| /* ---------------------------------------------------------------------- |
| * 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 |
| */ |
