/* ----------------------------------------------------------------------
|
* Copyright (C) 2010-2014 ARM Limited. All rights reserved.
|
*
|
* $Date: 19. March 2015
|
* $Revision: V.1.4.5
|
*
|
* Project: CMSIS DSP Library
|
* Title: arm_lms_q31.c
|
*
|
* Description: Processing function for the Q31 LMS filter.
|
*
|
* 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
|
*/
|
|
/**
|
* @addtogroup LMS
|
* @{
|
*/
|
|
/**
|
* @brief Processing function for Q31 LMS filter.
|
* @param[in] *S points to an instance of the Q15 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.
|
*
|
* \par Scaling and Overflow Behavior:
|
* The function is implemented using an internal 64-bit accumulator.
|
* The accumulator has a 2.62 format and maintains full precision of the intermediate
|
* multiplication results but provides only a single guard bit.
|
* Thus, if the accumulator result overflows it wraps around rather than clips.
|
* In order to avoid overflows completely the input signal must be scaled down by
|
* log2(numTaps) bits.
|
* The reference signal should not be scaled down.
|
* After all multiply-accumulates are performed, the 2.62 accumulator is shifted
|
* and saturated to 1.31 format to yield the final result.
|
* The output signal and error signal are in 1.31 format.
|
*
|
* \par
|
* In this filter, filter coefficients are updated for each sample and the updation of filter cofficients are saturted.
|
*/
|
|
void arm_lms_q31(
|
const arm_lms_instance_q31 * S,
|
q31_t * pSrc,
|
q31_t * pRef,
|
q31_t * pOut,
|
q31_t * pErr,
|
uint32_t blockSize)
|
{
|
q31_t *pState = S->pState; /* State pointer */
|
uint32_t numTaps = S->numTaps; /* Number of filter coefficients in the filter */
|
q31_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */
|
q31_t *pStateCurnt; /* Points to the current sample of the state */
|
q31_t mu = S->mu; /* Adaptive factor */
|
q31_t *px; /* Temporary pointer for state */
|
q31_t *pb; /* Temporary pointer for coefficient buffer */
|
uint32_t tapCnt, blkCnt; /* Loop counters */
|
q63_t acc; /* Accumulator */
|
q31_t e = 0; /* error of data sample */
|
q31_t alpha; /* Intermediate constant for taps update */
|
q31_t coef; /* Temporary variable for coef */
|
q31_t acc_l, acc_h; /* temporary input */
|
uint32_t uShift = ((uint32_t) S->postShift + 1u);
|
uint32_t lShift = 32u - uShift; /* Shift to be applied to the output */
|
|
/* 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)]);
|
|
/* Initializing blkCnt with blockSize */
|
blkCnt = blockSize;
|
|
|
#ifndef ARM_MATH_CM0_FAMILY
|
|
/* 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 state pointer */
|
px = pState;
|
|
/* Initialize coefficient pointer */
|
pb = pCoeffs;
|
|
/* 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 */
|
/* acc += b[N] * x[n-N] */
|
acc += ((q63_t) (*px++)) * (*pb++);
|
|
/* acc += b[N-1] * x[n-N-1] */
|
acc += ((q63_t) (*px++)) * (*pb++);
|
|
/* acc += b[N-2] * x[n-N-2] */
|
acc += ((q63_t) (*px++)) * (*pb++);
|
|
/* acc += b[N-3] * x[n-N-3] */
|
acc += ((q63_t) (*px++)) * (*pb++);
|
|
/* 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 += ((q63_t) (*px++)) * (*pb++);
|
|
/* Decrement the loop counter */
|
tapCnt--;
|
}
|
|
/* Converting the result to 1.31 format */
|
/* Calc lower part of acc */
|
acc_l = acc & 0xffffffff;
|
|
/* Calc upper part of acc */
|
acc_h = (acc >> 32) & 0xffffffff;
|
|
acc = (uint32_t) acc_l >> lShift | acc_h << uShift;
