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RE: [avr-gcc-list] How to (efficeiently !!!) test a bit withinamulti-byt

From: Vincent Trouilliez
Subject: RE: [avr-gcc-list] How to (efficeiently !!!) test a bit withinamulti-byte integer ?
Date: Fri, 04 Nov 2005 13:47:22 +0100

On Fri, 2005-11-04 at 13:23 +0100, niklo wrote:
> Does your lcd-routines rely on busy-waiting? That might be the reason why
> opt doesn't work. I don't know but "badly" written wait-loops might e opt'ed
> away.

Yeah I think we got the same idea... I did replace the _delay_us(40)
delay loop by a custom made empty for loop, as it's so much more
efficient, at least in this particular routine. But looks like -Os
doesn't like empty for loops ! I just checked the disassembler output,
and the loop has indeed been simply ignored/deleted !
I know, I know, I should wire the LCD R/W line and poll the 'busy' flag
instead.... I will get round to doing it... later... too many other,
more important pieces of code to write at the moment, plus, I don't
think the program will grow much bigger than 20KB max, and I have 32KB
to play with...
But that's no excuse for using empty loops instead of proper polling, as
polling it the only reliable way of doing it anyway... 

Vince, hiding in the corner...

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