/* ----------------------------------------------------------------------
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* Copyright (C) 2010-2014 ARM Limited. All rights reserved.
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*
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* $Date: 19. March 2015
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* $Revision: V.1.4.5
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*
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* Project: CMSIS DSP Library
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* Title: arm_lms_q15.c
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*
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* Description: Processing function for the Q15 LMS filter.
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*
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* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* - Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* - Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* - Neither the name of ARM LIMITED nor the names of its contributors
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* may be used to endorse or promote products derived from this
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* software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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* -------------------------------------------------------------------- */
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#include "arm_math.h"
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/**
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* @ingroup groupFilters
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*/
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/**
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* @addtogroup LMS
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* @{
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*/
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/**
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* @brief Processing function for Q15 LMS filter.
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* @param[in] *S points to an instance of the Q15 LMS filter structure.
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* @param[in] *pSrc points to the block of input data.
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* @param[in] *pRef points to the block of reference data.
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* @param[out] *pOut points to the block of output data.
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* @param[out] *pErr points to the block of error data.
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* @param[in] blockSize number of samples to process.
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* @return none.
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*
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* \par Scaling and Overflow Behavior:
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* The function is implemented using a 64-bit internal accumulator.
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* Both coefficients and state variables are represented in 1.15 format and multiplications yield a 2.30 result.
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* The 2.30 intermediate results are accumulated in a 64-bit accumulator in 34.30 format.
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* There is no risk of internal overflow with this approach and the full precision of intermediate multiplications is preserved.
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* After all additions have been performed, the accumulator is truncated to 34.15 format by discarding low 15 bits.
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* Lastly, the accumulator is saturated to yield a result in 1.15 format.
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*
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* \par
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* In this filter, filter coefficients are updated for each sample and the updation of filter cofficients are saturted.
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*
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*/
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void arm_lms_q15(
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const arm_lms_instance_q15 * S,
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q15_t * pSrc,
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q15_t * pRef,
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q15_t * pOut,
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q15_t * pErr,
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uint32_t blockSize)
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{
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q15_t *pState = S->pState; /* State pointer */
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uint32_t numTaps = S->numTaps; /* Number of filter coefficients in the filter */
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q15_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */
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q15_t *pStateCurnt; /* Points to the current sample of the state */
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q15_t mu = S->mu; /* Adaptive factor */
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q15_t *px; /* Temporary pointer for state */
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q15_t *pb; /* Temporary pointer for coefficient buffer */
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uint32_t tapCnt, blkCnt; /* Loop counters */
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q63_t acc; /* Accumulator */
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q15_t e = 0; /* error of data sample */
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q15_t alpha; /* Intermediate constant for taps update */
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q31_t coef; /* Teporary variable for coefficient */
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q31_t acc_l, acc_h;
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int32_t lShift = (15 - (int32_t) S->postShift); /* Post shift */
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int32_t uShift = (32 - lShift);
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#ifndef ARM_MATH_CM0_FAMILY
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/* Run the below code for Cortex-M4 and Cortex-M3 */
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/* S->pState points to buffer which contains previous frame (numTaps - 1) samples */
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/* pStateCurnt points to the location where the new input data should be written */
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pStateCurnt = &(S->pState[(numTaps - 1u)]);
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/* Initializing blkCnt with blockSize */
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blkCnt = blockSize;
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while(blkCnt > 0u)
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{
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/* Copy the new input sample into the state buffer */
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*pStateCurnt++ = *pSrc++;
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/* Initialize state pointer */
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px = pState;
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/* Initialize coefficient pointer */
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pb = pCoeffs;
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/* Set the accumulator to zero */
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acc = 0;
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/* Loop unrolling. Process 4 taps at a time. */
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tapCnt = numTaps >> 2u;
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while(tapCnt > 0u)
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{
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/* acc += b[N] * x[n-N] + b[N-1] * x[n-N-1] */
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/* Perform the multiply-accumulate */
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#ifndef UNALIGNED_SUPPORT_DISABLE
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acc = __SMLALD(*__SIMD32(px)++, (*__SIMD32(pb)++), acc);
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acc = __SMLALD(*__SIMD32(px)++, (*__SIMD32(pb)++), acc);
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#else
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acc += (q63_t) (((q31_t) (*px++) * (*pb++)));
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acc += (q63_t) (((q31_t) (*px++) * (*pb++)));
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acc += (q63_t) (((q31_t) (*px++) * (*pb++)));
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acc += (q63_t) (((q31_t) (*px++) * (*pb++)));
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#endif /* #ifndef UNALIGNED_SUPPORT_DISABLE */
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/* Decrement the loop counter */
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tapCnt--;
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}
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/* If the filter length is not a multiple of 4, compute the remaining filter taps */
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tapCnt = numTaps % 0x4u;
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while(tapCnt > 0u)
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{
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/* Perform the multiply-accumulate */
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acc += (q63_t) (((q31_t) (*px++) * (*pb++)));
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/* Decrement the loop counter */
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tapCnt--;
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}
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/* Calc lower part of acc */
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acc_l = acc & 0xffffffff;
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/* Calc upper part of acc */
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acc_h = (acc >> 32) & 0xffffffff;
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/* Apply shift for lower part of acc and upper part of acc */
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acc = (uint32_t) acc_l >> lShift | acc_h << uShift;
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/* Converting the result to 1.15 format and saturate the output */
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acc = __SSAT(acc, 16);
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/* Store the result from accumulator into the destination buffer. */
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*pOut++ = (q15_t) acc;
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/* Compute and store error */
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e = *pRef++ - (q15_t) acc;
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*pErr++ = (q15_t) e;
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/* Compute alpha i.e. intermediate constant for taps update */
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alpha = (q15_t) (((q31_t) e * (mu)) >> 15);
