/**************************************************************************************************
 *					XFunctionsMain.c
 *
 *			Written By: Brian Powell
 *			(c) 1991, All Rights Reserved.
 *			
 *			This contains the main function for the external modules.  Whenever Imagic makes a
 *			call to an external function, this is the function that gets called.  This then 
 *			interprets the type of call that Imagic made and calls the correct function from there.
 *
 *************************************************************************************************/

/* Include these files.
 */
#include "XFunctionNumbers.h"
#include "XFunctions.h"

ProcPtr 		(*(**functions)());

/* We don't want the file SetUpA4.h at the top of the program because this file generates code
 * that we don't want put into our program.  Therefore, it needs to go down here so that it will
 * not stick code into our file. */
 
#include <SetUpA4.h>

pascal OSErr main (message, Functions, parameters)
	int message;
	ProcPtr (*(**Functions)());
	InitStruct *parameters;
{
	OSErr Error = noErr;

	/* Set up register A4 so that we can use global variables correctly.
	 * See the Think C Users Manual, page 87 for more details.
	 * (The 1989 version of the Think C 4.0 manual).  
	 * ---> Addendum <---
	 * For Think C 5.0, see page 119 of the Think C 5.0 User's Manual. 
	 */
	RememberA0();
	SetUpA4();

	functions = Functions;
	switch (message) {
		case INITIALIZE:
			Error=Initialize(parameters);
			parameters->Version = EXTERNAL_FUNCTION_LIBRARY_VERSION_NUM; 
			break;
		case MENU_ITEM:
			Error=ExecuteMenu();
			break;
		case SHUT_DOWN:
			Error=Exit();
			break;
	}

	/* Restore register A4 to it's original value.
	 */
	RestoreA4();

	/* Return the error code (if any).
	 */
	return Error;
}