480 lines
13 KiB
C
480 lines
13 KiB
C
/* ----------------------------------------------------------------------
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* Project: CMSIS DSP Library
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* Title: arm_fir_interpolate_q15.c
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* Description: Q15 FIR interpolation
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*
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* $Date: 18. March 2019
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* $Revision: V1.6.0
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*
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* Target Processor: Cortex-M cores
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* -------------------------------------------------------------------- */
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/*
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* Copyright (C) 2010-2019 ARM Limited or its affiliates. All rights reserved.
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 (the License); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an AS IS BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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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_Interpolate
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@{
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*/
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/**
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@brief Processing function for the Q15 FIR interpolator.
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@param[in] S points to an instance of the Q15 FIR interpolator 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
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@return none
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@par Scaling and Overflow Behavior
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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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void arm_fir_interpolate_q15(
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const arm_fir_interpolate_instance_q15 * S,
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const 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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#if (1)
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//#if !defined(ARM_MATH_CM0_FAMILY)
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q15_t *pState = S->pState; /* State pointer */
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const q15_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */
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q15_t *pStateCur; /* Points to the current sample of the state */
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q15_t *ptr1; /* Temporary pointer for state buffer */
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const q15_t *ptr2; /* Temporary pointer for coefficient buffer */
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q63_t sum0; /* Accumulators */
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uint32_t i, blkCnt, tapCnt; /* Loop counters */
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uint32_t phaseLen = S->phaseLength; /* Length of each polyphase filter component */
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uint32_t j;
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#if defined (ARM_MATH_LOOPUNROLL)
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q63_t acc0, acc1, acc2, acc3;
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q15_t x0, x1, x2, x3;
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q15_t c0, c1, c2, c3;
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#endif
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/* S->pState buffer contains previous frame (phaseLen - 1) samples */
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/* pStateCur points to the location where the new input data should be written */
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pStateCur = S->pState + (phaseLen - 1U);
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#if defined (ARM_MATH_LOOPUNROLL)
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/* Loop unrolling: Compute 4 outputs at a time */
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blkCnt = blockSize >> 2U;
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while (blkCnt > 0U)
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{
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/* Copy new input sample into the state buffer */
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*pStateCur++ = *pSrc++;
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*pStateCur++ = *pSrc++;
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*pStateCur++ = *pSrc++;
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*pStateCur++ = *pSrc++;
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/* Address modifier index of coefficient buffer */
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j = 1U;
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/* Loop over the Interpolation factor. */
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i = (S->L);
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while (i > 0U)
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{
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/* Set accumulator 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 */
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ptr1 = pState;
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/* Initialize coefficient pointer */
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ptr2 = pCoeffs + (S->L - j);
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/* Loop over the polyPhase length. Unroll by a factor of 4.
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Repeat until we've computed numTaps-(4*S->L) coefficients. */
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tapCnt = phaseLen >> 2U;
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x0 = *(ptr1++);
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x1 = *(ptr1++);
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x2 = *(ptr1++);
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while (tapCnt > 0U)
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{
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/* Read the input sample */
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x3 = *(ptr1++);
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/* Read the coefficient */
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c0 = *(ptr2);
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/* Perform the multiply-accumulate */
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acc0 += (q63_t) x0 * c0;
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acc1 += (q63_t) x1 * c0;
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acc2 += (q63_t) x2 * c0;
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acc3 += (q63_t) x3 * c0;
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/* Read the coefficient */
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c1 = *(ptr2 + S->L);
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/* Read the input sample */
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x0 = *(ptr1++);
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/* Perform the multiply-accumulate */
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acc0 += (q63_t) x1 * c1;
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acc1 += (q63_t) x2 * c1;
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acc2 += (q63_t) x3 * c1;
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acc3 += (q63_t) x0 * c1;
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/* Read the coefficient */
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c2 = *(ptr2 + S->L * 2);
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/* Read the input sample */
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x1 = *(ptr1++);
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/* Perform the multiply-accumulate */
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acc0 += (q63_t) x2 * c2;
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acc1 += (q63_t) x3 * c2;
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acc2 += (q63_t) x0 * c2;
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acc3 += (q63_t) x1 * c2;
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/* Read the coefficient */
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c3 = *(ptr2 + S->L * 3);
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/* Read the input sample */
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x2 = *(ptr1++);
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/* Perform the multiply-accumulate */
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acc0 += (q63_t) x3 * c3;
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acc1 += (q63_t) x0 * c3;
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acc2 += (q63_t) x1 * c3;
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acc3 += (q63_t) x2 * c3;
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/* Upsampling is done by stuffing L-1 zeros between each sample.
