DSP_Lib/Source/FilteringFunctions/arm_fir_decimate_f32.c - third_party/github/STMicroelectronics/cmsis_core - Git at Google

 /* ----------------------------------------------------------------------
 * Copyright (C) 2010-2014 ARM Limited. All rights reserved.
 *
 * $Date:        19. March 2015
 * $Revision: 	V.1.4.5
 *
 * Project: 	    CMSIS DSP Library
 * Title:	    arm_fir_decimate_f32.c
 *
 * Description:	FIR decimation for floating-point sequences.
 *
 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in
 *     the documentation and/or other materials provided with the
 *     distribution.
 *   - Neither the name of ARM LIMITED nor the names of its contributors
 *     may be used to endorse or promote products derived from this
 *     software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 * -------------------------------------------------------------------- */

 #include "arm_math.h"

 /**
  * @ingroup groupFilters
  */

 /**
  * @defgroup FIR_decimate Finite Impulse Response (FIR) Decimator
  *
  * These functions combine an FIR filter together with a decimator.
  * They are used in multirate systems for reducing the sample rate of a signal without introducing aliasing distortion.
  * Conceptually, the functions are equivalent to the block diagram below:
  * \image html FIRDecimator.gif "Components included in the FIR Decimator functions"
  * When decimating by a factor of <code>M</code>, the signal should be prefiltered by a lowpass filter with a normalized
  * cutoff frequency of <code>1/M</code> in order to prevent aliasing distortion.
  * The user of the function is responsible for providing the filter coefficients.
  *
  * The FIR decimator functions provided in the CMSIS DSP Library combine the FIR filter and the decimator in an efficient manner.
  * Instead of calculating all of the FIR filter outputs and discarding <code>M-1</code> out of every <code>M</code>, only the
  * samples output by the decimator are computed.
  * The functions operate on blocks of input and output data.
  * <code>pSrc</code> points to an array of <code>blockSize</code> input values and
  * <code>pDst</code> points to an array of <code>blockSize/M</code> output values.
  * In order to have an integer number of output samples <code>blockSize</code>
  * must always be a multiple of the decimation factor <code>M</code>.
  *
  * The library provides separate functions for Q15, Q31 and floating-point data types.
  *
  * \par Algorithm:
  * The FIR portion of the algorithm uses the standard form filter:
  * <pre>
  *    y[n] = b[0] * x[n] + b[1] * x[n-1] + b[2] * x[n-2] + ...+ b[numTaps-1] * x[n-numTaps+1]
  * </pre>
  * where, <code>b[n]</code> are the filter coefficients.
  * \par
  * The <code>pCoeffs</code> points to a coefficient array of size <code>numTaps</code>.
  * Coefficients are stored in time reversed order.
  * \par
  * <pre>
  *    {b[numTaps-1], b[numTaps-2], b[N-2], ..., b[1], b[0]}
  * </pre>
  * \par
  * <code>pState</code> points to a state array of size <code>numTaps + blockSize - 1</code>.
  * Samples in the state buffer are stored in the order:
  * \par
  * <pre>
  *    {x[n-numTaps+1], x[n-numTaps], x[n-numTaps-1], x[n-numTaps-2]....x[0], x[1], ..., x[blockSize-1]}
  * </pre>
  * The state variables are updated after each block of data is processed, the coefficients are untouched.
  *
  * \par Instance Structure
  * The coefficients and state variables for a filter are stored together in an instance data structure.
  * A separate instance structure must be defined for each filter.
  * Coefficient arrays may be shared among several instances while state variable array should be allocated separately.
  * There are separate instance structure declarations for each of the 3 supported data types.
  *
  * \par Initialization Functions
  * There is also an associated initialization function for each data type.
  * The initialization function performs the following operations:
  * - Sets the values of the internal structure fields.
  * - Zeros out the values in the state buffer.
  * - Checks to make sure that the size of the input is a multiple of the decimation factor.
  * To do this manually without calling the init function, assign the follow subfields of the instance structure:
  * numTaps, pCoeffs, M (decimation factor), pState. Also set all of the values in pState to zero.
  *
  * \par
  * Use of the initialization function is optional.
  * However, if the initialization function is used, then the instance structure cannot be placed into a const data section.
  * To place an instance structure into a const data section, the instance structure must be manually initialized.
  * The code below statically initializes each of the 3 different data type filter instance structures
  * <pre>
  *arm_fir_decimate_instance_f32 S = {M, numTaps, pCoeffs, pState};
  *arm_fir_decimate_instance_q31 S = {M, numTaps, pCoeffs, pState};
  *arm_fir_decimate_instance_q15 S = {M, numTaps, pCoeffs, pState};
  * </pre>
  * where <code>M</code> is the decimation factor; <code>numTaps</code> is the number of filter coefficients in the filter;
  * <code>pCoeffs</code> is the address of the coefficient buffer;
  * <code>pState</code> is the address of the state buffer.
  * Be sure to set the values in the state buffer to zeros when doing static initialization.
  *
  * \par Fixed-Point Behavior
  * Care must be taken when using the fixed-point versions of the FIR decimate filter functions.
  * In particular, the overflow and saturation behavior of the accumulator used in each function must be considered.
  * Refer to the function specific documentation below for usage guidelines.
  */

