/*
 *	This is an example of using mrd_read_element_status to
 *	find out much data a read Read Element Status command
 *	needs.  It will only work when the underlying device is
 *	a SCSI device since it relies on behavior defined for
 *	SCSI.  It will make a best attempt to print out the
 *	the SCSI header to see what other implementations
 *	provide.
 *
 *	Usage:
 *
 *		mrd_res_size robot type start count
 */
#ifndef	lint
static	char	SccsId[] = "@(#)mrd_res_size.c	1.2 (mrd-example) 3/5/97" ;
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <mrd_common.h>
#include <mrd_message.h>

/*
 *	The SCSI specification says that a request size of 8
 *	bytes will have the underlying device only return a
 *	header indicating the number of bytes needed for the
 *	command.
 */
#define	SCSI_RES_MIN	(8)

/*
 *	Given a string, resembling one of the element types,
 *	return the SCSI type code for it.
 */
struct {
	int	code ;
	char	*string ;
} etypes[] = {
	TRANSPORT,	"transport",
	SLOT,		"slot",
	DRIVE,		"drive",
	PORT,		"port",
} ;

convert_type(char *etype)
{
	register i ;

	/*
	 *	For each entry in the array.
	 */
	for(i = 0; i < sizeof(etypes)/sizeof(etypes[0]); i++)
		/*
		 *	Do a case insensitive comparison, allowing
		 *	abbreviations.  Return as soon as a match is
		 *	found.  Return -1 if one isn't found.
		 */
#ifdef	vms
		if( strncmp(etypes[i].string, etype, strlen(etype)) == 0 )
#else
		if( strncasecmp(etypes[i].string, etype, strlen(etype)) == 0 )
#endif
			return etypes[i].code ;

	return 0 ;
}

main(int argc, char *argv[])
{
	int		status ;		/* return status */
	int		type ;			/* Element type */
	int		start ;			/* First element */
	int		count ;			/* Number of elements */
	int		bytes ;			/* Bytes of data */
	char		*robot ;		/* Robot to open */
	robot_info_t	robot_info ;		/* Robot data */
	dev_status_t	dev_status ;		/* Device status */
	unsigned char	data[SCSI_RES_MIN] ;	/* minimum data */
	char		log_info[MRD_MAX_LOG_STRING+1] ;

	/*
	 *	Check that there are enough arguments.
	 */
	if( argc < 5 ) {
		printf("usage: %s robot type start count\n", argv[0]) ;
		exit(1) ;
	}
	else {
		robot = argv[1] ;
		type  = convert_type(argv[2]) ;
		start = atoi(argv[3]) ;
		count = atoi(argv[4]) ;
	}

	/*
	 *	Initialize the channel field of the robot_info, so
	 *	mrd_startup(3mrd) will actually open the robot.
	 */
	robot_info.channel = BAD_CHANNEL ;

	status = mrd_startup(robot, &robot_info, log_info) ;

	if( status != MRD_STATUS_SUCCESS ) {
		printf("Startup failed: %s: %s.\n", mrd_strstatus(status),
			log_info[0] ? log_info : "none") ;

		exit(1) ;
	}

	switch( type ) {
	case SLOT:
		start += robot_info.slot_start ;
		break ;
	case PORT:
		start += robot_info.port_start ;
		break ;
	case TRANSPORT:
		start += robot_info.transport_start ;
		break ;
	case DRIVE:
		start += robot_info.device_start ;
		break ;
	}

	/*
	 *	Read Element Status commands rarely fail, they just
	 *	succeed, but return no data.  Clear all the fields
	 *	so we'll have an easier time seeing if any data was
	 *	returned.
	 */
	memset((void *)data, 0, SCSI_RES_MIN) ;

	status = mrd_read_element_status(&robot_info, type, start, count,
			data, SCSI_RES_MIN, &dev_status) ;

	/*
	 *	But sometimes they do fail.
	 */
	if( status != MRD_STATUS_SUCCESS ) {
		printf("Read Element Status failed on %s: %s.\n", robot,
			mrd_strstatus(status)) ;

		exit(1) ;
	}

	/*
	 *	The SCSI header for element status data has two bytes
	 *	for the first element address...
	 */
	start = (data[RES_FIRST_MSB] << 8) | data[RES_FIRST_LSB] ;

	/*
	 *	Two bytes for the number of elements reports...
	 */
	count = (data[RES_COUNT_MSB] << 8) | data[RES_COUNT_LSB] ;

	/*
	 *	And three bytes for the amount of data needed.
	 */
	bytes = (data[RES_REPORT_MSB] << 16) | (data[RES_REPORT_ISB] << 8) | 
		 data[RES_REPORT_LSB] ;

	printf("First Element: %d, Count: %d, Bytes needed: %d\n",
		start, count, bytes) ;

	(void)mrd_shutdown(&robot_info) ;

	return 0 ;
}