DOCUMENT:Q129787  23-JUL-2001  [visualc]
TITLE   :HOWTO: Build a Code Resource
PRODUCT :Microsoft C Compiler
PROD/VER:MAC:2.0;
OPER/SYS:
KEYWORDS:kbcode kbHWMAC kbVC kbhowto

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The information in this article applies to:

 - Microsoft Visual C++, Macintosh Cross-Development Addon, version 4.0 
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SUMMARY
=======

You can use Visual C++ to build Code Resources of type CDEF, cdev, INIT, LDEF,
MDEF, WDEF, and XCMD. This article illustrates how.

MORE INFORMATION
================

Applications use the register A5 to point to their global memory and as a base
for intersegment jumps. Stand-alone Code Resources cannot use A5 in this manner.
To use global memory in Visual C++, follow these steps:

1. Locate the entry points for the Code Resource types (CDEF, cdev, INIT, LDEF,
   MDEF, WDEF, and XCMD) at the beginning of the resource. When Visual C++
   compiles a code resource, it locates the global data at the beginning of the
   resource by default. To force the global data to be moved to the end of the
   resource use the code_seg pragma as in this example:

      #pragma code_seg("MAIN$2")

   This forces any declarations that follow to be placed in the second half of
   the MAIN Code Resource. The data is referenced as an offset from the PC
   register, rather than the A5 register.

2. To avoid an intersegment jump, merge the code from two segments together by
   using the Linker's MERGE option. This step is necessary if a Code Resource
   calls into a library such as the C Runtime libraries because a second segment
   is created and the call to the function becomes an intersegment jump.

   For example, if the C Runtime library is being merged with and INIT titled
   MAIN, add the following line to the Link:Project Options found in the Project
   Settings dialog:

   " MERGE:CRTSTRING?=MAIN " (without the quotation marks) Replace the question
   mark (?) with an ASCII character 1. The CRTSTRING? segment is titled CRTSTRIN
   by the Linker, so the name of the segments in the target application cannot
   be used. To determine the name of any segments generated by Visual C++, build
   the Code Resource as a 'CODE' resource first. Then check the .MAP file for
   the correct spelling of the segment.

   If a Code Resource is built without merging the segments the following Linker
   error is generated: error LNK1574: A5 reference to SomeFunction invalid in
   standalone code

Sample Code
-----------

Here is a sample INIT Code Resource including code and project settings:

The C/C++ Project Options:

   /nologo /W3 /YX /Oi /D "_WINDOWS" /D "_MAC" /D "_68K_" /D "NDEBUG" /D
   "_MBCS"
    /FR"MacRel/" /Fp"MacRel/CodRes.pch" /Fo"MacRel/" /c

The Link Project Options:

   libcs.lib /NOLOGO /MAC:bundle /MAC:type="rsrc" /MAC:creator="RSED"
    /PDB:"MacRel/CodRes.pdb" /MAP:"MacRel/SACODE.map" /DEBUG /MACHINE:M68K
    /NODEFAULTLIB:"swapd.lib" /NODEFAULTLIB /OUT:"MacRel/CODRES.exe"
   /entry:main
    /section:MAIN,,resource="INIT"@99 /MERGE:CRTSTRING =MAIN

The code for this sample:

      #include <string.h>
      #include <macos\osutils.h>
      #pragma code_seg("MAIN$2")
      char _declspec(allocate("_CODE")) java[10] =" Help Me!";
      #pragma code_seg("MAIN$1")
      void main(void)
         {
         char   bob[10];
         bob[0]=0;
         strcpy(bob,java);
         DebugStr(_c2pstr(bob));
         }

This code creates an INIT with a resource ID of 99. There will also be resources
of DATA, CODE, and MSCV. They are not needed for this Code Resource to function.

Additional query words:

======================================================================
Keywords          : kbcode kbHWMAC kbVC kbhowto 
Technology        : kbVCsearch kbHWMAC kbOSMAC kbAudDeveloper kbVCXDev400Mac
Version           : MAC:2.0;
Issue type        : kbhowto

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