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From: | David Kelly |
Subject: | Re: [avr-gcc-list] Initilizing complex const arrays : syntax ? |
Date: | Mon, 19 Sep 2005 07:33:05 -0500 |
On Sep 18, 2005, at 11:11 PM, Vincent Trouilliez wrote:
Okay, I got your dot_two() working (the another_dot_two() has one last fatal error that I can't figure out yet).
Yeah well, still not bad for code written in bed on laptop in the email editor.
I tested it in all fairness. That is, I modified the printf hack from printf ("%d.%03d", x / 1000, x % 1000), to printf ("%d.%02d", x / 100, x % 100) So that the functionality is the same as dot_two(). Doing this, printf doesn't take 13ms anymore, but 10ms. And your dot_two() takes... 6ms ! That's a whole 40% faster, not bad indeed !!! :o)
Your putchar() (or whatever) writes to an LCD? So how long does it take to latch a character into the LCD?
Another way I thought to write the code without utoa() was something like this (no I haven't tried this one either):
char buffer[4]; uint8_t i; strncpy_P( buffer, PGM_P("000"), 3 ); i = 2; while(x) { buffer[i--] = x%10 + '0'; x = x/10; } putchar(buffer[0]); putchar('.'); putchar(buffer[1]); putchar(buffer[2]);In the above I find myself wishing for the FORTH /mod operator. Avr- gcc calls exactly the same routine for division or modulo and stores the desired result. In assembly we could store both but I don't see how to get at both from C. Is possible the compiler could optimize it but plain -O didn't in recent tests.
-- David Kelly N4HHE, address@hidden ======================================================================== Whom computers would destroy, they must first drive mad.
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