text: /* ----------------------------------------------------------------------    
  * Copyright (C) 2010 ARM Limited. All rights reserved.    
  *    
  * $Date: 14/06/07 1:57a $Revision: 	V1.1.0  
  *    
  * Project: 	    CMSIS DSP Library    
  * Title:	    arm_lms_norm_q15.c    
  *    
  * Description:	Q15 NLMS filter.    
  *    
  * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
  *  
  * Version 1.1.0 2012/02/15 
  *    Updated with more optimizations, bug fixes and minor API changes.  
  *   
  * Version 1.0.10 2011/7/15  
  *    Big Endian support added and Merged M0 and M3/M4 Source code.   
  *    
  * Version 1.0.3 2010/11/29   
  *    Re-organized the CMSIS folders and updated documentation.    
  *     
  * Version 1.0.2 2010/11/11    
  *    Documentation updated.     
  *    
  * Version 1.0.1 2010/10/05     
  *    Production release and review comments incorporated.    
  *    
  * Version 1.0.0 2010/09/20     
  *    Production release and review comments incorporated    
  *    
  * Version 0.0.7  2010/06/10     
  *    Misra-C changes done    
  * -------------------------------------------------------------------- */
  
  #include "arm_math.h"
  
  /**    
   * @ingroup groupFilters    
   */
  
  /**    
   * @addtogroup LMS_NORM    
   * @{    
   */
  
  /**    
  * @brief Processing function for Q15 normalized LMS filter.    
  * @param[in] *S points to an instance of the Q15 normalized LMS filter structure.    
  * @param[in] *pSrc points to the block of input data.    
  * @param[in] *pRef points to the block of reference data.    
  * @param[out] *pOut points to the block of output data.    
  * @param[out] *pErr points to the block of error data.    
  * @param[in] blockSize number of samples to process.    
  * @return none.    
  *    
  * <b>Scaling and Overflow Behavior:</b>     
  * \par     
  * The function is implemented using a 64-bit internal accumulator.     
  * Both coefficients and state variables are represented in 1.15 format and    
  * multiplications yield a 2.30 result. The 2.30 intermediate results are    
  * accumulated in a 64-bit accumulator in 34.30 format.     
  * There is no risk of internal overflow with this approach and the full    
  * precision of intermediate multiplications is preserved. After all additions    
  * have been performed, the accumulator is truncated to 34.15 format by    
  * discarding low 15 bits. Lastly, the accumulator is saturated to yield a    
  * result in 1.15 format.    
  *    
  * \par   
  * 	In this filter, filter coefficients are updated for each sample and the updation of filter cofficients are saturted.    
  *    
   */
  
  void arm_lms_norm_q15(
    arm_lms_norm_instance_q15 * S,
    q15_t * pSrc,
    q15_t * pRef,
    q15_t * pOut,
    q15_t * pErr,
    uint32_t blockSize)
  {
    q15_t *pState = S->pState;                     /* State pointer */
    q15_t *pCoeffs = S->pCoeffs;                   /* Coefficient pointer */
    q15_t *pStateCurnt;                            /* Points to the current sample of the state */
    q15_t *px, *pb;                                /* Temporary pointers for state and coefficient buffers */
    q15_t mu = S->mu;                              /* Adaptive factor */
    uint32_t numTaps = S->numTaps;                 /* Number of filter coefficients in the filter */
    uint32_t tapCnt, blkCnt;                       /* Loop counters */
    q31_t energy;                                  /* Energy of the input */
    q63_t acc;                                     /* Accumulator */
    q15_t e = 0, d = 0;                            /* error, reference data sample */
    q15_t w = 0, in;                               /* weight factor and state */
    q15_t x0;                                      /* temporary variable to hold input sample */
    //uint32_t shift = (uint32_t) S->postShift + 1u; /* Shift to be applied to the output */ 
    q15_t errorXmu, oneByEnergy;                   /* Temporary variables to store error and mu product and reciprocal of energy */
    q15_t postShift;                               /* Post shift to be applied to weight after reciprocal calculation */
    q31_t coef;                                    /* Teporary variable for coefficient */
    q31_t acc_l, acc_h;
    int32_t lShift = (15 - (int32_t) S->postShift);       /*  Post shift  */
    int32_t uShift = (32 - lShift);
  
    energy = S->energy;
    x0 = S->x0;
  
    /* S->pState points to buffer 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)]);
  
    /* Loop over blockSize number of values */
    blkCnt = blockSize;
  
