usr/src/sys/vax/include/clock.h

/*      clock.h 4.6     82/09/04        */

/*
 * VAX clock registers
 */

#define ICCS_RUN        0x00000001
#define ICCS_TRANS      0x00000010
#define ICCS_SS         0x00000020
#define ICCS_IE         0x00000040
#define ICCS_INT        0x00000080
#define ICCS_ERR        0x80000000

#define SECDAY          ((unsigned)(24*60*60))          /* seconds per day */
#define SECYR           ((unsigned)(365*SECDAY))        /* per common year */
/*
 * TODRZERO is the what the TODR should contain when the ``year'' begins.
 * The TODR should always contain a number between 0 and SECYR+SECDAY.
 */
#define TODRZERO        ((unsigned)(1<<28))

#define YRREF           1970
#define LEAPYEAR(year)  ((year)%4==0)   /* good till time becomes negative */

/*
 * Start a 60 HZ clock.
 */
#define clkstart() {\
        mtpr(NICR, -16667);     /* 16.667 milli-seconds */\
        mtpr(ICCS, ICCS_RUN+ICCS_IE+ICCS_TRANS+ICCS_INT+ICCS_ERR);\
}
#define clkwrap()       (((unsigned)mfpr(TODR) - TODRZERO)/100 > SECYR+SECDAY)

/*
 * Software clock is software interrupt level 8,
 * implemented as mtpr(SIRR, 0x8) in asm.sed.
 */