internal void Sub(ParsedOperand opSrc, ParsedOperand opDst)
{
EmitDoubleOperandInstruction(0xE000, opSrc, opDst);
}
public void Dec(ParsedOperand op)
{
EmitSingleOperandInstruction(0x0AC0, op);
}
public void Movb(ParsedOperand opSrc, ParsedOperand opDst)
{
EmitDoubleOperandInstruction(0x9000, opSrc, opDst);
}
internal void Asr(ParsedOperand op)
{
EmitSingleOperandInstruction(0x0C80, op);
}
internal void Clrb(ParsedOperand op)
{
EmitSingleOperandInstruction(0x8A00, op);
}
internal void Jsr(ParsedOperand[] ops)
{
if (ops.Length != 2)
throw new ArgumentException("ops");
if (ops[0].Type != AddressMode.Register)
throw new ArgumentException("First argument must be a register.");
Debug.Print("ops(0): {0} {1}", ops[0].Register.Name, ops[0].Register.Number);
EmitSingleOperandInstruction(0x0800 | (ops[0].Register.Number << 6), ops[1]);
}
private int EncodeOperandField(ParsedOperand op)
{
var enc = 0;
switch (op.Type)
{
case AddressMode.Register:
enc = op.Register.Number;
break;
case AddressMode.RegDef:
enc = 0x08 | op.Register.Number;
break;
case AddressMode.AutoIncr:
enc = 0x10 | op.Register.Number;
break;
case AddressMode.AutoDecr:
enc = 0x20 | op.Register.Number;
break;
case AddressMode.Immediate:
enc = 0x17;
break;
case AddressMode.Absolute:
enc = 0x1F;
break;
default:
throw new NotImplementedException("type " + op.Type);
}
return enc;
}
private void EmitOperand(ParsedOperand op)
{
switch (op.Type)
{
case AddressMode.Register:
case AddressMode.AutoIncr:
case AddressMode.AutoDecr:
case AddressMode.RegDef:
break;
case AddressMode.Immediate:
emitter.EmitLeUInt16((int) BaseAddress.ToLinear() + op.Offset);
if (op.Symbol != null)
{
ReferToSymbol(op.Symbol, emitter.Length - 2, PrimitiveType.Word16);
}
break;
case AddressMode.Absolute:
emitter.EmitLeUInt16((int) BaseAddress.ToLinear());
if (op.Symbol != null)
{
ReferToSymbol(op.Symbol, emitter.Length - 2, PrimitiveType.Word16);
}
break;
default:
throw new NotImplementedException();
}
}
private void EmitSingleOperandInstruction(int opcode, ParsedOperand op)
{
opcode = opcode | EncodeOperandField(op);
emitter.EmitLeUInt16(opcode);
EmitOperand(op);
}
private void EmitDoubleOperandInstruction(int opcode, ParsedOperand opSrc, ParsedOperand opDst)
{
opcode = opcode | (EncodeOperandField(opSrc) << 6) | EncodeOperandField(opDst);
emitter.EmitLeUInt16(opcode);
EmitOperand(opSrc);
EmitOperand(opDst);
}