source: buchla-68k/orig/MT/MTSETP.C

/*
   =============================================================================
        mtsetp.c -- Multi-Tasker -- change task priority
        Version 4 -- 1988-04-11 -- D.N. Lynx Crowe
        (c) Copyright 1988 -- D.N. Lynx Crowe
   =============================================================================
*/

#include "stddefs.h"
#include "biosdefs.h"
#include "mtdefs.h"

extern  short           setipl();       /* set processor IPL function */

extern  struct  _mt_def *_MT_;

/*
   =============================================================================
        MTSetP() -- reset task priority and dispatch to highest priority task

                Returns old task priority.
   =============================================================================
*/

unsigned
MTSetP(pri)
unsigned pri;
{
        register short oldipl;
        register unsigned oldpri;

        if ((struct _mt_def *)NIL EQ _MT_)
                _MT_ = (struct _mt_def *)XBIOS(X_MTDEFS);

        oldipl = setipl(7);     /* DISABLE INTERRUPTS */

        oldpri = _MT_->mtp->CurP->pri;  /* get old task priority */
        _MT_->mtp->CurP->pri = pri;     /* set new priority for task */

        setipl(oldipl);         /* RESTORE INTERRUPTS */

        MTSwap();               /* swap to highest priority ready task */
        return(oldpri);         /* return old task priority */
}