Applecorn/mock_freq_table

#!/usr/bin/python3

#
# Make a table of Mockingboard wavelength values (high and low bytes)
# Corresponding to the frequency values used in BBC Micro
# SOUND statements.
#

d7       = 2349.32   # D7 is pitch value 253
clk      = 63780.27  # AY-3 clock (1.023MHz / 16)
freqs    = [0] * 256
divider  = [0] * 256

freqs[253] = d7

for i in range(254,256):
  freqs[i] = freqs[i-1] * (2 ** (1 / 48))

for i in range(252,-1,-1):
  freqs[i] = freqs[i+1] / (2 ** (1 / 48))

for i in range(0,256):
  divider[i] = int(round(clk / freqs[i]))
  coarse = int(divider[i] / 256)
  fine = int(divider[i] % 256)
#  print("{:3d}: {:9.3f} {:5d} ({:2d} {:3d})".format(i, freqs[i], divider[i], coarse, fine))

print("\nMFREQHIGH");
for i in range(0,256):
  print("          DB >{:.0f}".format(divider[i]))

print("\nMFREQLOW");
for i in range(0,256):
  print("          DB <{:.0f}".format(divider[i]))