|
|
/* Store the result from accumulator into the destination buffer. */
|
*pOut++ = (q31_t) acc;
|
|
/* Compute and store error */
|
e = *pRef++ - (q31_t) acc;
|
|
*pErr++ = (q31_t) e;
|
|
/* Compute alpha i.e. intermediate constant for taps update */
|
alpha = (q31_t) (((q63_t) e * mu) >> 31);
|
|
/* Initialize state pointer */
|
/* Advance state pointer by 1 for the next sample */
|
px = pState++;
|
|
/* Initialize coefficient pointer */
|
pb = pCoeffs;
|
|
/* Loop unrolling. Process 4 taps at a time. */
|
tapCnt = numTaps >> 2;
|
|
/* Update filter coefficients */
|
while(tapCnt > 0u)
|
{
|
/* coef is in 2.30 format */
|
coef = (q31_t) (((q63_t) alpha * (*px++)) >> (32));
|
/* get coef in 1.31 format by left shifting */
|
*pb = clip_q63_to_q31((q63_t) * pb + (coef << 1u));
|
/* update coefficient buffer to next coefficient */
|
pb++;
|
|
coef = (q31_t) (((q63_t) alpha * (*px++)) >> (32));
|
*pb = clip_q63_to_q31((q63_t) * pb + (coef << 1u));
|
pb++;
|
|
coef = (q31_t) (((q63_t) alpha * (*px++)) >> (32));
|
*pb = clip_q63_to_q31((q63_t) * pb + (coef << 1u));
|
pb++;
|
|
coef = (q31_t) (((q63_t) alpha * (*px++)) >> (32));
|
*pb = clip_q63_to_q31((q63_t) * pb + (coef << 1u));
|
pb++;
|
|
/* 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 = (q31_t) (((q63_t) alpha * (*px++)) >> (32));
|
*pb = clip_q63_to_q31((q63_t) * pb + (coef << 1u));
|
pb++;
|
|
/* Decrement the loop counter */
|
tapCnt--;
|
}
|
|
/* Decrement the loop counter */
|
blkCnt--;
|
}
|
|
/* 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;
|
|
/* Loop unrolling for (numTaps - 1u) samples copy */
|
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--;
|
}
|
|
#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;
|
|
/* Set the accumulator to zero */
|
acc = 0;
|
|
/* Loop over numTaps number of values */
|
tapCnt = numTaps;
|
|
while(tapCnt > 0u)
|
{
|
/* Perform the multiply-accumulate */
|
acc += ((q63_t) (*px++)) * (*pb++);
|
|
/* Decrement the loop counter */
|
tapCnt--;
|
}
|
|
/* Converting the result to 1.31 format */
|
/* Store the result from accumulator into the destination buffer. */
|
/* Calc lower part of acc */
|
acc_l = acc & 0xffffffff;
|
|
/* Calc upper part of acc */
|
acc_h = (acc >> 32) & 0xffffffff;
|
|
acc = (uint32_t) acc_l >> lShift | acc_h << uShift;
|
|
*pOut++ = (q31_t) acc;
|
|
/* Compute and store error */
|
e = *pRef++ - (q31_t) acc;
|
|
*pErr++ = (q31_t) e;
|
|
/* Weighting factor for the LMS version */
|
alpha = (q31_t) (((q63_t) e * mu) >> 31);
|
|
/* Initialize pState pointer */
|
/* Advance state pointer by 1 for the next sample */
|
px = pState++;
|
|
/* Initialize pCoeffs pointer */
|
pb = pCoeffs;
|
|
/* Loop over numTaps number of values */
|
tapCnt = numTaps;
|
|
while(tapCnt > 0u)
|
{
|
/* Perform the multiply-accumulate */
|
coef = (q31_t) (((q63_t) alpha * (*px++)) >> (32));
|
*pb = clip_q63_to_q31((q63_t) * pb + (coef << 1u));
|
pb++;
|
|
/* Decrement the loop counter */
|
tapCnt--;
|
}
|
|
/* Decrement the loop counter */
|
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 pState buffer */
|
pStateCurnt = S->pState;
|
|
/* Copy (numTaps - 1u) samples */
|
tapCnt = (numTaps - 1u);
|
|
/* Copy the data */
|
while(tapCnt > 0u)
|
{
|
*pStateCurnt++ = *pState++;
|
|
/* Decrement the loop counter */
|
tapCnt--;
|
}
|
|
#endif /* #ifndef ARM_MATH_CM0_FAMILY */
|
|
}
|
|
/**
|
* @} end of LMS group
|
*/
|
