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- /* ----------------------------------------------------------------------
- * Copyright (C) 2010-2013 ARM Limited. All rights reserved.
- *
- * $Date: 17. January 2013
- * $Revision: V1.4.1
- *
- * Project: CMSIS DSP Library
- * Title: arm_lms_q15.c
- *
- * Description: Processing function for the Q15 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 Q15 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 a 64-bit internal accumulator.
- * Both coefficients and state variables are represented in 1.15 format and multiplications yield a 2.30 result.
- * The 2.30 intermediate results are accumulated in a 64-bit accumulator in 34.30 format.
- * There is no risk of internal overflow with this approach and the full precision of intermediate multiplications is preserved.
- * After all additions have been performed, the accumulator is truncated to 34.15 format by discarding low 15 bits.
- * Lastly, the accumulator is saturated to yield a result in 1.15 format.
- *
- * \par
- * In this filter, filter coefficients are updated for each sample and the updation of filter cofficients are saturted.
- *
- */
-
- void arm_lms_q15(
- const arm_lms_instance_q15 * S,
- q15_t * pSrc,
- q15_t * pRef,
- q15_t * pOut,
- q15_t * pErr,
- uint32_t blockSize)
- {
- q15_t *pState = S->pState; /* State pointer */
- uint32_t numTaps = S->numTaps; /* Number of filter coefficients in the filter */
- q15_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */
- q15_t *pStateCurnt; /* Points to the current sample of the state */
- q15_t mu = S->mu; /* Adaptive factor */
- q15_t *px; /* Temporary pointer for state */
- q15_t *pb; /* Temporary pointer for coefficient buffer */
- uint32_t tapCnt, blkCnt; /* Loop counters */
- q63_t acc; /* Accumulator */
- q15_t e = 0; /* error of data sample */
- q15_t alpha; /* Intermediate constant for taps update */
- q31_t acc_l, acc_h;
- int32_t lShift = (15 - (int32_t) S->postShift); /* Post shift */
- int32_t uShift = (32 - lShift);
-
-
- #ifndef ARM_MATH_CM0_FAMILY
-
- /* Run the below code for Cortex-M4 and Cortex-M3 */
-
- q31_t coef; /* Teporary variable for coefficient */
-
- /* 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;
-
- 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 >> 2u;
-
- while(tapCnt > 0u)
- {
- /* acc += b[N] * x[n-N] + b[N-1] * x[n-N-1] */
- /* Perform the multiply-accumulate */
- #ifndef UNALIGNED_SUPPORT_DISABLE
-
- acc = __SMLALD(*__SIMD32(px)++, (*__SIMD32(pb)++), acc);
- acc = __SMLALD(*__SIMD32(px)++, (*__SIMD32(pb)++), acc);
-
- #else
-
- acc += (q63_t) (((q31_t) (*px++) * (*pb++)));
- acc += (q63_t) (((q31_t) (*px++) * (*pb++)));
- acc += (q63_t) (((q31_t) (*px++) * (*pb++)));
- acc += (q63_t) (((q31_t) (*px++) * (*pb++)));
-
-
- #endif /* #ifndef UNALIGNED_SUPPORT_DISABLE */
-
- /* 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) (((q31_t) (*px++) * (*pb++)));
-
- /* Decrement the loop counter */
- tapCnt--;
- }
-
- /* Calc lower part of acc */
- acc_l = acc & 0xffffffff;
-
- /* Calc upper part of acc */
- acc_h = (acc >> 32) & 0xffffffff;
-
- /* Apply shift for lower part of acc and upper part of acc */
- acc = (uint32_t) acc_l >> lShift | acc_h << uShift;
-
- /* Converting the result to 1.15 format and saturate the output */
- acc = __SSAT(acc, 16);
-
- /* Store the result from accumulator into the destination buffer. */
- *pOut++ = (q15_t) acc;
-
- /* Compute and store error */
- e = *pRef++ - (q15_t) acc;
-
- *pErr++ = (q15_t) e;
-
- /* Compute alpha i.e. intermediate constant for taps update */
- alpha = (q15_t) (((q31_t) e * (mu)) >> 15);
-
- /* 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 >> 2u;
-
- /* Update filter coefficients */
- while(tapCnt > 0u)
- {
- coef = (q31_t) * pb + (((q31_t) alpha * (*px++)) >> 15);
- *pb++ = (q15_t) __SSAT((coef), 16);
- coef = (q31_t) * pb + (((q31_t) alpha * (*px++)) >> 15);
- *pb++ = (q15_t) __SSAT((coef), 16);
- coef = (q31_t) * pb + (((q31_t) alpha * (*px++)) >> 15);
- *pb++ = (q15_t) __SSAT((coef), 16);
- coef = (q31_t) * pb + (((q31_t) alpha * (*px++)) >> 15);
- *pb++ = (q15_t) __SSAT((coef), 16);
-
- /* 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) * pb + (((q31_t) alpha * (*px++)) >> 15);
- *pb++ = (q15_t) __SSAT((coef), 16);
-
- /* 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;
-
- /* Calculation of count for copying integer writes */
- tapCnt = (numTaps - 1u) >> 2;
-
- while(tapCnt > 0u)
- {
-
- #ifndef UNALIGNED_SUPPORT_DISABLE
-
- *__SIMD32(pStateCurnt)++ = *__SIMD32(pState)++;
- *__SIMD32(pStateCurnt)++ = *__SIMD32(pState)++;
- #else
- *pStateCurnt++ = *pState++;
- *pStateCurnt++ = *pState++;
- *pStateCurnt++ = *pState++;
- *pStateCurnt++ = *pState++;
- #endif
-
- tapCnt--;
-
- }
-
- /* Calculation of count for remaining q15_t data */
- tapCnt = (numTaps - 1u) % 0x4u;
-
- /* copy data */
- while(tapCnt > 0u)
- {
- *pStateCurnt++ = *pState++;
-
- /* Decrement the loop counter */
- tapCnt--;
- }
-
- #else
-
- /* Run the below code for Cortex-M0 */
-
- /* 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)]);
-
- /* Loop over blockSize number of values */
- blkCnt = blockSize;
-
- 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) ((q31_t) (*px++) * (*pb++));
-
- /* Decrement the loop counter */
- tapCnt--;
- }
-
- /* Calc lower part of acc */
- acc_l = acc & 0xffffffff;
-
- /* Calc upper part of acc */
- acc_h = (acc >> 32) & 0xffffffff;
-
- /* Apply shift for lower part of acc and upper part of acc */
- acc = (uint32_t) acc_l >> lShift | acc_h << uShift;
-
- /* Converting the result to 1.15 format and saturate the output */
- acc = __SSAT(acc, 16);
-
- /* Store the result from accumulator into the destination buffer. */
- *pOut++ = (q15_t) acc;
-
- /* Compute and store error */
- e = *pRef++ - (q15_t) acc;
-
- *pErr++ = (q15_t) e;
-
- /* Compute alpha i.e. intermediate constant for taps update */
- alpha = (q15_t) (((q31_t) e * (mu)) >> 15);
-
- /* 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 */
- *pb++ += (q15_t) (((q31_t) alpha * (*px++)) >> 15);
-
- /* 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
- */
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