 /**
  * @addtogroup FIR_decimate
  * @{
  */

   /**
    * @brief Processing function for the floating-point FIR decimator.
    * @param[in] *S        points to an instance of the floating-point FIR decimator structure.
    * @param[in] *pSrc     points to the block of input data.
    * @param[out] *pDst    points to the block of output data.
    * @param[in] blockSize number of input samples to process per call.
    * @return none.
    */

 void arm_fir_decimate_f32(
   const arm_fir_decimate_instance_f32 * S,
   float32_t * pSrc,
   float32_t * pDst,
   uint32_t blockSize)
 {
   float32_t *pState = S->pState;                 /* State pointer */
   float32_t *pCoeffs = S->pCoeffs;               /* Coefficient pointer */
   float32_t *pStateCurnt;                        /* Points to the current sample of the state */
   float32_t *px, *pb;                            /* Temporary pointers for state and coefficient buffers */
   float32_t sum0;                                /* Accumulator */
   float32_t x0, c0;                              /* Temporary variables to hold state and coefficient values */
   uint32_t numTaps = S->numTaps;                 /* Number of filter coefficients in the filter */
   uint32_t i, tapCnt, blkCnt, outBlockSize = blockSize / S->M;  /* Loop counters */

 #ifndef ARM_MATH_CM0_FAMILY

   uint32_t blkCntN4;
   float32_t *px0, *px1, *px2, *px3;
   float32_t acc0, acc1, acc2, acc3;
   float32_t x1, x2, x3;

   /* Run the below code for Cortex-M4 and Cortex-M3 */

   /* S->pState buffer contains previous frame (numTaps - 1) samples */
   /* pStateCurnt points to the location where the new input data should be written */
   pStateCurnt = S->pState + (numTaps - 1u);

   /* Total number of output samples to be computed */
   blkCnt = outBlockSize / 4;
   blkCntN4 = outBlockSize - (4 * blkCnt);

   while(blkCnt > 0u)
   {
     /* Copy 4 * decimation factor number of new input samples into the state buffer */
     i = 4 * S->M;

     do
     {
       *pStateCurnt++ = *pSrc++;

     } while(--i);

     /* Set accumulators to zero */
     acc0 = 0.0f;
     acc1 = 0.0f;
     acc2 = 0.0f;
     acc3 = 0.0f;

     /* Initialize state pointer for all the samples */
     px0 = pState;
     px1 = pState + S->M;
     px2 = pState + 2 * S->M;
     px3 = pState + 3 * S->M;

     /* Initialize coeff pointer */
     pb = pCoeffs;

     /* Loop unrolling.  Process 4 taps at a time. */
     tapCnt = numTaps >> 2;

     /* Loop over the number of taps.  Unroll by a factor of 4.
      ** Repeat until we've computed numTaps-4 coefficients. */

     while(tapCnt > 0u)
     {
       /* Read the b[numTaps-1] coefficient */
       c0 = *(pb++);

