Demo/scripts/morse.py

# DAH should be three DOTs.
# Space between DOTs and DAHs should be one DOT.
# Space between two letters should be one DAH.
# Space between two words should be DOT DAH DAH.

import sys, math, audiodev

DOT = 30
DAH = 3 * DOT
OCTAVE = 2				# 1 == 441 Hz, 2 == 882 Hz, ...

morsetab = {
	'A': '.-',		'a': '.-',
	'B': '-...',		'b': '-...',
	'C': '-.-.',		'c': '-.-.',
	'D': '-..',		'd': '-..',
	'E': '.',		'e': '.',
	'F': '..-.',		'f': '..-.',
	'G': '--.',		'g': '--.',
	'H': '....',		'h': '....',
	'I': '..',		'i': '..',
	'J': '.---',		'j': '.---',
	'K': '-.-',		'k': '-.-',
	'L': '.-..',		'l': '.-..',
	'M': '--',		'm': '--',
	'N': '-.',		'n': '-.',
	'O': '---',		'o': '---',
	'P': '.--.',		'p': '.--.',
	'Q': '--.-',		'q': '--.-',
	'R': '.-.',		'r': '.-.',
	'S': '...',		's': '...',
	'T': '-',		't': '-',
	'U': '..-',		'u': '..-',
	'V': '...-',		'v': '...-',
	'W': '.--',		'w': '.--',
	'X': '-..-',		'x': '-..-',
	'Y': '-.--',		'y': '-.--',
	'Z': '--..',		'z': '--..',
	'0': '-----',
	'1': '.----',
	'2': '..---',
	'3': '...--',
	'4': '....-',
	'5': '.....',
	'6': '-....',
	'7': '--...',
	'8': '---..',
	'9': '----.',
	',': '--..--',
	'.': '.-.-.-',
	'?': '..--..',
	';': '-.-.-.',
	':': '---...',
	"'": '.----.',
	'-': '-....-',
	'/': '-..-.',
	'(': '-.--.-',
	')': '-.--.-',
	'_': '..--.-',
	' ': ' '
}

# If we play at 44.1 kHz (which we do), then if we produce one sine
# wave in 100 samples, we get a tone of 441 Hz.  If we produce two
# sine waves in these 100 samples, we get a tone of 882 Hz.  882 Hz
# appears to be a nice one for playing morse code.
def mkwave(octave):
	global sinewave, nowave
	sinewave = ''
	for i in range(100):
		val = int(math.sin(math.pi * float(i) * octave / 50.0) * 30000)
		sinewave = sinewave + chr((val >> 8) & 255) + chr(val & 255)
	nowave = '\0' * 200

mkwave(OCTAVE)

def main():
	import getopt, string
	try:
		opts, args = getopt.getopt(sys.argv[1:], 'o:p:')
	except getopt.error:
		sys.stderr.write('Usage ' + sys.argv[0] +
				 ' [ -o outfile ] [ args ] ...\n')
		sys.exit(1)
	dev = None
	for o, a in opts:
		if o == '-o':
			import aifc
			dev = aifc.open(a, 'w')
			dev.setframerate(44100)
			dev.setsampwidth(2)
			dev.setnchannels(1)
		if o == '-p':
			mkwave(string.atoi(a))
	if not dev:
		import audiodev
		dev = audiodev.AudioDev()
		dev.setoutrate(44100)
		dev.setsampwidth(2)
		dev.setnchannels(1)
		dev.close = dev.stop
		dev.writeframesraw = dev.writeframes
	if args:
		line = string.join(args)
	else:
		line = sys.stdin.readline()
	while line:
		mline = morse(line)
		play(mline, dev)
		if hasattr(dev, 'wait'):
			dev.wait()
		if not args:
			line = sys.stdin.readline()
		else:
			line = ''
	dev.close()

# Convert a string to morse code with \001 between the characters in
# the string.
def morse(line):
	res = ''
	for c in line:
		try:
			res = res + morsetab[c] + '\001'
		except KeyError:
			pass
	return res

# Play a line of morse code.
def play(line, dev):
	for c in line:
		if c == '.':
			sine(dev, DOT)
		elif c == '-':
			sine(dev, DAH)
		else:			# space
			pause(dev, DAH + DOT)
		pause(dev, DOT)

def sine(dev, length):
	for i in range(length):
		dev.writeframesraw(sinewave)

def pause(dev, length):
	for i in range(length):
		dev.writeframesraw(nowave)

if __name__ == '__main__' or sys.argv[0] == __name__:
	main()