/*                                  DoReadBlockZero.c                           */

/*

 * DoReadBlockZero.c

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

 * Read the first block off of the SCSI Device.

 */

#include "SCSISimpleSample.h"

/*

 * Read block zero from the indicated device..

 */

void

DoReadBlockZero(

        DeviceIdent             scsiDevice              /* -> Bus/target/LUN    */

    )

{

        ScsiCmdBlock                    scsiCmdBlock;

        unsigned long                   transferLength;

#define SCB (scsiCmdBlock)

        ShowSCSIBusID(scsiDevice, "\pRead Block Zero");

#define kLogicalBlockLength 512

#define kNumberOfBlocks     1

        /*

         * Note: this is slightly incorrect - it presumes that the device logical

         * block length is 512 bytes. The correct algorithme would have first

         * issued a Drive Capacity command to get the actual logical block length.

         * This would be stored in a per-drive information record.

         */

        transferLength = kNumberOfBlocks * kLogicalBlockLength;

        CLEAR(SCB);

        SCB.scsiDevice = scsiDevice;

        /*

         * The 6-byte read command can read up to 128 blocks of data (1-127

         * reads that number of blocks, while zero reads 128 blocks). For more

         * flexibility, you should use the 10-byte Read command.

         */

        SCB.command.scsi6.opcode = kScsiCmdRead6;

        SCB.command.scsi6.len = transferLength / kLogicalBlockLength;

        SCB.bufferPtr = NewPtrClear(transferLength);

        if (SCB.bufferPtr == NULL)

            LOG("\pNo Memory for ReadBlockZero data buffer");

        else {

            SCB.transferSize = transferLength;

            SCB.transferQuantum = kLogicalBlockLength;

            DoSCSICommandWithSense(&scsiCmdBlock, TRUE, TRUE);

            if (SCB.status == noErr)

                DisplayLogString(gLogListHandle, "\pRead was successful");

            /*

             * Here's where we can look at the data.

             */

            DisposePtr(SCB.bufferPtr);

        }

#undef SCB

}