transfer = (STp->buffer)->buffer_bytes < count - total ?
	  (STp->buffer)->buffer_bytes : count - total;
	memcpy_tofs(buf, (STp->buffer)->b_data +
		    (STp->buffer)->read_pointer,transfer);
	filp->f_pos += transfer;
	buf += transfer;
	total += transfer;
	(STp->buffer)->buffer_bytes -= transfer;
	(STp->buffer)->read_pointer += transfer;
      }
      else if (STp->eof != ST_NOEOF) {
	STp->eof_hit = 1;
	SCpnt->request.dev = -1;  /* Mark as not busy */
	if (total == 0 && STp->eof == ST_FM)
	  STp->eof = 0;
	if (total == 0 && STp->eof == ST_EOM_OK)
	  return (-EIO);  /* ST_EOM_ERROR not used in read */
	return total;
      }

      if (STp->block_size == 0)
	count = total;  /* Read only one variable length block */

    } /* for (total = 0; total < count; ) */

    SCpnt->request.dev = -1;  /* Mark as not busy */

    return total;
}


/* Internal ioctl function */
	static int
st_int_ioctl(struct inode * inode,struct file * file,
	     unsigned int cmd_in, unsigned long arg)
{
   int dev = MINOR(inode->i_rdev);
   int timeout = ST_LONG_TIMEOUT;
   long ltmp;
   int ioctl_result;
   unsigned char cmd[10];
   Scsi_Cmnd * SCpnt;
   Scsi_Tape * STp;

   dev = dev & 127;
   STp = &(scsi_tapes[dev]);

   memset(cmd, 0, 10);
   switch (cmd_in) {
     case MTFSF:
     case MTFSFM:
       cmd[0] = SPACE;
       cmd[1] = 0x01; /* Space FileMarks */
       cmd[2] = (arg >> 16);
       cmd[3] = (arg >> 8);
       cmd[4] = arg;
#ifdef DEBUG
       printk("st%d: Spacing tape forward over %d filemarks.\n", dev,
	      cmd[2] * 65536 + cmd[3] * 256 + cmd[4]);
#endif
       break; 
     case MTBSF:
     case MTBSFM:
       cmd[0] = SPACE;
       cmd[1] = 0x01; /* Space FileMarks */
       ltmp = (-arg);
       cmd[2] = (ltmp >> 16);
       cmd[3] = (ltmp >> 8);
       cmd[4] = ltmp;
#ifdef DEBUG
       if (cmd[2] & 0x80)
	 ltmp = 0xff000000;
       ltmp = ltmp | (cmd[2] << 16) | (cmd[3] << 8) | cmd[4];
       printk("st%d: Spacing tape backward over %d filemarks.\n", dev, (-ltmp));
#endif
       break; 
      case MTFSR:
       cmd[0] = SPACE;
       cmd[1] = 0x00; /* Space Blocks */
       cmd[2] = (arg >> 16);
       cmd[3] = (arg >> 8);
       cmd[4] = arg;
#ifdef DEBUG
       printk("st%d: Spacing tape forward %d blocks.\n", dev,
	      cmd[2] * 65536 + cmd[3] * 256 + cmd[4]);
#endif
       break; 
     case MTBSR:
       cmd[0] = SPACE;
       cmd[1] = 0x00; /* Space Blocks */
       ltmp = (-arg);
       cmd[2] = (ltmp >> 16);
       cmd[3] = (ltmp >> 8);
       cmd[4] = ltmp;
#ifdef DEBUG
       if (cmd[2] & 0x80)
	 ltmp = 0xff000000;
       ltmp = ltmp | (cmd[2] << 16) | (cmd[3] << 8) | cmd[4];
       printk("st%d: Spacing tape backward %d blocks.\n", dev, (-ltmp));
#endif
       break; 
     case MTWEOF:
       if (STp->write_prot)
	 return (-EACCES);
       cmd[0] = WRITE_FILEMARKS;
       cmd[2] = (arg >> 16);
       cmd[3] = (arg >> 8);
       cmd[4] = arg;
       timeout = ST_TIMEOUT;
#ifdef DEBUG
       printk("st%d: Writing %d filemarks.\n", dev,
	      cmd[2] * 65536 + cmd[3] * 256 + cmd[4]);
#endif
       break; 
     case MTREW:
       cmd[0] = REZERO_UNIT;
#ifdef ST_NOWAIT
       cmd[1] = 1;  /* Don't wait for completion */
       timeout = ST_TIMEOUT;
#endif
#ifdef DEBUG
       printk("st%d: Rewinding tape.\n", dev);
#endif
       break; 
     case MTOFFL:
       cmd[0] = START_STOP;
#ifdef ST_NOWAIT
       cmd[1] = 1;  /* Don't wait for completion */
       timeout = ST_TIMEOUT;
#endif
#ifdef DEBUG
       printk("st%d: Unloading tape.\n", dev);
#endif
       break; 
     case MTNOP:
#ifdef DEBUG
       printk("st%d: No op on tape.\n", dev);
#endif
       return 0;  /* Should do something ? */
       break;
     case MTRETEN:
       cmd[0] = START_STOP;
#ifdef ST_NOWAIT
       cmd[1] = 1;  /* Don't wait for completion */
       timeout = ST_TIMEOUT;
#endif
       cmd[4] = 3;
#ifdef DEBUG
       printk("st%d: Retensioning tape.\n", dev);
#endif
       break; 
     case MTEOM:
       cmd[0] = SPACE;
       cmd[1] = 3;
#ifdef DEBUG
       printk("st%d: Spacing to end of recorded medium.\n", dev);
#endif
       break; 
     case MTERASE:
       if (STp->write_prot)
	 return (-EACCES);
       cmd[0] = ERASE;
       cmd[1] = 1;  /* To the end of tape */
#ifdef DEBUG
       printk("st%d: Erasing tape.\n", dev);
#endif
       break;
     case MTSEEK:
       if ((STp->device)->scsi_level < SCSI_2) {
	 cmd[0] = QFA_SEEK_BLOCK;
	 cmd[2] = (arg >> 16);
	 cmd[3] = (arg >> 8);
	 cmd[4] = arg;
	 cmd[5] = 0;
       }
       else {
	 cmd[0] = SEEK_10;
	 cmd[1] = 4;
	 cmd[3] = (arg >> 24);
	 cmd[4] = (arg >> 16);
	 cmd[5] = (arg >> 8);
	 cmd[6] = arg;
       }
#ifdef ST_NOWAIT
       cmd[1] |= 1;  /* Don't wait for completion */
       timeout = ST_TIMEOUT;
#endif
#ifdef DEBUG
       printk("st%d: Seeking tape to block %d.\n", dev, arg);
#endif
       break;
     case MTSETBLK:  /* Set block length */
     case MTSETDENSITY: /* Set tape density */
     case MTSETDRVBUFFER: /* Set drive buffering */
       if (STp->dirty || (STp->buffer)->buffer_bytes != 0)
	 return (-EIO);   /* Not allowed if data in buffer */
       if (cmd_in == MTSETBLK &&
	   arg != 0 &&
	   (arg < STp->min_block || arg > STp->max_block ||
	    arg > ST_BUFFER_SIZE)) {
	 printk("st%d: Illegal block size.\n", dev);
	 return (-EINVAL);
       }
       cmd[0] = MODE_SELECT;
       cmd[4] = 12;

