text: /* ----------------------------------------------------------------------  
  * 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_f32.c  
  *  
  * Description:	Floating-point FIR filter processing function.  
  *  
  * 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 Finite Impulse Response (FIR) Filters  
  *  
  * This set of functions implements Finite Impulse Response (FIR) filters  
  * for Q7, Q15, Q31, and floating-point data types.  Fast versions of Q15 and Q31 are also provided.  
  * The functions operate on blocks of input and output data and each call to the function processes  
  * <code>blockSize</code> samples through the filter.  <code>pSrc</code> and  
  * <code>pDst</code> points to input and output arrays containing <code>blockSize</code> values.  
  *  
  * \par Algorithm:  
  * The FIR filter algorithm is based upon a sequence of multiply-accumulate (MAC) operations.  
  * Each filter coefficient <code>b[n]</code> is multiplied by a state variable which equals a previous input sample <code>x[n]</code>.  
  * <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>  
  * \par  
  * \image html FIR.gif "Finite Impulse Response filter"  
  * \par  
  * <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 following 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>  
  * \par  
  * Note that the length of the state buffer exceeds the length of the coefficient array by <code>blockSize-1</code>.  
  * The increased state buffer length allows circular addressing, which is traditionally used in the FIR filters,  
  * to be avoided and yields a significant speed improvement.  
  * 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 arrays cannot be shared.  
  * There are separate instance structure declarations for each of the 4 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.  
  * To do this manually without calling the init function, assign the follow subfields of the instance structure:
  * numTaps, pCoeffs, 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.  
  * Set the values in the state buffer to zeros before static initialization.  
  * The code below statically initializes each of the 4 different data type filter instance structures  
  * <pre>  
  *arm_fir_instance_f32 S = {numTaps, pState, pCoeffs};  
  *arm_fir_instance_q31 S = {numTaps, pState, pCoeffs};  
  *arm_fir_instance_q15 S = {numTaps, pState, pCoeffs};  
  *arm_fir_instance_q7 S =  {numTaps, pState, pCoeffs};  
  * </pre>  
  *  
  * where <code>numTaps</code> is the number of filter coefficients in the filter; <code>pState</code> is the address of the state buffer;  
  * <code>pCoeffs</code> is the address of the coefficient buffer.  
  *  
  * \par Fixed-Point Behavior  
  * Care must be taken when using the fixed-point versions of the FIR 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  
  * @{  
  */
  
  /**  
  *  
  * @param[in]  *S points to an instance of the floating-point FIR filter 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 samples to process per call.  
  * @return     none.  
  *  
  */
  
  #if defined(ARM_MATH_CM7)
  
  void arm_fir_f32(
  const arm_fir_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 acc0, acc1, acc2, acc3, acc4, acc5, acc6, acc7;     /* Accumulators */
     float32_t x0, x1, x2, x3, x4, x5, x6, x7, 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;                    /* Loop counters */
  
     /* S->pState points to state array which contains previous frame (numTaps - 1) samples */
     /* pStateCurnt points to the location where the new input data should be written */
     pStateCurnt = &(S->pState[(numTaps - 1u)]);
  
     /* Apply loop unrolling and compute 8 output values simultaneously.  
      * The variables acc0 ... acc7 hold output values that are being computed:  
      *  
      *    acc0 =  b[numTaps-1] * x[n-numTaps-1] + b[numTaps-2] * x[n-numTaps-2] + b[numTaps-3] * x[n-numTaps-3] +...+ b[0] * x[0]  
      *    acc1 =  b[numTaps-1] * x[n-numTaps] +   b[numTaps-2] * x[n-numTaps-1] + b[numTaps-3] * x[n-numTaps-2] +...+ b[0] * x[1]  
      *    acc2 =  b[numTaps-1] * x[n-numTaps+1] + b[numTaps-2] * x[n-numTaps] +   b[numTaps-3] * x[n-numTaps-1] +...+ b[0] * x[2]  
      *    acc3 =  b[numTaps-1] * x[n-numTaps+2] + b[numTaps-2] * x[n-numTaps+1] + b[numTaps-3] * x[n-numTaps]   +...+ b[0] * x[3]  
      */
     blkCnt = blockSize >> 3;
  
