Determining the Memory Model for Conditional Compilation

ID: Q44386

6.00 6.00a 6.00ax 7.00 | 6.00 6.00a | 1.00 1.50

MS-DOS                 | OS/2       | WINDOWS

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The information in this article applies to:

   The Microsoft C/C++ Compiler (CL.EXE) included with:
    - Microsoft C for MS-DOS, versions 6.0, 6.0a, and 6.0ax
    - Microsoft C for OS/2, versions 6.0, and 6.0a
    - Microsoft C/C++ for MS-DOS, versions 7.0
    - Microsoft Visual C++ for Windows, versions 1.0 and 1.5

SUMMARY

There is a predefined identifier that can be used to allow the preprocessor to determine which memory model has been chosen for the current compilation. The identifier is M_I86?M, where "?" is an identifier for one of the following five memory models:

   S = Small
   M = Medium
   L = Large
   C = Compact
   H = Huge

This identifier can be used with a preprocessor command to produce conditional compilation dependent upon the memory model. An example of its use is shown below.

Sample Code

/* Compile options needed: none
*/ 

/*
 *
 * This example demonstrates how to use the C compiler M_I86?M values.
 * It also shows other various preprocessor components. The memory
 * model is displayed using the message() pragma. If the memory model
 * is not recognized by the program, the compilation terminates using
 * the #error preprocessor directive. The identifier _MEMORY_MODEL_
 * has been chosen arbitrarily, and has no special value to the C
 * compiler.
 *
 */ 

#include <stdio.h>

#if defined (M_I86CM)

    #define _MEMORY_MODEL_ "compact"

#elif defined (M_I86SM)

    #define _MEMORY_MODEL_ "small"

#elif defined (M_I86MM)

    #define _MEMORY_MODEL_ "medium"

#elif defined (M_I86HM)

    #define _MEMORY_MODEL_ "huge"

#elif defined (M_I86LM)

    #define _MEMORY_MODEL_ "large"

#else

    #error "ERROR: unknown memory model!!"
    #define _MEMORY_MODEL_ "**UNKNOWN**"

#endif

#pragma message ("Using the " _MEMORY_MODEL_ " memory model...")

void main(void);

void main(void)

{

   printf("hello, world\n");

}

Additional reference words: kbinf 1.00 1.50 6.00 6.00a 6.00ax 7.00 8.00 8.00c KBCategory: kbtool KBSubcategory: CLIss Keywords : kb16bitonly

Last Reviewed: July 18, 1997