       /* Read x[n-numTaps-1] sample for acc0 */
       x0 = *(px0++);
       /* Read x[n-numTaps-1] sample for acc1 */
       x1 = *(px1++);
       /* Read x[n-numTaps-1] sample for acc2 */
       x2 = *(px2++);
       /* Read x[n-numTaps-1] sample for acc3 */
       x3 = *(px3++);

       /* Perform the multiply-accumulate */
       acc0 += x0 * c0;
       acc1 += x1 * c0;
       acc2 += x2 * c0;
       acc3 += x3 * c0;

       /* Read the b[numTaps-2] coefficient */
       c0 = *(pb++);

       /* Read x[n-numTaps-2] sample for acc0, acc1, acc2, acc3 */
       x0 = *(px0++);
       x1 = *(px1++);
       x2 = *(px2++);
       x3 = *(px3++);

       /* Perform the multiply-accumulate */
       acc0 += x0 * c0;
       acc1 += x1 * c0;
       acc2 += x2 * c0;
       acc3 += x3 * c0;

       /* Read the b[numTaps-3] coefficient */
       c0 = *(pb++);

       /* Read x[n-numTaps-3] sample acc0, acc1, acc2, acc3 */
       x0 = *(px0++);
       x1 = *(px1++);
       x2 = *(px2++);
       x3 = *(px3++);

       /* Perform the multiply-accumulate */
       acc0 += x0 * c0;
       acc1 += x1 * c0;
       acc2 += x2 * c0;
       acc3 += x3 * c0;

       /* Read the b[numTaps-4] coefficient */
       c0 = *(pb++);

       /* Read x[n-numTaps-4] sample acc0, acc1, acc2, acc3 */
       x0 = *(px0++);
       x1 = *(px1++);
       x2 = *(px2++);
       x3 = *(px3++);

       /* Perform the multiply-accumulate */
       acc0 += x0 * c0;
       acc1 += x1 * c0;
       acc2 += x2 * c0;
       acc3 += x3 * c0;

       /* Decrement the loop counter */
       tapCnt--;
     }

     /* If the filter length is not a multiple of 4, compute the remaining filter taps */
     tapCnt = numTaps % 0x4u;

     while(tapCnt > 0u)
     {
       /* Read coefficients */
       c0 = *(pb++);

       /* Fetch  state variables for acc0, acc1, acc2, acc3 */
       x0 = *(px0++);
       x1 = *(px1++);
       x2 = *(px2++);
       x3 = *(px3++);

       /* Perform the multiply-accumulate */
       acc0 += x0 * c0;
       acc1 += x1 * c0;
       acc2 += x2 * c0;
       acc3 += x3 * c0;

       /* Decrement the loop counter */
       tapCnt--;
     }

     /* Advance the state pointer by the decimation factor
      * to process the next group of decimation factor number samples */
     pState = pState + 4 * S->M;

     /* The result is in the accumulator, store in the destination buffer. */
     *pDst++ = acc0;
     *pDst++ = acc1;
     *pDst++ = acc2;
     *pDst++ = acc3;

     /* Decrement the loop counter */
     blkCnt--;
   }

   while(blkCntN4 > 0u)
   {
     /* Copy decimation factor number of new input samples into the state buffer */
     i = S->M;

     do
     {
       *pStateCurnt++ = *pSrc++;

     } while(--i);

     /* Set accumulator to zero */
     sum0 = 0.0f;

     /* Initialize state pointer */
     px = pState;

     /* Initialize coeff pointer */
     pb = pCoeffs;

     /* Loop unrolling.  Process 4 taps at a time. */
     tapCnt = numTaps >> 2;

     /* Loop over the number of taps.  Unroll by a factor of 4.
      ** Repeat until we've computed numTaps-4 coefficients. */
     while(tapCnt > 0u)
     {
       /* Read the b[numTaps-1] coefficient */
       c0 = *(pb++);

       /* Read x[n-numTaps-1] sample */
       x0 = *(px++);

       /* Perform the multiply-accumulate */
       sum0 += x0 * c0;

       /* Read the b[numTaps-2] coefficient */
       c0 = *(pb++);

