[avr-gcc-list] Optimization?

[Patrick Lanphier]

Well the below code works fine, flashing that is, when using the -O3
optimization but does not work with -O1 optimization, I don't understand.


/**************************************************************************

avr-gcc -O0 -mmcu=at90s2313 -c demo2.c -o main.o
avr-gcc -o main.elf main.o
avr-objcopy -O ihex main.elf main.hex

***************************************************************************/

#include <io.h>
#include <interrupt.h>
#include <sig-avr.h>

int main(void)
{
  uint8_t f,i, j, k;

  outp(255, DDRB);           /* port B all outputs */
  outp(0, PORTB);          /* turn all leds off  */

  while(1){
    outp(0, PORTB);        // turn led on
    for(f=0; f<255; f++)      // delay
      for(i=0; i<255; i++)
        for(j=0; j<255; j++)
          k=k+1;
    outp(255, PORTB);          // turn led off
    for(f=0; f<255; f++)        // delay
      for(i=0; i<255; i++)
        for(j=0; j<255; j++)
          k=k+1;
  }
}

Patrick Lanphier
The Artemis Group
http://www.artemisgroup.com
phone: 814-235-0444
  fax: 800-582-9710