Include Files

Description

This function sets the processor-specific code of the Intel IPP library according to the processor features specified in

cpuFeatures

. You can use the following predefined sets of features (the

FM

suffix below means

feature mask

):

32-bit code:

#define PX_FM ( ippCPUID_MMX | ippCPUID_SSE )
#define W7_FM ( PX_FM | ippCPUID_SSE2 )
#define V8_FM ( W7_FM | ippCPUID_SSE3 | ippCPUID_SSSE3 )
#define S8_FM ( V8_FM | ippCPUID_MOVBE )
#define P8_FM ( V8_FM | ippCPUID_SSE41 | ippCPUID_SSE42 | ippCPUID_AES | ippCPUID_CLMUL | ippCPUID_SHA )
#define G9_FM ( P8_FM | ippCPUID_AVX | ippAVX_ENABLEDBYOS | ippCPUID_RDRAND | ippCPUID_F16C )
#define H9_FM ( G9_FM | ippCPUID_MOVBE | ippCPUID_AVX2 | ippCPUID_ADCOX | ippCPUID_RDSEED | ippCPUID_PREFETCHW )

64-bit code:

#define PX_FM ( ippCPUID_MMX | ippCPUID_SSE | ippCPUID_SSE2 )
#define M7_FM ( PX_FM | ippCPUID_SSE3 )
#define U8_FM ( M7_FM | ippCPUID_SSSE3 )
#define N8_FM ( U8_FM | ippCPUID_MOVBE )
#define Y8_FM ( U8_FM | ippCPUID_SSE41 | ippCPUID_SSE42 | ippCPUID_AES | ippCPUID_CLMUL | ippCPUID_SHA )
#define E9_FM ( Y8_FM | ippCPUID_AVX | ippAVX_ENABLEDBYOS | ippCPUID_RDRAND | ippCPUID_F16C )
#define L9_FM ( E9_FM | ippCPUID_MOVBE | ippCPUID_AVX2 | ippCPUID_ADCOX | ippCPUID_RDSEED | ippCPUID_PREFETCHW )
#define K0_FM ( L9_FM | ippCPUID_AVX512F )

Intel IPP library supports two internal sets of CPU features:

Real CPU features
: the features that are supported by the CPU at which the library is executed. These features are read-only and can be obtained with the
ippGetCpuFeatures
function.
Enabled features
: the features that are enabled externally to Intel IPP by the application. These features are read-write and can be obtained with ippGetEnabledCpuFeatures
and set with
ippSetCpuFeatures
.

The

ippSetCpuFeatures

function provides additional flexibility in measuring performance improvements reached by using specific CPU features. For example, the call of the

ippInit()

(or the first call of any Intel IPP function for the library version starting with 9.0) function in an application running on the 4th Generation Intel® Core™ i7 processor with 64-bit OS installed dispatches the L9 code version optimized for Intel® Advanced Vector Extensions 2 (Intel® AVX2) with several other features like fast 16-bit floating point support, Intel® AES New Instructions (Intel® AES-NI), PCLMULQDQ new instructions support.

To check performance improvement for all Intel IPP functionality reached by using Intel® AVX2, you can run a benchmark for the currently dispatched version of code and then compare performance with the Intel® Advanced Vector Extensions (Intel® AVX) version of code with Intel® AVX2 disabled. To disable Intel AVX2, call

ippSetCpuFeatures(E9_FM)

. To enable Intel AVX2 back, call

ippSetCpuFeatures( L9_FM )

. Thus, you can use the

ippSetCpuFeatures

function to dispatch any version of Intel IPP code and enable/disable specific CPU features. If you are not well familiar with the features of your CPU, use the

ippInit()

function (or auto-initialization mechanism available starting with Intel IPP 9.0) for the default library behavior.