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/* ----------------------------------------------------------------------
* Project: CMSIS DSP Library
* Title: arm_max_q15.c
* Description: Maximum value of a Q15 vector
*
* $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 groupStats
*/
/**
* @addtogroup Max
* @{
*/
/**
* @brief Maximum value of a Q15 vector.
* @param[in] *pSrc points to the input vector
* @param[in] blockSize length of the input vector
* @param[out] *pResult maximum value returned here
* @param[out] *pIndex index of maximum value returned here
* @return none.
*/
void arm_max_q15(
q15_t * pSrc,
uint32_t blockSize,
q15_t * pResult,
uint32_t * pIndex)
{
#if defined (ARM_MATH_DSP)
/* Run the below code for Cortex-M4 and Cortex-M3 */
q15_t maxVal1, maxVal2, out; /* Temporary variables to store the output value. */
uint32_t blkCnt, outIndex, count; /* loop counter */
/* Initialise the count value. */
count = 0U;
/* Initialise the index value to zero. */
outIndex = 0U;
/* Load first input value that act as reference value for comparision */
out = *pSrc++;
/* Loop unrolling */
blkCnt = (blockSize - 1U) >> 2U;
while (blkCnt > 0U)
{
/* Initialize maxVal to the next consecutive values one by one */
maxVal1 = *pSrc++;
maxVal2 = *pSrc++;
/* compare for the maximum value */
if (out < maxVal1)
{
/* Update the maximum value and its index */
out = maxVal1;
outIndex = count + 1U;
}
/* compare for the maximum value */
if (out < maxVal2)
{
/* Update the maximum value and its index */
out = maxVal2;
outIndex = count + 2U;
}
/* Initialize maxVal to the next consecutive values one by one */
maxVal1 = *pSrc++;
maxVal2 = *pSrc++;
/* compare for the maximum value */
if (out < maxVal1)
{
/* Update the maximum value and its index */
out = maxVal1;
outIndex = count + 3U;
}
/* compare for the maximum value */
if (out < maxVal2)
{
/* Update the maximum value and its index */
out = maxVal2;
outIndex = count + 4U;
}
count += 4U;
/* Decrement the loop counter */
blkCnt--;
}
/* if (blockSize - 1U) is not multiple of 4 */
blkCnt = (blockSize - 1U) % 4U;
#else
/* Run the below code for Cortex-M0 */
q15_t maxVal1, out; /* Temporary variables to store the output value. */
uint32_t blkCnt, outIndex; /* loop counter */
/* Initialise the index value to zero. */
outIndex = 0U;
/* Load first input value that act as reference value for comparision */
out = *pSrc++;
blkCnt = (blockSize - 1U);
#endif /* #if defined (ARM_MATH_DSP) */
while (blkCnt > 0U)
{
/* Initialize maxVal to the next consecutive values one by one */
maxVal1 = *pSrc++;
/* compare for the maximum value */
if (out < maxVal1)
{
/* Update the maximum value and it's index */
out = maxVal1;
outIndex = blockSize - blkCnt;
}
/* Decrement the 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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