716 lines
20 KiB
C
716 lines
20 KiB
C
/* ----------------------------------------------------------------------
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* Project: CMSIS DSP Library
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* Title: arm_fir_f32.c
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* Description: Floating-point FIR filter processing function
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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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@defgroup FIR Finite Impulse Response (FIR) Filters
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This set of functions implements Finite Impulse Response (FIR) filters
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for Q7, Q15, Q31, and floating-point data types. Fast versions of Q15 and Q31 are also provided.
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The functions operate on blocks of input and output data and each call to the function processes
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<code>blockSize</code> samples through the filter. <code>pSrc</code> and
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<code>pDst</code> points to input and output arrays containing <code>blockSize</code> values.
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@par Algorithm
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The FIR filter algorithm is based upon a sequence of multiply-accumulate (MAC) operations.
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Each filter coefficient <code>b[n]</code> is multiplied by a state variable which equals a previous input sample <code>x[n]</code>.
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<pre>
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y[n] = b[0] * x[n] + b[1] * x[n-1] + b[2] * x[n-2] + ...+ b[numTaps-1] * x[n-numTaps+1]
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</pre>
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@par
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\image html FIR.GIF "Finite Impulse Response filter"
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@par
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<code>pCoeffs</code> points to a coefficient array of size <code>numTaps</code>.
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Coefficients are stored in time reversed order.
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@par
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<pre>
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{b[numTaps-1], b[numTaps-2], b[N-2], ..., b[1], b[0]}
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</pre>
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@par
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<code>pState</code> points to a state array of size <code>numTaps + blockSize - 1</code>.
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Samples in the state buffer are stored in the following order.
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@par
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<pre>
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{x[n-numTaps+1], x[n-numTaps], x[n-numTaps-1], x[n-numTaps-2]....x[0], x[1], ..., x[blockSize-1]}
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</pre>
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@par
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Note that the length of the state buffer exceeds the length of the coefficient array by <code>blockSize-1</code>.
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The increased state buffer length allows circular addressing, which is traditionally used in the FIR filters,
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to be avoided and yields a significant speed improvement.
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The state variables are updated after each block of data is processed; the coefficients are untouched.
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@par Instance Structure
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The coefficients and state variables for a filter are stored together in an instance data structure.
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A separate instance structure must be defined for each filter.
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Coefficient arrays may be shared among several instances while state variable arrays cannot be shared.
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There are separate instance structure declarations for each of the 4 supported data types.
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@par Initialization Functions
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There is also an associated initialization function for each data type.
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The initialization function performs the following operations:
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- Sets the values of the internal structure fields.
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- Zeros out the values in the state buffer.
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To do this manually without calling the init function, assign the follow subfields of the instance structure:
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numTaps, pCoeffs, pState. Also set all of the values in pState to zero.
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@par
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Use of the initialization function is optional.
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However, if the initialization function is used, then the instance structure cannot be placed into a const data section.
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To place an instance structure into a const data section, the instance structure must be manually initialized.
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Set the values in the state buffer to zeros before static initialization.
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The code below statically initializes each of the 4 different data type filter instance structures
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<pre>
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arm_fir_instance_f32 S = {numTaps, pState, pCoeffs};
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arm_fir_instance_q31 S = {numTaps, pState, pCoeffs};
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arm_fir_instance_q15 S = {numTaps, pState, pCoeffs};
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arm_fir_instance_q7 S = {numTaps, pState, pCoeffs};
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</pre>
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where <code>numTaps</code> is the number of filter coefficients in the filter; <code>pState</code> is the address of the state buffer;
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<code>pCoeffs</code> is the address of the coefficient buffer.
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@par Fixed-Point Behavior
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Care must be taken when using the fixed-point versions of the FIR filter functions.
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In particular, the overflow and saturation behavior of the accumulator used in each function must be considered.
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Refer to the function specific documentation below for usage guidelines.
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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 floating-point FIR filter.
