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692 lines
22 KiB
C
692 lines
22 KiB
C
/* ----------------------------------------------------------------------
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* Copyright (C) 2010-2014 ARM Limited. All rights reserved.
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*
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* $Date: 19. March 2015
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* $Revision: V.1.4.5
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*
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* Project: CMSIS DSP Library
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* Title: arm_fir_q15.c
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*
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* Description: Q15 FIR filter processing function.
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*
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* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* - Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* - Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* - Neither the name of ARM LIMITED nor the names of its contributors
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* may be used to endorse or promote products derived from this
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* software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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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 FIR
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* @{
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*/
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/**
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* @brief Processing function for the Q15 FIR filter.
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* @param[in] *S points to an instance of the Q15 FIR structure.
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* @param[in] *pSrc points to the block of input data.
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* @param[out] *pDst points to the block of output data.
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* @param[in] blockSize number of samples to process per call.
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* @return none.
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*
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*
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* \par Restrictions
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* If the silicon does not support unaligned memory access enable the macro UNALIGNED_SUPPORT_DISABLE
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* In this case input, output, state buffers should be aligned by 32-bit
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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 multiplications yield a 2.30 result.
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* The 2.30 intermediate results are 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 precision of intermediate multiplications is preserved.
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* After all additions have been performed, the accumulator is truncated to 34.15 format by discarding low 15 bits.
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* Lastly, the accumulator is saturated to yield a result in 1.15 format.
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*
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* \par
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* Refer to the function <code>arm_fir_fast_q15()</code> for a faster but less precise implementation of this function.
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*/
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#ifndef ARM_MATH_CM0_FAMILY
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/* Run the below code for Cortex-M4 and Cortex-M3 */
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#ifndef UNALIGNED_SUPPORT_DISABLE
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void arm_fir_q15(
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const arm_fir_instance_q15 * S,
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q15_t * pSrc,
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q15_t * pDst,
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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 *px1; /* Temporary q15 pointer for state buffer */
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q15_t *pb; /* Temporary pointer for coefficient buffer */
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q31_t x0, x1, x2, x3, c0; /* Temporary variables to hold SIMD state and coefficient values */
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q63_t acc0, acc1, acc2, acc3; /* Accumulators */
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uint32_t numTaps = S->numTaps; /* Number of taps in the filter */
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uint32_t tapCnt, blkCnt; /* Loop counters */
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/* S->pState points to state array 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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/* Apply loop unrolling and compute 4 output values simultaneously.
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* The variables acc0 ... acc3 hold output values that are being computed:
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*
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* acc0 = b[numTaps-1] * x[n-numTaps-1] + b[numTaps-2] * x[n-numTaps-2] + b[numTaps-3] * x[n-numTaps-3] +...+ b[0] * x[0]
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* acc1 = b[numTaps-1] * x[n-numTaps] + b[numTaps-2] * x[n-numTaps-1] + b[numTaps-3] * x[n-numTaps-2] +...+ b[0] * x[1]
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* acc2 = b[numTaps-1] * x[n-numTaps+1] + b[numTaps-2] * x[n-numTaps] + b[numTaps-3] * x[n-numTaps-1] +...+ b[0] * x[2]
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* acc3 = b[numTaps-1] * x[n-numTaps+2] + b[numTaps-2] * x[n-numTaps+1] + b[numTaps-3] * x[n-numTaps] +...+ b[0] * x[3]
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*/
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blkCnt = blockSize >> 2;
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/* First part of the processing with loop unrolling. Compute 4 outputs at a time.
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** a second loop below computes the remaining 1 to 3 samples. */
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while(blkCnt > 0u)
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{
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/* Copy four new input samples into the state buffer.
