Trouble with timers.h (SOLVED)

[sand7000]

I would like to create a timer that will tell me how many milliseconds have elapsed. This is apparently much more complicated than I expected as CLOCKS_PER_SEC and clock() from time.h do not function properly on my ds. From what I have scraped together in my internet search I wrote the following code, but it doesn't update the count. Any suggestions?

Code: Select all

#include <nds.h>
#include <stdlib.h>
#include <stdio.h>

using namespace std;
volatile int milliseconds=0;

void timer0_function( void )
{
  milliseconds++;
}

int main()
{
  consoleDemoInit();
  irqInit();
  irqSet( IRQ_TIMER0, timer0_function );
  TIMER0_DATA = TIMER_FREQ(1000);
  TIMER0_CR = TIMER_ENABLE | TIMER_IRQ_REQ;

  while(true)
  {
    printf( "%i\n" , milliseconds );
  }
}

[Copper]

Perhaps remove irqInit(); if you're using last versions (libnds 1.3.x)

[sand7000]

I tried removing irqInit(); and it did not change anything. I fell like i need the timerStart() called at some point but I don't understand the docs at http://libnds.devkitpro.org/a00102.html. What I would really like is an example of a millisecond timer if anyone can get one to compile.

[elhobbs]

you are just missing a call to enable the irq after the timer is setup

Code: Select all

irqEnable(IRQ_TIMER0);

you may want to take a look at the following thread as this setup has been known to cause issues http://forum.gbadev.org/viewtopic.php?t ... highlight=

[sand7000]

Thanks again elhobbs! Adding irqEnable(IRQ_TIMER0); does fix my code.

However, I cannot get the method suggested in the link you provided to work. My attempt is below, and milliseconds doesn't get updated. I tried adding irqSet(IRQ_TIMER0); but it requires that the second argument be a function. If I give it a function then I am still calling interrupts like crazy so what is the point?

Code: Select all

#include <nds.h>
#include <stdlib.h>
#include <stdio.h>

using namespace std;
int main()
{
  consoleDemoInit();
  TIMER0_CR = TIMER_ENABLE|TIMER_DIV_1024;
  TIMER1_CR = TIMER_ENABLE|TIMER_CASCADE;  
  irqEnable(IRQ_TIMER0);
  irqEnable(IRQ_TIMER1);
  double milliseconds;
  while(true)
  {
    milliseconds = ((TIMER1_DATA*(1<<16))+TIMER0_DATA)/32728500;
    printf("%E\n",milliseconds);
  }
}

[elhobbs]

neither irqSet or irqEnable are required for the second approach. if you had waited 1000 seconds you would have seen milliseconds change... the original code was for seconds - so multiple by a 1000 not divide. I tested this code and it works

Code: Select all

#include <nds.h>
#include <stdlib.h>
#include <stdio.h>

//---------------------------------------------------------------------------------
int main(void) {
int i = 0;
double milliseconds;
//---------------------------------------------------------------------------------
 consoleDemoInit();
        TIMER0_CR = TIMER_ENABLE|TIMER_DIV_1024;
        TIMER1_CR = TIMER_ENABLE|TIMER_CASCADE;
	while(1) {
		milliseconds = ((TIMER1_DATA*(1<<16))+TIMER0_DATA)/32.7285;
		printf("%d %f\n",i*1000/60,(float)milliseconds);
		swiWaitForVBlank();
		i++;
	}

}

[sand7000]

(*slaps forehead) Argh, I hate when I broadcast my own silly math mistakes out to the world. Thanks elhobbs!