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

[David Kelly]

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.