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Re: [avr-gcc-list] Initilizing complex const arrays : syntax ?

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;

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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