> -----Original Message-----
> From: Martijn van Aartrijk [SMTP:martijn@ROBOSAIL.COM]
> Sent: Thursday, June 05, 2003 1:11 PM
> To:   PICLIST@MITVMA.MIT.EDU
> Subject:      [PIC]: How to optimize?
>
> Hello all,
>
> I have this irritanting calculation which I must do on my PIC16F877, and
> I'm using CCS PIC C (PCM). Trouble is, this calculation alone takes up
> 4% of my code space, and I want it reduced. Unfortunately, my PIC asm
> isn't too good and I don't really know where to begin. I was hoping some
> of you might be able to help.
>
> The calculation includes a few calibration values (end on -Cal) and have
> to do with some timing intervals.
>
> y = (T1 - ((ZCal * T2) / T2Cal) / T2Cal;
>
> In itself, no real shocking formula. Point is, T1, ZCal, T2 and T2Cal
> are unsigned longs (int16), so their product is an int32. Result y is a
> float. As you can see, the compiler generates an incredible lot of code
> to handle all the int32, int16 and float stuff. So my question is: does
> anyone know how to handle this more efficiently? I've been trying to
> rewrite the equation but it doesn't seem to get any better.
>
> Thanks a lot!
> Martijn
>
> PS. Yes, this is a repost, but I'm still stuck with the problem. Sorry.
>
Do you really require the answer to be a float?  Have a look at the recent
thread on fixed point calculations (subject:  Tips to reduce Program Size
using CCS C)

Regards

Mike


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