FIRStreamGetStateSize, FIRMRStreamGetStateSize

Calculates the size of the stream FIR filter state structure.

Syntax

Case 1: Single-rate filter

IppStatus ippsFIRStreamGetStateSize_16s(int tapsLen, int* pBufferSize);

IppStatus ippsFIRStreamGetStateSize_32f(int tapsLen, int* pBufferSize);

Case 2: Multi-rate filter

IppStatus ippsFIRMRStreamGetStateSize_16s(int tapsLen, int upFactor, int downFactor, int* pBufferSize);

IppStatus ippsFIRMRStreamGetStateSize_32f(int tapsLen, int upFactor, int downFactor, int* pBufferSize);

Parameters

upFactor	Upsampling factor for the multi-rate filter.
downFactor	Downsampling factor for the multi-rate filter.
pBufferSize	Pointer to the computed value of the buffer size.

Description

The functions ippsFIRStreamGetStateSize and ippsFIRMRStreamGetStateSize are declared in the ipps.h file. These functions compute the size of the external buffer for a single-rate or multi-rate stream FIR filter state, tapsLen respectively, and store the result in pBufferSize.

To calculate the size of a buffer for the single-rate filter state, the filter state number of taps only need be specified. To calculate the size of a buffer for the multi-rate FIR filter state, the number of taps tapsLen and upsampling/downsampling parameters upFactor and downFactor must be specified.

The parameter upFactor is the factor by which the filtered signal is internally upsampled (see description of the function ippsSampleUp for more details). That is, upFactor-1 zeros are inserted between each sample of the input signal.

The parameter downFactor is the factor by which the FIR response obtained by filtering an upsampled input signal, is internally downsampled (see description of the function ippsSampleDown for more details). That is, downFactor-1 output samples are discarded from each downFactor-length output block of the upsampled filter response.

Return Values

ippStsNoErr	Indicates no error.
ippStsNullPtrErr	Indicates an error if the pBufferSize pointer is NULL.
ippStsFIRLenErr	IIndicates an error if tapsLen is less than or equal to 0.
ippStsFIRMRFactorErr	Indicates an error if upFactor (downFactor) is less than or equal to 0.