     /* First part of the processing with loop unrolling.  Compute 8 outputs at a time.  
     ** a second loop below computes the remaining 1 to 7 samples. */
     while(blkCnt > 0u)
     {
        /* Copy four new input samples into the state buffer */
        *pStateCurnt++ = *pSrc++;
        *pStateCurnt++ = *pSrc++;
        *pStateCurnt++ = *pSrc++;
        *pStateCurnt++ = *pSrc++;
  
        /* Set all accumulators to zero */
        acc0 = 0.0f;
        acc1 = 0.0f;
        acc2 = 0.0f;
        acc3 = 0.0f;
        acc4 = 0.0f;
        acc5 = 0.0f;
        acc6 = 0.0f;
        acc7 = 0.0f;		
  
        /* Initialize state pointer */
        px = pState;
  
        /* Initialize coeff pointer */
        pb = (pCoeffs);		
     
        /* This is separated from the others to avoid 
         * a call to __aeabi_memmove which would be slower
         */
        *pStateCurnt++ = *pSrc++;
        *pStateCurnt++ = *pSrc++;
        *pStateCurnt++ = *pSrc++;
        *pStateCurnt++ = *pSrc++;
  
        /* Read the first seven samples from the state buffer:  x[n-numTaps], x[n-numTaps-1], x[n-numTaps-2] */
        x0 = *px++;
        x1 = *px++;
        x2 = *px++;
        x3 = *px++;
        x4 = *px++;
        x5 = *px++;
        x6 = *px++;
  
        /* Loop unrolling.  Process 8 taps at a time. */
        tapCnt = numTaps >> 3u;
        
        /* Loop over the number of taps.  Unroll by a factor of 8.  
         ** Repeat until we've computed numTaps-8 coefficients. */
        while(tapCnt > 0u)
        {
           /* Read the b[numTaps-1] coefficient */
           c0 = *(pb++);
  
           /* Read x[n-numTaps-3] sample */
           x7 = *(px++);
  
           /* acc0 +=  b[numTaps-1] * x[n-numTaps] */
           acc0 += x0 * c0;
  
           /* acc1 +=  b[numTaps-1] * x[n-numTaps-1] */
           acc1 += x1 * c0;
  
           /* acc2 +=  b[numTaps-1] * x[n-numTaps-2] */
           acc2 += x2 * c0;
  
           /* acc3 +=  b[numTaps-1] * x[n-numTaps-3] */
           acc3 += x3 * c0;
  
           /* acc4 +=  b[numTaps-1] * x[n-numTaps-4] */
           acc4 += x4 * c0;
  
           /* acc1 +=  b[numTaps-1] * x[n-numTaps-5] */
           acc5 += x5 * c0;
  
           /* acc2 +=  b[numTaps-1] * x[n-numTaps-6] */
           acc6 += x6 * c0;
  
           /* acc3 +=  b[numTaps-1] * x[n-numTaps-7] */
           acc7 += x7 * c0;
           
           /* Read the b[numTaps-2] coefficient */
           c0 = *(pb++);
  
           /* Read x[n-numTaps-4] sample */
           x0 = *(px++);
  
           /* Perform the multiply-accumulate */
           acc0 += x1 * c0;
           acc1 += x2 * c0;   
           acc2 += x3 * c0;   
           acc3 += x4 * c0;   
           acc4 += x5 * c0;   
           acc5 += x6 * c0;   
           acc6 += x7 * c0;   
           acc7 += x0 * c0;   
           
           /* Read the b[numTaps-3] coefficient */
           c0 = *(pb++);
  
           /* Read x[n-numTaps-5] sample */
           x1 = *(px++);
  
           /* Perform the multiply-accumulates */      
           acc0 += x2 * c0;
           acc1 += x3 * c0;   
           acc2 += x4 * c0;   
           acc3 += x5 * c0;   
           acc4 += x6 * c0;   
           acc5 += x7 * c0;   
           acc6 += x0 * c0;   
           acc7 += x1 * c0;   
  
           /* Read the b[numTaps-4] coefficient */
           c0 = *(pb++);
  
