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Annotation of xinu/sys/vcuwrite.c, revision 1.1.1.1

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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