tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/FilteringFunctions/arm_fir_decimate_init_q15.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_fir_decimate_init_q15.c
   9 *
  10 * Description:  Initialization function for the Q15 FIR Decimator.
  11 *
  12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
  13 *
  14 * Redistribution and use in source and binary forms, with or without
  15 * modification, are permitted provided that the following conditions
  16 * are met:
  17 *   - Redistributions of source code must retain the above copyright
  18 *     notice, this list of conditions and the following disclaimer.
  19 *   - Redistributions in binary form must reproduce the above copyright
  20 *     notice, this list of conditions and the following disclaimer in
  21 *     the documentation and/or other materials provided with the
  22 *     distribution.
  23 *   - Neither the name of ARM LIMITED nor the names of its contributors
  24 *     may be used to endorse or promote products derived from this
  25 *     software without specific prior written permission.
  26 *
  27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  29 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  30 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  31 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  33 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  34 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  35 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  37 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  38 * POSSIBILITY OF SUCH DAMAGE.
  39 * ------------------------------------------------------------------- */
  40
  41 #include "arm_math.h"
  42
  43 /**
  44  * @ingroup groupFilters
  45  */
  46
  47 /**
  48  * @addtogroup FIR_decimate
  49  * @{
  50  */
  51
  52 /**
  53  * @brief  Initialization function for the Q15 FIR decimator.
  54  * @param[in,out] *S points to an instance of the Q15 FIR decimator structure.
  55  * @param[in] numTaps  number of coefficients in the filter.
  56  * @param[in] M  decimation factor.
  57  * @param[in] *pCoeffs points to the filter coefficients.
  58  * @param[in] *pState points to the state buffer.
  59  * @param[in] blockSize number of input samples to process per call.
  60  * @return    The function returns ARM_MATH_SUCCESS if initialization was successful or ARM_MATH_LENGTH_ERROR if
  61  * <code>blockSize</code> is not a multiple of <code>M</code>.
  62  *
  63  * <b>Description:</b>
  64  * \par
  65  * <code>pCoeffs</code> points to the array of filter coefficients stored in time reversed order:
  66  * <pre>
  67  *    {b[numTaps-1], b[numTaps-2], b[N-2], ..., b[1], b[0]}
  68  * </pre>
  69  * \par
  70  * <code>pState</code> points to the array of state variables.
  71  * <code>pState</code> is of length <code>numTaps+blockSize-1</code> words where <code>blockSize</code> is the number of input samples
  72  * to the call <code>arm_fir_decimate_q15()</code>.
  73  * <code>M</code> is the decimation factor.
  74  */
  75
  76 arm_status arm_fir_decimate_init_q15(
  77   arm_fir_decimate_instance_q15 * S,
  78   uint16_t numTaps,
  79   uint8_t M,
  80   q15_t * pCoeffs,
  81   q15_t * pState,
  82   uint32_t blockSize)
  83 {
  84
  85   arm_status status;
  86
  87   /* The size of the input block must be a multiple of the decimation factor */
  88   if((blockSize % M) != 0u)
  89   {
  90     /* Set status as ARM_MATH_LENGTH_ERROR */
  91     status = ARM_MATH_LENGTH_ERROR;
  92   }
  93   else
  94   {
  95     /* Assign filter taps */
  96     S->numTaps = numTaps;
  97
  98     /* Assign coefficient pointer */
  99     S->pCoeffs = pCoeffs;
 100
 101     /* Clear the state buffer.  The size of buffer is always (blockSize + numTaps - 1) */
 102     memset(pState, 0, (numTaps + (blockSize - 1u)) * sizeof(q15_t));
 103
 104     /* Assign state pointer */
 105     S->pState = pState;
 106
 107     /* Assign Decimation factor */
 108     S->M = M;
 109
 110     status = ARM_MATH_SUCCESS;
 111   }
 112
 113   return (status);
 114
 115 }
 116
 117 /**
 118  * @} end of FIR_decimate group
 119  */