#!/usr/bin/env python
from collections import namedtuple

Opcode = namedtuple('Opcode', ('mnemonic', 'rx', 'ry', 'addr'))

opcodes = [
	Opcode('halt', rx=False, ry=False, addr=False),
	Opcode('ret', rx=False, ry=False, addr=False),

	Opcode('shl', rx=True, ry=False, addr=False),
	Opcode('shr', rx=True, ry=False, addr=False),
	Opcode('rol', rx=True, ry=False, addr=False),
	Opcode('ror', rx=True, ry=False, addr=False),

	Opcode('nand', rx=True, ry=True, addr=False),
	Opcode('and', rx=True, ry=True, addr=False),
	Opcode('or', rx=True, ry=True, addr=False),
	Opcode('xor', rx=True, ry=True, addr=False),

	Opcode('load', rx=True, ry=False, addr=True),
	Opcode('store', rx=True, ry=False, addr=True),

	Opcode('breq', rx=True, ry=True, addr=True),
	Opcode('brneq', rx=True, ry=True, addr=True),
	Opcode('cleq', rx=True, ry=True, addr=True),
	Opcode('clneq', rx=True, ry=True, addr=True),
]

Instruction = namedtuple('Instruction', ['opcode', 'rx', 'ry', 'addr'])
Data = namedtuple('Data', ['byte'])

Statement = namedtuple('Statement', ['addr', 'raw', 'contents'])

def segment(binary, origin):
	statements = []
	ip = origin
	while ip < len(binary):
		byte = binary[ip]

		opcode = byte >> 4

		rx = (byte >> 2) & 3
		ry = byte & 3

		valid = True
		if not opcodes[opcode].rx and rx != 0: valid = False
		if not opcodes[opcode].ry and ry != 0: valid = False
		if opcodes[opcode].addr and ip + 2 >= len(binary): valid = False

		if not valid:
			raw = binary[ip:ip + 1]
			statements.append(Statement(ip, raw, Data(byte)))
			ip += 1
		elif opcodes[opcode].addr:
			raw = binary[ip:ip + 3]
			addr = (binary[ip + 1] << 8) + binary[ip + 2]
			instruction = Instruction(opcode, rx, ry, addr)
			statements.append(Statement(ip, raw, instruction))
			ip += 3
		else:
			raw = binary[ip:ip + 1]
			instruction = Instruction(opcode, rx, ry, None)
			statements.append(Statement(ip, raw, instruction))
			ip += 1

	return statements

def disasm(binary, origin = 0):
	for addr, raw, contents in segment(binary, origin):
		if type(contents) == Data:
			statement = f'db 0x{contents.byte:02x}'
		else:
			mnemonic = opcodes[contents.opcode].mnemonic
			fields = []
			if opcodes[contents.opcode].rx:
				fields.append(f'r{contents.rx}')
			if opcodes[contents.opcode].ry:
				fields.append(f'r{contents.ry}')
			if opcodes[contents.opcode].addr:
				fields.append(f'0x{contents.addr:04x}')

			if mnemonic == 'store':
				fields = ', '.join(reversed(fields))
			else:
				fields = ', '.join(fields)

			if len(fields) != 0:
				statement = f'{mnemonic} {fields}'
			else:
				statement = mnemonic
		print(f'{addr:04x} {raw.hex():6} {statement}')

if __name__ == '__main__':
	import sys
	with open(sys.argv[1], 'rb') as f:
		binary = f.read()
	disasm(binary)