arm_lms_q31.c
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r41 | /* ---------------------------------------------------------------------- | ||
* Copyright (C) 2010 ARM Limited. All rights reserved. | ||||
* | ||||
* $Date: 15. July 2011 | ||||
* $Revision: V1.0.10 | ||||
* | ||||
* 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 | ||||
* | ||||
* 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 | ||||
* @{ | ||||
*/ | ||||
/** | ||||
* @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 */ | ||||
uint8_t shift = (uint8_t) (32u - (S->postShift + 1u)); /* Shift to be applied to the output */ | ||||
q31_t coef; /* Temporary variable for coef */ | ||||
/* 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 | ||||
/* 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 */ | ||||
/* Store the result from accumulator into the destination buffer. */ | ||||
acc = (q31_t) (acc >> shift); | ||||
*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. */ | ||||
acc = (q31_t) (acc >> shift); | ||||
*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 += (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 */ | ||||
} | ||||
/** | ||||
* @} end of LMS group | ||||
*/ | ||||