simple script for converting a floating point to a fixed point with 16 bits of precision

to_fixed.by

#!/usr/bin/env python

import sys

N_FRAC_BITS = 16

val = val_orig = float(sys.argv[1])
frac_part = 0

for i in range(N_FRAC_BITS):
    weight = 1.0 / (1 << i)
    if (weight <= val):
        val -= weight
        frac_part |= (1 << (N_FRAC_BITS - i))

print "val was %f" % val_orig
print "frac_part is 0x%x" % frac_part

floating = frac_part / float(1 << N_FRAC_BITS)

print "converted back, that's %f" % floating
print "the error is %f" % abs(val_orig - floating)