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** Use 32-bit SIMD to move the 16-bit data. Only requires two copies. */
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*__SIMD32(pStateCurnt)++ = *__SIMD32(pSrc)++;
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*__SIMD32(pStateCurnt)++ = *__SIMD32(pSrc)++;
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/* Set all accumulators to zero */
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acc0 = 0;
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acc1 = 0;
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acc2 = 0;
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acc3 = 0;
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/* Initialize state pointer of type q15 */
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px1 = pState;
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/* Initialize coeff pointer of type q31 */
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pb = pCoeffs;
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/* Read the first two samples from the state buffer: x[n-N], x[n-N-1] */
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x0 = _SIMD32_OFFSET(px1);
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/* Read the third and forth samples from the state buffer: x[n-N-1], x[n-N-2] */
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x1 = _SIMD32_OFFSET(px1 + 1u);
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px1 += 2u;
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/* Loop over the number of taps. Unroll by a factor of 4.
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** Repeat until we've computed numTaps-4 coefficients. */
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tapCnt = numTaps >> 2;
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while(tapCnt > 0u)
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{
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/* Read the first two coefficients using SIMD: b[N] and b[N-1] coefficients */
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c0 = *__SIMD32(pb)++;
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/* acc0 += b[N] * x[n-N] + b[N-1] * x[n-N-1] */
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acc0 = __SMLALD(x0, c0, acc0);
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/* acc1 += b[N] * x[n-N-1] + b[N-1] * x[n-N-2] */
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acc1 = __SMLALD(x1, c0, acc1);
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/* Read state x[n-N-2], x[n-N-3] */
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x2 = _SIMD32_OFFSET(px1);
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/* Read state x[n-N-3], x[n-N-4] */
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x3 = _SIMD32_OFFSET(px1 + 1u);
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/* acc2 += b[N] * x[n-N-2] + b[N-1] * x[n-N-3] */
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acc2 = __SMLALD(x2, c0, acc2);
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/* acc3 += b[N] * x[n-N-3] + b[N-1] * x[n-N-4] */
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acc3 = __SMLALD(x3, c0, acc3);
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/* Read coefficients b[N-2], b[N-3] */
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c0 = *__SIMD32(pb)++;
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/* acc0 += b[N-2] * x[n-N-2] + b[N-3] * x[n-N-3] */
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acc0 = __SMLALD(x2, c0, acc0);
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/* acc1 += b[N-2] * x[n-N-3] + b[N-3] * x[n-N-4] */
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acc1 = __SMLALD(x3, c0, acc1);
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/* Read state x[n-N-4], x[n-N-5] */
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x0 = _SIMD32_OFFSET(px1 + 2u);
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/* Read state x[n-N-5], x[n-N-6] */
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x1 = _SIMD32_OFFSET(px1 + 3u);
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/* acc2 += b[N-2] * x[n-N-4] + b[N-3] * x[n-N-5] */
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acc2 = __SMLALD(x0, c0, acc2);
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/* acc3 += b[N-2] * x[n-N-5] + b[N-3] * x[n-N-6] */
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acc3 = __SMLALD(x1, c0, acc3);
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px1 += 4u;
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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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** This is always be 2 taps since the filter length is even. */
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if((numTaps & 0x3u) != 0u)
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{
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/* Read 2 coefficients */
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c0 = *__SIMD32(pb)++;
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/* Fetch 4 state variables */
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x2 = _SIMD32_OFFSET(px1);
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x3 = _SIMD32_OFFSET(px1 + 1u);
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/* Perform the multiply-accumulates */
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acc0 = __SMLALD(x0, c0, acc0);
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px1 += 2u;
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acc1 = __SMLALD(x1, c0, acc1);
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acc2 = __SMLALD(x2, c0, acc2);
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acc3 = __SMLALD(x3, c0, acc3);
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}
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/* The results in the 4 accumulators are in 2.30 format. Convert to 1.15 with saturation.