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@param[in] S points to an instance of the floating-point FIR filter 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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*/
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#if defined(ARM_MATH_NEON)
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void arm_fir_f32(
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const arm_fir_instance_f32 * S,
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const float32_t * pSrc,
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float32_t * pDst,
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uint32_t blockSize)
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{
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float32_t *pState = S->pState; /* State pointer */
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const float32_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */
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float32_t *pStateCurnt; /* Points to the current sample of the state */
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float32_t *px; /* Temporary pointers for state buffer */
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const float32_t *pb; /* Temporary pointers for coefficient buffer */
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uint32_t numTaps = S->numTaps; /* Number of filter coefficients in the filter */
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uint32_t i, tapCnt, blkCnt; /* Loop counters */
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float32x4_t accv0,accv1,samples0,samples1,x0,x1,x2,xa,xb,x,b,accv;
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uint32x4_t x0_u,x1_u,x2_u,xa_u,xb_u;
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float32_t acc;
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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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/* Loop unrolling */
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blkCnt = blockSize >> 3;
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while (blkCnt > 0U)
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{
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/* Copy 8 samples at a time into state buffers */
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samples0 = vld1q_f32(pSrc);
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vst1q_f32(pStateCurnt,samples0);
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pStateCurnt += 4;
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pSrc += 4 ;
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samples1 = vld1q_f32(pSrc);
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vst1q_f32(pStateCurnt,samples1);
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pStateCurnt += 4;
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pSrc += 4 ;
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/* Set the accumulators to zero */
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accv0 = vdupq_n_f32(0);
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accv1 = vdupq_n_f32(0);
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/* Initialize state pointer */
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px = pState;
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/* Initialize coefficient pointer */
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pb = pCoeffs;
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/* Loop unroling */
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i = numTaps >> 2;
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/* Perform the multiply-accumulates */
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x0 = vld1q_f32(px);
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x1 = vld1q_f32(px + 4);
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while(i > 0)
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{
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/* 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] */
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x2 = vld1q_f32(px + 8);
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b = vld1q_f32(pb);
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xa = x0;
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xb = x1;
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accv0 = vmlaq_n_f32(accv0,xa,b[0]);
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accv1 = vmlaq_n_f32(accv1,xb,b[0]);
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xa = vextq_f32(x0,x1,1);
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xb = vextq_f32(x1,x2,1);
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accv0 = vmlaq_n_f32(accv0,xa,b[1]);
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accv1 = vmlaq_n_f32(accv1,xb,b[1]);
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xa = vextq_f32(x0,x1,2);
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xb = vextq_f32(x1,x2,2);
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accv0 = vmlaq_n_f32(accv0,xa,b[2]);
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accv1 = vmlaq_n_f32(accv1,xb,b[2]);
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xa = vextq_f32(x0,x1,3);
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xb = vextq_f32(x1,x2,3);
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accv0 = vmlaq_n_f32(accv0,xa,b[3]);
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accv1 = vmlaq_n_f32(accv1,xb,b[3]);
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pb += 4;
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x0 = x1;
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x1 = x2;
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px += 4;
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i--;
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}
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/* Tail */
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i = numTaps & 3;