  
  #ifndef ARM_MATH_CM0
  
    /* Run the below code for Cortex-M4 and Cortex-M3 */
  
    while(blkCnt > 0u)
    {
      /* Copy the new input sample into the state buffer */
      *pStateCurnt++ = *pSrc;
  
      /* Initialize pState pointer */
      px = pState;
  
      /* Initialize coeff pointer */
      pb = (pCoeffs);
  
      /* Read the sample from input buffer */
      in = *pSrc++;
  
      /* Update the energy calculation */
      energy -= (((q31_t) x0 * (x0)) >> 15);
      energy += (((q31_t) in * (in)) >> 15);
  
      /* Set the accumulator to zero */
      acc = 0;
  
      /* Loop unrolling.  Process 4 taps at a time. */
      tapCnt = numTaps >> 2;
  
      while(tapCnt > 0u)
      {
  
        /* Perform the multiply-accumulate */
  #ifndef UNALIGNED_SUPPORT_DISABLE
  
        acc = __SMLALD(*__SIMD32(px)++, (*__SIMD32(pb)++), acc);
        acc = __SMLALD(*__SIMD32(px)++, (*__SIMD32(pb)++), acc);
  
  #else
  
        acc += (((q31_t) * px++ * (*pb++)));
        acc += (((q31_t) * px++ * (*pb++)));
        acc += (((q31_t) * px++ * (*pb++)));
        acc += (((q31_t) * px++ * (*pb++)));
  
  #endif	/*	#ifndef UNALIGNED_SUPPORT_DISABLE	*/
  
        /* 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)
      {
        /* Perform the multiply-accumulate */
        acc += (((q31_t) * px++ * (*pb++)));
  
        /* Decrement the loop counter */
        tapCnt--;
      }
  
      /* Calc lower part of acc */
      acc_l = acc & 0xffffffff;
  
      /* Calc upper part of acc */
      acc_h = (acc >> 32) & 0xffffffff;
  
      /* Apply shift for lower part of acc and upper part of acc */
      acc = (uint32_t) acc_l >> lShift | acc_h << uShift;
  
      /* Converting the result to 1.15 format and saturate the output */
      acc = __SSAT(acc, 16u);
  
      /* Store the result from accumulator into the destination buffer. */
      *pOut++ = (q15_t) acc;
  
      /* Compute and store error */
      d = *pRef++;
      e = d - (q15_t) acc;
      *pErr++ = e;
  
      /* Calculation of 1/energy */
      postShift = arm_recip_q15((q15_t) energy + DELTA_Q15,
                                &oneByEnergy, S->recipTable);
  
      /* Calculation of e * mu value */
      errorXmu = (q15_t) (((q31_t) e * mu) >> 15);
  
      /* Calculation of (e * mu) * (1/energy) value */
      acc = (((q31_t) errorXmu * oneByEnergy) >> (15 - postShift));
  
      /* Weighting factor for the normalized version */
      w = (q15_t) __SSAT((q31_t) acc, 16);
  
      /* Initialize pState pointer */
      px = pState;
  
      /* Initialize coeff pointer */
      pb = (pCoeffs);
  
      /* Loop unrolling.  Process 4 taps at a time. */
      tapCnt = numTaps >> 2;
  
      /* Update filter coefficients */
      while(tapCnt > 0u)
      {
        coef = *pb + (((q31_t) w * (*px++)) >> 15);
        *pb++ = (q15_t) __SSAT((coef), 16);
        coef = *pb + (((q31_t) w * (*px++)) >> 15);
        *pb++ = (q15_t) __SSAT((coef), 16);
        coef = *pb + (((q31_t) w * (*px++)) >> 15);
        *pb++ = (q15_t) __SSAT((coef), 16);
        coef = *pb + (((q31_t) w * (*px++)) >> 15);
        *pb++ = (q15_t) __SSAT((coef), 16);
  
        /* 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)
      {
        /* Perform the multiply-accumulate */
        coef = *pb + (((q31_t) w * (*px++)) >> 15);
        *pb++ = (q15_t) __SSAT((coef), 16);
  
        /* Decrement the loop counter */
        tapCnt--;
      }
  
      /* Read the sample from state buffer */
      x0 = *pState;
  
      /* Advance state pointer by 1 for the next sample */
      pState = pState + 1u;
  
      /* Decrement the loop counter */
      blkCnt--;
    }
  
    /* Save energy and x0 values for the next frame */
    S->energy = (q15_t) energy;
    S->x0 = x0;
  
    /* 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 pState buffer */
    pStateCurnt = S->pState;
  