       memset((STp->buffer)->b_data, 0, 12);
       if (cmd_in == MTSETDRVBUFFER)
	 (STp->buffer)->b_data[2] = (arg & 7) << 4;
       else
	 (STp->buffer)->b_data[2] = 
	   STp->drv_buffer << 4;
       (STp->buffer)->b_data[3] = 8;     /* block descriptor length */
       if (cmd_in == MTSETDENSITY)
	 (STp->buffer)->b_data[4] = arg;
       else
	 (STp->buffer)->b_data[4] = STp->density;
       if (cmd_in == MTSETBLK)
	 ltmp = arg;
       else
	 ltmp = STp->block_size;
       (STp->buffer)->b_data[9] = (ltmp >> 16);
       (STp->buffer)->b_data[10] = (ltmp >> 8);
       (STp->buffer)->b_data[11] = ltmp;
       timeout = ST_TIMEOUT;
#ifdef DEBUG
       if (cmd_in == MTSETBLK)
	 printk("st%d: Setting block size to %d bytes.\n", dev,
		(STp->buffer)->b_data[9] * 65536 +
		(STp->buffer)->b_data[10] * 256 +
		(STp->buffer)->b_data[11]);
       else if (cmd_in == MTSETDENSITY)
	 printk("st%d: Setting density code to %x.\n", dev,
		(STp->buffer)->b_data[4]);
       else
	 printk("st%d: Setting drive buffer code to %d.\n", dev,
		((STp->buffer)->b_data[2] >> 4) & 7);
#endif
       break;
     default:
       printk("st%d: Unknown st_ioctl command %x.\n", dev, cmd_in);
       return (-ENOSYS);
     }

