#ifndef PRESERVE68KREGSACTIVEPROC

#define PRESERVE68KREGSACTIVEPROC

//------------------------------------------------------------------------------

//

//  Macintosh Developer Technical Support

//

//  Preserve68KRegsActiveProc PPC library

//

//  File:   Preserve68KRegsActiveProc.h -   C interface

//

//  Copyright © 1996 Apple Computer, Inc.

//  All rights reserved.

//

//  Versions:   1.0     09/04/96    AB  Original design.

//  Versions:   1.0.1   09/05/96    AB  Changed parameter from long to struct, to

//                                      enable passing a refcon to the PPC function.

//              1.1     11/06/96    AB  New version created for send function.

//                                      Fixed a bug where we weren't properly returning the

//                                      error value we got from the real send function.

//                                      Changed name from PPCYieldFrom68KActive

//                                      to Preserve68KRegsActiveProc.

//

//  Components: Preserve68KRegsActiveProc.h

//              Preserve68KRegsActiveProc.xcoff

//

//------------------------------------------------------------------------------

//  

//  purpose     To provide a 68K wrapper function, named Preserve68KRegsActiveProc, 

//              to be installed as an OSAActiveProc. The purpose of this function

//              is to save and restore a group of emulated 68K registers around

//              calls to a PowerPC function, which in turn calls YieldToAnyThread.

//

//              This work-around is necessary because, at the current time, the 

//              PPC Thread Manager doesn't do anything with the emulated 68K registers,

//              and without this work-around, the OSA AppleScript component get totally

//              confused and blows-up.

//

//------------------------------------------------------------------------------

//

//  How do I use this library?

//

//  You will need to add the file Preserve68KRegsActiveProc.xcoff to your project.

//  Through some DTS Magic(TM), this library contains the 68K code for the

//  Preserve68KRegsActiveProc function. This stub function saves the emulated 

//  68K registers, calls the real PPC active function (which contains the yield call)

//  and then restores the emulated registers, passing through any error value

//  returned by the real active function.

//

//  Next, you must write your real active function (in PPC code) that contains a 

//  call to a Thread Manager yield function. See pg 10-95 of Inside Macintosh:

//  Interapplication Communication for information on writing an active function.

//

//  You will need to declare a variable of type RefRec. Its address will be installed

//  as the refCon value in your call to OSASetActiveProc. The RefRec structure will be

//  used to pass the real refCon value and a UPP for the real active function to the 

//  Preserve68KRegsActiveProc function.

//

//  When called, the Preserve68KRegsActiveProc function will then pass along the real

//  refCon value from the RefRec structure, and call the real send function via the

//  UPP passed in the procEntry field of the RefRec.

//

//  The following snippet shows how to:

//   *  create the UPP for the active function

//   *  initialize the RefRec variable's fields

//   *  install Preserve68KRegsActiveProc as the send function.

//

//      OSAActiveUPP    myOSAActiveUPP;

//      RefRec          myRefRec;

//      

//      myOSAActiveUPP = NewOSAActiveProc( myPPCActiveProcWithYield );

//      myRefRec.procEntry = myOSAActiveUPP;

//      myRefRec.refCon = nil;

//      

//      err = OSASetActiveProc( scriptingComponent, &Preserve68KRegsActiveProc, (long)&myRefRec);

//

//------------------------------------------------------------------------------

//  parameter type for variable passed in refCon field in the call to OSASetActiveProc

struct RefRec {

    UniversalProcPtr    procEntry;

    long                refCon;

};

typedef struct RefRec RefRec;

//  entry point for the 68K emulated register preserving code

extern  RoutineDescriptor   Preserve68KRegsActiveProc;

#endif// PRESERVE68KREGSACTIVEPROC