Xinu7/src/sys/h/sleep.h
/* sleep.h */
#define CVECTOR 0100 /* location of clock interrupt vector */
extern int clkruns; /* 1 iff clock exists; 0 otherwise */
/* Set at system startup. */
extern int clockq; /* q index of sleeping process list */
extern int count6; /* used to ignore 5 of 6 interrupts */
extern int count10; /* used to ignore 9 of 10 ticks */
extern long clktime; /* current time in secs since 1/1/70 */
extern int clmutex; /* mutual exclusion sem. for clock */
extern int *sltop; /* address of first key on clockq */
extern int slnempty; /* 1 iff clockq is nonempty */
extern int defclk; /* >0 iff clock interrupts are deferred */
extern int clkdiff; /* number of clock ticks deferred */
extern int clkint(); /* clock interrupt handler */