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/* Initialize state pointer */
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/* Advance state pointer by 1 for the next sample */
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px = pState++;
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/* Initialize coefficient pointer */
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pb = pCoeffs;
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/* Loop unrolling. Process 4 taps at a time. */
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tapCnt = numTaps >> 2u;
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/* Update filter coefficients */
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while(tapCnt > 0u)
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{
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coef = (q31_t) * pb + (((q31_t) alpha * (*px++)) >> 15);
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*pb++ = (q15_t) __SSAT((coef), 16);
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coef = (q31_t) * pb + (((q31_t) alpha * (*px++)) >> 15);
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*pb++ = (q15_t) __SSAT((coef), 16);
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coef = (q31_t) * pb + (((q31_t) alpha * (*px++)) >> 15);
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*pb++ = (q15_t) __SSAT((coef), 16);
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coef = (q31_t) * pb + (((q31_t) alpha * (*px++)) >> 15);
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*pb++ = (q15_t) __SSAT((coef), 16);
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/* Decrement the loop counter */
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tapCnt--;
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}
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/* If the filter length is not a multiple of 4, compute the remaining filter taps */
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tapCnt = numTaps % 0x4u;
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while(tapCnt > 0u)
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{
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/* Perform the multiply-accumulate */
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coef = (q31_t) * pb + (((q31_t) alpha * (*px++)) >> 15);
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*pb++ = (q15_t) __SSAT((coef), 16);
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/* Decrement the loop counter */
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tapCnt--;
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}
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/* Decrement the loop counter */
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blkCnt--;
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}
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/* Processing is complete. Now copy the last numTaps - 1 samples to the
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satrt of the state buffer. This prepares the state buffer for the
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next function call. */
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/* Points to the start of the pState buffer */
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pStateCurnt = S->pState;
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/* Calculation of count for copying integer writes */
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tapCnt = (numTaps - 1u) >> 2;
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while(tapCnt > 0u)
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{
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#ifndef UNALIGNED_SUPPORT_DISABLE
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*__SIMD32(pStateCurnt)++ = *__SIMD32(pState)++;
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*__SIMD32(pStateCurnt)++ = *__SIMD32(pState)++;
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#else
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*pStateCurnt++ = *pState++;
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*pStateCurnt++ = *pState++;
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*pStateCurnt++ = *pState++;
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*pStateCurnt++ = *pState++;
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#endif
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tapCnt--;
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}
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/* Calculation of count for remaining q15_t data */
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tapCnt = (numTaps - 1u) % 0x4u;
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/* copy data */
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while(tapCnt > 0u)
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{
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*pStateCurnt++ = *pState++;
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/* Decrement the loop counter */
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tapCnt--;
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}
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#else
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/* Run the below code for Cortex-M0 */
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/* S->pState points to buffer which contains previous frame (numTaps - 1) samples */
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/* pStateCurnt points to the location where the new input data should be written */
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pStateCurnt = &(S->pState[(numTaps - 1u)]);
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/* Loop over blockSize number of values */
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blkCnt = blockSize;
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while(blkCnt > 0u)
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{
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/* Copy the new input sample into the state buffer */
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*pStateCurnt++ = *pSrc++;
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/* Initialize pState pointer */
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px = pState;
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/* Initialize pCoeffs pointer */
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pb = pCoeffs;
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/* Set the accumulator to zero */
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acc = 0;
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/* Loop over numTaps number of values */
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tapCnt = numTaps;
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while(tapCnt > 0u)
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{
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/* Perform the multiply-accumulate */
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acc += (q63_t) ((q31_t) (*px++) * (*pb++));
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/* Decrement the loop counter */
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tapCnt--;
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}
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/* Calc lower part of acc */
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acc_l = acc & 0xffffffff;
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/* Calc upper part of acc */
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acc_h = (acc >> 32) & 0xffffffff;
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/* Apply shift for lower part of acc and upper part of acc */
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acc = (uint32_t) acc_l >> lShift | acc_h << uShift;
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/* Converting the result to 1.15 format and saturate the output */
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acc = __SSAT(acc, 16);
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/* Store the result from accumulator into the destination buffer. */
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*pOut++ = (q15_t) acc;
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/* Compute and store error */
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e = *pRef++ - (q15_t) acc;
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*pErr++ = (q15_t) e;
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/* Compute alpha i.e. intermediate constant for taps update */
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alpha = (q15_t) (((q31_t) e * (mu)) >> 15);
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/* Initialize pState pointer */
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/* Advance state pointer by 1 for the next sample */
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px = pState++;
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/* Initialize pCoeffs pointer */
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pb = pCoeffs;
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/* Loop over numTaps number of values */
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tapCnt = numTaps;
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while(tapCnt > 0u)
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{
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/* Perform the multiply-accumulate */
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coef = (q31_t) * pb + (((q31_t) alpha * (*px++)) >> 15);
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*pb++ = (q15_t) __SSAT((coef), 16);
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/* Decrement the loop counter */
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tapCnt--;
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}
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/* Decrement the loop counter */
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blkCnt--;
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}
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/* Processing is complete. Now copy the last numTaps - 1 samples to the
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start of the state buffer. This prepares the state buffer for the
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next function call. */
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/* Points to the start of the pState buffer */
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pStateCurnt = S->pState;
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/* Copy (numTaps - 1u) samples */
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tapCnt = (numTaps - 1u);
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/* Copy the data */
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while(tapCnt > 0u)
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{
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*pStateCurnt++ = *pState++;
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/* Decrement the loop counter */
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tapCnt--;
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}
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#endif /* #ifndef ARM_MATH_CM0_FAMILY */
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}
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/**
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* @} end of LMS group
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*/
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