult();
}
return(true);
// Non-execute states are ignored
default:
return(true);
}
PC = (PC + 1) & 0x1FF;
InstructionCode = (CogInstructionCodes)(Operation & 0xFC000000);
ConditionCode = (CogConditionCodes)((Operation & 0x003C0000) >> 18);
WriteZero = (Operation & 0x02000000) != 0;
WriteCarry = (Operation & 0x01000000) != 0;
WriteResult = (Operation & 0x00800000) != 0;
ImmediateValue = (Operation & 0x00400000) != 0;
SourceValue = Operation & 0x1FF;
if (!ImmediateValue)
{
SourceValue = ReadLong(SourceValue);
}
Destination = (Operation >> 9) & 0x1FF;
DestinationValue = ReadLong(Destination);
if (ConditionCompare(ConditionCode, Zero, Carry))
{
Operation = ReadLong(PC);
State = CogRunState.WAIT_PREWAIT;
NextState = CogRunState.STATE_EXECUTE;
StateCount = 4;
return(true);
}
switch (InstructionCode)
{
// RESERVED FOR FUTURE EXPANSION
case CogInstructionCodes.MUL:
case CogInstructionCodes.MULS:
case CogInstructionCodes.ENC:
case CogInstructionCodes.ONES:
// TODO: RAISE INVALID OP CODE HERE
DataResult = 0;
Carry = true;
Zero = true;
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
// HUB Operations (6 cycles for instruction decode... 1-15 cycles for operation)
case CogInstructionCodes.RWBYTE:
State = CogRunState.WAIT_PREWAIT;
NextState = CogRunState.HUB_RDBYTE;
StateCount = 6;
break;
case CogInstructionCodes.RWWORD:
State = CogRunState.WAIT_PREWAIT;
NextState = CogRunState.HUB_RDWORD;
StateCount = 6;
break;
case CogInstructionCodes.RWLONG:
State = CogRunState.WAIT_PREWAIT;
NextState = CogRunState.HUB_RDLONG;
StateCount = 6;
break;
case CogInstructionCodes.HUBOP:
State = CogRunState.WAIT_PREWAIT;
NextState = CogRunState.HUB_HUBOP;
StateCount = 6;
break;
// Standard operations (4 cycles)
case CogInstructionCodes.ROR:
InstructionROR();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.ROL:
InstructionROL();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.RCR:
InstructionRCR();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.RCL:
InstructionRCL();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.SHR:
InstructionSHR();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.SHL:
InstructionSHL();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.SAR:
InstructionSAR();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.OR:
InstructionOR();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.XOR:
InstructionXOR();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.AND:
InstructionAND();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.ANDN:
InstructionANDN();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.MUXC:
InstructionMUXC();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.MUXNC:
InstructionMUXNC();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.MUXZ:
InstructionMUXZ();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.MUXNZ:
InstructionMUXNZ();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.REV:
InstructionREV();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.NEG:
InstructionNEG();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.ABS:
InstructionABS();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.ABSNEG:
InstructionABSNEG();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.NEGC:
InstructionNEGC();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.NEGNC:
InstructionNEGNC();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.NEGZ:
InstructionNEGZ();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.NEGNZ:
InstructionNEGNZ();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.MOV:
InstructionMOV();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.MOVS:
InstructionMOVS();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.MOVD:
InstructionMOVD();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.MOVI:
InstructionMOVI();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.JMPRET:
InstructionJMPRET();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.MINS:
InstructionMINS();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.MAXS:
InstructionMAXS();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.MIN:
InstructionMIN();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.MAX:
InstructionMAX();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.ADD:
InstructionADD();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.ADDABS:
InstructionADDABS();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.ADDX:
InstructionADDX();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.ADDS:
InstructionADDS();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.ADDSX:
InstructionADDSX();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.SUB:
InstructionSUB();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.SUBABS:
InstructionSUBABS();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.SUBX:
InstructionSUBX();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.SUBS:
InstructionSUBS();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.SUBSX:
InstructionSUBSX();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.SUMC:
InstructionSUMC();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.SUMNC:
InstructionSUMNC();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.SUMZ:
InstructionSUMZ();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.SUMNZ:
InstructionSUMNZ();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.CMPS:
InstructionCMPS();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.CMPSX:
InstructionCMPSX();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
case CogInstructionCodes.CMPSUB:
InstructionCMPSUB();
State = CogRunState.WAIT_CYCLES;
StateCount = 4;
break;
// Decrement and continue instructions ( 4/8 cycles )
case CogInstructionCodes.DJNZ:
StateCount = InstructionDJNZ() ? 4 : 8;
State = CogRunState.WAIT_CYCLES;
break;
case CogInstructionCodes.TJNZ:
StateCount = InstructionTJNZ() ? 4 : 8;
State = CogRunState.WAIT_CYCLES;
break;
case CogInstructionCodes.TJZ:
StateCount = InstructionTJZ() ? 4 : 8;
State = CogRunState.WAIT_CYCLES;
break;
// Delay execution instructions ( 4 cycles for instruction decode, 1+ for instruction )
case CogInstructionCodes.WAITPEQ:
NextState = CogRunState.WAIT_PEQ;
State = CogRunState.WAIT_PREWAIT;
StateCount = 4;
break;
case CogInstructionCodes.WAITPNE:
NextState = CogRunState.WAIT_PNE;
State = CogRunState.WAIT_PREWAIT;
StateCount = 4;
break;
case CogInstructionCodes.WAITCNT:
NextState = CogRunState.WAIT_CNT;
State = CogRunState.WAIT_PREWAIT;
StateCount = 4;
break;
case CogInstructionCodes.WAITVID:
NextState = CogRunState.WAIT_VID;
State = CogRunState.WAIT_PREWAIT;
StateCount = 4;
break;
}
// Prefetch instruction
Operation = ReadLong(PC);
// Check if it's time to trigger a breakpoint
return(PC != BreakPointCogCursor);
}
/// @todo Document method Gear.EmulationCore.Cog.ConditionCompare.
///
public static bool ConditionCompare(CogConditionCodes condition, bool a, bool b)
{
switch (condition)
{
case CogConditionCodes.IF_NEVER:
break;
case CogConditionCodes.IF_NZ_AND_NC:
if (!a && !b)
{
return(false);
}
break;
case CogConditionCodes.IF_NC_AND_Z:
if (a && !b)
{
return(false);
}
break;
case CogConditionCodes.IF_NC:
if (!b)
{
return(false);
}
break;
case CogConditionCodes.IF_C_AND_NZ:
if (!a && b)
{
return(false);
}
break;
case CogConditionCodes.IF_NZ:
if (!a)
{
return(false);
}
break;
case CogConditionCodes.IF_C_NE_Z:
if (a != b)
{
return(false);
}
break;
case CogConditionCodes.IF_NC_OR_NZ:
if (!a || !b)
{
return(false);
}
break;
case CogConditionCodes.IF_C_AND_Z:
if (a && b)
{
return(false);
}
break;
case CogConditionCodes.IF_C_EQ_Z:
if (a == b)
{
return(false);
}
break;
case CogConditionCodes.IF_Z:
if (a)
{
return(false);
}
break;
case CogConditionCodes.IF_NC_OR_Z:
if (a || !b)
{
return(false);
}
break;
case CogConditionCodes.IF_C:
if (b)
{
return(false);
}
break;
case CogConditionCodes.IF_C_OR_NZ:
if (!a || b)
{
return(false);
}
break;
case CogConditionCodes.IF_Z_OR_C:
if (a || b)
{
return(false);
}
break;
case CogConditionCodes.IF_ALWAYS:
return(false);
}
return(true);
}