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[unix-history] / usr / sys / dmr / tc.c

#
/*
*      Copyright 1973 Bell Telephone Laboratories Inc
*/

/*
* TC-11 DECtape driver
*/

#include "../param.h"
#include "../conf.h"
#include "../buf.h"
#include "../user.h"

struct {
       int     tccsr;
       int     tccm;
       int     tcwc;
       int     tcba;
       int     tcdt;
};

struct  devtab  tctab;

#define TCADDR  0177340
#define NTCBLK  578

#define TAPERR  0100000
#define TREV    04000
#define READY   0200
#define IENABLE 0100
#define UPS     0200
#define ENDZ    0100000
#define BLKM    02000
#define ILGOP   010000
#define SELERR  04000

#define SAT     0
#define RNUM    02
#define RDATA   04
#define SST     010
#define WDATA   014
#define GO      01

#define SFORW   1
#define SREV    2
#define SIO     3

tcclose(dev)
{
       bflush(dev);
}

tcstrategy(abp)
struct buf *abp;
{
       register struct buf *bp;

       bp = abp;
       if(bp->b_blkno >= NTCBLK) {
               bp->b_flags =| B_ERROR;
               iodone(bp);
               return;
       }
       bp->av_forw = 0;
       spl6();
       if (tctab.d_actf==0)
               tctab.d_actf = bp;
       else
               tctab.d_actl->av_forw = bp;
       tctab.d_actl = bp;
       if (tctab.d_active==0)
               tcstart();
       spl0();
}

tcstart()
{
       register struct buf *bp;
       register int *tccmp, com;

       if ((bp = tctab.d_actf) == 0)
               return;
       tccmp = &TCADDR->tccm;
       if (((*tccmp).hibyte&07) != bp->b_dev.d_minor)
               (*tccmp).lobyte = SAT|GO;
       tctab.d_errcnt = 20;
       tctab.d_active = SFORW;
       com = (bp->b_dev.d_minor<<8) | IENABLE|RNUM|GO;
       if ((TCADDR->tccsr & UPS) == 0) {
               com =| TREV;
               tctab.d_active = SREV;
       }
       *tccmp = com;
}

tcintr()
{
       register struct buf *bp;
       register int *tccmp;
       register int *tcdtp;

       tccmp = &TCADDR->tccm;
       tcdtp = &TCADDR->tccsr;
       bp = tctab.d_actf;
       if (*tccmp&TAPERR) {
               if((*tcdtp & (ENDZ|BLKM)) == 0)
                       deverror(bp, *tcdtp);
               if(*tcdtp & (ILGOP|SELERR))
                       tctab.d_errcnt = 0;
               *tccmp =& ~TAPERR;
               if (--tctab.d_errcnt  <= 0) {
                       bp->b_flags =| B_ERROR;
                       goto done;
               }
               if (*tccmp&TREV) {
               setforw:
                       tctab.d_active = SFORW;
                       *tccmp =& ~TREV;
               } else {
               setback:
                       tctab.d_active = SREV;
                       *tccmp =| TREV;
               }
               (*tccmp).lobyte = IENABLE|RNUM|GO;
               return;
       }
       tcdtp = &TCADDR->tcdt;
       switch (tctab.d_active) {

       case SIO:
       done:
               tctab.d_active = 0;
               if (tctab.d_actf = bp->av_forw)
                       tcstart();
               else
                       TCADDR->tccm.lobyte = SAT|GO;
               iodone(bp);
               return;

       case SFORW:
               if (*tcdtp > bp->b_blkno)
                       goto setback;
               if (*tcdtp < bp->b_blkno)
                       goto setforw;
               *--tcdtp = bp->b_addr;          /* core address */
               *--tcdtp = bp->b_wcount;
               tccmp->lobyte = (bp->b_flags&B_XMEM) | IENABLE|GO
                   | (bp->b_flags&B_READ?RDATA:WDATA);
               tctab.d_active = SIO;
               return;

       case SREV:
               if (*tcdtp+3 > bp->b_blkno)
                       goto setback;
               goto setforw;
       }
}