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x2 = vld1q_f32(px + 8);
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/* Perform the multiply-accumulates */
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switch(i)
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{
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case 3:
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{
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accv0 = vmlaq_n_f32(accv0,x0,*pb);
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accv1 = vmlaq_n_f32(accv1,x1,*pb);
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pb++;
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xa = vextq_f32(x0,x1,1);
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xb = vextq_f32(x1,x2,1);
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accv0 = vmlaq_n_f32(accv0,xa,*pb);
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accv1 = vmlaq_n_f32(accv1,xb,*pb);
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pb++;
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xa = vextq_f32(x0,x1,2);
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xb = vextq_f32(x1,x2,2);
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accv0 = vmlaq_n_f32(accv0,xa,*pb);
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accv1 = vmlaq_n_f32(accv1,xb,*pb);
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}
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break;
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case 2:
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{
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accv0 = vmlaq_n_f32(accv0,x0,*pb);
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accv1 = vmlaq_n_f32(accv1,x1,*pb);
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pb++;
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xa = vextq_f32(x0,x1,1);
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xb = vextq_f32(x1,x2,1);
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accv0 = vmlaq_n_f32(accv0,xa,*pb);
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accv1 = vmlaq_n_f32(accv1,xb,*pb);
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}
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break;
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case 1:
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{
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accv0 = vmlaq_n_f32(accv0,x0,*pb);
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accv1 = vmlaq_n_f32(accv1,x1,*pb);
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}
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break;
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default:
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break;
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}
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/* The result is stored in the destination buffer. */
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vst1q_f32(pDst,accv0);
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pDst += 4;
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vst1q_f32(pDst,accv1);
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pDst += 4;
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/* Advance state pointer by 8 for the next 8 samples */
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pState = pState + 8;
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blkCnt--;
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}
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/* Tail */
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blkCnt = blockSize & 0x7;
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while (blkCnt > 0U)
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{
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/* Copy one sample at a time into state buffer */
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*pStateCurnt++ = *pSrc++;
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/* Set the accumulator to zero */
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acc = 0.0f;
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/* Initialize state pointer */
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px = pState;
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/* Initialize Coefficient pointer */
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pb = pCoeffs;
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i = numTaps;
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/* Perform the multiply-accumulates */
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do
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{
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/* 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] */
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acc += *px++ * *pb++;
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i--;
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} while (i > 0U);
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/* The result is stored in the destination buffer. */
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*pDst++ = acc;
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/* Advance state pointer by 1 for the next sample */
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pState = pState + 1;
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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 starting 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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/* Copy numTaps number of values */
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tapCnt = numTaps - 1U;
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/* Copy 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
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void arm_fir_f32(
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const arm_fir_instance_f32 * S,
