csong@1: '''
csong@1: Author: Chunyang Song
csong@1: Institution: Centre for Digital Music, Queen Mary University of London
csong@1: 
csong@1: '''
csong@1: ## Problems! Note indices, post bar
csong@1: 
csong@2: from BasicFuncs import get_min_timeSpan, get_note_indices, repeat
csong@1: 
csong@1: # To find the nearest power of 2 equal to or less than the given number
csong@1: def roundDownPower2(number):
csong@1: 	i = 0
csong@1: 	if number > 0:
csong@1: 		while pow(2,i) > number or number >= pow(2,i+1):
csong@1: 			i = i+1
csong@1: 		power2 = pow(2,i)
csong@1: 	else:
csong@1: 		print 'Error: numbers that are less than 1 cannot be rounded down to its nearest power of two.'
csong@1: 		power2 = None
csong@1: 	return power2
csong@1: 
csong@1: # To find the nearest power of 2 equal to or more than the given number
csong@1: def roundUpPower2(number):
csong@1: 	i = 0
csong@1: 	while pow(2,i) < number:
csong@1: 		i = i + 1
csong@1: 	return pow(2,i)
csong@1: 
csong@1: # To examine whether start_time is 'off-beat'
csong@1: def start(start_time, c_n):
csong@1: 	s = 0
csong@1: 	if start_time % c_n != 0:
csong@1: 		s = 2
csong@1: 	return s
csong@1: 
csong@1: # To examine whether end_time is 'off-beat'
csong@1: def end(end_time, c_n):
csong@1: 	s = 0
csong@1: 	if end_time % c_n != 0:
csong@1: 		s = 1
csong@1: 	return s
csong@1: 
csong@1: # To calculate syncopation value of the sequence in the given time-signature.
csong@1: def get_syncopation(seq, timesig, postbar_seq):
csong@1: 	syncopation = 0
csong@1: 
csong@1: 	numerator = int(timesig.split("/")[0])
csong@1: 	if numerator == roundDownPower2(numerator):	# if is a binary time-signature
csong@1: 		# converting to minimum time-span format
csong@1: 		seq = get_min_timeSpan(seq)	
csong@1: 		if postbar_seq != None:
csong@1: 			postbar_seq = get_min_timeSpan(postbar_seq)
csong@1: 
csong@1: 		# sf is a stretching factor matching rhythm sequence and meter, as Keith defines the note duration as a multiple of 1/(2^d) beats where d is number of metrical level
csong@1: 		sf = roundUpPower2(len(seq))
csong@1: 		
csong@1: 		# retrieve all the indices of all the notes in this sequence
csong@1: 		note_indices = get_note_indices(seq)
csong@1: 
csong@1: 		for i in range(len(note_indices)):
csong@1: 			# Assuming start_time is the index of this note, end_time is the index of the following note
csong@1: 			start_time = note_indices[i]*sf/float(len(seq))
csong@1: 
csong@1: 			if i == len(note_indices)-1:	# if this is the last note, end_time is the index of the following note in the next bar
csong@1: 				if postbar_seq != None and postbar_seq != repeat([0],len(postbar_seq)):
csong@1: 					next_index = get_note_indices(postbar_seq)[0]+len(seq)
csong@1: 					end_time = next_index*sf/float(len(seq))
csong@1: 				else:	# or if the next bar is none or full rest, end_time is the end of this sequence.
csong@1: 					end_time = sf
csong@1: 			else:
csong@1: 				end_time = note_indices[i+1]*sf/float(len(seq))
csong@1: 
csong@1: 			duration = end_time - start_time
csong@1: 			c_n = roundDownPower2(duration)
csong@1: 			syncopation = syncopation + start(start_time,c_n) + end(end_time,c_n)
csong@1: 	else: 
csong@1: 		print 'Error: KTH model can only deal with binary time-signature, e.g. 2/4 and 4/4. '
csong@1: 		syncopation = None
csong@1: 
csong@1: 	return syncopation