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134 lines
3.3 KiB
134 lines
3.3 KiB
/* ----------------------------------------------------------------------
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* Project: CMSIS DSP Library
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* Title: arm_sub_q31.c
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* Description: Q31 vector subtraction
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*
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* $Date: 27. January 2017
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* $Revision: V.1.5.1
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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) 2010-2017 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 groupMath
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*/
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/**
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* @addtogroup BasicSub
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* @{
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*/
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/**
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* @brief Q31 vector subtraction.
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* @param[in] *pSrcA points to the first input vector
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* @param[in] *pSrcB points to the second input vector
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* @param[out] *pDst points to the output vector
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* @param[in] blockSize number of samples in each vector
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* @return none.
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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 uses saturating arithmetic.
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* Results outside of the allowable Q31 range [0x80000000 0x7FFFFFFF] will be saturated.
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*/
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void arm_sub_q31(
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q31_t * pSrcA,
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q31_t * pSrcB,
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q31_t * pDst,
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uint32_t blockSize)
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{
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uint32_t blkCnt; /* loop counter */
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#if defined (ARM_MATH_DSP)
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/* Run the below code for Cortex-M4 and Cortex-M3 */
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q31_t inA1, inA2, inA3, inA4;
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q31_t inB1, inB2, inB3, inB4;
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/*loop Unrolling */
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blkCnt = blockSize >> 2U;
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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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/* C = A - B */
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/* Subtract and then store the results in the destination buffer. */
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inA1 = *pSrcA++;
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inA2 = *pSrcA++;
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inB1 = *pSrcB++;
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inB2 = *pSrcB++;
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inA3 = *pSrcA++;
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inA4 = *pSrcA++;
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inB3 = *pSrcB++;
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inB4 = *pSrcB++;
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*pDst++ = __QSUB(inA1, inB1);
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*pDst++ = __QSUB(inA2, inB2);
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*pDst++ = __QSUB(inA3, inB3);
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*pDst++ = __QSUB(inA4, inB4);
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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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/* C = A - B */
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/* Subtract and then store the result in the destination buffer. */
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*pDst++ = __QSUB(*pSrcA++, *pSrcB++);
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/* Decrement the loop counter */
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blkCnt--;
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}
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#else
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/* Run the below code for Cortex-M0 */
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/* Initialize blkCnt with number of samples */
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blkCnt = blockSize;
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while (blkCnt > 0U)
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{
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/* C = A - B */
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/* Subtract and then store the result in the destination buffer. */
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*pDst++ = (q31_t) clip_q63_to_q31((q63_t) * pSrcA++ - *pSrcB++);
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/* Decrement the loop counter */
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blkCnt--;
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}
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#endif /* #if defined (ARM_MATH_DSP) */
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}
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/**
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* @} end of BasicSub group
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*/
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