1 8ad51794 2004-03-25 devnull #include <u.h>
2 b2cfc4e2 2003-09-30 devnull #include <unistd.h>
3 b2cfc4e2 2003-09-30 devnull #include <sched.h>
4 8ad51794 2004-03-25 devnull #include <libc.h>
6 b2cfc4e2 2003-09-30 devnull int _ntas;
7 b2cfc4e2 2003-09-30 devnull static int
8 b2cfc4e2 2003-09-30 devnull _xtas(void *v)
13 b2cfc4e2 2003-09-30 devnull x = _tas(v);
14 a995e477 2003-10-01 devnull return x;
18 b2cfc4e2 2003-09-30 devnull canlock(Lock *l)
20 b2cfc4e2 2003-09-30 devnull return !_xtas(&l->val);
24 b2cfc4e2 2003-09-30 devnull unlock(Lock *l)
26 b2cfc4e2 2003-09-30 devnull l->val = 0;
30 b2cfc4e2 2003-09-30 devnull lock(Lock *lk)
34 b2cfc4e2 2003-09-30 devnull /* once fast */
35 b2cfc4e2 2003-09-30 devnull if(!_xtas(&lk->val))
37 b2cfc4e2 2003-09-30 devnull /* a thousand times pretty fast */
38 b2cfc4e2 2003-09-30 devnull for(i=0; i<1000; i++){
39 b2cfc4e2 2003-09-30 devnull if(!_xtas(&lk->val))
41 b2cfc4e2 2003-09-30 devnull sched_yield();
43 b2cfc4e2 2003-09-30 devnull /* now nice and slow */
44 b2cfc4e2 2003-09-30 devnull for(i=0; i<1000; i++){
45 b2cfc4e2 2003-09-30 devnull if(!_xtas(&lk->val))
47 b2cfc4e2 2003-09-30 devnull usleep(100*1000);
49 b2cfc4e2 2003-09-30 devnull /* take your time */
50 b2cfc4e2 2003-09-30 devnull while(_xtas(&lk->val))
51 b2cfc4e2 2003-09-30 devnull usleep(1000*1000);