Yep, I understood the compiler problems from the get-go.  However, the
fact that, in 15 seconds, I could type that line of code, and not have
to think about it, was very nice.  That's what initial testing was for.

The initial idea was just to see if the darn idea was going to work in
the first place.  And it most definitely did, so now it's time to find
the right tool for the job and get it actually working well. :)

I haven't had to do fixed point math in years.  This should be fun. :)

That and making this PWM stuff work.

-David

-----Original Message-----
From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf
Of Alan B. Pearce
Sent: Monday, July 18, 2005 3:16 AM
To: Microcontroller discussion list - Public.
Subject: Re: [PIC] Looking for a PIC with ADC, DAC, and UART...

>Simple - typing:
>
>WORD Output = pow(input,somepower);
>
>is a lot easier than writing my own fixed point function, when the
>compiler does it for me.  Rapid Application Development at its finest.
>
>For the PIC, obviously I'm just going to have to write/find something
>written in fixed point.

Yes, but ----

As you have already discovered, the compiler is likely to pull in a heap
of
floating point code to do the calculation (slow) and then convert it to
fixed point. Now this may be fine for a
get-you-up-and-running-to-test-the-idea type solution, but is not an
efficient way to do it, and also suggests that you may be missing or
introducing some underlying side effect which could have an effect on
the
end performance.

Do think through the math and how to do it in fixed point (faster) and
what
the calculation is actually doing.

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