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/* ----------------------------------------------------------------------
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* Copyright (C) 2010 ARM Limited. All rights reserved.
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*
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* $Date: 15. July 2011
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* $Revision: V1.0.10
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*
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* Project: CMSIS DSP Library
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* Title: arm_lms_norm_q15.c
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*
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* Description: Q15 NLMS 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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* Version 1.0.10 2011/7/15
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* Big Endian support added and Merged M0 and M3/M4 Source code.
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*
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* Version 1.0.3 2010/11/29
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* Re-organized the CMSIS folders and updated documentation.
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*
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* Version 1.0.2 2010/11/11
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* Documentation updated.
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*
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* Version 1.0.1 2010/10/05
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* Production release and review comments incorporated.
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*
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* Version 1.0.0 2010/09/20
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* Production release and review comments incorporated
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*
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* Version 0.0.7 2010/06/10
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* Misra-C changes done
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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 Q15 normalized LMS filter.
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* @param[in] *S points to an instance of the Q15 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 a 64-bit internal accumulator.
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* Both coefficients and state variables are represented in 1.15 format and
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* multiplications yield a 2.30 result. The 2.30 intermediate results are
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* 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
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* precision of intermediate multiplications is preserved. After all additions
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* have been performed, the accumulator is truncated to 34.15 format by
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* discarding low 15 bits. Lastly, the accumulator is saturated to yield a
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* 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_norm_q15(
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arm_lms_norm_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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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 *px, *pb; /* Temporary pointers for state and coefficient buffers */
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q15_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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q31_t energy; /* Energy of the input */
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q63_t acc; /* Accumulator */
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q15_t e = 0, d = 0; /* error, reference data sample */
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q15_t w = 0, in; /* weight factor and state */
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q15_t x0; /* temporary variable to hold input sample */
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uint32_t shift = (uint32_t) S->postShift + 1u; /* Shift to be applied to the output */
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q15_t errorXmu, oneByEnergy; /* Temporary variables to store error and mu product and reciprocal of energy */
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q15_t postShift; /* Post shift to be applied to weight after reciprocal calculation */
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q31_t coef; /* Teporary variable for coefficient */
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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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#ifndef ARM_MATH_CM0
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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) x0 * (x0)) >> 15);
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energy += (((q31_t) in * (in)) >> 15);
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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 = __SMLALD(*__SIMD32(px)++, (*__SIMD32(pb)++), acc);
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acc = __SMLALD(*__SIMD32(px)++, (*__SIMD32(pb)++), acc);
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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 += (((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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/* Converting the result to 1.15 format */
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acc = __SSAT((acc >> (16u - shift)), 16u);
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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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d = *pRef++;
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e = d - (q15_t) acc;
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*pErr++ = e;
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/* Calculation of 1/energy */
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postShift = arm_recip_q15((q15_t) energy + DELTA_Q15,
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&oneByEnergy, S->recipTable);
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/* Calculation of e * mu value */
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errorXmu = (q15_t) (((q31_t) e * mu) >> 15);
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/* Calculation of (e * mu) * (1/energy) value */
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acc = (((q31_t) errorXmu * oneByEnergy) >> (15 - postShift));
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/* Weighting factor for the normalized version */
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w = (q15_t) __SSAT((q31_t) acc, 16);
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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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coef = *pb + (((q31_t) w * (*px++)) >> 15);
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*pb++ = (q15_t) __SSAT((coef), 16);
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coef = *pb + (((q31_t) w * (*px++)) >> 15);
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*pb++ = (q15_t) __SSAT((coef), 16);
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coef = *pb + (((q31_t) w * (*px++)) >> 15);
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*pb++ = (q15_t) __SSAT((coef), 16);
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coef = *pb + (((q31_t) w * (*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 = *pb + (((q31_t) w * (*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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/* 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 + 1u;
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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 = (q15_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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/* 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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*__SIMD32(pStateCurnt)++ = *__SIMD32(pState)++;
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*__SIMD32(pStateCurnt)++ = *__SIMD32(pState)++;
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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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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 -= (((q31_t) x0 * (x0)) >> 15);
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energy += (((q31_t) in * (in)) >> 15);
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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 += (((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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/* Converting the result to 1.15 format */
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acc = __SSAT((acc >> (16u - shift)), 16u);
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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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d = *pRef++;
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e = d - (q15_t) acc;
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*pErr++ = e;
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/* Calculation of 1/energy */
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postShift = arm_recip_q15((q15_t) energy + DELTA_Q15,
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&oneByEnergy, S->recipTable);
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/* Calculation of e * mu value */
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errorXmu = (q15_t) (((q31_t) e * mu) >> 15);
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/* Calculation of (e * mu) * (1/energy) value */
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acc = (((q31_t) errorXmu * oneByEnergy) >> (15 - postShift));
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/* Weighting factor for the normalized version */
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w = (q15_t) __SSAT((q31_t) acc, 16);
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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 = *pb + (((q31_t) w * (*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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/* 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 + 1u;
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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 = (q15_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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/* copy (numTaps - 1u) data */
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tapCnt = (numTaps - 1u);
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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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#endif /* #ifndef ARM_MATH_CM0 */
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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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