           /* Read x[n-numTaps-6] sample */
           x2 = *(px++);
  
           /* Perform the multiply-accumulates */      
           acc0 += x3 * c0;
           acc1 += x4 * c0;   
           acc2 += x5 * c0;   
           acc3 += x6 * c0;   
           acc4 += x7 * c0;   
           acc5 += x0 * c0;   
           acc6 += x1 * c0;   
           acc7 += x2 * c0;   
  
           /* Read the b[numTaps-4] coefficient */
           c0 = *(pb++);
  
           /* Read x[n-numTaps-6] sample */
           x3 = *(px++);
           /* Perform the multiply-accumulates */      
           acc0 += x4 * c0;
           acc1 += x5 * c0;   
           acc2 += x6 * c0;   
           acc3 += x7 * c0;   
           acc4 += x0 * c0;   
           acc5 += x1 * c0;   
           acc6 += x2 * c0;   
           acc7 += x3 * c0;   
  
           /* Read the b[numTaps-4] coefficient */
           c0 = *(pb++);
  
           /* Read x[n-numTaps-6] sample */
           x4 = *(px++);
  
           /* Perform the multiply-accumulates */      
           acc0 += x5 * c0;
           acc1 += x6 * c0;   
           acc2 += x7 * c0;   
           acc3 += x0 * c0;   
           acc4 += x1 * c0;   
           acc5 += x2 * c0;   
           acc6 += x3 * c0;   
           acc7 += x4 * c0;   
  
           /* Read the b[numTaps-4] coefficient */
           c0 = *(pb++);
  
           /* Read x[n-numTaps-6] sample */
           x5 = *(px++);
  
           /* Perform the multiply-accumulates */      
           acc0 += x6 * c0;
           acc1 += x7 * c0;   
           acc2 += x0 * c0;   
           acc3 += x1 * c0;   
           acc4 += x2 * c0;   
           acc5 += x3 * c0;   
           acc6 += x4 * c0;   
           acc7 += x5 * c0;   
  
           /* Read the b[numTaps-4] coefficient */
           c0 = *(pb++);
  
           /* Read x[n-numTaps-6] sample */
           x6 = *(px++);
  
           /* Perform the multiply-accumulates */      
           acc0 += x7 * c0;
           acc1 += x0 * c0;   
           acc2 += x1 * c0;   
           acc3 += x2 * c0;   
           acc4 += x3 * c0;   
           acc5 += x4 * c0;   
           acc6 += x5 * c0;   
           acc7 += x6 * c0;   
  
           tapCnt--;
        }
  
        /* If the filter length is not a multiple of 8, compute the remaining filter taps */
        tapCnt = numTaps % 0x8u;
  
        while(tapCnt > 0u)
        {
           /* Read coefficients */
           c0 = *(pb++);
  
           /* Fetch 1 state variable */
           x7 = *(px++);
  
           /* Perform the multiply-accumulates */      
           acc0 += x0 * c0;
           acc1 += x1 * c0;   
           acc2 += x2 * c0;   
           acc3 += x3 * c0;   
           acc4 += x4 * c0;   
           acc5 += x5 * c0;   
           acc6 += x6 * c0;   
           acc7 += x7 * c0;   
  
           /* Reuse the present sample states for next sample */
           x0 = x1;
           x1 = x2;
           x2 = x3;
           x3 = x4;
           x4 = x5;
           x5 = x6;
           x6 = x7;
  
           /* Decrement the loop counter */
           tapCnt--;
        }
  
        /* Advance the state pointer by 8 to process the next group of 8 samples */
        pState = pState + 8;
  
        /* The results in the 8 accumulators, store in the destination buffer. */
        *pDst++ = acc0;
        *pDst++ = acc1;
        *pDst++ = acc2;
        *pDst++ = acc3;
        *pDst++ = acc4;
        *pDst++ = acc5;
        *pDst++ = acc6;
        *pDst++ = acc7;
  
        blkCnt--;
     }
  
     /* If the blockSize is not a multiple of 8, compute any remaining output samples here.  
     ** No loop unrolling is used. */
     blkCnt = blockSize % 0x8u;
  
     while(blkCnt > 0u)
     {
        /* Copy one sample at a time into state buffer */
        *pStateCurnt++ = *pSrc++;
  
