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Annotation of researchv10no/sys/io/drbit.c, revision 1.1

1.1     ! root        1: /*
        !             2:  *  DR-11C interface
        !             3:  *  The routines in this driver are not called through the normal
        !             4:  *  device interface.  Instead, they are available for other device
        !             5:  *  drivers to use to send arbitrary information out on a DR-11C.
        !             6:  */
        !             7: 
        !             8: #include "sys/param.h"
        !             9: #include "sys/ubaddr.h"
        !            10: 
        !            11: /* number of output bits available in a DR -- must be a power of 2 */
        !            12: #define DRWIDTH 16
        !            13: 
        !            14: /* DRWIDTH is 2**DRSHIFT */
        !            15: #define DRSHIFT 4
        !            16: 
        !            17: extern int drcnt;
        !            18: extern struct ubaddr draddr[];
        !            19: extern caddr_t drreg[];
        !            20: 
        !            21: struct drreg {
        !            22:        u_short drcsr, drout, drin;
        !            23: };
        !            24: 
        !            25: /* set bit n of the dr-11 complex to v */
        !            26: drsetbit (n, v)
        !            27:        register int n;
        !            28:        register int v;
        !            29: {
        !            30:        register struct drreg *drptr;
        !            31:        register int i;
        !            32: 
        !            33:        i = n>>DRSHIFT;
        !            34:        if (i < 0 || i >= drcnt)
        !            35:                return;
        !            36:        if ((drptr = (struct drreg *)drreg[i]) == NULL) {
        !            37:                if ((drptr = (struct drreg *)ubaddr(&draddr[i])) == NULL
        !            38:                ||   ubbadaddr(draddr[i].ubno, &drptr->drout, sizeof(short))) {
        !            39:                        printf("drbit dr11 %d absent\n", i);
        !            40:                        return;
        !            41:                }
        !            42:                drreg[i] = (caddr_t)drptr;
        !            43:        }
        !            44:        i = 1 << (n & (DRWIDTH - 1));
        !            45:        if (v)
        !            46:                drptr->drout |= i;
        !            47:        else
        !            48:                drptr->drout &= ~i;
        !            49: }

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