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CPUID Sample: Determines CPU Capabilities 

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The CPUID sample provides a routine that uses the CPUID instruction to determine the capabilities of the CPU being run.

The sample provides the function int _cpuid(_p_info *pinfo), which returns data about the CPU. The int return value is a bitmask of flags for major processor features. The bits that might be set are:

  • #define _CPU_FEATURE_MMX 0x0001

  • #define _CPU_FEATURE_SSE 0x0002

  • #define _CPU_FEATURE_SSE2 0x0004

  • #define _CPU_FEATURE_3DNOW 0x0008

Security noteSecurity Note

This sample code is provided to illustrate a concept and should not be used in applications or Web sites, as it may not illustrate the safest coding practices. Microsoft assumes no liability for incidental or consequential damages should the sample code be used for purposes other than as intended.

Building and Running the Sample

NoteNote

If you are running Visual C++ Express Edition, you might need to install the Platform SDK before running this sample. For information on how to do this, see How to: Use Visual C++ Express Edition with the Microsoft Platform SDK.

To build and run this sample

  1. Open the solution cpuid.sln.

  2. From the Build menu, click Build.

  3. From the Debug menu, select Start Without Debugging.

Example Program Output

The sample includes a test.cpp file that trivially calls _cpuid and outputs the values in the resulting _p_info struct. For example, on a Pentium III computer that supports MMX and SSE, the program output would look something like this:

C:\work\cpuid>test
v_name:         GenuineIntel
model:          INTEL Pentium-III
family:         6
model:          8
stepping:       3
feature:        00000003
        yes     _CPU_FEATURE_MMX
        yes     _CPU_FEATURE_SSE
        no      _CPU_FEATURE_SSE2
        no      _CPU_FEATURE_3DNOW
os_support:     00000003
        yes     _CPU_FEATURE_MMX
        yes     _CPU_FEATURE_SSE
        no      _CPU_FEATURE_SSE2
        no      _CPU_FEATURE_3DNOW
checks:         0000000f

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