private void DecodeRTypeInstruction(Instruction i, string[] registers)
{
RTypeInstruction r = (RTypeInstruction)i;
int[] registersUsed = DetermineRegistersUsed(registers, r.instructionSubType);
switch (r.instructionSubType)
{
case InstructionSubType.arithmetic:
r.destinationRegister = registersUsed[0];
r.AddSourceRegister(registersUsed[2]);
r.AddSourceRegister(registersUsed[1]);
break;
case InstructionSubType.jr:
r.AddSourceRegister(registersUsed[0]);
break;
case InstructionSubType.cmp:
r.AddSourceRegister(registersUsed[1]);
r.AddSourceRegister(registersUsed[0]);
break;
case InstructionSubType.srl:
r.destinationRegister = registersUsed[0];
r.AddSourceRegister(registersUsed[2]);
r.AddSourceRegister(registersUsed[1]);
break;
}
}
private Instruction SetSBit(Instruction i)
{
if (i.instructionType == InstructionType.RType)
{
RTypeInstruction r = (RTypeInstruction)i;
r.sBit = 1;
return(r);
}
else
{
DTypeInstruction d = (DTypeInstruction)i;
d.sBit = 1;
return(d);
}
}
// Sets the conditional bits
private void SetConditional(Instruction i, Conditional cond)
{
switch (i.instructionType)
{
case InstructionType.RType:
RTypeInstruction r = (RTypeInstruction)i;
r.cond = cond;
break;
case InstructionType.BType:
BTypeInstruction b = (BTypeInstruction)i;
b.cond = cond;
break;
case InstructionType.DType:
DTypeInstruction d = (DTypeInstruction)i;
d.cond = cond;
break;
}
}
// Determines which type of instruction to create based on if instruction is in a specific dictionary
// and creates a new instruction of that type. Instructions are in the form of lw, sw, add, bal, etc.
private Instruction CreateCorrectTypeOfInstruction(string instruction, int lineNum)
{
InstructionSubType subType;
Instruction i = null;
if (JInstructions.TryGetValue(instruction, out subType))
{
JTypeInstruction j = new JTypeInstruction();
j.instructionSubType = subType;
i = j;
}
else if (BInstructions.TryGetValue(instruction, out subType))
{
BTypeInstruction b = new BTypeInstruction();
b.instructionSubType = subType;
i = b;
}
else if (DInstructions.TryGetValue(instruction, out subType))
{
DTypeInstruction d = new DTypeInstruction();
d.instructionSubType = subType;
i = d;
}
else if (RInstructions.TryGetValue(instruction, out subType))
{
RTypeInstruction r = new RTypeInstruction();
r.instructionSubType = subType;
// Determines what the OpX bits should be based on the instruction given in the form add, sub, xor, etc.
r.OpX = (RTypeInstruction.Opx)Enum.Parse(typeof(RTypeInstruction.Opx), instruction);
i = r;
}
else
{
throw new InvalidInstructionException(String.Format("The instruction on line {0} is an invalid instruction.", lineNum));
}
return(i);
}
