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Annotation of xinu/sys/vcuwrite.c, revision 1.1

1.1     ! root        1: /* vcuwrite.c - vcuwrite, vwritecopy */
        !             2: 
        !             3: #include <conf.h>
        !             4: #include <kernel.h>
        !             5: #include <tty.h>
        !             6: #include <io.h>
        !             7: #include <vcu.h>
        !             8: #include <procreg.h>
        !             9: 
        !            10: /*------------------------------------------------------------------------
        !            11:  *  vcuwrite - write one or more characters to the vax console device
        !            12:  *------------------------------------------------------------------------
        !            13:  */
        !            14: vcuwrite(devptr, buff, count)
        !            15: struct devsw   *devptr;
        !            16: char   *buff;
        !            17: int    count;
        !            18: {
        !            19:        register struct tty *ttyp;
        !            20:        int ncopied;
        !            21:        PStype ps;
        !            22: 
        !            23:        if (count < 0)
        !            24:                return(SYSERR);
        !            25:        if (count == 0)
        !            26:                return(OK);
        !            27:        disable(ps);
        !            28:        ttyp = &tty[devptr->dvminor];
        !            29:        count -= (ncopied = vwritcopy(buff, ttyp, count));
        !            30:        buff += ncopied;
        !            31:        for ( ; count>0 ; count--)
        !            32:                vcuputc(devptr, *buff++);
        !            33:        restore(ps);
        !            34:        return(OK);
        !            35: }
        !            36: 
        !            37: /*------------------------------------------------------------------------
        !            38:  *  vwritcopy - high-speed copy from user's buffer into system buffer
        !            39:  *------------------------------------------------------------------------
        !            40:  */
        !            41: LOCAL vwritcopy(buff, ttyp, count)
        !            42: char   *buff;
        !            43: struct tty *ttyp;
        !            44: int    count;
        !            45: {
        !            46:        register int    avail;
        !            47:        register char   *cp, *qhead, *qend, *uend;
        !            48: 
        !            49:        avail = scount(ttyp->osem);
        !            50:        qhead = &ttyp->obuff[ttyp->ohead];
        !            51:        qend  = &ttyp->obuff[OBUFLEN];
        !            52:        cp    = buff;
        !            53:        uend  = buff + count;
        !            54:        while (avail-- > 1 && cp < uend) {
        !            55:                if (*cp == NEWLINE && ttyp->ocrlf) {
        !            56:                        *qhead++ = RETURN;
        !            57:                        --avail;
        !            58:                        if ( qhead >= qend )
        !            59:                                qhead = ttyp->obuff;
        !            60:                }
        !            61:                *qhead++ = *cp++;
        !            62:                if ( qhead >= qend )
        !            63:                        qhead = ttyp->obuff;
        !            64:        }                                       /* avail decremented one*/
        !            65:        ttyp->ohead = qhead - ttyp->obuff;      /* extra time when loop */
        !            66:        sreset(ttyp->osem, ++avail);            /* condition fails.     */
        !            67:        mtpr (VCUTXCSENBL, TXCS);
        !            68:        return(cp - buff);
        !            69: }

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