import sys, array

#
# constants
#
state_assign = 1
state_compare = 2
state_done = 3

#
# functions
#
def prettyip(ip):
	return ("ROMC:%04X" % (ip + 0x4000 - 0x30000))

def arg_standard(mode):
	global ip
	if mode in (0, 1, 2):
		sys.stdout.write("@CF%02X.%c " % (data[ip], "bwl"[mode]))
		ip += 1
	elif mode in (3, 4):
		sys.stdout.write("@(CF%02X).%c " % (data[ip], "bw"[mode - 3]))
		ip += 1
	elif mode == 5:
		sys.stdout.write("RANDOM(0x%02X) " % data[ip])
		ip += 1
	elif mode == 6:
		sys.stdout.write("0x%02X " % data[ip])
		ip += 1
	else:
		sys.stdout.write("0x%04X " % (data[ip] + 0x100 * data[ip+1]))
		ip += 2

def arg_random(mode):
	global ip, state, state_compare
	sys.stdout.write("RANDOM(@CF%02X.b) " % data[ip])
	if mode:
		sys.stderr.write("%s: Modeless token has mode bits set; wtf?!\n" % prettyip(ip - 1))
	if state == state_compare:
		sys.stderr.write("%s: RANDOM(address) used in an IF statement; this doesn't work!\n" % prettyip(ip - 1))
	ip += 1

def arg_16bit(mode):
	global ip
	if mode in (0, 1, 2):
		sys.stdout.write("@%04X.%c " % ((data[ip] + 0x100 * data[ip+1]), "bwl"[mode]))
	elif mode in (3, 4):
		sys.stdout.write("@(%04X).%c " % ((data[ip] + 0x100 * data[ip+1]), "bw"[mode - 3]))
	else:
		sys.stdout.write("@(%04X).l " % (data[ip] + 0x100 * data[ip+1]))
		sys.stderr.write("%s: 16-bit address token has weird mode bits set; wtf?!\n" % prettyip(ip - 1))
	ip += 2

def arg_let(mode):
	global ip
	if mode in (0, 1, 2):
		sys.stdout.write("@CF%02X.%c " % (data[ip], "bwl"[mode]))
		ip += 1
	elif mode in (3, 4):
		sys.stdout.write("@(CF%02X).%c " % (data[ip], "bw"[mode - 3]))
		ip += 1
	else:
		sys.stdout.write("@%04X.%c " % ((data[ip] + 0x100 * data[ip+1]), "bwl"[mode - 5]))
		ip += 2

def arg_jump(mode):
	global ip
	sys.stdout.write("%04X " % (data[ip] + 0x100 * data[ip+1]))
	if mode:
		sys.stderr.write("%s: Modeless token has mode bits set; wtf?!\n" % prettyip(ip - 1))
	ip += 2

def arg_incdec(mode):
	global ip
	if mode in (0, 1, 2):
		sys.stdout.write("@CF%02X.%c " % (data[ip], "bwl"[mode]))
	else:
		sys.stdout.write("@CF%02X.l " % data[ip])
		sys.stderr.write("%s: INC/DEC token has weird mode bits set; wtf?!\n" % prettyip(ip - 1))
	ip += 1

def arg_indirect(mode):
	global ip
	sys.stdout.write("@CF%02X " % data[ip])
	if mode:
		sys.stderr.write("%s: Modeless token has mode bits set; wtf?!\n" % prettyip(ip - 1))
	ip += 1

def arg_unknown(mode):
	global ip
	sys.stdout.write("%02X " % data[ip])
	if mode:
		sys.stderr.write("%s: Modeless token has mode bits set; wtf?!\n" % prettyip(ip - 1))
	ip += 1

def arg_none(mode):
	if mode:
		sys.stderr.write("%s: Argumentless token has mode bits set; wtf?!\n" % prettyip(ip - 1))

def arg_illegal(mode):
	sys.stderr.write("%s: Illegal token; looks like we hit data!\n" % prettyip(ip - 1))

