private MachineOperand ParseOperandInner(byte addressMode, byte operandBits, PrimitiveType dataWidth, ImageReader rdr)
{
Constant offset;
switch (addressMode)
{
case 0: // Data register direct.
return DataRegisterOperand(operandBits, 0);
case 1: // Address register direct
return new RegisterOperand(AddressRegister(operandBits, 0));
case 2: // Address register indirect
return MemoryOperand.Indirect(dataWidth, AddressRegister(operandBits, 0));
case 3: // Address register indirect with postincrement.
return MemoryOperand.PostIncrement(dataWidth, AddressRegister(operandBits, 0));
case 4: // Address register indirect with predecrement.
return MemoryOperand.PreDecrement(dataWidth, AddressRegister(operandBits, 0));
case 5: // Address register indirect with displacement.
offset = Constant.Int16(rdr.ReadBeInt16());
return MemoryOperand.Indirect(dataWidth, AddressRegister(operandBits, 0), offset);
case 6: // Address register indirect with index
return AddressRegisterIndirectWithIndex(dataWidth, rdr);
case 7:
switch (operandBits)
{
case 0: // Absolute short address
return new M68kAddressOperand(rdr.ReadBeUInt16());
case 1: // Absolute long address
return new M68kAddressOperand(rdr.ReadBeUInt32());
case 2: // Program counter with displacement
var off = rdr.Address - dasm.instr.Address;
off += rdr.ReadBeInt16();
return new MemoryOperand(dataWidth, Registers.pc, Constant.Int16((short) off));
case 3:
// Program counter with index
var addrExt = rdr.Address;
ushort extension = rdr.ReadBeUInt16();
if (EXT_FULL(extension))
{
if (EXT_EFFECTIVE_ZERO(extension))
{
return new M68kImmediateOperand(Constant.Word32(0));
}
Constant @base = null;
Constant outer = null;
if (EXT_BASE_DISPLACEMENT_PRESENT(extension))
@base = EXT_BASE_DISPLACEMENT_LONG(extension)
? rdr.ReadBe(PrimitiveType.Word32)
: rdr.ReadBe(PrimitiveType.Int16);
if (EXT_OUTER_DISPLACEMENT_PRESENT(extension))
outer = EXT_OUTER_DISPLACEMENT_LONG(extension)
? rdr.ReadBe(PrimitiveType.Word32)
: rdr.ReadBe(PrimitiveType.Int16);
RegisterStorage base_reg = EXT_BASE_REGISTER_PRESENT(extension)
? Registers.pc
: null;
RegisterStorage index_reg = null;
PrimitiveType index_width = null;
int index_scale = 0;
if (EXT_INDEX_REGISTER_PRESENT(extension))
{
index_reg = EXT_INDEX_AR(extension)
? Registers.AddressRegister((int)EXT_INDEX_REGISTER(extension))
: Registers.DataRegister((int)EXT_INDEX_REGISTER(extension));
index_width = EXT_INDEX_LONG(extension) ? PrimitiveType.Word32 : PrimitiveType.Int16;
index_scale = (EXT_INDEX_SCALE(extension) != 0)
? 1 << EXT_INDEX_SCALE(extension)
: 0;
}
return new IndexedOperand(dataWidth, @base, outer, base_reg, index_reg, index_width, index_scale,
(extension & 7) > 0 && (extension & 7) < 4,
(extension & 7) > 4);
}
return new IndirectIndexedOperand(
EXT_8BIT_DISPLACEMENT(extension),
Registers.pc,
EXT_INDEX_AR(extension) ? Registers.AddressRegister((int)EXT_INDEX_REGISTER(extension)) : Registers.DataRegister((int)EXT_INDEX_REGISTER(extension)),
EXT_INDEX_LONG(extension) ? PrimitiveType.Word32 : PrimitiveType.Int16,
1 << EXT_INDEX_SCALE(extension));
case 4:
// Immediate
if (dataWidth.Size == 1) // don't want the instruction stream to get misaligned!
rdr.ReadByte();
return new M68kImmediateOperand(rdr.ReadBe(dataWidth));
default:
throw new NotImplementedException(string.Format("Address mode {0}:{1} not implemented.", addressMode, operandBits));
}
default:
throw new NotImplementedException(string.Format("Address mode {0:X1} not implemented.", addressMode));
}
}
public MachineOperand GetOperand(ImageReader rdr, string args, PrimitiveType dataWidth)
{
if (i >= args.Length)
return null;
for (; ; )
{
if (args[i] == ',')
++i;
Address addr;
switch (args[i++])
{
case 'A': // Address register A0-A7 encoded in in instrution
return new RegisterOperand(AddressRegister(opcode, GetOpcodeOffset(args[i++])));
case 'c': // CCR register
return new RegisterOperand(Registers.ccr);
case 'D': // Data register D0-D7 encoded in instruction
return DataRegisterOperand(opcode, GetOpcodeOffset(args[i++]));
case 'E': // Effective address (EA)
return ParseOperand(opcode, GetOpcodeOffset(args[i++]), dataWidth, rdr);
case 'e': // Effective address with 3-bit halves swapped
return ParseSwappedOperand(opcode, GetOpcodeOffset(args[i++]), dataWidth, rdr);
case 'I': // Immediate operand
return GetImmediate(rdr, GetSizeType(0, args[i++], dataWidth));
case 'J': // PC Relative jump
addr = rdr.Address;
int offset = opcode & 0xFF;
if (offset == 0xFF)
offset = rdr.ReadBeInt32();
else if (offset == 0x00)
offset = rdr.ReadBeInt16();
else
offset = (sbyte) offset;
return new M68kAddressOperand(addr + offset);
case 'M': // Register bitset
return new RegisterSetOperand(rdr.ReadBeUInt16());
case 'n': // cache bitset
bitSet = rdr.ReadBeUInt16();
break;
case 'm': // Register bitset reversed
return RegisterSetOperand.CreateReversed(bitSet);
case 'q': // "Small" quick constant (3-bit part of the opcode)
return GetQuickImmediate(GetOpcodeOffset(args[i++]), 0x07, 8, PrimitiveType.Byte);
case 'Q': // "Large" quick constant (8-bit part of the opcode)
return GetQuickImmediate(GetOpcodeOffset(args[i++]), 0xFF, 0, PrimitiveType.SByte);
case 'R': // relative
addr = rdr.Address;
int relative = 0;
switch (args[i++])
{
case 'w': relative = rdr.ReadBeInt16(); break;
case 'l': relative = rdr.ReadBeInt32(); break;
default: throw new NotImplementedException();
}
return new M68kAddressOperand(addr + relative);
case 's': // SR register
return new RegisterOperand(Registers.sr);
case '+': // Postincrement operator; following character specifies bit offset of the address register code.
return new PostIncrementMemoryOperand(dataWidth, AddressRegister(opcode, GetOpcodeOffset(args[i++])));
case '-': // Predecrement operator; following character specifies bit offset of the address register code.
return new PredecrementMemoryOperand(dataWidth, AddressRegister(opcode, GetOpcodeOffset(args[i++])));
default: throw new FormatException(string.Format("Unknown argument type {0}.", args[--i]));
}
}
}
public virtual short read_word(ImageReader f)
{
if (!f.IsValid)
return -1;
if (!f.IsValidOffset(1))
return -2;
return f.ReadBeInt16();
}