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** Then store the 4 outputs in the destination buffer. */
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#ifndef ARM_MATH_BIG_ENDIAN
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*__SIMD32(pDst)++ =
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__PKHBT(__SSAT((acc0 >> 15), 16), __SSAT((acc1 >> 15), 16), 16);
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*__SIMD32(pDst)++ =
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__PKHBT(__SSAT((acc2 >> 15), 16), __SSAT((acc3 >> 15), 16), 16);
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#else
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*__SIMD32(pDst)++ =
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__PKHBT(__SSAT((acc1 >> 15), 16), __SSAT((acc0 >> 15), 16), 16);
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*__SIMD32(pDst)++ =
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__PKHBT(__SSAT((acc3 >> 15), 16), __SSAT((acc2 >> 15), 16), 16);
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#endif /* #ifndef ARM_MATH_BIG_ENDIAN */
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/* Advance the state pointer by 4 to process the next group of 4 samples */
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pState = pState + 4;
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/* Decrement the loop counter */
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blkCnt--;
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}
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/* If the blockSize is not a multiple of 4, compute any remaining output samples here.
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** No loop unrolling is used. */
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blkCnt = blockSize % 0x4u;
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while(blkCnt > 0u)
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{
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/* Copy two samples into state buffer */
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*pStateCurnt++ = *pSrc++;
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/* Set the accumulator to zero */
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acc0 = 0;
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/* Initialize state pointer of type q15 */
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px1 = pState;
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/* Initialize coeff pointer of type q31 */
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pb = pCoeffs;
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tapCnt = numTaps >> 1;
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do
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{
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c0 = *__SIMD32(pb)++;
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x0 = *__SIMD32(px1)++;
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acc0 = __SMLALD(x0, c0, acc0);
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tapCnt--;
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}
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while(tapCnt > 0u);
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/* The result is in 2.30 format. Convert to 1.15 with saturation.
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** Then store the output in the destination buffer. */
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*pDst++ = (q15_t) (__SSAT((acc0 >> 15), 16));
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/* Advance state pointer by 1 for the next sample */
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pState = pState + 1;
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/* Decrement the loop counter */
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blkCnt--;
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}
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/* Processing is complete.
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** Now copy the last numTaps - 1 samples to the satrt of the state buffer.
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** This prepares the state buffer for the next function call. */
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/* Points to the start of the state 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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/* Copy state values to start of state buffer */
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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 remaining 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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}
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#else /* UNALIGNED_SUPPORT_DISABLE */
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void arm_fir_q15(
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const arm_fir_instance_q15 * S,
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q15_t * pSrc,
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q15_t * pDst,
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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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q63_t acc0, acc1, acc2, acc3; /* Accumulators */
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q15_t *pb; /* Temporary pointer for coefficient buffer */
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q15_t *px; /* Temporary q31 pointer for SIMD state buffer accesses */
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q31_t x0, x1, x2, c0; /* Temporary variables to hold SIMD state and coefficient values */
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uint32_t numTaps = S->numTaps; /* Number of taps in the filter */
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uint32_t tapCnt, blkCnt; /* Loop counters */
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/* S->pState points to state array 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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/* Apply loop unrolling and compute 4 output values simultaneously.
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* The variables acc0 ... acc3 hold output values that are being computed:
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*
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* acc0 = b[numTaps-1] * x[n-numTaps-1] + b[numTaps-2] * x[n-numTaps-2] + b[numTaps-3] * x[n-numTaps-3] +...+ b[0] * x[0]
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* acc1 = b[numTaps-1] * x[n-numTaps] + b[numTaps-2] * x[n-numTaps-1] + b[numTaps-3] * x[n-numTaps-2] +...+ b[0] * x[1]
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* acc2 = b[numTaps-1] * x[n-numTaps+1] + b[numTaps-2] * x[n-numTaps] + b[numTaps-3] * x[n-numTaps-1] +...+ b[0] * x[2]
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* acc3 = b[numTaps-1] * x[n-numTaps+2] + b[numTaps-2] * x[n-numTaps+1] + b[numTaps-3] * x[n-numTaps] +...+ b[0] * x[3]
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*/
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blkCnt = blockSize >> 2;
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/* First part of the processing with loop unrolling. Compute 4 outputs at a time.
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** a second loop below computes the remaining 1 to 3 samples. */
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while(blkCnt > 0u)
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{
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/* Copy four new input samples into the state buffer.
