Intel MMX Technology Support in Visual C++

The information in this article applies to:

- The Microsoft C/C++ Compiler (CL.EXE), included with:

  Microsoft Visual C++, 32-bit Edition, versions 4.1, 4.2, 5.0
  on the following platform: x86

SUMMARY

Beginning with Microsoft Visual C++ version 4.1 for Intel, support of Intel's MMX Technology is available in the Microsoft C/C++ compiler CL.EXE. This capability is enabled with the /GM compiler switch and is only available within inline assembly.

MORE INFORMATION

Microsoft provides MMX Technology compiler support but does not provide programming support. For this information, view Intel Corporation's web page at:

   http://www.intel.com/pc-supp/multimed/mmx

Included here is a trivial sample using the PAND instruction with the two MMX registers MM0 and MM1. This sample does nothing programmatically useful but is meant simply to illustrate MMX Technology support. For information on MMX programming, refer to Intel documentation.

Note that running a program that uses MMX instructions on a standard Pentium (P5) processor will generate an invalid instruction exception. This is the expected behavior because the P5C processor is required. Again, for more information, refer to the Intel web site.

Sample Code

/* Compile options needed: /GM
*/

void main(void)

    _asm {
        pand mm0, mm1  ; packed and
        emms           ; empty MMX state
    }