420 lines
12 KiB
C
420 lines
12 KiB
C
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/* ----------------------------------------------------------------------
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* Project: CMSIS DSP Library
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* Title: arm_lms_norm_q31.c
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* Description: Processing function for the Q31 NLMS filter
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*
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* $Date: 27. January 2017
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* $Revision: V.1.5.1
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*
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* Target Processor: Cortex-M cores
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* -------------------------------------------------------------------- */
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/*
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* Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved.
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 (the License); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an AS IS BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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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_NORM
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* @{
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*/
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/**
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* @brief Processing function for Q31 normalized LMS filter.
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* @param[in] *S points to an instance of the Q31 normalized 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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* <b>Scaling and Overflow Behavior:</b>
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* \par
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* The function is implemented using an internal 64-bit accumulator.
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* The accumulator has a 2.62 format and maintains full precision of the intermediate
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* multiplication results but provides only a single guard bit.
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* Thus, if the accumulator result overflows it wraps around rather than clip.
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* In order to avoid overflows completely the input signal must be scaled down by
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* log2(numTaps) bits. The reference signal should not be scaled down.
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* After all multiply-accumulates are performed, the 2.62 accumulator is shifted
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* and saturated to 1.31 format to yield the final result.
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* The output signal and error signal are in 1.31 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
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* updation of filter cofficients are saturted.
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*
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*/
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void arm_lms_norm_q31(
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arm_lms_norm_instance_q31 * S,
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q31_t * pSrc,
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q31_t * pRef,
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q31_t * pOut,
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q31_t * pErr,
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uint32_t blockSize)
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{
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q31_t *pState = S->pState; /* State pointer */
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q31_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */
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q31_t *pStateCurnt; /* Points to the current sample of the state */
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q31_t *px, *pb; /* Temporary pointers for state and coefficient buffers */
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q31_t mu = S->mu; /* Adaptive factor */
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uint32_t numTaps = S->numTaps; /* Number of filter coefficients in the filter */
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uint32_t tapCnt, blkCnt; /* Loop counters */
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q63_t energy; /* Energy of the input */
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q63_t acc; /* Accumulator */
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q31_t e = 0, d = 0; /* error, reference data sample */
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q31_t w = 0, in; /* weight factor and state */
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q31_t x0; /* temporary variable to hold input sample */
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// uint32_t shift = 32U - ((uint32_t) S->postShift + 1U); /* Shift to be applied to the output */
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q31_t errorXmu, oneByEnergy; /* Temporary variables to store error and mu product and reciprocal of energy */
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q31_t postShift; /* Post shift to be applied to weight after reciprocal calculation */
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q31_t coef; /* Temporary variable for coef */
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q31_t acc_l, acc_h; /* temporary input */
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uint32_t uShift = ((uint32_t) S->postShift + 1U);
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uint32_t lShift = 32U - uShift; /* Shift to be applied to the output */
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energy = S->energy;
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x0 = S->x0;
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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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#if defined (ARM_MATH_DSP)
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/* Run the below code for Cortex-M4 and Cortex-M3 */
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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 coeff pointer */
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pb = (pCoeffs);
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/* Read the sample from input buffer */
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in = *pSrc++;
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/* Update the energy calculation */
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energy = (q31_t) ((((q63_t) energy << 32) -
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(((q63_t) x0 * x0) << 1)) >> 32);
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energy = (q31_t) (((((q63_t) in * in) << 1) + (energy << 32)) >> 32);
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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 >> 2;
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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) (*px++)) * (*pb++);
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acc += ((q63_t) (*px++)) * (*pb++);
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acc += ((q63_t) (*px++)) * (*pb++);
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acc += ((q63_t) (*px++)) * (*pb++);
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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) (*px++)) * (*pb++);
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/* Decrement the loop counter */
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tapCnt--;
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}
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/* Converting the result to 1.31 format */
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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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acc = (uint32_t) acc_l >> lShift | acc_h << uShift;
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/* Store the result from accumulator into the destination buffer. */
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*pOut++ = (q31_t) acc;
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/* Compute and store error */
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d = *pRef++;
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e = d - (q31_t) acc;
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*pErr++ = e;
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/* Calculates the reciprocal of energy */
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postShift = arm_recip_q31(energy + DELTA_Q31,
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&oneByEnergy, &S->recipTable[0]);
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/* Calculation of product of (e * mu) */
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errorXmu = (q31_t) (((q63_t) e * mu) >> 31);
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/* Weighting factor for the normalized version */
