TopK

Returns maximum K values of an array.

Syntax

IppStatus ippsTopK_32f(const Ipp32f pSrc, Ipp64s srcIndex, Ipp64s srcLen, Ipp32f* pDstValue, Ipp64s* pDstIndex, Ipp64s dstLen, IppTopKMode hint, Ipp8u* pBuffer);

IppStatus ippsTopK_32s(const Ipp32s pSrc, Ipp64s srcIndex, Ipp64s srcLen, Ipp32s* pDstValue, Ipp64s* pDstIndex, Ipp64s dstLen, IppTopKMode hint, Ipp8u* pBuffer);

Include Files

ipps.h

Domain Dependencies

Headers: ippcore.h, ippvm.h

Libraries: ippcore.lib, ippvm.lib

Parameters

pSrc	Pointer to the source vector.
srcIndex	Index of the pSrc[0] element, index of pSrc[n] is equal to `srcIndex+n`.
srcLen	Number of elements in the source vector.
pDstValue	Maximum values found by the function.
dstIndex	Indexes of maximum values.
dstLen	Number of `K` values to be returned, the function returns `min(K, dstLen)` elements.
hint	Parameter to choose the optimization that is most suitable for the `srcLen+dstlen(K)` combination, supported values: ippTopKAuto/ ippTopKDirect/ ippTopKRadix.
pBuffer	Pointer to the work buffer.

Description

This function searches for dstLen maximum values and their indexes in an input vector. The function is designed to process large input vectors by small blocks, it takes into account results of previous blocks processing getting maximum values of pSrc and pDstValue and then combining the final results into pDstValue.

The srcIndex parameter stores the index of the first element pSrc[0] of each new block, thus supporting the continuous numbering of elements. Before calling the ippsTopK function, compute the required buffer size and initialize pDstValue and pDstIndex using the ippsTopKGetBufferSize and ippsTopKInit_32s functions, respectively.

Return Values

ippStsNoErr	Indicates no error.
ippStsNullPtrErr	Indicates an error when at least one of the pointers is NULL.
ippStsSizeErr	Indicates an error when at least one of the srcLen or dstLen values is less than, or equal to zero.
ippStsBadArgErr	Indicates an error when the hint value is not supported.