103 lines
4.1 KiB
C
103 lines
4.1 KiB
C
/*-----------------------------------------------------------------------------
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* Copyright (C) 2010-2014 ARM Limited. All rights reserved.
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*
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* $Date: 19. March 2015
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* $Revision: V.1.4.5
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*
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* Project: CMSIS DSP Library
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* Title: arm_biquad_cascade_df2T_init_f64.c
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*
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* Description: Initialization function for the floating-point transposed
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* direct form II Biquad cascade filter.
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*
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* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* - Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* - Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* - Neither the name of ARM LIMITED nor the names of its contributors
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* may be used to endorse or promote products derived from this
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* software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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* ---------------------------------------------------------------------------*/
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#include "arm_math.h"
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/**
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* @ingroup groupFilters
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*/
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/**
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* @addtogroup BiquadCascadeDF2T
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* @{
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*/
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/**
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* @brief Initialization function for the floating-point transposed direct form II Biquad cascade filter.
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* @param[in,out] *S points to an instance of the filter data structure.
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* @param[in] numStages number of 2nd order stages in the filter.
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* @param[in] *pCoeffs points to the filter coefficients.
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* @param[in] *pState points to the state buffer.
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* @return none
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*
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* <b>Coefficient and State Ordering:</b>
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* \par
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* The coefficients are stored in the array <code>pCoeffs</code> in the following order:
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* <pre>
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* {b10, b11, b12, a11, a12, b20, b21, b22, a21, a22, ...}
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* </pre>
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*
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* \par
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* where <code>b1x</code> and <code>a1x</code> are the coefficients for the first stage,
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* <code>b2x</code> and <code>a2x</code> are the coefficients for the second stage,
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* and so on. The <code>pCoeffs</code> array contains a total of <code>5*numStages</code> values.
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*
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* \par
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* The <code>pState</code> is a pointer to state array.
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* Each Biquad stage has 2 state variables <code>d1,</code> and <code>d2</code>.
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* The 2 state variables for stage 1 are first, then the 2 state variables for stage 2, and so on.
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* The state array has a total length of <code>2*numStages</code> values.
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* The state variables are updated after each block of data is processed; the coefficients are untouched.
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*/
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void arm_biquad_cascade_df2T_init_f64(
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arm_biquad_cascade_df2T_instance_f64 * S,
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uint8_t numStages,
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float64_t * pCoeffs,
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float64_t * pState)
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{
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/* Assign filter stages */
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S->numStages = numStages;
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/* Assign coefficient pointer */
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S->pCoeffs = pCoeffs;
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/* Clear state buffer and size is always 2 * numStages */
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memset(pState, 0, (2u * (uint32_t) numStages) * sizeof(float64_t));
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/* Assign state pointer */
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S->pState = pState;
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}
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/**
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* @} end of BiquadCascadeDF2T group
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*/
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