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Annotation of researchv10no/sys/io/fineclock.c, revision 1.1.1.1

1.1       root        1: /*
                      2:  * read a fine-resolution clock,
                      3:  * derived from the VAX interval timer
                      4:  */
                      5: #include "sys/param.h"
                      6: #include "sys/mtpr.h"
                      7: #include "sys/clock.h"
                      8: #include "sys/systm.h" /* for time and lbolt */
                      9: #include "sys/buf.h"   /* just for B_READ */
                     10: #include "sys/conf.h"
                     11: #include "sys/user.h"
                     12: 
                     13: static int clkread();
                     14: struct cdevsw clkcdev = cdinit(nulldev, nulldev, clkread, nodev, nodev);
                     15: 
                     16: #define        FINERES (-CLK60HZ)
                     17: 
                     18: static
                     19: clkread(dev)
                     20: int dev;
                     21: {
                     22:        register int s;
                     23:        long finetime;
                     24: 
                     25:        s = spl7();
                     26:        finetime = FINERES + mfpr(ICR); /* ICR is negative remaining count */
                     27:        if (mfpr(ICCS) & ICCS_INT)
                     28:                finetime += FINERES;    /* one tick already past */
                     29:        finetime += (lbolt * FINERES) + (time * FINERES * HZ);
                     30:        splx(s);
                     31:        iomove((caddr_t)&finetime, MIN(u.u_count, sizeof(finetime)), B_READ);
                     32: }

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