Topic       : TOS - The Operating System
Author      : 
Version     : tos.hyp (December 19, 2008)
Subject     : Programmieren/Atari
Nodes       : 3010
Index Size  : 93790
HCP-Version : 5
Compiled on : Atari
@charset    : atarist
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@default    : Title
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View Ref-File12.1.9  XCMDs under MagiC Mac                                      TOS

XCMDs are small external code modules for Macintosh applications. As a 
rule these can be created fairly easily with the development tools 
under MacOS (e.g. with Metrowerks' CodeWarrior or Symantec C). As of 
version 1.2.2 MagiC Mac also permits the simple use of such code 
modules by programs that run under MagiC. This greatly simplifies the 
development of programs or drivers that want to use the Macintosh 
functions, as these portions can then be created with a Macintosh 
compiler, rather than having to recreate the interfaces laboriously 
under an Atari development system.

An example of such a XCMD can be found in the 'Demo XCMD' folder of 
the original MagiC Mac documentation. The created module can then just 
be placed in the MagiC Mac XCMDs folder. This folder must lie in the 
same directory as the MagiC Mac application. At the launch of MagiC 
Mac this folder is searched through for files with the filetype 'xCmd' 
and the XCMD resources contained in it loaded and executed. These 
XCMDs can then register themselves with MagiC Mac and so become 
available for MagiC programs.

An application is shown by the Pure-C program in the 'MGMC_API' folder 
of the original MagiC Mac documentation. This shows how easily an 
installed XCMD can be opened and called. The functions offered here by 
the cookie (xcmdMgrPtr) go automatically into the supervisor-mode if 
required and switch to the Mac environment (with callMacContext), and 
also control parameter passing. The call of the XCMD functions in this 
way is therefore permitted only when the Atari-mode is active and if 
the call is not made from an interrupt.

If the XCMD functions are to be called from interrupts or in Mac-mode, 
one can use 'xcmdMgrPtr->getAdr' to get the entry address of the XCMD 
dispatcher and then jump to it directly.

Further information for XCMDs can be found in the source text 'Demo 
XCMD.c' of the original MagiC Mac documentation.