        /* Set the accumulator to zero */
        acc0 = 0.0f;
  
        /* Initialize state pointer */
        px = pState;
  
        /* Initialize Coefficient pointer */
        pb = (pCoeffs);
  
        i = numTaps;
  
        /* Perform the multiply-accumulates */
        do
        {
           acc0 += *px++ * *pb++;
           i--;
  
        } while(i > 0u);
  
        /* The result is store in the destination buffer. */
        *pDst++ = acc0;
  
        /* Advance state pointer by 1 for the next sample */
        pState = pState + 1;
  
        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;
  
     tapCnt = (numTaps - 1u) >> 2u;
  
     /* copy data */
     while(tapCnt > 0u)
     {
        *pStateCurnt++ = *pState++;
        *pStateCurnt++ = *pState++;
        *pStateCurnt++ = *pState++;
        *pStateCurnt++ = *pState++;
  
        /* Decrement the loop counter */
        tapCnt--;
     }
  
     /* Calculate remaining number of copies */
     tapCnt = (numTaps - 1u) % 0x4u;
  
     /* Copy the remaining q31_t data */
     while(tapCnt > 0u)
     {
        *pStateCurnt++ = *pState++;
  
        /* Decrement the loop counter */
        tapCnt--;
     }
  }
  
  #elif defined(ARM_MATH_CM0_FAMILY)
  
  void arm_fir_f32(
  const arm_fir_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 */
     uint32_t numTaps = S->numTaps;                 /* Number of filter coefficients in the filter */
     uint32_t i, tapCnt, blkCnt;                    /* Loop counters */
  
     /* Run the below code for Cortex-M0 */
  
     float32_t acc;
  
     /* S->pState points to state array which contains previous frame (numTaps - 1) samples */
     /* pStateCurnt points to the location where the new input data should be written */
     pStateCurnt = &(S->pState[(numTaps - 1u)]);
  
     /* Initialize blkCnt with blockSize */
     blkCnt = blockSize;
  
     while(blkCnt > 0u)
     {
        /* Copy one sample at a time into state buffer */
        *pStateCurnt++ = *pSrc++;
  
        /* Set the accumulator to zero */
        acc = 0.0f;
  
        /* Initialize state pointer */
        px = pState;
  
        /* Initialize Coefficient pointer */
        pb = pCoeffs;
  
        i = numTaps;
  
        /* Perform the multiply-accumulates */
        do
        {
           /* acc =  b[numTaps-1] * x[n-numTaps-1] + b[numTaps-2] * x[n-numTaps-2] + b[numTaps-3] * x[n-numTaps-3] +...+ b[0] * x[0] */
           acc += *px++ * *pb++;
           i--;
  
        } while(i > 0u);
  
        /* The result is store in the destination buffer. */
        *pDst++ = acc;
  
        /* Advance state pointer by 1 for the next sample */
        pState = pState + 1;
  
        blkCnt--;
     }
  
     /* Processing is complete.         
     ** Now copy the last numTaps - 1 samples to the starting 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 */
     tapCnt = numTaps - 1u;
  
     /* Copy data */
     while(tapCnt > 0u)
     {
        *pStateCurnt++ = *pState++;
  
        /* Decrement the loop counter */
        tapCnt--;
     }
  
  }
  
  #else
  
  /* Run the below code for Cortex-M4 and Cortex-M3 */
  
  void arm_fir_f32(
  const arm_fir_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 acc0, acc1, acc2, acc3, acc4, acc5, acc6, acc7;     /* Accumulators */
     float32_t x0, x1, x2, x3, x4, x5, x6, x7, 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;                    /* Loop counters */
     float32_t p0,p1,p2,p3,p4,p5,p6,p7;             /* Temporary product values */
  
     /* S->pState points to state array which contains previous frame (numTaps - 1) samples */
     /* pStateCurnt points to the location where the new input data should be written */
     pStateCurnt = &(S->pState[(numTaps - 1u)]);
  
