// Patching a trap

// An example of patching the GetNewDialog() trap. This patch

// does nothing but call the real GetNewDialog() trap.

#include

// Assumes inclusion of

#define _GetNewDialog 0xA97C

/* save regs not p reserved by THINK C */

#define SaveRegs()

asm { movem.l a0-a1/d0-d2,-(sp) }

/* restore regs not p reserved by THINK C */

#define RestoreRegs()

asm { movem.l (sp)+,a0-a1/d0-d2 }

typedef pascal DialogPtr (*GetNewDialogProcPtr) ( short, Ptr, WindowPtr);

GetNewDialogProcPtr gOldGetNewDialog;

extern void GetNewDialogJmp(void);

static pascal DialogPtr GetNewDialogHook( short dlogID, Ptr storage,

{

SaveRegs();

SetUpA4();

dlogPtr = gOldGetNewDialog(dlogID, storage, behind);

RestoreA4();

RestoreRegs();

return dlogPtr;

}

static void InstallPatch(void)

{

gOldGetNewDialog =

(GetNewDialogProcPtr)NGetTrapAddress(_GetNewDialog);

NSetTrapAddress((long)GetNewDialogHook,

_GetNewDialog);

}