int main()
{
int i;
int ids[BLOB_COUNT];
__dpmi_regs regs;
clrscr();
printf("\nLWP: Example 3. Pre-emptive/Cooperative\n");
printf("This program spawns %d threads that each draw\n", BLOB_COUNT);
printf("a dot on the screen that moves in a random direction.\n");
printf("Each thread yields after it draws a pixel, to smooth\n");
printf("out the dot motion\n");
printf("Press any key to continue...");
fflush(stdout);
getch();
regs.x.ax = 0x13;
srandom(time(0));
__dpmi_int(0x10, ®s);
lwpInit(RTC128, 1);
lwpEnterCriticalSection();
_farsetsel(_dos_ds);
lwpLeaveCriticalSection();
for(i=0;(i<BLOB_COUNT) && !kbhit();i++)
{
ids[i] = lwpSpawn(blobProc, NULL, 4096, 1, TRUE);
lwpYield(); /* let the blob move a little */
}
while(!kbhit())
{
if(plotCount == BLOB_COUNT)
{
plotCount = 0;
waitVBL();
}
plotCount++;
lwpYield();
}
/* key was hit, all other threads start dying here */
while(lwpThreadCount() > 0)
{
lwpYield(); /* wait for all the other threads to die */
}
getch();
lwpEnterCriticalSection();
regs.x.ax = 0x3;
__dpmi_int(0x10, ®s);
lwpLeaveCriticalSection();
return(0);
}
void
lwp_rwlock_unlock(struct lwp_rwlock *rwlock)
{
struct lwpProc *p;
int maxpri;
lwpStatus(LwpCurrent, "unlocking rwlock %s", rwlock->name);
if (CANT_HAPPEN(rwlock->count == 0))
return;
if (rwlock->count < 0)
rwlock->count = 0;
else
rwlock->count--;
if (rwlock->count == 0 && rwlock->wq.head) {
p = lwpGetFirst(&rwlock->wq);
lwpStatus(p, "wake up next writer of rwlock %s", rwlock->name);
maxpri = p->pri;
lwpReady(p);
} else if (rwlock->count >= 0 && rwlock->rq.head && !rwlock->wq.head) {
maxpri = 0;
while ((p = lwpGetFirst(&rwlock->rq))) {
lwpStatus(p, "wake up next reader of rwlock %s", rwlock->name);
maxpri = MAX(maxpri, p->pri);
lwpReady(p);
}
} else
return;
if (LwpCurrent->pri < maxpri) {
lwpStatus(LwpCurrent, "yielding to thread with higher priority");
lwpYield();
}
}
void blobProc(void *p)
{
int x, y, xspeed,yspeed ;
char col;
lwpEnterCriticalSection();
x = (int) (319 * (float)((float) random() / (float) RAND_MAX ));
y = (int) (199 * (float)((float) random() / (float) RAND_MAX ));
col = (int) (255 * (float)((float) random() / (float) RAND_MAX ));
xspeed = (int) (3 * (float)((float) random() / (float) RAND_MAX ));
yspeed = (int) (3 * (float)((float) random() / (float) RAND_MAX ));
_farsetsel(_dos_ds);
lwpLeaveCriticalSection();
/* loop until keypress */
while(!kbhit())
{
putpixel(x,y,0);
plotCount++;
x+=xspeed;
if(x>=319)
{
xspeed=-xspeed;
x = 319;
}
if(x<=0)
{
xspeed=-xspeed;
x = 0;
}
y+=yspeed;
if(y>=199)
{
yspeed=-yspeed;
y=199;
}
if(y<=0)
{
yspeed=-yspeed;
y=0;
}
putpixel(x,y,col);
lwpYield();
}
putpixel(x,y,0);
/* erase pixel */
/* thread dies here */
}
void
empth_yield(void)
{
ef_make_stale();
lwpYield();
}
