146 lines
3.8 KiB
C
146 lines
3.8 KiB
C
/* ----------------------------------------------------------------------
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* Project: CMSIS DSP Library
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* Title: arm_abs_q7.c
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* Description: Q7 vector absolute value
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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 BasicAbs
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* @{
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*/
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/**
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* @brief Q7 vector absolute value.
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* @param[in] *pSrc points to the input buffer
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* @param[out] *pDst points to the output buffer
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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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* \par Conditions for optimum performance
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* Input and output buffers should be aligned by 32-bit
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*
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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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* The Q7 value -1 (0x80) will be saturated to the maximum allowable positive value 0x7F.
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*/
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void arm_abs_q7(
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q7_t * pSrc,
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q7_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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q7_t in; /* Input value1 */
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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 in1, in2, in3, in4; /* temporary input variables */
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q31_t out1, out2, out3, out4; /* temporary output variables */
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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| */
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/* Read inputs */
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in1 = (q31_t) * pSrc;
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in2 = (q31_t) * (pSrc + 1);
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in3 = (q31_t) * (pSrc + 2);
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/* find absolute value */
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out1 = (in1 > 0) ? in1 : (q31_t)__QSUB8(0, in1);
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/* read input */
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in4 = (q31_t) * (pSrc + 3);
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/* find absolute value */
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out2 = (in2 > 0) ? in2 : (q31_t)__QSUB8(0, in2);
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/* store result to destination */
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*pDst = (q7_t) out1;
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/* find absolute value */
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out3 = (in3 > 0) ? in3 : (q31_t)__QSUB8(0, in3);
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/* find absolute value */
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out4 = (in4 > 0) ? in4 : (q31_t)__QSUB8(0, in4);
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/* store result to destination */
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*(pDst + 1) = (q7_t) out2;
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/* store result to destination */
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*(pDst + 2) = (q7_t) out3;
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/* store result to destination */
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*(pDst + 3) = (q7_t) out4;
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/* update pointers to process next samples */
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pSrc += 4U;
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pDst += 4U;
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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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#else
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/* Run the below code for Cortex-M0 */
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blkCnt = blockSize;
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#endif /* #define ARM_MATH_CM0_FAMILY */
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while (blkCnt > 0U)
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{
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/* C = |A| */
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/* Read the input */
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in = *pSrc++;
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/* Store the Absolute result in the destination buffer */
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*pDst++ = (in > 0) ? in : ((in == (q7_t) 0x80) ? 0x7f : -in);
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/* Decrement the 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 BasicAbs group
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*/
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