Date: Sat, 05 May 2001 18:16:54 +0300
From: "Eli Zaretskii" <eliz AT is DOT elta DOT co DOT il>
Sender: halo1 AT zahav DOT net DOT il
To: "Rafal Maj" <maj_rafal AT poczta DOT onet DOT pl>
Message-Id: <2950-Sat05May2001181653+0300-eliz@is.elta.co.il>
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CC: djgpp AT delorie DOT com
In-reply-to: <9d0i9v$hdv$1@info.cyf-kr.edu.pl> (maj_rafal@poczta.onet.pl)
Subject: Re: busy-wait loop - djgpp_yeld
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> From: "Rafal Maj" <maj_rafal AT poczta DOT onet DOT pl>
> Newsgroups: comp.os.msdos.djgpp
> Date: Sat, 5 May 2001 11:35:35 +0200
> 
> what functions should I all inside my busy-wait loop to make my program nice
> to other tasks ? How can I control "nice" level (Idle or realtime) ?
> With function is most portable ?
> And maybe some Allegro functions are better ?
> 
> while (!finish) {
>   do_calculations();
>   djgpp_yeld();  // ?
>   rest(100); // ?
> }

That function is called __dpmi_yield in DJGPP.

AFAIK, there's no portable function which accomplishes this function.
If you can afford delaying the program a bit, call usleep or sleep,
they both call __dpmi_yield internally, and should have similar
effects on other multitasking OSes.