     /* Apply loop unrolling and compute 8 output values simultaneously.  
      * The variables acc0 ... acc7 hold output values that are being computed:  
      *  
      *    acc0 =  b[numTaps-1] * x[n-numTaps-1] + b[numTaps-2] * x[n-numTaps-2] + b[numTaps-3] * x[n-numTaps-3] +...+ b[0] * x[0]  
      *    acc1 =  b[numTaps-1] * x[n-numTaps] +   b[numTaps-2] * x[n-numTaps-1] + b[numTaps-3] * x[n-numTaps-2] +...+ b[0] * x[1]  
      *    acc2 =  b[numTaps-1] * x[n-numTaps+1] + b[numTaps-2] * x[n-numTaps] +   b[numTaps-3] * x[n-numTaps-1] +...+ b[0] * x[2]  
      *    acc3 =  b[numTaps-1] * x[n-numTaps+2] + b[numTaps-2] * x[n-numTaps+1] + b[numTaps-3] * x[n-numTaps]   +...+ b[0] * x[3]  
      */
     blkCnt = blockSize >> 3;
  
     /* First part of the processing with loop unrolling.  Compute 8 outputs at a time.  
     ** a second loop below computes the remaining 1 to 7 samples. */
     while(blkCnt > 0u)
     {
        /* Copy four new input samples into the state buffer */
        *pStateCurnt++ = *pSrc++;
        *pStateCurnt++ = *pSrc++;
        *pStateCurnt++ = *pSrc++;
        *pStateCurnt++ = *pSrc++;
  
        /* Set all accumulators to zero */
        acc0 = 0.0f;
        acc1 = 0.0f;
        acc2 = 0.0f;
        acc3 = 0.0f;
        acc4 = 0.0f;
        acc5 = 0.0f;
        acc6 = 0.0f;
        acc7 = 0.0f;		
  
        /* Initialize state pointer */
        px = pState;
  
        /* Initialize coeff pointer */
        pb = (pCoeffs);		
     
        /* This is separated from the others to avoid 
         * a call to __aeabi_memmove which would be slower
         */
        *pStateCurnt++ = *pSrc++;
        *pStateCurnt++ = *pSrc++;
        *pStateCurnt++ = *pSrc++;
        *pStateCurnt++ = *pSrc++;
  
        /* Read the first seven samples from the state buffer:  x[n-numTaps], x[n-numTaps-1], x[n-numTaps-2] */
        x0 = *px++;
        x1 = *px++;
        x2 = *px++;
        x3 = *px++;
        x4 = *px++;
        x5 = *px++;
        x6 = *px++;
  
        /* Loop unrolling.  Process 8 taps at a time. */
        tapCnt = numTaps >> 3u;
        
        /* Loop over the number of taps.  Unroll by a factor of 8.  
         ** Repeat until we've computed numTaps-8 coefficients. */
        while(tapCnt > 0u)
        {
           /* Read the b[numTaps-1] coefficient */
           c0 = *(pb++);
  
           /* Read x[n-numTaps-3] sample */
           x7 = *(px++);
  
           /* acc0 +=  b[numTaps-1] * x[n-numTaps] */
           p0 = x0 * c0;
  
           /* acc1 +=  b[numTaps-1] * x[n-numTaps-1] */
           p1 = x1 * c0;
  
           /* acc2 +=  b[numTaps-1] * x[n-numTaps-2] */
           p2 = x2 * c0;
  
           /* acc3 +=  b[numTaps-1] * x[n-numTaps-3] */
           p3 = x3 * c0;
  
           /* acc4 +=  b[numTaps-1] * x[n-numTaps-4] */
           p4 = x4 * c0;
  
           /* acc1 +=  b[numTaps-1] * x[n-numTaps-5] */
           p5 = x5 * c0;
  
           /* acc2 +=  b[numTaps-1] * x[n-numTaps-6] */
           p6 = x6 * c0;
  
           /* acc3 +=  b[numTaps-1] * x[n-numTaps-7] */
           p7 = x7 * c0;
           
           /* Read the b[numTaps-2] coefficient */
           c0 = *(pb++);
  