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const float32_t * pSrc,
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float32_t * pDst,
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uint32_t blockSize)
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{
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float32_t *pState = S->pState; /* State pointer */
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const float32_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */
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float32_t *pStateCurnt; /* Points to the current sample of the state */
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float32_t *px; /* Temporary pointer for state buffer */
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const float32_t *pb; /* Temporary pointer for coefficient buffer */
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float32_t acc0; /* Accumulator */
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uint32_t numTaps = S->numTaps; /* Number of filter coefficients in the filter */
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uint32_t i, tapCnt, blkCnt; /* Loop counters */
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#if defined (ARM_MATH_LOOPUNROLL)
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float32_t acc1, acc2, acc3, acc4, acc5, acc6, acc7; /* Accumulators */
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float32_t x0, x1, x2, x3, x4, x5, x6, x7; /* Temporary variables to hold state values */
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float32_t c0; /* Temporary variable to hold coefficient value */
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#endif
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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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#if defined (ARM_MATH_LOOPUNROLL)
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/* Loop unrolling: Compute 8 output values simultaneously.
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* The variables acc0 ... acc7 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 >> 3U;
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while (blkCnt > 0U)
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{
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/* Copy 4 new input samples into the state buffer. */
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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 = 0.0f;
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acc1 = 0.0f;
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acc2 = 0.0f;
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acc3 = 0.0f;
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acc4 = 0.0f;
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acc5 = 0.0f;
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acc6 = 0.0f;
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acc7 = 0.0f;
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/* Initialize state pointer */
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px = pState;
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/* Initialize coefficient pointer */
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pb = pCoeffs;
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/* This is separated from the others to avoid
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* a call to __aeabi_memmove which would be slower
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*/
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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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/* Read the first 7 samples from the state buffer: x[n-numTaps], x[n-numTaps-1], x[n-numTaps-2] */
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x0 = *px++;
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x1 = *px++;
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x2 = *px++;
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x3 = *px++;
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x4 = *px++;
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x5 = *px++;
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x6 = *px++;
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/* Loop unrolling: process 8 taps at a time. */
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tapCnt = numTaps >> 3U;
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while (tapCnt > 0U)
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{
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/* Read the b[numTaps-1] coefficient */
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c0 = *(pb++);
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/* Read x[n-numTaps-3] sample */
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x7 = *(px++);
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/* acc0 += b[numTaps-1] * x[n-numTaps] */
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acc0 += x0 * c0;
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/* acc1 += b[numTaps-1] * x[n-numTaps-1] */
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acc1 += x1 * c0;
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/* acc2 += b[numTaps-1] * x[n-numTaps-2] */
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acc2 += x2 * c0;
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/* acc3 += b[numTaps-1] * x[n-numTaps-3] */
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acc3 += x3 * c0;
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/* acc4 += b[numTaps-1] * x[n-numTaps-4] */
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acc4 += x4 * c0;
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/* acc1 += b[numTaps-1] * x[n-numTaps-5] */
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acc5 += x5 * c0;
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/* acc2 += b[numTaps-1] * x[n-numTaps-6] */
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acc6 += x6 * c0;
