Allegro timer bug?

[Zepper]

- It works perfectly for 50, 55... but not with 60 or a bit less. The number of frames per second isn't constant, but around 62~63. I wonder why...

Code: Select all

install_int_ex(gfx_timer_proc,BPS_TO_TIMER(60));

- Yes, I need 60 FPS, but it doesn't work, keeps displaying 62~63 FPS.

[hap]

Maybe its timer runs at cycles of 1ms?
What does BPS_TO_TIMER(x) do?

[Zepper]

Code: Select all

      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

[tepples]

- It works perfectly for 50, 55... but not with 60 or a bit less. The number of frames per second isn't constant, but around 62~63. I wonder why...

Code: Select all

install_int_ex(gfx_timer_proc,BPS_TO_TIMER(60));

- Yes, I need 60 FPS, but it doesn't work, keeps displaying 62~63 FPS.

Under what operating system?

60.0 Hz is 16.67 milliseconds per cycle. 16.0 milliseconds per cycle is 62.5 Hz. Not all operating systems make microsecond resolution timers available to processes running as a limited user. If you make a limited test case and send it to the Allegro team, someone with more knowledge of the program's insides might be able to make a more detailed diagnosis.

[Zepper]

Windows XP.

[kyuusaku]

Do you need to use Allegro or can you use Windows' timer(s)?

I find QueryPerformanceCounter() + Sleep() to work very well.

[blargg]

I think the point of using only Allegro is to be cross-platform.

[randilyn]

High-resolution timers don't work on some laptops and whatnot. Don't use them unless you have some sort of fallback timing solution, such as threads (which is how Allegro does timing in all versions up to and including 4.2).

Allegro 4.3 and onward is a completely separate codebase with a completely different API and much better design goals.

[Zepper]

Yes, and...?