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** Use 32-bit SIMD to move the 16-bit data. Only requires two copies. */
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*pStateCurnt++ = *pSrc++;
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*pStateCurnt++ = *pSrc++;
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*pStateCurnt++ = *pSrc++;
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*pStateCurnt++ = *pSrc++;
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/* Set all accumulators to zero */
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acc0 = 0;
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acc1 = 0;
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acc2 = 0;
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acc3 = 0;
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/* Typecast q15_t pointer to q31_t pointer for state reading in q31_t */
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px = pState;
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/* Typecast q15_t pointer to q31_t pointer for coefficient reading in q31_t */
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pb = pCoeffs;
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/* Read the first two samples from the state buffer: x[n-N], x[n-N-1] */
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x0 = *__SIMD32(px)++;
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/* Read the third and forth samples from the state buffer: x[n-N-2], x[n-N-3] */
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x2 = *__SIMD32(px)++;
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/* Loop over the number of taps. Unroll by a factor of 4.
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** Repeat until we've computed numTaps-(numTaps%4) coefficients. */
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tapCnt = numTaps >> 2;
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while(tapCnt > 0)
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{
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/* Read the first two coefficients using SIMD: b[N] and b[N-1] coefficients */
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c0 = *__SIMD32(pb)++;
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/* acc0 += b[N] * x[n-N] + b[N-1] * x[n-N-1] */
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acc0 = __SMLALD(x0, c0, acc0);
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/* acc2 += b[N] * x[n-N-2] + b[N-1] * x[n-N-3] */
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acc2 = __SMLALD(x2, c0, acc2);
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/* pack x[n-N-1] and x[n-N-2] */
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#ifndef ARM_MATH_BIG_ENDIAN
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x1 = __PKHBT(x2, x0, 0);
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#else
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x1 = __PKHBT(x0, x2, 0);
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#endif
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/* Read state x[n-N-4], x[n-N-5] */
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x0 = _SIMD32_OFFSET(px);
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/* acc1 += b[N] * x[n-N-1] + b[N-1] * x[n-N-2] */
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acc1 = __SMLALDX(x1, c0, acc1);
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/* pack x[n-N-3] and x[n-N-4] */
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#ifndef ARM_MATH_BIG_ENDIAN
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x1 = __PKHBT(x0, x2, 0);
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#else
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x1 = __PKHBT(x2, x0, 0);
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#endif
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/* acc3 += b[N] * x[n-N-3] + b[N-1] * x[n-N-4] */
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acc3 = __SMLALDX(x1, c0, acc3);
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/* Read coefficients b[N-2], b[N-3] */
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c0 = *__SIMD32(pb)++;
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/* acc0 += b[N-2] * x[n-N-2] + b[N-3] * x[n-N-3] */
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acc0 = __SMLALD(x2, c0, acc0);
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/* Read state x[n-N-6], x[n-N-7] with offset */
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x2 = _SIMD32_OFFSET(px + 2u);
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/* acc2 += b[N-2] * x[n-N-4] + b[N-3] * x[n-N-5] */
|
|
acc2 = __SMLALD(x0, c0, acc2);
|
|
|
|
/* acc1 += b[N-2] * x[n-N-3] + b[N-3] * x[n-N-4] */
|
|
acc1 = __SMLALDX(x1, c0, acc1);
|
|
|
|
/* pack x[n-N-5] and x[n-N-6] */
|
|
#ifndef ARM_MATH_BIG_ENDIAN
|
|
x1 = __PKHBT(x2, x0, 0);
|
|
#else
|
|
x1 = __PKHBT(x0, x2, 0);
|
|
#endif
|
|
|
|
/* acc3 += b[N-2] * x[n-N-5] + b[N-3] * x[n-N-6] */
|
|
acc3 = __SMLALDX(x1, c0, acc3);
|
|
|
|
/* Update state pointer for next state reading */
|
|
px += 4u;
|
|
|
|
/* Decrement tap count */
|
|
tapCnt--;
|
|
|
|
}
|
|
|
|
/* If the filter length is not a multiple of 4, compute the remaining filter taps.