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w = clip_q63_to_q31(((q63_t) errorXmu * oneByEnergy) >> (31 - postShift));
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/* Initialize pState pointer */
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px = pState;
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/* Initialize coeff 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 >> 2;
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/* Update filter coefficients */
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while (tapCnt > 0U)
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{
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/* Perform the multiply-accumulate */
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/* coef is in 2.30 format */
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coef = (q31_t) (((q63_t) w * (*px++)) >> (32));
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/* get coef in 1.31 format by left shifting */
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*pb = clip_q63_to_q31((q63_t) * pb + (coef << 1U));
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/* update coefficient buffer to next coefficient */
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pb++;
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coef = (q31_t) (((q63_t) w * (*px++)) >> (32));
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*pb = clip_q63_to_q31((q63_t) * pb + (coef << 1U));
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pb++;
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coef = (q31_t) (((q63_t) w * (*px++)) >> (32));
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*pb = clip_q63_to_q31((q63_t) * pb + (coef << 1U));
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pb++;
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coef = (q31_t) (((q63_t) w * (*px++)) >> (32));
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*pb = clip_q63_to_q31((q63_t) * pb + (coef << 1U));
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pb++;
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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) (((q63_t) w * (*px++)) >> (32));
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*pb = clip_q63_to_q31((q63_t) * pb + (coef << 1U));
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pb++;
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/* Decrement the loop counter */
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tapCnt--;
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}
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/* Read the sample from state buffer */
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x0 = *pState;
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/* Advance state pointer by 1 for the next sample */
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pState = pState + 1;
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/* Decrement the loop counter */
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blkCnt--;
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}
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/* Save energy and x0 values for the next frame */
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S->energy = (q31_t) energy;
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S->x0 = x0;
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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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/* Loop unrolling for (numTaps - 1U) samples copy */
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tapCnt = (numTaps - 1U) >> 2U;
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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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*pStateCurnt++ = *pState++;
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*pStateCurnt++ = *pState++;
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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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/* Calculate remaining number of copies */
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tapCnt = (numTaps - 1U) % 0x4U;
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/* Copy the remaining q31_t 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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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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/* Read the sample from input buffer */
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in = *pSrc++;
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/* Update the energy calculation */
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energy =
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(q31_t) ((((q63_t) energy << 32) - (((q63_t) x0 * x0) << 1)) >> 32);
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energy = (q31_t) (((((q63_t) in * in) << 1) + (energy << 32)) >> 32);
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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) (*px++)) * (*pb++);
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/* Decrement the loop counter */
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tapCnt--;
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}
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/* Converting the result to 1.31 format */
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/* Converting the result to 1.31 format */
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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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acc = (uint32_t) acc_l >> lShift | acc_h << uShift;
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//acc = (q31_t) (acc >> shift);
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/* Store the result from accumulator into the destination buffer. */
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*pOut++ = (q31_t) acc;
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/* Compute and store error */
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d = *pRef++;
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e = d - (q31_t) acc;
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*pErr++ = e;
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/* Calculates the reciprocal of energy */
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postShift =
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arm_recip_q31(energy + DELTA_Q31, &oneByEnergy, &S->recipTable[0]);
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/* Calculation of product of (e * mu) */
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errorXmu = (q31_t) (((q63_t) e * mu) >> 31);
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/* Weighting factor for the normalized version */
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w = clip_q63_to_q31(((q63_t) errorXmu * oneByEnergy) >> (31 - postShift));
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/* Initialize pState pointer */
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px = pState;
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/* Initialize coeff 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 is in 2.30 format */
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coef = (q31_t) (((q63_t) w * (*px++)) >> (32));
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/* get coef in 1.31 format by left shifting */
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*pb = clip_q63_to_q31((q63_t) * pb + (coef << 1U));
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/* update coefficient buffer to next coefficient */
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pb++;
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/* Decrement the loop counter */
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tapCnt--;
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}
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/* Read the sample from state buffer */
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x0 = *pState;
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/* Advance state pointer by 1 for the next sample */
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pState = pState + 1;
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/* Decrement the loop counter */
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blkCnt--;
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}
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/* Save energy and x0 values for the next frame */
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S->energy = (q31_t) energy;
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S->x0 = x0;
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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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/* Loop for (numTaps - 1U) samples copy */
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tapCnt = (numTaps - 1U);
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/* Copy the remaining q31_t 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 /* #if defined (ARM_MATH_DSP) */
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}
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/**
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* @} end of LMS_NORM group
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*/
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