Microsoft KB Archive/154853

= Intel MMX Technology Support in Visual C++ =

Article ID: 154853

Article Last Modified on 7/5/2005

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APPLIES TO


 * Microsoft Visual C++ 4.1 Subscription
 * Microsoft Visual C++ 4.2 Professional Edition
 * Microsoft Visual C++ 5.0 Standard Edition
 * Microsoft Visual C++ 6.0 Service Pack 5

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This article was previously published under Q154853



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.

NOTE: The /GM switch is not necessary in Visual C++ versions 5.0 and 6.0.



MORE INFORMATION
Microsoft provides MMX Technology compiler support but does not provide programming support.

Included here is a trivial sample using the PAND instruction with the two MMX registers MM0 and MM1. This sample just illustrates 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 }  }

Additional query words: Pentium P5C Pro illegal instruction

Keywords: kbcompiler KB154853

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