/*
Hi Glen,

I bought and installed a HP1533A last month for an
Indigo running 5.2.  Works fine.

I have a special hack program called "dat" that tweaks
the compression flag.  This is necessary to make
portable tapes.

Here it is...  You can post or hand this out as you wish.
I would myself, but I don't have a net connection at the 
moment.

*/

/*
 * Tweak a HP1533A DAT drive compression mode on an SGI
 *
 * Author:	Ken Chin-Purcell
 *		Innovative Research, Inc.
 * Date:	November 9, 1994
 *
 * Public domain, no copyright, use as you wish.
 *
 * This has only been used for SGI IRIX 5.2
 *
 * To make: cc -o dat dat.c -lds
 *
 * To use:
 *
 *	Install the HP1533A tape drive:
 *		Dip switches 3, 7, 8 OFF
 *		All others ON
 *
 *	Add to /var/sysgen/master.d/scsi, after "Python" entry:
    { DATTAPE, TPDAT, 2, 6, "HP", "C1533A", 0, 0, {0, 0, 0, 0},
      MTCAN_BSF|MTCAN_BSR|MTCAN_APPEND|MTCAN_SETMK|MTCAN_PART|MTCAN_PREV|
	MTCAN_SYNC|MTCAN_SPEOD|MTCAN_CHKRDY|MTCAN_VAR|MTCAN_SETSZ|
	MTCAN_SILI|MTCAN_SEEK|MTCAN_CHTYPEANY,
      40, 4*60, 4*60, 5*60, 512, 64*512 },
 *
 *	Then cd /, lboot -T, reboot
 *
 *	Make this program, and either:
 *	  install it suid root,
 *	  or make the appropriate /dev/scsi/... entry writable (hmmmm),
 *	  or deny non-root users
 *
 *	usage: dat [-t dev] [-d] [-q] [-c | -u]
 *	  Dat will try to find the first DAT drive
 *	  in the system inventory.  The environment
 *	  variable DATDEVICE can also be used.
 *	  You must have write permission.
 *	    -t dev	specify scsi device
 *	    -d		verbose debug mode
 *	    -q		quiet
 *	    -c		compression ON
 *	    -u		compression OFF
 *
 *	  Dat with no arguments returns the status of the drive.
 */

#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <dslib.h>
#include <fcntl.h>
#include <getopt.h>
#include <invent.h>

#define BUFLEN 32	/* Good enough */

ModeSelect(struct dsreq *dsp, caddr_t data, long datalen)
{
    /* SGI's mode select doesn't set the SCSI-2 voodoo flag
     */
    fillg0cmd(dsp, CMDBUF(dsp), G0_MSEL, 0x10, 0, 0, B1(datalen), 0);
    filldsreq(dsp, data, datalen, DSRQ_WRITE|DSRQ_SENSE);
    return(doscsireq(getfd(dsp), dsp));
}

void 
DebugSep()
{
    if (dsdebug)
	fputs("\n----------------------------------------\n", stderr);
}

char*
LocateDat()
{
    /* Return the first DAT drive found
     */
    inventory_t* inv;
    static char devName[64];
    
    while (inv = getinvent())
	if (inv->inv_class == INV_TAPE  &&
	    inv->inv_type == INV_SCSIQIC  &&
	    inv->inv_state == TPDAT) {
	    sprintf(devName, "/dev/scsi/sc%dd%dl0", 
		    inv->inv_controller, inv->inv_unit);
	    return devName;
	}
    
    return 0;
}

int
main(int argc, char* argv[])
{
    struct dsreq *dat;
    char mode[BUFLEN];
    int i;
    int compress = 0;
    int uncompress = 0;
    int quiet = 0;
    char* datDevice = LocateDat();
    
    dsdebug = 0;
    if (getenv("DATDEVICE"))
	datDevice = getenv("DATDEVICE");
    
    while ((i = getopt(argc, argv, "cdhqut:")) != EOF)
	switch (i) {
	  case 'c':
	    compress = 1;
	    uncompress = 0;
	    break;
	  case 'u':
	    compress = 0;
	    uncompress = 1;
	    break;
	  case 'd':
	    dsdebug++;
	    break;
	  case 'q':
	    quiet = 1;
	    break;
	  case 't':
	    datDevice = optarg;
	    break;
	  case 'h':
	  case '?':
	    fprintf(stderr, "usage: dat [-t dev] [-d] [-q] [-c | -u]\n");
	    fprintf(stderr, "  Dat will try to find the first DAT drive\n");
	    fprintf(stderr, "  in the system inventory.  The environment\n");
	    fprintf(stderr, "  variable DATDEVICE can also be used.\n");
	    fprintf(stderr, "  You must have write permission.\n");
	    fprintf(stderr, "    -t dev	specify scsi device\n");
	    fprintf(stderr, "    -d		verbose debug mode\n");
	    fprintf(stderr, "    -q		quiet\n");
	    fprintf(stderr, "    -c		compression ON\n");
	    fprintf(stderr, "    -u		compression OFF\n");
	    return 1;
	}

    if (!datDevice) {
	fprintf(stderr, "Cannot find DAT device\n");
	return 1;
    }
    
    DebugSep();
    dat = dsopen(datDevice, O_RDWR);
    if (!dat) {
	fprintf(stderr, "Cannot open scsi device %s\n", datDevice);
	fprintf(stderr, "    Do you have permission?\n");
	return 1;
    }
    
    if (testunitready00(dat) > 2) {
	fprintf(stderr, "Device %s not ready (hmmmmm...)\n", datDevice);
	return 1;
    }
    
    if (compress || uncompress) {
	memset(mode, 0, BUFLEN);
	mode[2] = 0x10;		/* Buffered mode */
	mode[4] = 0x0f;		/* Mode page 15 */
	mode[5] = 0x0e;		/* 14 bytes to the page */
	mode[6] = compress ? 0xc0 : 0x40;
	mode[7] = 0x80;		/* enable decompression */
	mode[11] = 0x20;	/* LZ compression */
	
	DebugSep();
	ModeSelect(dat, mode, 20);
    }

    memset(mode, 0, BUFLEN);
    DebugSep();
    modesense1a(dat, mode, 28, 0, 0xf, 0);

    if (!quiet)
	if (mode[14] == 0xc0)
	    printf("DAT compression on\n");
	else
	    printf("DAT compression off\n");

    return 0;
}