/*

    File:       SerialDriverArbitration.c

    Contains:   This is an example of how to correctly arbitrate the serial ports.  It's taken

                from tech note DV 11 - Opening the Serial Ports.

    Written by: Brian Bechtel.  Updated by Lenae Rowland.   

    Copyright:  Copyright © 1993-1999 by Apple Computer, Inc., All Rights Reserved.

                You may incorporate this Apple sample source code into your program(s) without

                restriction. This Apple sample source code has been provided "AS IS" and the

                responsibility for its operation is yours. You are not permitted to redistribute

                this Apple sample source code as "Apple sample source code" after having made

                changes. If you're going to re-distribute the source, we require that you make

                it clear in the source that the code was descended from Apple sample source

                code, but that you've made changes.

    Change History (most recent first):

                7/7/1999    Karl Groethe    Updated for Metrowerks Codewarror Pro 2.1

                12/5/96     Lenae Rowland   Updated

                10/7/93     Brian Bechtel   Created

*/

// Comments beginning with -LR- are changes made to

// accomodate new Universal Headers

// -LR-  Changed GestaltEqu.h to Gestalt.h

#include <Gestalt.h>

// -LR-  Changed SysEqu.h to LowMem.h

#include <LowMem.h>

#include <Devices.h>

#include <stdio.h>

#include <StringCompare.h>

#define gestaltArbitorAttr              'arb '

#define gestaltSerialArbitrationExists  0

#define dRAMBased       0x0040

#define dOpened         0x0020

// This is a list of drivers used for test purposes in this code

Str255  gDriverNames[] = 

    {

        "\p.NoDrvr",    // non-existant driver

        "\p.AOut",      // serial port A output

        "\p.BIn",       // serial port B input 

        "\p.BOut",      // serial port B output

        "\p.AppleCD",   // CD-ROM output

        "\p.MPP",       // AppleTalk

        "\p.ASYC00",    // a hard disk driver

        "\p.AIn"        // serial port A input

    };

Boolean SerialArbitrationExists(void);

Boolean DriverIsOpen(StringPtr driverName);

Boolean CRMInstalled(void);

// Test Gestalt to see if serial arbitration exists

// on this machine

Boolean SerialArbitrationExists(void)

{

    long    response;

    OSErr   err;

    err = Gestalt(gestaltArbitorAttr, &response);

    if (err)

        return false;

    return ((response >> gestaltSerialArbitrationExists) & 1);

}

Boolean DriverIsOpen(StringPtr driverName)

{

    Boolean canOpen = false;

    Boolean match = false;

    short   index = 0;

    short   count;

    DCtlHandle  dceHandle;

    StringPtr   namePtr;

    DCtlHandle  *theUnitTable;

    // -LR- changed this to a low memory accessor function

    count = LMGetUnitTableEntryCount();

    // -LR- changed this to a low memory accessor function

    theUnitTable = (DCtlHandle*)LMGetUTableBase();

    while ( !match && (index < count)) {

        // get handle to a device control entry

        dceHandle = theUnitTable[index];

        if (dceHandle) {

            if (!( (**dceHandle).dCtlFlags & dRAMBased) )

                // RAM based drivers have a handle to their driver

                namePtr = (StringPtr)(**dceHandle).dCtlDriver+18;

            else

                // ROM based drivers have a pointer to their driver

                namePtr = (StringPtr) (*(DCtlPtr)dceHandle).dCtlDriver+18;

            // not case sensitive, diacritical marks count

            if (RelString(driverName, namePtr, false, true) == 0) {

                match = true;

                canOpen = ((**dceHandle).dCtlFlags & dOpened) ? true : false;

            }

        }

        index++;

    }

    return canOpen;

}

Boolean CRMInstalled(void)

{

    long    response;

    OSErr   err;

    err = Gestalt(gestaltCRMAttr, &response);

    if (err)

        return false;

    return ((response >> gestaltCRMPresent) & 1);

}

#define TEST_CALL

void main()

{

    OSErr   err = noErr;

    SInt16  i;

    SInt16  numDrivers;

    printf("Test of serial port stuff\n");

    if (CRMInstalled())

        printf("Communication Resource Manager is installed.\n");

    if (SerialArbitrationExists())

        printf("Serial Arbitration exists\n");

#ifdef TEST_CALL

    numDrivers = sizeof(gDriverNames) / sizeof(Str255);

    for (i = 0; i < numDrivers; i++)

        printf("DriverIsOpen(%#s)\treturned %s\n", 

                gDriverNames[i], DriverIsOpen(gDriverNames[i])?"True ":"False");

#endif

#ifdef TEST_OPEN

    SInt16  refNum;

    if (!DriverIsOpen("\p.AIn"))

        err = OpenDriver("\p.AIn", &refNum);

    if (err)

        printf("OpenDriver returned %d\n", err);

    err = CloseDriver(refNum);

    if (err)

        printf("CloseDriver returned %d\n", err);

#endif

}