[avr-gcc-list] possible compiler/optimizer problem (?)

[Gary Douglas]

Hi all,

Not sure if this is a bug, or if what I'm trying to do is just incorrect 
C syntax.  Regardless, the compiler doesn't warn about the following:

void led_blinky()
{
        static uint8_t value= 1;
        value != value;//This is the problem line - always true 
        if(value)
        {
                PORTD &= ~(1<<7);
        }
        else
        {
                PORTD |= (1<<7);
        }
}

If I change it to this it works:

void led_blinky()
{
        static uint8_t value= 1;
        value = (!value); //This works...
        if(value)
        {
                PORTD &= ~(1<<7);
        }
        else
        {
                PORTD |= (1<<7);
        }
}

Are these not fundamentally the same?

FYI: Using avr-gcc 3.4.3 on FC1 Linux.
Configured with: ../../source/gcc-3.4.3/configure -v --target=avr 
--disable-nls --prefix=/tools/avr --with-gnu-ld --with-gnu-as 
--enable-languages=c,c++ --quiet --with-dwarf2
Thread model: single
gcc version 3.4.3

Regards,

Gary Douglas


--
Gary Douglas
Manager - Network Products

Pathway Connectivity Inc.
Inglewood Plaza, Unit 103
1439 - 17 Avenue SE
Calgary, Alberta
Canada. T2G 1J9
+1.403.243-8110 x43
www.pathwayconnect.com