allegro timer

**ichijoji** · 12-06-2004

I'm need a pretty precise clock for a game I'm making with allegro, but I can't seem to get the allegro timer to run the way it's supposed to. I wrote this code to try to get it to tick 1000 times a second, but it just counts seconds:

Code:

#include "allegro.h"

volatile long timer;

void timerisr() {
  ++timer;
}
END_OF_FUNCTION(timerisr);

int main() {
  allegro_init();
  install_timer();
  install_keyboard();
  set_gfx_mode(GFX_AUTODETECT_WINDOWED,800,600,0,0);
  BITMAP *buffer = create_bitmap(SCREEN_W,SCREEN_H);
  LOCK_VARIABLE(timer);
  LOCK_FUNCTION(timerisr);
  install_int(timerisr,MSEC_TO_TIMER(1));
  while (!key[KEY_ESC]) {
    clear_bitmap(buffer);
    textprintf_centre(buffer,font,SCREEN_W/2,SCREEN_H/2,15,"%d",timer);
    blit(buffer,screen,0,0,0,0,SCREEN_W,SCREEN_H);
  }
  destroy_bitmap(buffer);
}
END_OF_MAIN();

In my game I've been calling install_int(timerisr,1), and the way I did it here with
install_int(timerisr,MSEC_TO_TIMER(1)) didn't work either. Does anybody know what I'm doing wrong?

**Draco** · 12-06-2004

I've taken this from the description of install_int() in Allegro's readme file

int install_int_ex(void (*proc)(), int speed);
Adds a function to the list of user timer handlers or, if it is already
installed, retroactively adjusts its speed (i.e makes as though the speed
change occured precisely at the last tick). The speed is given in hardware
clock ticks, of which there are 1193181 a second. You can convert from
other time formats to hardware clock ticks with the macros:

SECS_TO_TIMER(secs) - give the number of seconds between
each tick
MSEC_TO_TIMER(msec) - give the number of milliseconds
between ticks
BPS_TO_TIMER(bps) - give the number of ticks each second
BPM_TO_TIMER(bpm) - give the number of ticks per minute

Using MSEC_TO_TIMER(1) should give you what you need. Maybe you were thinking of the install_timer() function instead, which works the same but has its speed natively in milliseconds.

**ichijoji** · 12-07-2004

I tried MSEC_TO_TIMER(1), and it counts once every second. Maybe allegro isn't installed right or is conflicting with my system?

**Draco** · 12-07-2004

That's odd. I guess it's a possibility that allegro is installed correctly, but I doubt it. Have you made any other programs with allergo before? When I can get home in a few minutes I will play around with it and see if I figure it out.

**ichijoji** · 12-07-2004

This is the first problem I've had. Everything else works just like it's supposed to.

**Draco** · 12-07-2004

For some reason I can't compile your code, so I can't do much. Maybe you should try re-installing allegro, it may help. I really have no idea why it won't work anymore.

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