       /* Read x[n-numTaps-2] sample */
       x0 = *(px++);

       /* Perform the multiply-accumulate */
       sum0 += x0 * c0;

       /* Read the b[numTaps-3] coefficient */
       c0 = *(pb++);

       /* Read x[n-numTaps-3] sample */
       x0 = *(px++);

       /* Perform the multiply-accumulate */
       sum0 += x0 * c0;

       /* Read the b[numTaps-4] coefficient */
       c0 = *(pb++);

       /* Read x[n-numTaps-4] sample */
       x0 = *(px++);

       /* Perform the multiply-accumulate */
       sum0 += x0 * c0;

       /* Decrement the loop counter */
       tapCnt--;
     }

     /* If the filter length is not a multiple of 4, compute the remaining filter taps */
     tapCnt = numTaps % 0x4u;

     while(tapCnt > 0u)
     {
       /* Read coefficients */
       c0 = *(pb++);

       /* Fetch 1 state variable */
       x0 = *(px++);

       /* Perform the multiply-accumulate */
       sum0 += x0 * c0;

       /* Decrement the loop counter */
       tapCnt--;
     }

     /* Advance the state pointer by the decimation factor
      * to process the next group of decimation factor number samples */
     pState = pState + S->M;

     /* The result is in the accumulator, store in the destination buffer. */
     *pDst++ = sum0;

     /* Decrement the loop counter */
     blkCntN4--;
   }

   /* Processing is complete.
    ** Now copy the last numTaps - 1 samples to the satrt of the state buffer.
    ** This prepares the state buffer for the next function call. */

   /* Points to the start of the state buffer */
   pStateCurnt = S->pState;

   i = (numTaps - 1u) >> 2;

   /* copy data */
   while(i > 0u)
   {
     *pStateCurnt++ = *pState++;
     *pStateCurnt++ = *pState++;
     *pStateCurnt++ = *pState++;
     *pStateCurnt++ = *pState++;

     /* Decrement the loop counter */
     i--;
   }

   i = (numTaps - 1u) % 0x04u;

   /* copy data */
   while(i > 0u)
   {
     *pStateCurnt++ = *pState++;

     /* Decrement the loop counter */
     i--;
   }

 #else

 /* Run the below code for Cortex-M0 */

   /* S->pState buffer contains previous frame (numTaps - 1) samples */
   /* pStateCurnt points to the location where the new input data should be written */
   pStateCurnt = S->pState + (numTaps - 1u);

   /* Total number of output samples to be computed */
   blkCnt = outBlockSize;

   while(blkCnt > 0u)
   {
     /* Copy decimation factor number of new input samples into the state buffer */
     i = S->M;

     do
     {
       *pStateCurnt++ = *pSrc++;

     } while(--i);

     /* Set accumulator to zero */
     sum0 = 0.0f;

     /* Initialize state pointer */
     px = pState;

     /* Initialize coeff pointer */
     pb = pCoeffs;

     tapCnt = numTaps;

     while(tapCnt > 0u)
     {
       /* Read coefficients */
       c0 = *pb++;

       /* Fetch 1 state variable */
       x0 = *px++;

       /* Perform the multiply-accumulate */
       sum0 += x0 * c0;

       /* Decrement the loop counter */
       tapCnt--;
     }

     /* Advance the state pointer by the decimation factor
      * to process the next group of decimation factor number samples */
     pState = pState + S->M;

     /* The result is in the accumulator, store in the destination buffer. */
     *pDst++ = sum0;

     /* Decrement the loop counter */
     blkCnt--;
   }

   /* Processing is complete.
    ** Now copy the last numTaps - 1 samples to the start of the state buffer.
    ** This prepares the state buffer for the next function call. */

   /* Points to the start of the state buffer */
   pStateCurnt = S->pState;

   /* Copy numTaps number of values */
   i = (numTaps - 1u);

   /* copy data */
   while(i > 0u)
   {
     *pStateCurnt++ = *pState++;

