public AArch64Instruction Decode(AArch64Disassembler dasm, uint instr, string fmt)
{
AA64Opcode opcode = this.opcode;
List <MachineOperand> ops = new List <MachineOperand>();
MachineOperand op = null;
int i = 0;
int off;
while (i < fmt.Length)
{
switch (fmt[i++])
{
default: throw new InvalidOperationException(string.Format("Bad format character {0}.", fmt[i - 1]));
case ',':
continue;
case 'B': // Logical Bitmask
op = LogicalBitmask(dasm, instr, fmt[i++] == 'x');
break;
case 'H': // 16-bit Immediate constant
off = GetOffset(fmt, ref i);
op = ArmImmediateOperand.Word32(GetImm(instr, off, 16));
break;
case 'I': // 12-bit Immediate constant
off = GetOffset(fmt, ref i);
op = ArmImmediateOperand.Word32(GetImm(instr, off, 12));
break;
case 'J': // long relative branch
int offset = (((int)instr) << 6) >> 4;
op = new AddressOperand(dasm.rdr.Address + offset);
break;
case 'W': // (32-bit) W register operand
op = GetWReg(instr, GetOffset(fmt, ref i));
break;
case 'X': // (64-bit) X register operand
op = GetXReg(instr, GetOffset(fmt, ref i));
break;
case 's': // Shift operand by 12
off = GetOffset(fmt, ref i);
op = ops[ops.Count - 1];
ops.RemoveAt(ops.Count - 1);
uint shiftCode = GetImm(instr, off, 2);
switch (shiftCode)
{
case 0: break;
case 1:
op = new ShiftOperand(op, Opcode.lsl, 12); break;
default: throw new FormatException("Reserved value for shift code.");
}
break;
}
ops.Add(op);
}
return(AArch64Instruction.Create(opcode, ops));
}
public ShiftOperand(MachineOperand op, Opcode opcode, int shAmt)
: this(op, opcode, ArmImmediateOperand.Byte((byte)shAmt))
{
}