WIP Implementing manchester encoding

encode.py

@@ -0,0 +1,140 @@
+#!/usr/bin/env python3
+
+""" @package docstring
+Manchester encoder
+
+Encodes a file using the manchester encoding and outputs it as audio file
+See https://www.youtube.com/watch?v=8BhjXqw9MqI&list=PLowKtXNTBypH19whXTVoG3oKSuOcw_XeW&index=3
+and following videos by awesome Ben Eater
+Very slow and inefficient implementation, meant only to be clear and didactic
+
+@author Daniele Verducci <daniele.verducci@ichibi.eu>
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU 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 General Public License for more details.
+You should have received a copy of the GNU General Public License
+along with this program. If not, see <http://www.gnu.org/licenses/>.
+"""
+
+import os
+import sys
+import logging
+
+
+NAME = 'manchester-encoder'
+VERSION = '0.1'
+DESCRIPTION = 'Encodes a file using the manchester encoding and outputs it as audio file'
+
+FRAME_DELIMITER = 129 # (1, 0, 0, 0, 0, 0, 0, 1)
+
+
+
+class Main:
+
+	def __init__(self):
+		self._log = logging.getLogger('main')
+
+	def run(self, inputFile, outputFile, clock):
+		# Open output file
+
+		# Read input file
+		bytesToEncode = []
+		with open(inputFile, 'rb') as f:
+			position = 0
+			while 1:
+				byte = f.read(1)
+				if not byte:
+					# Finished reading file
+					# Terminate with delimiter and exit
+					self.encodeByte(FRAME_DELIMITER)
+					break
+				byte = byte[0]
+
+				# Every 64 bytes, outputs a frame delimiter: 01111110
+				# This is used by receiver to syncronize to the start of a byte
+				if position % 64 == 0:
+					self.encodeByte(FRAME_DELIMITER)
+				position = position + 1
+
+				# Encode byte
+				self.encodeByte(byte)
+		
+		self._log.info('Completed')
+
+	def encodeByte(self, byte):
+		# Encodes a byte with the Mancester Encoding
+		# Note that the byte is read from the most important to the least important bit
+		# Es: 10000010 is not 130, but 65
+		consecutiveOnes = 0
+
+		for x in range(8):
+			# Shift byte and take last bit (with bitwise AND)
+			lastBit = ( byte >> x ) & 1
+
+			# Write bit
+			self.encodeBit(lastBit)
+
+			# If we have 5 consecutive "1", add a 0 after, to avoid being interpreted as a frame delimiter
+			if lastBit:
+				consecutiveOnes = consecutiveOnes + 1
+			else:
+				consecutiveOnes = 0
+			
+			if consecutiveOnes == 5:
+				self.encodeBit(0)
+				consecutiveOnes = 0
+
+	def outputPreamble(self):
+		# Outputs the preable: a sequence of 64 "1" and "0" used to facilitate the receiver
+		# syncronizing on our clock. The sequence starts with 1 and ends with 0
+		for x in range(64):
+			self.encode(x % 2 == 0)
+
+	def encodeBit(self, bit):
+		# Encodes a single bit in a pair of bits to be written on the media.
+		# The "1" is encoded as a transition from 0 to 1 (01) while the "0" is endoded as a 
+		# transition from 1 to 0 (10)
+		if bit:
+			self.out(0)
+			self.out(1)
+		else:
+			self.out(1)
+			self.out(0)
+
+	def out(self, encodedBit):
+		# Write already encoded bit on the media
+		if encodedBit:
+			print('―', end='')
+		else:
+			print('_', end='')
+
+
+if __name__ == '__main__':
+	import argparse
+
+	parser = argparse.ArgumentParser(
+		prog = NAME + '.py',
+		description = NAME + ' ' + VERSION + '\n' + DESCRIPTION,
+		formatter_class = argparse.RawTextHelpFormatter
+	)
+	parser.add_argument('inputFile', help="file to encode")
+	parser.add_argument('outputFile', help="audio file to write")
+	parser.add_argument('clock', help="clock speed, in hz")
+	parser.add_argument('-v', '--verbose', action='store_true', help="verbose output")
+	args = parser.parse_args()
+
+	if args.verbose:
+		logging.basicConfig(level=logging.INFO)
+	else:
+		logging.basicConfig()
+
+	main = Main()
+	main.run(args.inputFile, args.outputFile, args.clock)
+
+	sys.exit(0)