ref: 5c448c618a89ab8933838da1b5b97ed7c4a42e08
dir: /sys/src/ape/lib/ap/power/lock.c/
#include "../plan9/lib.h" #include "../plan9/sys9.h" #define _LOCK_EXTENSION #include <lock.h> int tas(int*); void lock(Lock *lk) { int i; /* once fast */ if(!tas(&lk->val)) return; /* a thousand times pretty fast */ for(i=0; i<1000; i++){ if(!tas(&lk->val)) return; _SLEEP(0); } /* now nice and slow */ for(i=0; i<1000; i++){ if(!tas(&lk->val)) return; _SLEEP(100); } /* take your time */ while(tas(&lk->val)) _SLEEP(1000); } int canlock(Lock *lk) { if(tas(&lk->val)) return 0; return 1; } void unlock(Lock *lk) { lk->val = 0; }