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* So instead of multiplying zeros with coefficients,
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* Increment the coefficient pointer by interpolation factor times. */
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ptr2 += 4 * S->L;
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/* Decrement loop counter */
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tapCnt--;
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}
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/* If the polyPhase length is not a multiple of 4, compute the remaining filter taps */
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tapCnt = phaseLen % 0x4U;
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while (tapCnt > 0U)
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{
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/* Read the input sample */
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x3 = *(ptr1++);
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/* Read the coefficient */
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c0 = *(ptr2);
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/* Perform the multiply-accumulate */
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acc0 += (q63_t) x0 * c0;
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acc1 += (q63_t) x1 * c0;
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acc2 += (q63_t) x2 * c0;
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acc3 += (q63_t) x3 * c0;
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/* Increment the coefficient pointer by interpolation factor times. */
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ptr2 += S->L;
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/* update states for next sample processing */
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x0 = x1;
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x1 = x2;
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x2 = x3;
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/* Decrement loop counter */
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tapCnt--;
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}
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/* The result is in the accumulator, store in the destination buffer. */
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*(pDst ) = (q15_t) (__SSAT((acc0 >> 15), 16));
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*(pDst + S->L) = (q15_t) (__SSAT((acc1 >> 15), 16));
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*(pDst + 2 * S->L) = (q15_t) (__SSAT((acc2 >> 15), 16));
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*(pDst + 3 * S->L) = (q15_t) (__SSAT((acc3 >> 15), 16));
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pDst++;
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/* Increment the address modifier index of coefficient buffer */
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j++;
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/* Decrement loop counter */
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i--;
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}
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/* Advance the state pointer by 1
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* to process the next group of interpolation factor number samples */
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pState = pState + 4;
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pDst += S->L * 3;
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/* Decrement loop counter */
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blkCnt--;
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}
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/* Loop unrolling: Compute remaining outputs */
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blkCnt = blockSize % 0x4U;
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#else
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/* Initialize blkCnt with number of samples */
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blkCnt = blockSize;
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#endif /* #if defined (ARM_MATH_LOOPUNROLL) */
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while (blkCnt > 0U)
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{
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/* Copy new input sample into the state buffer */
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*pStateCur++ = *pSrc++;
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/* Address modifier index of coefficient buffer */
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j = 1U;
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/* Loop over the Interpolation factor. */
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i = S->L;
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while (i > 0U)
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{
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/* Set accumulator to zero */
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sum0 = 0;
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/* Initialize state pointer */
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ptr1 = pState;
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/* Initialize coefficient pointer */
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ptr2 = pCoeffs + (S->L - j);
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/* Loop over the polyPhase length.
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Repeat until we've computed numTaps-(4*S->L) coefficients. */
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#if defined (ARM_MATH_LOOPUNROLL)
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/* Loop unrolling: Compute 4 outputs at a time */
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tapCnt = phaseLen >> 2U;
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while (tapCnt > 0U)
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{
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/* Perform the multiply-accumulate */
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sum0 += (q63_t) *ptr1++ * *ptr2;
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/* Upsampling is done by stuffing L-1 zeros between each sample.
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* So instead of multiplying zeros with coefficients,
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* Increment the coefficient pointer by interpolation factor times. */
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ptr2 += S->L;
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sum0 += (q63_t) *ptr1++ * *ptr2;
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ptr2 += S->L;
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sum0 += (q63_t) *ptr1++ * *ptr2;
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ptr2 += S->L;
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sum0 += (q63_t) *ptr1++ * *ptr2;
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ptr2 += S->L;
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/* Decrement loop counter */
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tapCnt--;
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}
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/* Loop unrolling: Compute remaining outputs */
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tapCnt = phaseLen % 0x4U;
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#else
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/* Initialize tapCnt with number of samples */
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tapCnt = phaseLen;
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#endif /* #if defined (ARM_MATH_LOOPUNROLL) */
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while (tapCnt > 0U)
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{
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/* Perform the multiply-accumulate */
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sum0 += (q63_t) *ptr1++ * *ptr2;
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/* Upsampling is done by stuffing L-1 zeros between each sample.