     /* Decrement the loop counter */
     i--;
   }

 #endif /*   #ifndef ARM_MATH_CM0_FAMILY        */

 }

 /**
  * @} end of FIR_decimate group
  */
	/* ----------------------------------------------------------------------
	* Copyright (C) 2010-2014 ARM Limited. All rights reserved.
	*
	* $Date: 19. March 2015
	* $Revision: V.1.4.5
	*
	* Project: CMSIS DSP Library
	* Title: arm_fir_decimate_f32.c
	*
	* Description: FIR decimation for floating-point sequences.
	*
	* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	* - Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	* - Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in
	* the documentation and/or other materials provided with the
	* distribution.
	* - Neither the name of ARM LIMITED nor the names of its contributors
	* may be used to endorse or promote products derived from this
	* software without specific prior written permission.
	*
	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
	* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
	* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
	* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
	* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
	* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
	* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
	* POSSIBILITY OF SUCH DAMAGE.
	* -------------------------------------------------------------------- */

	#include "arm_math.h"

	/**
	* @ingroup groupFilters
	*/

	/**
	* @defgroup FIR_decimate Finite Impulse Response (FIR) Decimator
	*
	* These functions combine an FIR filter together with a decimator.
	* They are used in multirate systems for reducing the sample rate of a signal without introducing aliasing distortion.
	* Conceptually, the functions are equivalent to the block diagram below:
	* \image html FIRDecimator.gif "Components included in the FIR Decimator functions"
	* When decimating by a factor of <code>M</code>, the signal should be prefiltered by a lowpass filter with a normalized
	* cutoff frequency of <code>1/M</code> in order to prevent aliasing distortion.
	* The user of the function is responsible for providing the filter coefficients.
	*
	* The FIR decimator functions provided in the CMSIS DSP Library combine the FIR filter and the decimator in an efficient manner.
	* Instead of calculating all of the FIR filter outputs and discarding <code>M-1</code> out of every <code>M</code>, only the
	* samples output by the decimator are computed.
	* The functions operate on blocks of input and output data.
	* <code>pSrc</code> points to an array of <code>blockSize</code> input values and
	* <code>pDst</code> points to an array of <code>blockSize/M</code> output values.
	* In order to have an integer number of output samples <code>blockSize</code>
	* must always be a multiple of the decimation factor <code>M</code>.
	*
	* The library provides separate functions for Q15, Q31 and floating-point data types.
	*
	* \par Algorithm:
	* The FIR portion of the algorithm uses the standard form filter:
	* <pre>
	* y[n] = b[0] * x[n] + b[1] * x[n-1] + b[2] * x[n-2] + ...+ b[numTaps-1] * x[n-numTaps+1]
	* </pre>
	* where, <code>b[n]</code> are the filter coefficients.
	* \par
	* The <code>pCoeffs</code> points to a coefficient array of size <code>numTaps</code>.
	* Coefficients are stored in time reversed order.
	* \par
	* <pre>
	* {b[numTaps-1], b[numTaps-2], b[N-2], ..., b[1], b[0]}
	* </pre>
	* \par
	* <code>pState</code> points to a state array of size <code>numTaps + blockSize - 1</code>.
	* Samples in the state buffer are stored in the order:
	* \par
	* <pre>
	* {x[n-numTaps+1], x[n-numTaps], x[n-numTaps-1], x[n-numTaps-2]....x[0], x[1], ..., x[blockSize-1]}
	* </pre>
	* The state variables are updated after each block of data is processed, the coefficients are untouched.
	*
	* \par Instance Structure
	* The coefficients and state variables for a filter are stored together in an instance data structure.
	* A separate instance structure must be defined for each filter.
	* Coefficient arrays may be shared among several instances while state variable array should be allocated separately.
	* There are separate instance structure declarations for each of the 3 supported data types.
	*
	* \par Initialization Functions
	* There is also an associated initialization function for each data type.
	* The initialization function performs the following operations:
	* - Sets the values of the internal structure fields.
	* - Zeros out the values in the state buffer.
	* - Checks to make sure that the size of the input is a multiple of the decimation factor.
	* To do this manually without calling the init function, assign the follow subfields of the instance structure:
	* numTaps, pCoeffs, M (decimation factor), pState. Also set all of the values in pState to zero.
	*
	* \par
	* Use of the initialization function is optional.
	* However, if the initialization function is used, then the instance structure cannot be placed into a const data section.
	* To place an instance structure into a const data section, the instance structure must be manually initialized.
	* The code below statically initializes each of the 3 different data type filter instance structures
	* <pre>
	*arm_fir_decimate_instance_f32 S = {M, numTaps, pCoeffs, pState};
	*arm_fir_decimate_instance_q31 S = {M, numTaps, pCoeffs, pState};
	*arm_fir_decimate_instance_q15 S = {M, numTaps, pCoeffs, pState};
	* </pre>
	* where <code>M</code> is the decimation factor; <code>numTaps</code> is the number of filter coefficients in the filter;
	* <code>pCoeffs</code> is the address of the coefficient buffer;
	* <code>pState</code> is the address of the state buffer.
	* Be sure to set the values in the state buffer to zeros when doing static initialization.
	*
	* \par Fixed-Point Behavior
	* Care must be taken when using the fixed-point versions of the FIR decimate filter functions.
	* In particular, the overflow and saturation behavior of the accumulator used in each function must be considered.
	* Refer to the function specific documentation below for usage guidelines.
	*/

