From: mckinneyj@cpva.saic.com
Sent: Tuesday, July 06, 1999 1:34 PM
To: Info-VAX@Mvb.Saic.Com
Subject: Re: ZDEC for OpenVMS Alpha V7.x?

In article <3780B904.193303D4@winternet.com>, Ed Wilts <ewilts@winternet.com> writes:
> I've got an old ZDEC.MAR utility dating back many years that has served
> me well over the years.  Yesterday, I built it on a V7.1-2 system, and
> although it compiled/linked without any problems, when zeroing a device
> error count, it did it a little more aggressively than I would have
> liked (can you say bugcheck boys & girls?)...
> 
> Does anyone have a utility that zeros device error counts for V7.1?  An
> internals programmer I am not.
> 
> Thanks,
> 	.../Ed
> mailto:ewilts@winternet.com
-- 
	Here's a hack that'll work on V7.1. I think that it was
	originally posted here many years ago (don't recall the
	author though it could possibly have been Ehud) as a
	combination of 	C and Macro. I've rewritten the assembler
	portion so that it's now all in C...


- Jim

============================ ZERO.C  =========================

/*
 * zero() - Clear device error count
 *
 *	Usage:
 *	$ zero == "$location:zero.exe"
 *	$ zero [device]
 *
 *      Build:
 *      $ cc zero+sys$library:sys$lib_c.tlb/lib
 *      $ link/sysexe/notrace zero
 *
 */

#define module_name Zero
#define module_vers "V1.0.0"

#ifdef __alpha
#pragma module module_name module_vers
#else /* __vax */
#module module_name module_vers
#endif /* __alpha */

#include <descrip.h>	/* Descriptor structure definitions (for prompt) */
#include <lib$routines.h> /* RTL routines */
#include <prvdef.h>	/* Privilege definitions (to get BYPASS and *_IO) */
#include <ssdef.h>	/* System service status values */
#include <starlet.h>	/* System service routines */
#include <ccbdef.h>	/* Channel control block */
#include <ucbdef.h>	/* Unit control block */
#include <ioc_routines.h> /* IO routines (ioc$verify_chan) */

#define check	if(!(status & 1)) sys$exit(status);

#ifdef __alpha
main() 
#else  /* __vax   */
cmain()
#endif /* __alpha */
{
  $DESCRIPTOR(prompt,"_Device: ");
  struct dsc$descriptor_s device;
  char _align(quadword) devbuf[32];
  int32 _align(quadword) privmsk[2];
  int32 status;
  int16 channel;
  CCB	*ccb_p;				/* pointer to device's CCB */
  struct
    {
    int32 arg_count;			/* number of args passed */
    int32 ucb;				/* 32bit address of ucb */
    } cmkrnl_args;

  int32 reset_errcnt(int32 ucb);

  device.dsc$a_pointer = (char *) &devbuf;
  device.dsc$w_length  = sizeof(devbuf);
  device.dsc$b_class   = DSC$K_CLASS_S;
  device.dsc$b_dtype   = DSC$K_DTYPE_T;

  /* Get the device name from the command line */
  status = lib$get_foreign(&device,&prompt,&device.dsc$w_length,0);
  check;

  /* Enable privileges for access to device */
  privmsk[0] = PRV$M_BYPASS | PRV$M_PHY_IO | PRV$M_LOG_IO;
  status = sys$setprv(1,&privmsk,0,0);
  check;

  /* Assign a channel to the device */
  status = sys$assign(&device,&channel,0,0,0);
  check;
	
  /* Get UCB address from CCB */
  status = ioc$verify_chan(channel, &ccb_p);	/* get the device's CCB */
  check;

  /* Call the kernel-mode routine to fixup UCB */	
  cmkrnl_args.arg_count = 1;			/* a single argument */
  cmkrnl_args.ucb = (int32) ccb_p->ccb$l_ucb;	/* 32bit UCB address from CCB */
  status = sys$cmkrnl(&reset_errcnt, &cmkrnl_args);
  check;

  /* Deassign the channel to device */
  status = sys$dassgn(channel);
  check;

  return(SS$_NORMAL);
}

/* reset_errcnt	- the kernel mode code */
/* we'll only be receiving the 32 significant bits of the UCB's address */
/* since sys$cmkrnl wants an arg list consisting of 32bit integers      */
int32 reset_errcnt(int32 ucb)
{
  UCB *ucb_p;				/* allocate a pointer to UCB */
  ucb_p = (UCB *) ucb;			/* cast our argument there */
  ucb_p->ucb$l_errcnt = 0;
  ucb_p->ucb$l_softerrcnt = 0;
  return(SS$_NORMAL);
}