#!/usr/bin/env python3
#    synacor.py - An implementation of the Synacor Challenge
#    Copyright © 2017  RunasSudo
#
#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU Affero General Public License as published by
#    the Free Software Foundation, either version 3 of the License, or
#    (at your option) any later version.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU Affero General Public License for more details.
#
#    You should have received a copy of the GNU Affero General Public License
#    along with this program.  If not, see <http://www.gnu.org/licenses/>.

import struct
import sys

if len(sys.argv) < 3:
	print('Usage: {} <input> <output>'.format(sys.argv[0]))
else:
	# Read code into memory
	SYN_MEM = [0] * 32768
	
	with open(sys.argv[1], 'rb') as data:
		i = 0
		while True:
			byteData = data.read(2)
			if len(byteData) < 2:
				break
			SYN_MEM[i] = struct.unpack('<H', byteData)[0]
			i += 1
	
	# Emulate 06bb
	for R1 in range(0x17b4, 0x7562):
		R0 = SYN_MEM[R1]
		R0 ^= pow(R1, 2, 32768)
		R0 ^= 0x4154
		SYN_MEM[R1] = R0
	
	# Write
	with open(sys.argv[2], 'wb') as f:
		f.write(struct.pack('<32768H', *SYN_MEM))