#
# token definitions
#
statement_tokens = (
	("LET ",    arg_let,      state_assign),
	("IF ",     arg_standard, state_compare),
	("GOTO ",   arg_jump,     state_done),
	("SYS ",    arg_jump,     state_done),
	("SET ",    arg_unknown,  state_done),
	("GOSUB ",  arg_jump,     state_done),
	("RETURN ", arg_none,     state_done),
	("INC ",    arg_incdec,   state_done),
	("DEC ",    arg_incdec,   state_done),
	("GOSUB ",  arg_indirect, state_done),
	("??? ",    arg_illegal,  state_done),
	("??? ",    arg_illegal,  state_done),
	("??? ",    arg_illegal,  state_done),
	("??? ",    arg_illegal,  state_done),
	("??? ",    arg_illegal,  state_done),
	("??? ",    arg_illegal,  state_done),
	("??? ",    arg_illegal,  state_done),
	("??? ",    arg_illegal,  state_done),
	("??? ",    arg_illegal,  state_done),
	("??? ",    arg_illegal,  state_done),
	("??? ",    arg_illegal,  state_done),
	("??? ",    arg_illegal,  state_done),
	("??? ",    arg_illegal,  state_done),
	("??? ",    arg_illegal,  state_done),
	("??? ",    arg_illegal,  state_done),
	("??? ",    arg_illegal,  state_done),
	("??? ",    arg_illegal,  state_done),
	("??? ",    arg_illegal,  state_done),
	("??? ",    arg_illegal,  state_done),
	("??? ",    arg_illegal,  state_done),
	("??? ",    arg_illegal,  state_done),
	("END ",    arg_none,     state_done))

expression_tokens = (
	("",      arg_standard, 0),
	("* ",    arg_standard, 0),
	("/ ",    arg_standard, 0),
	("+ ",    arg_standard, 0),
	("- ",    arg_standard, 0),
	("AND ",  arg_standard, 0),
	("OR ",   arg_standard, 0),
	("NAND ", arg_standard, 0),
	("XOR ",  arg_standard, 0),
	("NOT ",  arg_standard, 0),
	(">> ",   arg_standard, 0),
	("<< ",   arg_standard, 0),
	("= ",    arg_standard, 0),
	("< ",    arg_standard, 0),
	("> ",    arg_standard, 0),
	("<= ",   arg_standard, 0),
	(">= ",   arg_standard, 0),
	("-- ",   arg_standard, 0),
	("= ",    arg_random,   0),
	("= ",    arg_16bit,    0),
	("",      arg_standard, 0),
	("",      arg_standard, 0),
	("",      arg_standard, 0),
	("",      arg_standard, 0),
	("",      arg_standard, 0),
	("",      arg_standard, 0),
	("",      arg_standard, 0),
	("",      arg_standard, 0),
	("",      arg_standard, 0),
	("",      arg_standard, 0),
	("",      arg_standard, 0),
	("",      arg_none, state_done))

#
# main program
#
try:
	fn      = sys.argv[1]
	startip = int(sys.argv[2],0)
	endip   = int(sys.argv[3],0)
except (IndexError, ValueError):
	sys.exit("Usage: debasic filename start end\n")

f = open(fn, "rb")
data = array.array('B')
data.fromstring(f.read())
f.close()

ip = startip
state = state_done

while ip <= endip:
	sys.stdout.write("%s " % prettyip(ip))
	token = data[ip] & 0x1F
	mode = data[ip] >> 5
	ip += 1
	sys.stdout.write(statement_tokens[token][0])
	statement_tokens[token][1](mode)
	state = statement_tokens[token][2]
	while state != state_done:
		token = data[ip] & 0x1F
		mode = data[ip] >> 5
		ip += 1
		sys.stdout.write(expression_tokens[token][0])
		expression_tokens[token][1](mode)
		if expression_tokens[token][2]: state = expression_tokens[token][2] 
	sys.stdout.write("\n")