   SCpnt = allocate_device(NULL, (STp->device)->index, 1);
   SCpnt->sense_buffer[0] = 0;
   SCpnt->request.dev = dev;
   scsi_do_cmd(SCpnt,
	       (void *) cmd, (void *) (STp->buffer)->b_data, ST_BLOCK_SIZE,
	       st_sleep_done, timeout, MAX_RETRIES);

   if (SCpnt->request.dev == dev) sleep_on( &(STp->waiting) );

   ioctl_result = (STp->buffer)->last_result_fatal;

   SCpnt->request.dev = -1;  /* Mark as not busy */

   if (!ioctl_result) {
     if (cmd_in == MTBSFM)
       ioctl_result = st_int_ioctl(inode, file, MTFSF, 1);
     else if (cmd_in == MTFSFM)
       ioctl_result = st_int_ioctl(inode, file, MTBSF, 1);
     else if (cmd_in == MTSETBLK) {
       STp->block_size = arg;
       if (arg != 0) {
	 (STp->buffer)->buffer_blocks =
	   ST_BUFFER_SIZE / STp->block_size;
	 (STp->buffer)->buffer_size =
	   (STp->buffer)->buffer_blocks * STp->block_size;
       }
       else {
	 (STp->buffer)->buffer_blocks = 1;
	 (STp->buffer)->buffer_size = ST_BUFFER_SIZE;
       }
       (STp->buffer)->buffer_bytes =
	 (STp->buffer)->read_pointer = 0;
     }
     else if (cmd_in == MTSETDRVBUFFER)
       STp->drv_buffer = arg;
     else if (cmd_in == MTSETDENSITY)
       STp->density = arg;
     if (cmd_in == MTEOM || cmd_in == MTWEOF) {
       STp->eof = ST_EOM_OK;
       STp->eof_hit = 0;
     }
     else if (cmd_in != MTSETBLK && cmd_in != MTNOP) {
       STp->eof = ST_NOEOF;
       STp->eof_hit = 0;
     }
   }

   return ioctl_result ;
}



/* The ioctl command */
	static int
st_ioctl(struct inode * inode,struct file * file,
	 unsigned int cmd_in, unsigned long arg)
{
   int dev = MINOR(inode->i_rdev);
   int i, cmd, result;
   struct mtop mtc;
   struct mtpos mt_pos;
   unsigned char scmd[10];
   Scsi_Cmnd *SCpnt;
   Scsi_Tape *STp;

   dev = dev & 127;
   STp = &(scsi_tapes[dev]);
#ifdef DEBUG
   if (!STp->in_use) {
     printk("st%d: Incorrect device.\n", dev);
     return (-EIO);
   }
#endif

   cmd = cmd_in & IOCCMD_MASK;
   if (cmd == (MTIOCTOP & IOCCMD_MASK)) {

     if (((cmd_in & IOCSIZE_MASK) >> IOCSIZE_SHIFT) != sizeof(mtc))
       return (-EINVAL);

     i = verify_area(VERIFY_WRITE, (void *)arg, sizeof(mtc));
     if (i)
        return i;

     memcpy_fromfs((char *) &mtc, (char *)arg, sizeof(struct mtop));

     i = flush_buffer(inode, file, mtc.mt_op == MTSEEK ||
		      mtc.mt_op == MTREW || mtc.mt_op == MTOFFL ||
		      mtc.mt_op == MTRETEN || mtc.mt_op == MTEOM);
     if (i < 0)
       return i;

     return st_int_ioctl(inode, file, mtc.mt_op, mtc.mt_count);
   }
   else if (cmd == (MTIOCGET & IOCCMD_MASK)) {

     if (((cmd_in & IOCSIZE_MASK) >> IOCSIZE_SHIFT) != sizeof(struct mtget))
       return (-EINVAL);
     i = verify_area(VERIFY_WRITE, (void *)arg, sizeof(struct mtget));
     if (i)
       return i;

     memcpy_tofs((char *)arg, (char *)(STp->buffer)->mt_status,
		 sizeof(struct mtget));
     return 0;
   }
   else if (cmd == (MTIOCPOS & IOCCMD_MASK)) {
#ifdef DEBUG
     printk("st%d: get tape position.\n", dev);
#endif
     if (((cmd_in & IOCSIZE_MASK) >> IOCSIZE_SHIFT) != sizeof(struct mtpos))
       return (-EINVAL);

     i = flush_buffer(inode, file, 0);
     if (i < 0)
       return i;

     i = verify_area(VERIFY_WRITE, (void *)arg, sizeof(struct mtpos));
     if (i)
       return i;

     SCpnt = allocate_device(NULL, (STp->device)->index, 1);