	/**
	* @addtogroup FIR_decimate
	* @{
	*/

	/**
	* @brief Processing function for the floating-point FIR decimator.
	* @param[in] *S points to an instance of the floating-point FIR decimator structure.
	* @param[in] *pSrc points to the block of input data.
	* @param[out] *pDst points to the block of output data.
	* @param[in] blockSize number of input samples to process per call.
	* @return none.
	*/

	void arm_fir_decimate_f32(
	const arm_fir_decimate_instance_f32 * S,
	float32_t * pSrc,
	float32_t * pDst,
	uint32_t blockSize)
	{
	float32_t pState = S->pState; / State pointer */
	float32_t pCoeffs = S->pCoeffs; / Coefficient pointer */
	float32_t pStateCurnt; / Points to the current sample of the state */
	float32_t px, pb; /* Temporary pointers for state and coefficient buffers */
	float32_t sum0; /* Accumulator */
	float32_t x0, c0; /* Temporary variables to hold state and coefficient values */
	uint32_t numTaps = S->numTaps; /* Number of filter coefficients in the filter */
	uint32_t i, tapCnt, blkCnt, outBlockSize = blockSize / S->M; /* Loop counters */

	#ifndef ARM_MATH_CM0_FAMILY

	uint32_t blkCntN4;
	float32_t px0, px1, px2, px3;
	float32_t acc0, acc1, acc2, acc3;
	float32_t x1, x2, x3;

	/* Run the below code for Cortex-M4 and Cortex-M3 */

	/* S->pState buffer contains previous frame (numTaps - 1) samples */
	/* pStateCurnt points to the location where the new input data should be written */
	pStateCurnt = S->pState + (numTaps - 1u);

	/* Total number of output samples to be computed */
	blkCnt = outBlockSize / 4;
	blkCntN4 = outBlockSize - (4 * blkCnt);

	while(blkCnt > 0u)
	{
	/* Copy 4 * decimation factor number of new input samples into the state buffer */
	i = 4 * S->M;

	do
	{
	pStateCurnt++ = pSrc++;

	} while(--i);

	/* Set accumulators to zero */
	acc0 = 0.0f;
	acc1 = 0.0f;
	acc2 = 0.0f;
	acc3 = 0.0f;

	/* Initialize state pointer for all the samples */
	px0 = pState;
	px1 = pState + S->M;
	px2 = pState + 2 * S->M;
	px3 = pState + 3 * S->M;

	/* Initialize coeff pointer */
	pb = pCoeffs;

	/* Loop unrolling. Process 4 taps at a time. */
	tapCnt = numTaps >> 2;

	/* Loop over the number of taps. Unroll by a factor of 4.
	** Repeat until we've computed numTaps-4 coefficients. */

	while(tapCnt > 0u)
	{
	/* Read the b[numTaps-1] coefficient */
	c0 = *(pb++);

