Fixed Point Implementation

[tractionmate]

Hi guys, i was wondering if any one has any material on fixed point implementation?

Thanks

[Salem]

Have you googled already?

[ssharish2005]

http://en.wikipedia.org/wiki/Fixed-point_math

ssharish

[tractionmate]

hey guys thanks for replying, i have googled and i have read the wikipedia page before. I am bit dubious on the scaling part of it. embedded.com has a very good article on fixed point implementation. But it is a bit too complicated for the project i am doing!

[ssharish2005]

So where excatly are u stuck. Which part dont you understand. And what is your project you are doing?

ssharish

[alsoumhi]

I may help you in doing this

could you wait me because I just read your message

thanks

[tractionmate]

Well I implemented an algorithm to calculate inverse of a complex matrix, so it reduces the complexity of code. Need to implement it in fixed point because it needs to be converted so that it can run on a dsp. I can't get my head around the scaling bit, it would help if anyone can post a link explaining the basic idea of scaling.

Thanks

[Salem]

Consider 2 numbers in 4.4 fixed point format.
So 1 would (in binary) be 00010000, which is in fact 16 if treated as a regular value

Now if we were to do 1 * 1, we would end up with 100000000, but to make the actual result mean 1 once more, we need to shift the result to the right by 4 places.