           /* Read x[n-numTaps-4] sample */
           x0 = *(px++);
           
           acc0 += p0;
           acc1 += p1;
           acc2 += p2;
           acc3 += p3;
           acc4 += p4;
           acc5 += p5;
           acc6 += p6;
           acc7 += p7;
  
  
           /* Perform the multiply-accumulate */
           p0 = x1 * c0;
           p1 = x2 * c0;   
           p2 = x3 * c0;   
           p3 = x4 * c0;   
           p4 = x5 * c0;   
           p5 = x6 * c0;   
           p6 = x7 * c0;   
           p7 = x0 * c0;   
           
           /* Read the b[numTaps-3] coefficient */
           c0 = *(pb++);
  
           /* Read x[n-numTaps-5] sample */
           x1 = *(px++);
           
           acc0 += p0;
           acc1 += p1;
           acc2 += p2;
           acc3 += p3;
           acc4 += p4;
           acc5 += p5;
           acc6 += p6;
           acc7 += p7;
  
           /* Perform the multiply-accumulates */      
           p0 = x2 * c0;
           p1 = x3 * c0;   
           p2 = x4 * c0;   
           p3 = x5 * c0;   
           p4 = x6 * c0;   
           p5 = x7 * c0;   
           p6 = x0 * c0;   
           p7 = x1 * c0;   
  
           /* Read the b[numTaps-4] coefficient */
           c0 = *(pb++);
  
           /* Read x[n-numTaps-6] sample */
           x2 = *(px++);
           
           acc0 += p0;
           acc1 += p1;
           acc2 += p2;
           acc3 += p3;
           acc4 += p4;
           acc5 += p5;
           acc6 += p6;
           acc7 += p7;
  
           /* Perform the multiply-accumulates */      
           p0 = x3 * c0;
           p1 = x4 * c0;   
           p2 = x5 * c0;   
           p3 = x6 * c0;   
           p4 = x7 * c0;   
           p5 = x0 * c0;   
           p6 = x1 * c0;   
           p7 = x2 * c0;   
  
           /* Read the b[numTaps-4] coefficient */
           c0 = *(pb++);
  
           /* Read x[n-numTaps-6] sample */
           x3 = *(px++);
           
           acc0 += p0;
           acc1 += p1;
           acc2 += p2;
           acc3 += p3;
           acc4 += p4;
           acc5 += p5;
           acc6 += p6;
           acc7 += p7;
  
           /* Perform the multiply-accumulates */      
           p0 = x4 * c0;
           p1 = x5 * c0;   
           p2 = x6 * c0;   
           p3 = x7 * c0;   
           p4 = x0 * c0;   
           p5 = x1 * c0;   
           p6 = x2 * c0;   
           p7 = x3 * c0;   
  
           /* Read the b[numTaps-4] coefficient */
           c0 = *(pb++);
  
           /* Read x[n-numTaps-6] sample */
           x4 = *(px++);
           
           acc0 += p0;
           acc1 += p1;
           acc2 += p2;
           acc3 += p3;
           acc4 += p4;
           acc5 += p5;
           acc6 += p6;
           acc7 += p7;
  
           /* Perform the multiply-accumulates */      
           p0 = x5 * c0;
           p1 = x6 * c0;   
           p2 = x7 * c0;   
           p3 = x0 * c0;   
           p4 = x1 * c0;   
           p5 = x2 * c0;   
           p6 = x3 * c0;   
           p7 = x4 * c0;   
  
           /* Read the b[numTaps-4] coefficient */
           c0 = *(pb++);
  
           /* Read x[n-numTaps-6] sample */
           x5 = *(px++);
           
           acc0 += p0;
           acc1 += p1;
           acc2 += p2;
           acc3 += p3;
           acc4 += p4;
           acc5 += p5;
           acc6 += p6;
           acc7 += p7;
  
           /* Perform the multiply-accumulates */      
           p0 = x6 * c0;
           p1 = x7 * c0;   
           p2 = x0 * c0;   
           p3 = x1 * c0;   
           p4 = x2 * c0;   
           p5 = x3 * c0;   
           p6 = x4 * c0;   
           p7 = x5 * c0;   
  
           /* Read the b[numTaps-4] coefficient */
           c0 = *(pb++);
  