	/* Read x[n-numTaps-1] sample for acc0 */
	x0 = *(px0++);
	/* Read x[n-numTaps-1] sample for acc1 */
	x1 = *(px1++);
	/* Read x[n-numTaps-1] sample for acc2 */
	x2 = *(px2++);
	/* Read x[n-numTaps-1] sample for acc3 */
	x3 = *(px3++);

	/* Perform the multiply-accumulate */
	acc0 += x0 * c0;
	acc1 += x1 * c0;
	acc2 += x2 * c0;
	acc3 += x3 * c0;

	/* Read the b[numTaps-2] coefficient */
	c0 = *(pb++);

	/* Read x[n-numTaps-2] sample for acc0, acc1, acc2, acc3 */
	x0 = *(px0++);
	x1 = *(px1++);
	x2 = *(px2++);
	x3 = *(px3++);

	/* Perform the multiply-accumulate */
	acc0 += x0 * c0;
	acc1 += x1 * c0;
	acc2 += x2 * c0;
	acc3 += x3 * c0;

	/* Read the b[numTaps-3] coefficient */
	c0 = *(pb++);

	/* Read x[n-numTaps-3] sample acc0, acc1, acc2, acc3 */
	x0 = *(px0++);
	x1 = *(px1++);
	x2 = *(px2++);
	x3 = *(px3++);

	/* Perform the multiply-accumulate */
	acc0 += x0 * c0;
	acc1 += x1 * c0;
	acc2 += x2 * c0;
	acc3 += x3 * c0;

	/* Read the b[numTaps-4] coefficient */
	c0 = *(pb++);

	/* Read x[n-numTaps-4] sample acc0, acc1, acc2, acc3 */
	x0 = *(px0++);
	x1 = *(px1++);
	x2 = *(px2++);
	x3 = *(px3++);

	/* Perform the multiply-accumulate */
	acc0 += x0 * c0;
	acc1 += x1 * c0;
	acc2 += x2 * c0;
	acc3 += x3 * c0;

	/* Decrement the loop counter */
	tapCnt--;
	}

	/* If the filter length is not a multiple of 4, compute the remaining filter taps */
	tapCnt = numTaps % 0x4u;

	while(tapCnt > 0u)
	{
	/* Read coefficients */
	c0 = *(pb++);

	/* Fetch state variables for acc0, acc1, acc2, acc3 */
	x0 = *(px0++);
	x1 = *(px1++);
	x2 = *(px2++);
	x3 = *(px3++);

	/* Perform the multiply-accumulate */
	acc0 += x0 * c0;
	acc1 += x1 * c0;
	acc2 += x2 * c0;
	acc3 += x3 * c0;

	/* Decrement the loop counter */
	tapCnt--;
	}

	/* Advance the state pointer by the decimation factor
	* to process the next group of decimation factor number samples */
	pState = pState + 4 * S->M;

	/* The result is in the accumulator, store in the destination buffer. */
	*pDst++ = acc0;
	*pDst++ = acc1;
	*pDst++ = acc2;
	*pDst++ = acc3;

	/* Decrement the loop counter */
	blkCnt--;
	}

	while(blkCntN4 > 0u)
	{
	/* Copy decimation factor number of new input samples into the state buffer */
	i = S->M;

	do
	{
	pStateCurnt++ = pSrc++;

	} while(--i);

	/* Set accumulator to zero */
	sum0 = 0.0f;

	/* Initialize state pointer */
	px = pState;

	/* Initialize coeff pointer */
	pb = pCoeffs;

	/* Loop unrolling. Process 4 taps at a time. */
	tapCnt = numTaps >> 2;

	/* Loop over the number of taps. Unroll by a factor of 4.
	** Repeat until we've computed numTaps-4 coefficients. */
	while(tapCnt > 0u)
	{
	/* Read the b[numTaps-1] coefficient */
	c0 = *(pb++);

	/* Read x[n-numTaps-1] sample */
	x0 = *(px++);

	/* Perform the multiply-accumulate */
	sum0 += x0 * c0;

	/* Read the b[numTaps-2] coefficient */
	c0 = *(pb++);

