Calculating checksum without the mod function

neutron001 · 06-12-2008, 07:43 AM

I'm using a proprietary language very similar to C, but doesn't have the mod function built in.. Here is what I would normally do to calc checksum:

mod( (sum( all ascii values) / 256) );

Does anyone know of an alternative to the mod function to get the remainder of a division operation?
Thanks,
D

ewolf · 06-12-2008, 08:52 AM

r = remainder
d = denominator
n = numerator

r = d - n/d

if your language is giving n/d as a decimal or float, you can try casting it as an integer or using a floor() function to trim the decimal.

Guttorm · 06-12-2008, 08:53 AM

Hi

Doesn't the % operator work? I never tried a mod function. I can't understand how it can work like you write it. Are you sure you don't mean the fmod function? But it is for floating point numbers.

Floating point: fmod(sum( all ascii values), 256);

Integers: sum(all ascii values) % 256

If the number is 256, you can also write it as:
sum(all ascii values) & 255

neutron001 · 06-12-2008, 02:02 PM

Found something else... be back w/ more info..

neutron001 · 06-12-2008, 04:22 PM

This seems to work:
nDenom = 256;
nSum = ascii total;

nQuotient = (nSum / nDenom);
nRemain = nSum - (nDenom * nQuotient);
return(nRemain);