           /* Read x[n-numTaps-6] sample */
           x6 = *(px++);
           
           acc0 += p0;
           acc1 += p1;
           acc2 += p2;
           acc3 += p3;
           acc4 += p4;
           acc5 += p5;
           acc6 += p6;
           acc7 += p7;
  
           /* Perform the multiply-accumulates */      
           p0 = x7 * c0;
           p1 = x0 * c0;   
           p2 = x1 * c0;   
           p3 = x2 * c0;   
           p4 = x3 * c0;   
           p5 = x4 * c0;   
           p6 = x5 * c0;   
           p7 = x6 * c0;   
  
           tapCnt--;
           
           acc0 += p0;
           acc1 += p1;
           acc2 += p2;
           acc3 += p3;
           acc4 += p4;
           acc5 += p5;
           acc6 += p6;
           acc7 += p7;
        }
  
        /* If the filter length is not a multiple of 8, compute the remaining filter taps */
        tapCnt = numTaps % 0x8u;
  
        while(tapCnt > 0u)
        {
           /* Read coefficients */
           c0 = *(pb++);
  
           /* Fetch 1 state variable */
           x7 = *(px++);
  
           /* Perform the multiply-accumulates */      
           p0 = x0 * c0;
           p1 = x1 * c0;   
           p2 = x2 * c0;   
           p3 = x3 * c0;   
           p4 = x4 * c0;   
           p5 = x5 * c0;   
           p6 = x6 * c0;   
           p7 = x7 * c0;   
  
           /* Reuse the present sample states for next sample */
           x0 = x1;
           x1 = x2;
           x2 = x3;
           x3 = x4;
           x4 = x5;
           x5 = x6;
           x6 = x7;
           
           acc0 += p0;
           acc1 += p1;
           acc2 += p2;
           acc3 += p3;
           acc4 += p4;
           acc5 += p5;
           acc6 += p6;
           acc7 += p7;
  
           /* Decrement the loop counter */
           tapCnt--;
        }
  
        /* Advance the state pointer by 8 to process the next group of 8 samples */
        pState = pState + 8;
  
        /* The results in the 8 accumulators, store in the destination buffer. */
        *pDst++ = acc0;
        *pDst++ = acc1;
        *pDst++ = acc2;
        *pDst++ = acc3;
        *pDst++ = acc4;
        *pDst++ = acc5;
        *pDst++ = acc6;
        *pDst++ = acc7;
  
        blkCnt--;
     }
  
     /* If the blockSize is not a multiple of 8, compute any remaining output samples here.  
     ** No loop unrolling is used. */
     blkCnt = blockSize % 0x8u;
  
     while(blkCnt > 0u)
     {
        /* Copy one sample at a time into state buffer */
        *pStateCurnt++ = *pSrc++;
  
        /* Set the accumulator to zero */
        acc0 = 0.0f;
  
        /* Initialize state pointer */
        px = pState;
  
        /* Initialize Coefficient pointer */
        pb = (pCoeffs);
  
        i = numTaps;
  
        /* Perform the multiply-accumulates */
        do
        {
           acc0 += *px++ * *pb++;
           i--;
  
        } while(i > 0u);
  
        /* The result is store in the destination buffer. */
        *pDst++ = acc0;
  
        /* Advance state pointer by 1 for the next sample */
        pState = pState + 1;
  
        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;
  
     tapCnt = (numTaps - 1u) >> 2u;
  
     /* copy data */
     while(tapCnt > 0u)
     {
        *pStateCurnt++ = *pState++;
        *pStateCurnt++ = *pState++;
        *pStateCurnt++ = *pState++;
        *pStateCurnt++ = *pState++;
  
        /* Decrement the loop counter */
        tapCnt--;
     }
  
     /* Calculate remaining number of copies */
     tapCnt = (numTaps - 1u) % 0x4u;
  
     /* Copy the remaining q31_t data */
     while(tapCnt > 0u)
     {
        *pStateCurnt++ = *pState++;
  
        /* Decrement the loop counter */
        tapCnt--;
     }
  }
  
  #endif 
  
  /**  
  * @} end of FIR group  
  */
  