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]));
         }
     }
 }
Exemple #3
0
 public virtual short read_word(ImageReader f)
 {
     if (!f.IsValid)
         return -1;
     if (!f.IsValidOffset(1))
         return -2;
     return f.ReadBeInt16();
 }