tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/FilteringFunctions/arm_biquad_cascade_df2T_init_f32.c

   1 /*-----------------------------------------------------------------------------
   2 * Copyright (C) 2010-2013 ARM Limited. All rights reserved.
   3 *
   4 * $Date:        17. January 2013
   5 * $Revision:    V1.4.1
   6 *
   7 * Project:          CMSIS DSP Library
   8 * Title:        arm_biquad_cascade_df2T_init_f32.c
   9 *
  10 * Description:  Initialization function for the floating-point transposed
  11 *               direct form II Biquad cascade filter.
  12 *
  13 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
  14 *
  15 * Redistribution and use in source and binary forms, with or without
  16 * modification, are permitted provided that the following conditions
  17 * are met:
  18 *   - Redistributions of source code must retain the above copyright
  19 *     notice, this list of conditions and the following disclaimer.
  20 *   - Redistributions in binary form must reproduce the above copyright
  21 *     notice, this list of conditions and the following disclaimer in
  22 *     the documentation and/or other materials provided with the
  23 *     distribution.
  24 *   - Neither the name of ARM LIMITED nor the names of its contributors
  25 *     may be used to endorse or promote products derived from this
  26 *     software without specific prior written permission.
  27 *
  28 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  29 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  30 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  31 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  32 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  33 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  34 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  35 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  36 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  37 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  38 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  39 * POSSIBILITY OF SUCH DAMAGE.
  40 * ---------------------------------------------------------------------------*/
  41
  42 #include "arm_math.h"
  43
  44 /**
  45  * @ingroup groupFilters
  46  */
  47
  48 /**
  49  * @addtogroup BiquadCascadeDF2T
  50  * @{
  51  */
  52
  53 /**
  54  * @brief  Initialization function for the floating-point transposed direct form II Biquad cascade filter.
  55  * @param[in,out] *S           points to an instance of the filter data structure.
  56  * @param[in]     numStages    number of 2nd order stages in the filter.
  57  * @param[in]     *pCoeffs     points to the filter coefficients.
  58  * @param[in]     *pState      points to the state buffer.
  59  * @return        none
  60  *
  61  * <b>Coefficient and State Ordering:</b>
  62  * \par
  63  * The coefficients are stored in the array <code>pCoeffs</code> in the following order:
  64  * <pre>
  65  *     {b10, b11, b12, a11, a12, b20, b21, b22, a21, a22, ...}
  66  * </pre>
  67  *
  68  * \par
  69  * where <code>b1x</code> and <code>a1x</code> are the coefficients for the first stage,
  70  * <code>b2x</code> and <code>a2x</code> are the coefficients for the second stage,
  71  * and so on.  The <code>pCoeffs</code> array contains a total of <code>5*numStages</code> values.
  72  *
  73  * \par
  74  * The <code>pState</code> is a pointer to state array.
  75  * Each Biquad stage has 2 state variables <code>d1,</code> and <code>d2</code>.
  76  * The 2 state variables for stage 1 are first, then the 2 state variables for stage 2, and so on.
  77  * The state array has a total length of <code>2*numStages</code> values.
  78  * The state variables are updated after each block of data is processed; the coefficients are untouched.
  79  */
  80
  81 void arm_biquad_cascade_df2T_init_f32(
  82   arm_biquad_cascade_df2T_instance_f32 * S,
  83   uint8_t numStages,
  84   float32_t * pCoeffs,
  85   float32_t * pState)
  86 {
  87   /* Assign filter stages */
  88   S->numStages = numStages;
  89
  90   /* Assign coefficient pointer */
  91   S->pCoeffs = pCoeffs;
  92
  93   /* Clear state buffer and size is always 2 * numStages */
  94   memset(pState, 0, (2u * (uint32_t) numStages) * sizeof(float32_t));
  95
  96   /* Assign state pointer */
  97   S->pState = pState;
  98 }
  99
 100 /**
 101  * @} end of BiquadCascadeDF2T group
 102  */