    /* Calculation of count for copying integer writes */
    tapCnt = (numTaps - 1u) >> 2;
  
    while(tapCnt > 0u)
    {
  
  #ifndef UNALIGNED_SUPPORT_DISABLE
  
      *__SIMD32(pStateCurnt)++ = *__SIMD32(pState)++;
      *__SIMD32(pStateCurnt)++ = *__SIMD32(pState)++;
  
  #else
  
      *pStateCurnt++ = *pState++;
      *pStateCurnt++ = *pState++;
      *pStateCurnt++ = *pState++;
      *pStateCurnt++ = *pState++;
  
  #endif
  
      tapCnt--;
  
    }
  
    /* Calculation of count for remaining q15_t data */
    tapCnt = (numTaps - 1u) % 0x4u;
  
    /* copy data */
    while(tapCnt > 0u)
    {
      *pStateCurnt++ = *pState++;
  
      /* Decrement the loop counter */
      tapCnt--;
    }
  
  #else
  
    /* Run the below code for Cortex-M0 */
  
    while(blkCnt > 0u)
    {
      /* Copy the new input sample into the state buffer */
      *pStateCurnt++ = *pSrc;
  
      /* Initialize pState pointer */
      px = pState;
  
      /* Initialize pCoeffs pointer */
      pb = pCoeffs;
  
      /* Read the sample from input buffer */
      in = *pSrc++;
  
      /* Update the energy calculation */
      energy -= (((q31_t) x0 * (x0)) >> 15);
      energy += (((q31_t) in * (in)) >> 15);
  
      /* Set the accumulator to zero */
      acc = 0;
  
      /* Loop over numTaps number of values */
      tapCnt = numTaps;
  
      while(tapCnt > 0u)
      {
        /* Perform the multiply-accumulate */
        acc += (((q31_t) * px++ * (*pb++)));
  
        /* Decrement the loop counter */
        tapCnt--;
      }
  
      /* Calc lower part of acc */
      acc_l = acc & 0xffffffff;
  
      /* Calc upper part of acc */
      acc_h = (acc >> 32) & 0xffffffff;
  
      /* Apply shift for lower part of acc and upper part of acc */
      acc = (uint32_t) acc_l >> lShift | acc_h << uShift;
  
      /* Converting the result to 1.15 format and saturate the output */
      acc = __SSAT(acc, 16u);
  
      /* Converting the result to 1.15 format */
      //acc = __SSAT((acc >> (16u - shift)), 16u); 
  
      /* Store the result from accumulator into the destination buffer. */
      *pOut++ = (q15_t) acc;
  
      /* Compute and store error */
      d = *pRef++;
      e = d - (q15_t) acc;
      *pErr++ = e;
  
      /* Calculation of 1/energy */
      postShift = arm_recip_q15((q15_t) energy + DELTA_Q15,
                                &oneByEnergy, S->recipTable);
  
      /* Calculation of e * mu value */
      errorXmu = (q15_t) (((q31_t) e * mu) >> 15);
  
      /* Calculation of (e * mu) * (1/energy) value */
      acc = (((q31_t) errorXmu * oneByEnergy) >> (15 - postShift));
  
      /* Weighting factor for the normalized version */
      w = (q15_t) __SSAT((q31_t) acc, 16);
  
      /* Initialize pState pointer */
      px = pState;
  
      /* Initialize coeff pointer */
      pb = (pCoeffs);
  
      /* Loop over numTaps number of values */
      tapCnt = numTaps;
  
      while(tapCnt > 0u)
      {
        /* Perform the multiply-accumulate */
        coef = *pb + (((q31_t) w * (*px++)) >> 15);
        *pb++ = (q15_t) __SSAT((coef), 16);
  
        /* Decrement the loop counter */
        tapCnt--;
      }
  
      /* Read the sample from state buffer */
      x0 = *pState;
  
      /* Advance state pointer by 1 for the next sample */
      pState = pState + 1u;
  
      /* Decrement the loop counter */
      blkCnt--;
    }
  
    /* Save energy and x0 values for the next frame */
    S->energy = (q15_t) energy;
    S->x0 = x0;
  
    /* 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 pState buffer */
    pStateCurnt = S->pState;
  
    /* copy (numTaps - 1u) data */
    tapCnt = (numTaps - 1u);
  
    /* copy data */
    while(tapCnt > 0u)
    {
      *pStateCurnt++ = *pState++;
  
      /* Decrement the loop counter */
      tapCnt--;
    }
  
  #endif /*   #ifndef ARM_MATH_CM0 */
  
  }
  
  
  /**    
     * @} end of LMS_NORM group    
     */
  