bus.py

#!/usr/bin/env python

import math
import random

totalnotes = 256;

def clamp(n,mn,mx):
	return max(mn,min(mx,n));

def fixperiod(p):
	# Attenuation/period values seem to be inverted like with other Yamaha chips.
	# Alternatively, BEX does this itself for convenience...
	# High values overflow (but always seem to be the highest period?).
	p = ~clamp(p, 0, 1024) & 1023;
	# Note: clamping to >44 to prevent ear destroying pitches.
	return clamp(p, 44, 1023);

def periodtofreqNTSC(p):
	return (3479545.0 / 32.0) / fixperiod(p);

def periodtofreqPAL(p):
	return (3546894.93 / 32.0) / fixperiod(p);

def freqtonote(f):
	return round(12.0 * math.log2(f / 440)) + 48 + 9;

notes = [ 'C-', 'C#', 'D-', 'D#', 'E-', 'F-', 'F#', 'G-', 'G#', 'A-', 'A#', 'B-' ];
def notestr(n):
	return notes[n % 12] + str(clamp(n // 12, 1, 8));

def PSGtoMPT(p, prev):
	n = notestr(freqtonote(periodtofreqPAL(p))) + '01';
	return [ n == prev and '.....' or n, n ];

def rnd(n):
	return random.randrange(n) + 1;

print('ModPlug Tracker IT');
prev0 = '';
prev1 = '';
prev2 = '';
for i in range(totalnotes):
	# Title.
	p0 = rnd(40) * 10 + 500;
	p1 = rnd(40) * 10 + 600;
	p2 = rnd(40) * 10 + 700;
	# Selection screen.
	#p0 = rnd(40) * 10 + 200;
	#p1 = rnd(40) * 10 + 250;
	#p2 = rnd(40) * 10 + 325;
	[s0, prev0] = PSGtoMPT(p0, prev0);
	[s1, prev1] = PSGtoMPT(p1, prev1);
	[s2, prev2] = PSGtoMPT(p2, prev2);
	print('|' + s0 + '......|' + s1 + '......|' + s2 + '......');