	/* Read x[n-numTaps-2] sample */
	x0 = *(px++);

	/* Perform the multiply-accumulate */
	sum0 += x0 * c0;

	/* Read the b[numTaps-3] coefficient */
	c0 = *(pb++);

	/* Read x[n-numTaps-3] sample */
	x0 = *(px++);

	/* Perform the multiply-accumulate */
	sum0 += x0 * c0;

	/* Read the b[numTaps-4] coefficient */
	c0 = *(pb++);

	/* Read x[n-numTaps-4] sample */
	x0 = *(px++);

	/* Perform the multiply-accumulate */
	sum0 += x0 * c0;

	/* Decrement the loop counter */
	tapCnt--;
	}

	/* If the filter length is not a multiple of 4, compute the remaining filter taps */
	tapCnt = numTaps % 0x4u;

	while(tapCnt > 0u)
	{
	/* Read coefficients */
	c0 = *(pb++);

	/* Fetch 1 state variable */
	x0 = *(px++);

	/* Perform the multiply-accumulate */
	sum0 += x0 * c0;

	/* Decrement the loop counter */
	tapCnt--;
	}

	/* Advance the state pointer by the decimation factor
	* to process the next group of decimation factor number samples */
	pState = pState + S->M;

	/* The result is in the accumulator, store in the destination buffer. */
	*pDst++ = sum0;

	/* Decrement the loop counter */
	blkCntN4--;
	}

	/* Processing is complete.
	** Now copy the last numTaps - 1 samples to the satrt of the state buffer.
	** This prepares the state buffer for the next function call. */

	/* Points to the start of the state buffer */
	pStateCurnt = S->pState;

	i = (numTaps - 1u) >> 2;

	/* copy data */
	while(i > 0u)
	{
	pStateCurnt++ = pState++;
	pStateCurnt++ = pState++;
	pStateCurnt++ = pState++;
	pStateCurnt++ = pState++;

	/* Decrement the loop counter */
	i--;
	}

	i = (numTaps - 1u) % 0x04u;

	/* copy data */
	while(i > 0u)
	{
	pStateCurnt++ = pState++;

	/* Decrement the loop counter */
	i--;
	}

	#else

	/* Run the below code for Cortex-M0 */

	/* S->pState buffer contains previous frame (numTaps - 1) samples */
	/* pStateCurnt points to the location where the new input data should be written */
	pStateCurnt = S->pState + (numTaps - 1u);

	/* Total number of output samples to be computed */
	blkCnt = outBlockSize;

	while(blkCnt > 0u)
	{
	/* Copy decimation factor number of new input samples into the state buffer */
	i = S->M;

	do
	{
	pStateCurnt++ = pSrc++;

	} while(--i);

	/* Set accumulator to zero */
	sum0 = 0.0f;

	/* Initialize state pointer */
	px = pState;

	/* Initialize coeff pointer */
	pb = pCoeffs;

	tapCnt = numTaps;

	while(tapCnt > 0u)
	{
	/* Read coefficients */
	c0 = *pb++;

	/* Fetch 1 state variable */
	x0 = *px++;

	/* Perform the multiply-accumulate */
	sum0 += x0 * c0;

	/* Decrement the loop counter */
	tapCnt--;
	}

	/* Advance the state pointer by the decimation factor
	* to process the next group of decimation factor number samples */
	pState = pState + S->M;

	/* The result is in the accumulator, store in the destination buffer. */
	*pDst++ = sum0;

	/* Decrement the loop counter */
	blkCnt--;
	}

	/* Processing is complete.
	** Now copy the last numTaps - 1 samples to the start of the state buffer.
	** This prepares the state buffer for the next function call. */

	/* Points to the start of the state buffer */
	pStateCurnt = S->pState;

	/* Copy numTaps number of values */
	i = (numTaps - 1u);

	/* copy data */
	while(i > 0u)
	{
	pStateCurnt++ = pState++;

	/* Decrement the loop counter */
	i--;
	}

	#endif /* #ifndef ARM_MATH_CM0_FAMILY */

	}

	/**
	* @} end of FIR_decimate group
	*/