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* So instead of multiplying zeros with coefficients,
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* Increment the coefficient pointer by interpolation factor times. */
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ptr2 += S->L;
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/* Decrement loop counter */
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tapCnt--;
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}
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/* The result is in the accumulator, store in the destination buffer. */
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*pDst++ = (q15_t) (__SSAT((sum0 >> 15), 16));
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/* Increment the address modifier index of coefficient buffer */
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j++;
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/* Decrement the loop counter */
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i--;
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}
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/* Advance the state pointer by 1
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* to process the next group of interpolation factor number samples */
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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 phaseLen - 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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pStateCur = S->pState;
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#if defined (ARM_MATH_LOOPUNROLL)
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/* Loop unrolling: Compute 4 outputs at a time */
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tapCnt = (phaseLen - 1U) >> 2U;
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/* copy data */
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while (tapCnt > 0U)
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{
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write_q15x2_ia (&pStateCur, read_q15x2_ia (&pState));
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write_q15x2_ia (&pStateCur, read_q15x2_ia (&pState));
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/* Decrement loop counter */
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tapCnt--;
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}
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/* Loop unrolling: Compute remaining outputs */
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tapCnt = (phaseLen - 1U) % 0x04U;
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#else
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/* Initialize tapCnt with number of samples */
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tapCnt = (phaseLen - 1U);
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#endif /* #if defined (ARM_MATH_LOOPUNROLL) */
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/* Copy data */
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while (tapCnt > 0U)
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{
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*pStateCur++ = *pState++;
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/* Decrement loop counter */
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tapCnt--;
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}
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#else
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/* alternate version for CM0_FAMILY */
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q15_t *pState = S->pState; /* State pointer */
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const q15_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */
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q15_t *pStateCur; /* Points to the current sample of the state */
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q15_t *ptr1; /* Temporary pointer for state buffer */
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const q15_t *ptr2; /* Temporary pointer for coefficient buffer */
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q63_t sum0; /* Accumulators */
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uint32_t i, blkCnt, tapCnt; /* Loop counters */
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uint32_t phaseLen = S->phaseLength; /* Length of each polyphase filter component */
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/* S->pState buffer contains previous frame (phaseLen - 1) samples */
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/* pStateCur points to the location where the new input data should be written */
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pStateCur = S->pState + (phaseLen - 1U);
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/* Total number of intput samples */
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blkCnt = blockSize;
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/* Loop over the blockSize. */
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while (blkCnt > 0U)
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{
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/* Copy new input sample into the state buffer */
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*pStateCur++ = *pSrc++;
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/* Loop over the Interpolation factor. */
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i = S->L;
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while (i > 0U)
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{
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/* Set accumulator to zero */
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sum0 = 0;
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/* Initialize state pointer */
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ptr1 = pState;
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/* Initialize coefficient pointer */
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ptr2 = pCoeffs + (i - 1U);
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/* Loop over the polyPhase length */
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tapCnt = phaseLen;
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while (tapCnt > 0U)
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{
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/* Perform the multiply-accumulate */
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sum0 += ((q63_t) *ptr1++ * *ptr2);
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/* Increment the coefficient pointer by interpolation factor times. */
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ptr2 += S->L;
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/* Decrement the loop counter */
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tapCnt--;
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}
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/* Store the result after converting to 1.15 format in the destination buffer. */
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*pDst++ = (q15_t) (__SSAT((sum0 >> 15), 16));
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/* Decrement loop counter */
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i--;
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}
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/* Advance the state pointer by 1
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* to process the next group of interpolation factor number samples */
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pState = pState + 1;
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/* Decrement 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 phaseLen - 1 samples to the start 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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pStateCur = S->pState;
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tapCnt = phaseLen - 1U;
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/* Copy data */
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while (tapCnt > 0U)
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{
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*pStateCur++ = *pState++;
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/* Decrement loop counter */
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tapCnt--;
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}
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#endif /* #if !defined(ARM_MATH_CM0_FAMILY) */
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}
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/**
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@} end of FIR_Interpolate group
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*/
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