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/* ----------------------------------------------------------------------
* Project: CMSIS DSP Library
* Title: arm_max_q15.c
* Description: Maximum value of a Q15 vector
*
* $Date: 18. March 2019
* $Revision: V1.6.0
*
* Target Processor: Cortex-M cores
* -------------------------------------------------------------------- */
/*
* Copyright (C) 2010-2019 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 groupStats
*/
/**
@addtogroup Max
@{
*/
/**
@brief Maximum value of a Q15 vector.
@param[in] pSrc points to the input vector
@param[in] blockSize number of samples in input vector
@param[out] pResult maximum value returned here
@param[out] pIndex index of maximum value returned here
@return none
*/
void arm_max_q15(
const q15_t * pSrc,
uint32_t blockSize,
q15_t * pResult,
uint32_t * pIndex)
{
q15_t maxVal, out; /* Temporary variables to store the output value. */
uint32_t blkCnt, outIndex; /* Loop counter */
#if defined (ARM_MATH_LOOPUNROLL)
uint32_t index; /* index of maximum value */
#endif
/* Initialise index value to zero. */
outIndex = 0U;
/* Load first input value that act as reference value for comparision */
out = *pSrc++;
#if defined (ARM_MATH_LOOPUNROLL)
/* Initialise index of maximum value. */
index = 0U;
/* Loop unrolling: Compute 4 outputs at a time */
blkCnt = (blockSize - 1U) >> 2U;
while (blkCnt > 0U)
{
/* Initialize maxVal to next consecutive values one by one */
maxVal = *pSrc++;
/* compare for the maximum value */
if (out < maxVal)
{
/* Update the maximum value and it's index */
out = maxVal;
outIndex = index + 1U;
}
maxVal = *pSrc++;
if (out < maxVal)
{
out = maxVal;
outIndex = index + 2U;
}
maxVal = *pSrc++;
if (out < maxVal)
{
out = maxVal;
outIndex = index + 3U;
}
maxVal = *pSrc++;
if (out < maxVal)
{
out = maxVal;
outIndex = index + 4U;
}
index += 4U;
/* Decrement loop counter */
blkCnt--;
}
/* Loop unrolling: Compute remaining outputs */
blkCnt = (blockSize - 1U) % 4U;
#else
/* Initialize blkCnt with number of samples */
blkCnt = (blockSize - 1U);
#endif /* #if defined (ARM_MATH_LOOPUNROLL) */
while (blkCnt > 0U)
{
/* Initialize maxVal to the next consecutive values one by one */
maxVal = *pSrc++;
/* compare for the maximum value */
if (out < maxVal)
{
/* Update the maximum value and it's index */
out = maxVal;
outIndex = blockSize - blkCnt;
}
/* Decrement loop counter */
blkCnt--;
}
/* Store the maximum value and it's index into destination pointers */
*pResult = out;
*pIndex = outIndex;
}
/**
@} end of Max group
*/
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