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/* ----------------------------------------------------------------------
* Project: CMSIS DSP Library
* Title: arm_abs_q7.c
* Description: Q7 vector absolute value
*
* $Date: 27. January 2017
* $Revision: V.1.5.1
*
* Target Processor: Cortex-M cores
* -------------------------------------------------------------------- */
/*
* Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved.
*
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the License); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an AS IS BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "arm_math.h"
/**
* @ingroup groupMath
*/
/**
* @addtogroup BasicAbs
* @{
*/
/**
* @brief Q7 vector absolute value.
* @param[in] *pSrc points to the input buffer
* @param[out] *pDst points to the output buffer
* @param[in] blockSize number of samples in each vector
* @return none.
*
* \par Conditions for optimum performance
* Input and output buffers should be aligned by 32-bit
*
*
* <b>Scaling and Overflow Behavior:</b>
* \par
* The function uses saturating arithmetic.
* The Q7 value -1 (0x80) will be saturated to the maximum allowable positive value 0x7F.
*/
void arm_abs_q7(
q7_t * pSrc,
q7_t * pDst,
uint32_t blockSize)
{
uint32_t blkCnt; /* loop counter */
q7_t in; /* Input value1 */
#if defined (ARM_MATH_DSP)
/* Run the below code for Cortex-M4 and Cortex-M3 */
q31_t in1, in2, in3, in4; /* temporary input variables */
q31_t out1, out2, out3, out4; /* temporary output variables */
/*loop Unrolling */
blkCnt = blockSize >> 2U;
/* First part of the processing with loop unrolling. Compute 4 outputs at a time.
** a second loop below computes the remaining 1 to 3 samples. */
while (blkCnt > 0U)
{
/* C = |A| */
/* Read inputs */
in1 = (q31_t) * pSrc;
in2 = (q31_t) * (pSrc + 1);
in3 = (q31_t) * (pSrc + 2);
/* find absolute value */
out1 = (in1 > 0) ? in1 : (q31_t)__QSUB8(0, in1);
/* read input */
in4 = (q31_t) * (pSrc + 3);
/* find absolute value */
out2 = (in2 > 0) ? in2 : (q31_t)__QSUB8(0, in2);
/* store result to destination */
*pDst = (q7_t) out1;
/* find absolute value */
out3 = (in3 > 0) ? in3 : (q31_t)__QSUB8(0, in3);
/* find absolute value */
out4 = (in4 > 0) ? in4 : (q31_t)__QSUB8(0, in4);
/* store result to destination */
*(pDst + 1) = (q7_t) out2;
/* store result to destination */
*(pDst + 2) = (q7_t) out3;
/* store result to destination */
*(pDst + 3) = (q7_t) out4;
/* update pointers to process next samples */
pSrc += 4U;
pDst += 4U;
/* Decrement the loop counter */
blkCnt--;
}
/* If the blockSize is not a multiple of 4, compute any remaining output samples here.
** No loop unrolling is used. */
blkCnt = blockSize % 0x4U;
#else
/* Run the below code for Cortex-M0 */
blkCnt = blockSize;
#endif /* #define ARM_MATH_CM0_FAMILY */
while (blkCnt > 0U)
{
/* C = |A| */
/* Read the input */
in = *pSrc++;
/* Store the Absolute result in the destination buffer */
*pDst++ = (in > 0) ? in : ((in == (q7_t) 0x80) ? 0x7f : -in);
/* Decrement the loop counter */
blkCnt--;
}
}
/**
* @} end of BasicAbs group
*/
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