127 lines
3.3 KiB
C
127 lines
3.3 KiB
C
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/* ----------------------------------------------------------------------
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* Project: CMSIS DSP Library
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* Title: arm_negate_q15.c
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* Description: Negates Q15 vectors
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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 groupMath
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*/
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/**
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@addtogroup BasicNegate
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@{
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*/
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/**
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@brief Negates the elements of a Q15 vector.
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@param[in] pSrc points to the 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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@par Conditions for optimum performance
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Input and output buffers should be aligned by 32-bit
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@par Scaling and Overflow Behavior
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The function uses saturating arithmetic.
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The Q15 value -1 (0x8000) is saturated to the maximum allowable positive value 0x7FFF.
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*/
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void arm_negate_q15(
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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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uint32_t blkCnt; /* Loop counter */
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q15_t in; /* Temporary input variable */
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#if defined (ARM_MATH_LOOPUNROLL)
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#if defined (ARM_MATH_DSP)
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q31_t in1; /* Temporary input variables */
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#endif
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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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/* C = -A */
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#if defined (ARM_MATH_DSP)
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/* Negate and store result in destination buffer (2 samples at a time). */
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in1 = read_q15x2_ia ((q15_t **) &pSrc);
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write_q15x2_ia (&pDst, __QSUB16(0, in1));
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in1 = read_q15x2_ia ((q15_t **) &pSrc);
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write_q15x2_ia (&pDst, __QSUB16(0, in1));
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#else
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in = *pSrc++;
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*pDst++ = (in == (q15_t) 0x8000) ? (q15_t) 0x7fff : -in;
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in = *pSrc++;
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*pDst++ = (in == (q15_t) 0x8000) ? (q15_t) 0x7fff : -in;
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in = *pSrc++;
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*pDst++ = (in == (q15_t) 0x8000) ? (q15_t) 0x7fff : -in;
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in = *pSrc++;
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*pDst++ = (in == (q15_t) 0x8000) ? (q15_t) 0x7fff : -in;
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#endif
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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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/* C = -A */
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/* Negate and store result in destination buffer. */
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in = *pSrc++;
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*pDst++ = (in == (q15_t) 0x8000) ? (q15_t) 0x7fff : -in;
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/* Decrement loop counter */
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blkCnt--;
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}
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}
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/**
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@} end of BasicNegate group
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*/
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