     SCpnt->sense_buffer[0]=0;
     memset (scmd, 0, 10);
     if ((STp->device)->scsi_level < SCSI_2) {
       scmd[0] = QFA_REQUEST_BLOCK;
       scmd[4] = 3;
     }
     else {
       scmd[0] = READ_POSITION;
       scmd[1] = 1;
     }
     SCpnt->request.dev = dev;
     SCpnt->sense_buffer[0] = 0;
     scsi_do_cmd(SCpnt,
		 (void *) scmd, (void *) (STp->buffer)->b_data,
		 ST_BLOCK_SIZE, st_sleep_done, ST_TIMEOUT, MAX_READY_RETRIES);

     if (SCpnt->request.dev == dev) sleep_on( &(STp->waiting) );
     
     if ((STp->buffer)->last_result_fatal != 0) {
       mt_pos.mt_blkno = (-1);
#ifdef DEBUG
       printk("st%d: Can't read tape position.\n", dev);
#endif
       result = (-EIO);
     }
     else {
       result = 0;
       if ((STp->device)->scsi_level < SCSI_2)
	 mt_pos.mt_blkno = ((STp->buffer)->b_data[0] << 16) 
	   + ((STp->buffer)->b_data[1] << 8) 
	     + (STp->buffer)->b_data[2];
       else
	 mt_pos.mt_blkno = ((STp->buffer)->b_data[4] << 24)
	   + ((STp->buffer)->b_data[5] << 16) 
	     + ((STp->buffer)->b_data[6] << 8) 
	       + (STp->buffer)->b_data[7];

     }

     SCpnt->request.dev = -1;  /* Mark as not busy */

     memcpy_tofs((char *)arg, (char *) (&mt_pos), sizeof(struct mtpos));
     return result;
   }
   else
     return scsi_ioctl(STp->device, cmd_in, (void *) arg);
}



static struct file_operations st_fops = {
   NULL,            /* lseek - default */
   st_read,         /* read - general block-dev read */
   st_write,        /* write - general block-dev write */
   NULL,            /* readdir - bad */
   NULL,            /* select */
   st_ioctl,        /* ioctl */
   NULL,            /* mmap */
   scsi_tape_open,  /* open */
   scsi_tape_close, /* release */
   NULL		    /* fsync */
};

void st_attach(Scsi_Device * SDp){
  scsi_tapes[NR_ST++].device = SDp;
  if(NR_ST > MAX_ST) panic ("scsi_devices corrupt (st)");
};

unsigned long st_init1(unsigned long mem_start, unsigned long mem_end){
  scsi_tapes = (Scsi_Tape *) mem_start;
  mem_start += MAX_ST * sizeof(Scsi_Tape);
  return mem_start;
};

/* Driver initialization */
unsigned long st_init(unsigned long mem_start, unsigned long mem_end)
{
  int i;

  if (register_chrdev(MAJOR_NR,"st",&st_fops)) {
    printk("Unable to get major %d for SCSI tapes\n",MAJOR_NR);
    return mem_start;
  }
  if (NR_ST == 0) return mem_start;

#ifdef DEBUG
  printk("st: Init tape.\n");
#endif

  for (i=0; i < NR_ST; ++i) {
    scsi_tapes[i].capacity = 0xfffff;
    scsi_tapes[i].dirty = 0;
    scsi_tapes[i].rw = ST_IDLE;
    scsi_tapes[i].eof = ST_NOEOF;
    scsi_tapes[i].waiting = NULL;
    scsi_tapes[i].in_use = 0;
    scsi_tapes[i].drv_buffer = 1;  /* Try buffering if no mode sense */
    scsi_tapes[i].density = 0;
  }


  /* Allocate the buffers */
  if (NR_ST == 1)
    st_nbr_buffers = 1;
  else
    st_nbr_buffers = 2;
  for (i=0; i < st_nbr_buffers; i++) {
    st_buffers[i] = (ST_buffer *) mem_start;
#ifdef DEBUG
    printk("st: Buffer address: %p\n", st_buffers[i]);
#endif
    mem_start += sizeof(ST_buffer) - 1 + ST_BUFFER_BLOCKS * ST_BLOCK_SIZE;
    st_buffers[i]->mt_status = (struct mtget *) mem_start;
    mem_start += sizeof(struct mtget);
    st_buffers[i]->in_use = 0;
    st_buffers[i]->writing = 0;

    /* "generic" status */
    memset((void *) st_buffers[i]->mt_status, 0, sizeof(struct mtget));
    st_buffers[i]->mt_status->mt_type = MT_ISSCSI1;
  }

  return mem_start;
}