1991/0428/gnot/lock.c (diff list | history)

gnot/lock.c on 1990/03091
1990/03091		#include "u.h" #include "lib.h" #include "mem.h" #include "dat.h" #include "fns.h"
1990/0617		#define PCOFF -1
1990/0403		/* * N.B. Ken's compiler generates a TAS instruction for the sequence: * * if(l->key >= 0){ * l->key |= 0x80; * ...
1990/0601		* * DO NOT TAKE THE ADDRESS OF l->key or the TAS will disappear.
1990/0403		*/
1990/03091		void lock(Lock *l) {
1990/1226		Lock *ll = l; /* do NOT take the address of ll */
1990/03091		int i; /* * Try the fast grab first */
1990/0705		if(ll->key >= 0){ ll->key |= 0x80; ll->pc = ((ulong*)&l)[PCOFF];
1990/03091		return; } for(i=0; i<10000000; i++)
1990/0705		if(ll->key >= 0){ ll->key |= 0x80; ll->pc = ((ulong*)&l)[PCOFF];
1990/03091		return;
1990/0601		}
1990/0705		ll->key = 0;
1991/0109		print("lock loop %lux pc %lux held by pc %lux\n", l, ((ulong*)&l)[PCOFF], l->pc);
1990/03091		} int canlock(Lock *l) {
1990/1226		Lock *ll = l; /* do NOT take the address of ll */
1990/0705		if(ll->key >= 0){ ll->key |= 0x80; ll->pc = ((ulong*)&l)[PCOFF];
1990/03091		return 1; } return 0; } void unlock(Lock *l) { l->pc = 0;
1990/0403		l->key = 0;
1990/03091		}