|
|
** This is always be 2 taps since the filter length is even. */
|
|
if((numTaps & 0x3u) != 0u)
|
|
{
|
|
|
|
/* Read last two coefficients */
|
|
c0 = *__SIMD32(pb)++;
|
|
|
|
/* Perform the multiply-accumulates */
|
|
acc0 = __SMLALD(x0, c0, acc0);
|
|
acc2 = __SMLALD(x2, c0, acc2);
|
|
|
|
/* pack state variables */
|
|
#ifndef ARM_MATH_BIG_ENDIAN
|
|
x1 = __PKHBT(x2, x0, 0);
|
|
#else
|
|
x1 = __PKHBT(x0, x2, 0);
|
|
#endif
|
|
|
|
/* Read last state variables */
|
|
x0 = *__SIMD32(px);
|
|
|
|
/* Perform the multiply-accumulates */
|
|
acc1 = __SMLALDX(x1, c0, acc1);
|
|
|
|
/* pack state variables */
|
|
#ifndef ARM_MATH_BIG_ENDIAN
|
|
x1 = __PKHBT(x0, x2, 0);
|
|
#else
|
|
x1 = __PKHBT(x2, x0, 0);
|
|
#endif
|
|
|
|
/* Perform the multiply-accumulates */
|
|
acc3 = __SMLALDX(x1, c0, acc3);
|
|
}
|
|
|
|
/* The results in the 4 accumulators are in 2.30 format. Convert to 1.15 with saturation.
|
|
** Then store the 4 outputs in the destination buffer. */
|
|
|
|
#ifndef ARM_MATH_BIG_ENDIAN
|
|
|
|
*__SIMD32(pDst)++ =
|
|
__PKHBT(__SSAT((acc0 >> 15), 16), __SSAT((acc1 >> 15), 16), 16);
|
|
|
|
*__SIMD32(pDst)++ =
|
|
__PKHBT(__SSAT((acc2 >> 15), 16), __SSAT((acc3 >> 15), 16), 16);
|
|
|
|
#else
|
|
|
|
*__SIMD32(pDst)++ =
|
|
__PKHBT(__SSAT((acc1 >> 15), 16), __SSAT((acc0 >> 15), 16), 16);
|
|
|
|
*__SIMD32(pDst)++ =
|
|
__PKHBT(__SSAT((acc3 >> 15), 16), __SSAT((acc2 >> 15), 16), 16);
|
|
|
|
#endif /* #ifndef ARM_MATH_BIG_ENDIAN */
|
|
|
|
/* Advance the state pointer by 4 to process the next group of 4 samples */
|
|
pState = pState + 4;
|
|
|
|
/* Decrement the loop counter */
|
|
blkCnt--;
|
|
}
|
|
|
|
/* If the blockSize is not a multiple of 4, compute any remaining output samples here.
|
|
** No loop unrolling is used. */
|
|
blkCnt = blockSize % 0x4u;
|
|
while(blkCnt > 0u)
|
|
{
|
|
/* Copy two samples into state buffer */
|
|
*pStateCurnt++ = *pSrc++;
|
|
|
|
/* Set the accumulator to zero */
|
|
acc0 = 0;
|
|
|
|
/* Use SIMD to hold states and coefficients */
|
|
px = pState;
|
|
pb = pCoeffs;
|
|
|
|
tapCnt = numTaps >> 1u;
|
|
|
|
do
|
|
{
|
|
acc0 += (q31_t) * px++ * *pb++;
|
|
acc0 += (q31_t) * px++ * *pb++;
|
|
tapCnt--;
|
|
}
|
|
while(tapCnt > 0u);
|
|
|
|
/* The result is in 2.30 format. Convert to 1.15 with saturation.
