Developer Reference

  • 2020
  • 07/15/2020
  • Public Content
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 2015-2020 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:

Product and Performance Information

1

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Notice revision #20110804