/*                          SCSICheckForDevicePreseent.c                        */

/*

 * SCSICheckForDevicePreseent.c

 * Copyright © 1992-94 Apple Computer Inc. All Rights Reserved.

 *

 * Return TRUE if the indicated device is present on this system. This function

 * only logs unexpected errors..

 */

#include "SCSISimpleSample.h"

Boolean

SCSICheckForDevicePresent(

        DeviceIdent             scsiDevice,

        Boolean                 enableAsynchSCSI

    )

{

        Boolean                     result;

        ScsiCmdBlock                scsiCmdBlock;

        SCSI_Inquiry_Data           inquiry;

#define SCB     (scsiCmdBlock)

#define SENSE   (SCB.sense)

        if (gVerboseDisplay)

            ShowSCSIBusID(scsiDevice, "\pChecking for device presence");

        CLEAR(SCB);

        SCB.scsiDevice = scsiDevice;

        SCB.command.scsi6.opcode = kScsiCmdInquiry;

        SCB.command.scsi6.len = sizeof inquiry;

        SCB.bufferPtr = (Ptr) &inquiry;

        SCB.transferSize = sizeof inquiry;

        SCB.transferQuantum = 1;                        /* Force handshake      */

        /* All other command bytes are zero */

        DoSCSICommandWithSense(&scsiCmdBlock, FALSE, enableAsynchSCSI);

        switch (SCB.status) {

        case noErr:

            if (inquiry.devType == kScsiDevTypeMissing) {

                VERBOSE("\pNo such device");

                result = FALSE;

            }

            else {

                VERBOSE("\pDevice is present");

                result = TRUE;

            }

            break;

        case statusErr:

            /*

             * The target returned Check Condition. We need to look at the sense

             * data, if any, to distinguish between an "offline" but present device,

             * and a non-existant logical unit. Note: some drives return Check

             * Condition, and "no sense error" if we try to access an incorrect

             * logical unit. This might reasonably be remapped as "illegal request.

             */

            if (SCB.requestSenseStatus == noErr

             && (SENSE.errorCode & kScsiSenseInfoMask) != kScsiSenseInfoValid)

                result = 0;

             else {

                switch (SENSE.senseKey) {

                case kScsiSenseIllegalReq:

                    result = FALSE;

                    break;

                default:

                    ShowRequestSense(&scsiCmdBlock);

                    result = TRUE;

                    break;

                }

            }

            break;  

        default:                                /* Strange error        */

            ShowRequestSense(&scsiCmdBlock);

            /* Fall through */

        case scsiDeviceNotThere:

        case scsiSelectTimeout:

        case scsiBusInvalid:

        case scsiTIDInvalid:

        case scCommErr:                         /* No such device       */

        case scsiIdentifyMessageRejected:

            result = FALSE;

            break;

        }

        return (result);

#undef SCB

}