|
|
** Then store the output in the destination buffer. */
|
|
*pDst++ = (q15_t) (__SSAT((acc0 >> 15), 16));
|
|
|
|
/* Advance state pointer by 1 for the next sample */
|
|
pState = pState + 1u;
|
|
|
|
/* 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 state buffer */
|
|
pStateCurnt = S->pState;
|
|
|
|
/* Calculation of count for copying integer writes */
|
|
tapCnt = (numTaps - 1u) >> 2;
|
|
|
|
while(tapCnt > 0u)
|
|
{
|
|
*pStateCurnt++ = *pState++;
|
|
*pStateCurnt++ = *pState++;
|
|
*pStateCurnt++ = *pState++;
|
|
*pStateCurnt++ = *pState++;
|
|
|
|
tapCnt--;
|
|
|
|
}
|
|
|
|
/* Calculation of count for remaining q15_t data */
|
|
tapCnt = (numTaps - 1u) % 0x4u;
|
|
|
|
/* copy remaining data */
|
|
while(tapCnt > 0u)
|
|
{
|
|
*pStateCurnt++ = *pState++;
|
|
|
|
/* Decrement the loop counter */
|
|
tapCnt--;
|
|
}
|
|
}
|
|
|
|
|
|
#endif /* #ifndef UNALIGNED_SUPPORT_DISABLE */
|
|
|
|
#else /* ARM_MATH_CM0_FAMILY */
|
|
|
|
|
|
/* Run the below code for Cortex-M0 */
|
|
|
|
void arm_fir_q15(
|
|
const arm_fir_instance_q15 * S,
|
|
q15_t * pSrc,
|
|
q15_t * pDst,
|
|
uint32_t blockSize)
|
|
{
|
|
q15_t *pState = S->pState; /* State pointer */
|
|
q15_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */
|
|
q15_t *pStateCurnt; /* Points to the current sample of the state */
|
|
|
|
|
|
|
|
q15_t *px; /* Temporary pointer for state buffer */
|
|
q15_t *pb; /* Temporary pointer for coefficient buffer */
|
|
q63_t acc; /* Accumulator */
|
|
uint32_t numTaps = S->numTaps; /* Number of nTaps in the filter */
|
|
uint32_t tapCnt, blkCnt; /* Loop counters */
|
|
|
|
/* S->pState buffer contains previous frame (numTaps - 1) samples */
|
|
/* pStateCurnt points to the location where the new input data should be written */
|
|
pStateCurnt = &(S->pState[(numTaps - 1u)]);
|
|
|
|
/* Initialize blkCnt with blockSize */
|
|
blkCnt = blockSize;
|
|
|
|
while(blkCnt > 0u)
|
|
{
|
|
/* Copy one sample at a time into state buffer */
|
|
*pStateCurnt++ = *pSrc++;
|
|
|
|
/* Set the accumulator to zero */
|
|
acc = 0;
|
|
|
|
/* Initialize state pointer */
|
|
px = pState;
|
|
|
|
/* Initialize Coefficient pointer */
|
|
pb = pCoeffs;
|
|
|
|
tapCnt = numTaps;
|
|
|
|
/* Perform the multiply-accumulates */
|
|
do
|
|
{
|
|
/* acc = b[numTaps-1] * x[n-numTaps-1] + b[numTaps-2] * x[n-numTaps-2] + b[numTaps-3] * x[n-numTaps-3] +...+ b[0] * x[0] */
|
|
acc += (q31_t) * px++ * *pb++;
|
|
tapCnt--;
|
|
} while(tapCnt > 0u);
|
|
|
|
/* The result is in 2.30 format. Convert to 1.15
|
|
** Then store the output in the destination buffer. */
|
|
*pDst++ = (q15_t) __SSAT((acc >> 15u), 16);
|
|
|
|
/* Advance state pointer by 1 for the next sample */
|
|
pState = pState + 1;
|
|
|
|
/* Decrement the samples 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 state buffer */
|
|
pStateCurnt = S->pState;
|
|
|
|
/* Copy numTaps number of values */
|
|
tapCnt = (numTaps - 1u);
|
|
|
|
/* copy data */
|
|
while(tapCnt > 0u)
|
|
{
|
|
*pStateCurnt++ = *pState++;
|
|
|
|
/* Decrement the loop counter */
|
|
tapCnt--;
|
|
}
|
|
|
|
}
|
|
|
|
#endif /* #ifndef ARM_MATH_CM0_FAMILY */
|
|
|
|
|
|
|
|
|
|
/**
|
|
* @} end of FIR group
|
|
*/
|