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/* acc3 += b[numTaps-1] * x[n-numTaps-7] */
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acc7 += x7 * c0;
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/* Read the b[numTaps-2] coefficient */
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c0 = *(pb++);
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/* Read x[n-numTaps-4] sample */
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x0 = *(px++);
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/* Perform the multiply-accumulate */
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acc0 += x1 * c0;
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acc1 += x2 * c0;
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acc2 += x3 * c0;
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acc3 += x4 * c0;
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acc4 += x5 * c0;
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acc5 += x6 * c0;
|
|
acc6 += x7 * c0;
|
|
acc7 += x0 * c0;
|
|
|
|
/* Read the b[numTaps-3] coefficient */
|
|
c0 = *(pb++);
|
|
|
|
/* Read x[n-numTaps-5] sample */
|
|
x1 = *(px++);
|
|
|
|
/* Perform the multiply-accumulates */
|
|
acc0 += x2 * c0;
|
|
acc1 += x3 * c0;
|
|
acc2 += x4 * c0;
|
|
acc3 += x5 * c0;
|
|
acc4 += x6 * c0;
|
|
acc5 += x7 * c0;
|
|
acc6 += x0 * c0;
|
|
acc7 += x1 * c0;
|
|
|
|
/* Read the b[numTaps-4] coefficient */
|
|
c0 = *(pb++);
|
|
|
|
/* Read x[n-numTaps-6] sample */
|
|
x2 = *(px++);
|
|
|
|
/* Perform the multiply-accumulates */
|
|
acc0 += x3 * c0;
|
|
acc1 += x4 * c0;
|
|
acc2 += x5 * c0;
|
|
acc3 += x6 * c0;
|
|
acc4 += x7 * c0;
|
|
acc5 += x0 * c0;
|
|
acc6 += x1 * c0;
|
|
acc7 += x2 * c0;
|
|
|
|
/* Read the b[numTaps-4] coefficient */
|
|
c0 = *(pb++);
|
|
|
|
/* Read x[n-numTaps-6] sample */
|
|
x3 = *(px++);
|
|
/* Perform the multiply-accumulates */
|
|
acc0 += x4 * c0;
|
|
acc1 += x5 * c0;
|
|
acc2 += x6 * c0;
|
|
acc3 += x7 * c0;
|
|
acc4 += x0 * c0;
|
|
acc5 += x1 * c0;
|
|
acc6 += x2 * c0;
|
|
acc7 += x3 * c0;
|
|
|
|
/* Read the b[numTaps-4] coefficient */
|
|
c0 = *(pb++);
|
|
|
|
/* Read x[n-numTaps-6] sample */
|
|
x4 = *(px++);
|
|
|
|
/* Perform the multiply-accumulates */
|
|
acc0 += x5 * c0;
|
|
acc1 += x6 * c0;
|
|
acc2 += x7 * c0;
|
|
acc3 += x0 * c0;
|
|
acc4 += x1 * c0;
|
|
acc5 += x2 * c0;
|
|
acc6 += x3 * c0;
|
|
acc7 += x4 * c0;
|
|
|
|
/* Read the b[numTaps-4] coefficient */
|
|
c0 = *(pb++);
|
|
|
|
/* Read x[n-numTaps-6] sample */
|
|
x5 = *(px++);
|
|
|
|
/* Perform the multiply-accumulates */
|
|
acc0 += x6 * c0;
|
|
acc1 += x7 * c0;
|
|
acc2 += x0 * c0;
|
|
acc3 += x1 * c0;
|
|
acc4 += x2 * c0;
|
|
acc5 += x3 * c0;
|
|
acc6 += x4 * c0;
|
|
acc7 += x5 * c0;
|
|
|
|
/* Read the b[numTaps-4] coefficient */
|
|
c0 = *(pb++);
|
|
|
|
/* Read x[n-numTaps-6] sample */
|
|
x6 = *(px++);
|
|
|
|
/* Perform the multiply-accumulates */
|
|
acc0 += x7 * c0;
|
|
acc1 += x0 * c0;
|
|
acc2 += x1 * c0;
|
|
acc3 += x2 * c0;
|
|
acc4 += x3 * c0;
|
|
acc5 += x4 * c0;
|
|
acc6 += x5 * c0;
|
|
acc7 += x6 * c0;
|
|
|
|
/* Decrement loop counter */
|
|
tapCnt--;
|
|
}
|
|
|
|
/* Loop unrolling: Compute remaining outputs */
|
|
tapCnt = numTaps % 0x8U;
|
|
|
|
while (tapCnt > 0U)
|
|
{
|
|
/* Read coefficients */
|
|
c0 = *(pb++);
|
|
|
|
/* Fetch 1 state variable */
|
|
x7 = *(px++);
|
|
|
|
/* Perform the multiply-accumulates */
|
|
acc0 += x0 * c0;
|
|
acc1 += x1 * c0;
|
|
acc2 += x2 * c0;
|
|
acc3 += x3 * c0;
|
|
acc4 += x4 * c0;
|
|
acc5 += x5 * c0;
|
|
acc6 += x6 * c0;
|
|
acc7 += x7 * c0;
|
|
|
|
/* Reuse the present sample states for next sample */
|
|
x0 = x1;
|
|
x1 = x2;
|
|
x2 = x3;
|
|
x3 = x4;
|
|
x4 = x5;
|
|
x5 = x6;
|
|
x6 = x7;
|
|
|
|
/* Decrement loop counter */
|
|
tapCnt--;
|
|
}
|
|
|
|
/* Advance the state pointer by 8 to process the next group of 8 samples */
|
|
pState = pState + 8;
|
|
|
|
/* The results in the 8 accumulators, store in the destination buffer. */
|
|
*pDst++ = acc0;
|
|
*pDst++ = acc1;
|
|
*pDst++ = acc2;
|
|
*pDst++ = acc3;
|
|
*pDst++ = acc4;
|
|
*pDst++ = acc5;
|
|
*pDst++ = acc6;
|
|
*pDst++ = acc7;
|
|
|
|
|
|
/* Decrement loop counter */
|
|
blkCnt--;
|
|
}
|
|
|
|
/* Loop unrolling: Compute remaining output samples */
|
|
blkCnt = blockSize % 0x8U;
|
|
|
|
#else
|
|
|
|
/* Initialize blkCnt with number of taps */
|
|
blkCnt = blockSize;
|
|
|
|
#endif /* #if defined (ARM_MATH_LOOPUNROLL) */
|
|
|
|
while (blkCnt > 0U)
|
|
{
|
|
/* Copy one sample at a time into state buffer */
|
|
*pStateCurnt++ = *pSrc++;
|
|
|
|
/* Set the accumulator to zero */
|
|
acc0 = 0.0f;
|
|
|
|
/* Initialize state pointer */
|
|
px = pState;
|
|
|
|
/* Initialize Coefficient pointer */
|
|
pb = pCoeffs;
|
|
|
|
i = 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] */
|
|
acc0 += *px++ * *pb++;
|
|
|
|
i--;
|
|
} while (i > 0U);
|
|
|
|
/* Store result in destination buffer. */
|
|
*pDst++ = acc0;
|
|
|
|
/* Advance state pointer by 1 for the next sample */
|
|
pState = pState + 1U;
|
|
|
|
/* Decrement 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 state buffer */
|
|
pStateCurnt = S->pState;
|
|
|
|
#if defined (ARM_MATH_LOOPUNROLL)
|
|
|
|
/* Loop unrolling: Compute 4 taps at a time */
|
|
tapCnt = (numTaps - 1U) >> 2U;
|
|
|
|
/* Copy data */
|
|
while (tapCnt > 0U)
|
|
{
|
|
*pStateCurnt++ = *pState++;
|
|
*pStateCurnt++ = *pState++;
|
|
*pStateCurnt++ = *pState++;
|
|
*pStateCurnt++ = *pState++;
|
|
|
|
/* Decrement loop counter */
|
|
tapCnt--;
|
|
}
|
|
|
|
/* Calculate remaining number of copies */
|
|
tapCnt = (numTaps - 1U) % 0x4U;
|
|
|
|
#else
|
|
|
|
/* Initialize tapCnt with number of taps */
|
|
tapCnt = (numTaps - 1U);
|
|
|
|
#endif /* #if defined (ARM_MATH_LOOPUNROLL) */
|
|
|
|
/* Copy remaining data */
|
|
while (tapCnt > 0U)
|
|
{
|
|
*pStateCurnt++ = *pState++;
|
|
|
|
/* Decrement loop counter */
|
|
tapCnt--;
|
|
}
|
|
|
|
}
|
|
|
|
#endif /* #if defined(ARM_MATH_NEON) */
|
|
/**
|
|
* @} end of FIR group
|
|
*/
|