Intel® Integrated Performance Primitives Developer Guide and Reference

ID 790148
Date 11/07/2023
Public

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Document Table of Contents

FIRGenBandpass

Computes bandpass FIR filter coefficients.

Syntax

IppStatus ippsFIRGenBandpass_64f(Ipp64f rLowFreq, Ipp64f rHighFreq, Ipp64f* pTaps, int tapsLen, IppWinType winType, IppBool doNormal, Ipp8u* pBuffer);

Include Files

ipps.h

Domain Dependencies

Headers: ippcore.h, ippvm.h

Libraries: ippcore.lib, ippvm.lib

Parameters

rLowFreq

Normalized low cutoff frequency, must be in the range (0, 0.5) and less than rHighFreq.

rHighFreq

Normalized high cutoff frequency, must be in the range (0, 0.5) and greater than rLowFreq.

pTaps

Pointer to the array where computed tap values are stored. The number of elements in the array is tapsLen.

tapsLen

Number of elements in the array containing the tap values; should be equal or greater than 5.

winType

Specifies what type of window is used in computations. The winType must have one of the following values:

ippWinBartlett Bartlett window;

ippWinBlackman Blackman window;

ippWinHamming Hamming window;

ippWinHann Hann window.

doNormal

Specifies normalized or non-normalized sequence of the filter coefficients is computed. The doNormal must have one of the following values:

ippTrue The function computes normalized sequence of coefficients.

ippFalse The function computes non-normalized sequence of coefficients.

pBuffer

Pointer to the buffer for internal calculations. To get the size of the buffer, use the ippsFIRGenGetBufferSize function.

Description

This function computes tapsLen coefficients for bandpass FIR filter with the cutoff frequencies rLowFreq and rHighFreq by windowing the ideal infinite filter coefficients. The parameter winType specifies the type of the window. For more information on window types used by the function, see Windowing Functions. The computed coefficients are stored in the array pTaps.

Return Values

ippStsNoErr

Indicates no error.

ippStsNullPtrErr

Indicates an error when the pTaps pointer is NULL.

ippStsSizeErr

Indicates an error when the tapsLen is less than 5, or rLowFreq is greater than or equal to rHighFreq, or one of the frequency parameters rLowFreq and rHighFreq is out of the range.

Example

/*******************************************************************************
* Copyright 2015 Intel Corporation.
*
*
* This software and the related documents are Intel copyrighted materials, and your use of them is governed by
* the express license under which they were provided to you ('License'). Unless the License provides otherwise,
* you may not use, modify, copy, publish, distribute, disclose or transmit this software or the related
* documents without Intel's prior written permission.
* This software and the related documents are provided as is, with no express or implied warranties, other than
* those that are expressly stated in the License.
*******************************************************************************/

#include <stdio.h>
#include "ipp.h"

/* Next two defines are created to simplify code reading and understanding */
#define EXIT_MAIN exitLine:                                  /* Label for Exit */
#define check_sts(st) if((st) != ippStsNoErr) goto exitLine; /* Go to Exit if Intel(R) Integrated Primitives (Intel(R) IPP) function returned status different from ippStsNoErr */

/* Results of ippMalloc() are not validated because Intel(R) IPP functions perform bad arguments check and will return an appropriate status  */

int main()
{
    int len = 512;
    Ipp64f pDst[512];
    Ipp64f magn = 4095;
    Ipp64f rLowFreq = 0.2;
    Ipp64f rHighFreq = 0.3;
    int tapslen = 27;
    int numIters = 512;
    IppsFIRSpec_64f* pSpec = NULL;
    IppStatus status = ippStsNoErr;
    int i = 0, bufSize = 0, specSize = 0;
    Ipp8u* pBuffer = NULL;
    IppAlgType algType = ippAlgDirect;
    Ipp64f*  pDlySrc = NULL;
    Ipp64f*  pDlyDst = NULL;

    Ipp64f* FIRDst = ippsMalloc_64f(numIters * sizeof(Ipp64f));
    Ipp64f* taps = ippsMalloc_64f(tapslen*sizeof(Ipp64f));

    pDlySrc = ippsMalloc_64f(tapslen*sizeof(Ipp64f));
    check_sts( status = ippsZero_64f(pDlySrc, tapslen) )

    /* generate source vector */
    check_sts( status = ippsVectorJaehne_64f(pDst, len, magn) ) /* create a Jaehne vector */
    printf("\nSource vector\n");
    for (i = 0; i < 32; i++) printf("%f,", pDst[i]);

    /* computes tapsLen coefficients for lowpass FIR filter */
    check_sts( status = ippsFIRGenGetBufferSize(tapslen, &bufSize) )

    pBuffer     = ippsMalloc_8u(bufSize);

    check_sts( status = ippsFIRGenBandpass_64f(rLowFreq, rHighFreq, taps, tapslen, ippWinBartlett, ippTrue, pBuffer) )

    printf("\nGenerated taps:\n");
    for (i = 0; i < tapslen; i++) printf("%f,", taps[i]);

    check_sts( status = ippsFIRSRGetSize(tapslen, ipp64f, &specSize, &bufSize) )
    pSpec       = (IppsFIRSpec_64f*)ippsMalloc_8u(specSize);
    pBuffer     =                     ippsMalloc_8u(bufSize);

    check_sts( status = ippsFIRSRInit_64f(taps, tapslen, algType, pSpec) )

    /*filter an input vector*/
    check_sts( status = ippsFIRSR_64f(pDst, FIRDst, numIters, pSpec, pDlySrc, pDlyDst, pBuffer) )

    printf("\nAfter LowPass filter\n");
    for (i = 0; i < 32; i++) printf("%f,", FIRDst[i]);
    printf("\n\n");

EXIT_MAIN
    ippsFree(FIRDst);
    ippsFree(taps);
    printf("Exit status %d (%s)\n", (int)status, ippGetStatusString(status));
    return 0;
}


Result: