113 lines
3.5 KiB
Python
113 lines
3.5 KiB
Python
#!/usr/bin/env python
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from collections import namedtuple
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import enum
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class rfield(enum.Enum):
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none, reg, imm_flag = range(3)
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Opcode = namedtuple('Opcode', ('mnemonic', 'rx', 'ry', 'addr'))
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opcodes = [
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Opcode('halt', rx=rfield.none, ry=rfield.none, addr=False),
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Opcode('ret', rx=rfield.none, ry=rfield.none, addr=False),
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Opcode('shl', rx=rfield.reg, ry=rfield.none, addr=False),
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Opcode('shr', rx=rfield.reg, ry=rfield.none, addr=False),
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Opcode('rol', rx=rfield.reg, ry=rfield.none, addr=False),
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Opcode('ror', rx=rfield.reg, ry=rfield.none, addr=False),
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Opcode('nand', rx=rfield.reg, ry=rfield.reg, addr=False),
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Opcode('and', rx=rfield.reg, ry=rfield.reg, addr=False),
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Opcode('or', rx=rfield.reg, ry=rfield.reg, addr=False),
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Opcode('xor', rx=rfield.reg, ry=rfield.reg, addr=False),
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Opcode('load', rx=rfield.reg, ry=rfield.imm_flag, addr=True),
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Opcode('store', rx=rfield.none, ry=rfield.reg, addr=True),
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Opcode('breq', rx=rfield.reg, ry=rfield.reg, addr=True),
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Opcode('brneq', rx=rfield.reg, ry=rfield.reg, addr=True),
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Opcode('cleq', rx=rfield.reg, ry=rfield.reg, addr=True),
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Opcode('clneq', rx=rfield.reg, ry=rfield.reg, addr=True),
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]
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Instruction = namedtuple('Instruction', ['opcode', 'rx', 'ry', 'addr', 'immediate'])
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Data = namedtuple('Data', ['byte'])
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Statement = namedtuple('Statement', ['addr', 'raw', 'contents'])
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def segment(binary, origin):
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statements = []
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ip = origin
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while ip < len(binary):
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byte = binary[ip]
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opcode = byte >> 4
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rx = (byte >> 2) & 3
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ry = byte & 3
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immediate = opcodes[opcode].ry == rfield.imm_flag and ry == 3
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valid = True
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if opcodes[opcode].rx == rfield.none and rx != 0: valid = False
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if opcodes[opcode].ry == rfield.none and ry != 0: valid = False
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if opcodes[opcode].ry == rfield.imm_flag and ry not in (0, 3): valid = False
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if opcodes[opcode].addr and not immediate and ip + 2 >= len(binary): valid = False
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if immediate and ip + 1 >= len(binary): valid = False
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if not valid:
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raw = binary[ip:ip + 1]
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statements.append(Statement(ip, raw, Data(byte)))
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ip += 1
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elif immediate:
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raw = binary[ip:ip + 2]
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instruction = Instruction(opcode, rx, ry, None, binary[ip + 1])
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statements.append(Statement(ip, raw, instruction))
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ip += 2
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elif opcodes[opcode].addr:
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raw = binary[ip:ip + 3]
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addr = (binary[ip + 1] << 8) + binary[ip + 2]
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instruction = Instruction(opcode, rx, ry, addr, None)
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statements.append(Statement(ip, raw, instruction))
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ip += 3
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else:
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raw = binary[ip:ip + 1]
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instruction = Instruction(opcode, rx, ry, None, None)
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statements.append(Statement(ip, raw, instruction))
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ip += 1
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return statements
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def disasm(binary, origin = 0):
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for addr, raw, contents in segment(binary, origin):
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if type(contents) == Data:
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statement = f'data {contents.byte:02x}'
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else:
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mnemonic = opcodes[contents.opcode].mnemonic
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fields = []
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if opcodes[contents.opcode].rx == rfield.reg:
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fields.append(f'r{contents.rx}')
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if opcodes[contents.opcode].ry == rfield.reg:
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fields.append(f'r{contents.ry}')
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if contents.immediate is not None:
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fields.append(f'#{contents.immediate:02x}')
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elif opcodes[contents.opcode].addr:
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fields.append(f'{contents.addr:04x}')
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if mnemonic == 'store':
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fields = ', '.join(reversed(fields))
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else:
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fields = ', '.join(fields)
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if len(fields) != 0:
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statement = f'{mnemonic} {fields}'
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else:
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statement = mnemonic
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print(f'{addr:04x} {raw.hex():6} {statement}')
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if __name__ == '__main__':
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import sys
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with open(sys.argv[1], 'rb') as f:
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binary = f.read()
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disasm(binary)
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