/*

    File:       ReadResource.c

    Contains:   Routines demonstrating how to read resource files without using

                the Resource Manager.

    Written by: Mark Cookson    

    Copyright:  Copyright © 1996-1999 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):

                8/31/1999   Karl Groethe    Updated for Metrowerks Codewarror Pro 2.1

*/

#include "ReadResource.h"

/*  Purpose:        This finds the number of the first resource of chosen

                    type and returns that number, along with any error.

    Side Effects:   None.

*/

/*-----------------------------------------------------------------------*/

        OSErr   MyGetFirstResource      (short refNum,

                                        OSType targetType,

                                        short *targetID)

/*-----------------------------------------------------------------------*/

{

    ResReference    theRes;

    long            dataOffset      = 0,

                    typeOffset      = 0,

                    ResRefSize      = 0,

                    oldPos          = 0;

    short           numResources    = 0;

    OSErr           theErr          = noErr;

    theErr = GetFPos (refNum, &oldPos);     /* Be nice and don't move the file pointer without puting it back */

    if (theErr == noErr) {

        /* Find the location of the first resource of the type we want */

        theErr = MyGetTypesPosition (refNum, targetType, &numResources, &dataOffset, &typeOffset);

    }

    if (theErr == noErr) {

        /* Position the file to the start of the list of resources */

        theErr = SetFPos (refNum, fsFromStart, typeOffset);

    }

    if (theErr == noErr) {

        ResRefSize = sizeof (theRes);

        if (numResources != 0) {

            theErr = FSRead (refNum, &ResRefSize, &theRes);

            *targetID = theRes.ID;

            if (theErr == noErr) {

                theErr = SetFPos (refNum, fsFromStart, oldPos);

            }

        }

        else {

            theErr = resNotFound;

        }

    }

    return theErr;

}

/*  Purpose:        This finds the requested resource and positions the file

                    pointer to point to the first byte of that resource.  It

                    returns the position, inside the resource fork, of that

                    resource, or if unsuccessful the error.

    Side Effects:   None.

*/

/*-----------------------------------------------------------------------*/

        OSErr   MyGetResourcePosition   (short refNum,

                                        OSType targetType,

                                        short targetID,

                                        long *firstByte)

/*-----------------------------------------------------------------------*/

{

    ResReference    theRes;

    long            position        = 0,

                    dataOffset      = 0,

                    typeOffset      = 0,

                    ResRefSize      = 0;

    short           numResources    = 0;

    OSErr           theErr          = noErr;

    Boolean         found           = false;

    /* Find the location of the first resource of the type we want */

    theErr = MyGetTypesPosition (refNum, targetType, &numResources, &dataOffset, &typeOffset);

    if (theErr == noErr) {

        /* Position the file to the start of the list of resources */

        theErr = SetFPos (refNum, fsFromStart, typeOffset);

    }

    if (theErr == noErr) {

        ResRefSize = sizeof (theRes);

    }

    while (theErr == noErr && numResources-- && found == false) {

        theErr = FSRead (refNum, &ResRefSize, &theRes);

        if (theErr == noErr && theRes.ID == targetID) {

            position = (theRes.dataOffset & kDataOffset) + dataOffset;

            *firstByte = position + sizeof (long);

            found = true;

        }

    }

    if (theErr == noErr) {

        theErr = SetFPos (refNum, fsFromStart, *firstByte);

    }

    if (found == false) {

        theErr = resNotFound;

    }

    return theErr;

}

/*  Purpose:        This finds the beginning of the list of requested

                    resource types (i.e. all 'snd ' resources).  It returns

                    the offset to these resources, or if unsuccessful the

                    error.

    Side Effects:   None.

*/

/*-----------------------------------------------------------------------*/

        OSErr   MyGetTypesPosition  (short refNum,

                                    OSType targetType,

                                    short *numResources,

                                    long *dataOffset,

                                    long *firstByteOfTypeList)

/*-----------------------------------------------------------------------*/

{

    ResourceHeader          ResForkHeader;

    ResourceMap             ResMap;

    ResourceTypeListEntry   typeListEntry;

    long                    numTypes        = 0,

                            numBytes        = 0,

                            numBytesToRead  = 0,

                            position        = 0,

                            oldPos          = 0;

    OSErr                   theErr          = noErr;

    Boolean                 found           = false;

    theErr = GetFPos (refNum, &oldPos);     /* Be nice and don't move the file pointer without puting it back */

    if (theErr == noErr) {

        theErr = SetFPos (refNum, fsFromStart, 0);

    }

    if (theErr == noErr) {

        /* Read the resource file header */

        numBytesToRead = sizeof (ResForkHeader);

        theErr = FSRead (refNum, &numBytesToRead, &ResForkHeader);

    }

    if (theErr == noErr) {

        /* Read the resource map */

        theErr = SetFPos (refNum, fsFromStart, ResForkHeader.resMapOffset);

    }

    if (theErr == noErr) {

        numBytesToRead = sizeof (ResMap);

        theErr = FSRead (refNum, &numBytesToRead, &ResMap);

    }

    if (theErr == noErr) {

        /* Find the type list */

        position = ResMap.typesListOffset + ResForkHeader.resMapOffset + 2;

        theErr = SetFPos (refNum, fsFromStart, position);

    }

    if (theErr == noErr) {

        numTypes = ResMap.numTypesInMap + 1;

        position += sizeof (numTypes);

        numBytes = sizeof (typeListEntry);

    }

    while (theErr == noErr && numTypes-- && found == false) {

        theErr = FSRead (refNum, &numBytes, &typeListEntry);

        if (theErr == noErr && typeListEntry.resType == targetType) {

            *firstByteOfTypeList = ResForkHeader.resMapOffset + ResMap.typesListOffset + typeListEntry.referenceOffset;

            *numResources = typeListEntry.numEntries + 1;

            *dataOffset = ResForkHeader.resDataOffset;

            found = true;

        }

    }

    theErr = SetFPos (refNum, fsFromStart, oldPos);

    if (found == false) {

        theErr = resNotFound;

    }

    return theErr;

}