156 lines
3.8 KiB
C
156 lines
3.8 KiB
C
/* ----------------------------------------------------------------------
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* Project: CMSIS DSP Library
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* Title: arm_max_f32.c
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* Description: Maximum value of a floating-point vector
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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 groupStats
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*/
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/**
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@defgroup Max Maximum
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Computes the maximum value of an array of data.
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The function returns both the maximum value and its position within the array.
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There are separate functions for floating-point, Q31, Q15, and Q7 data types.
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*/
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/**
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@addtogroup Max
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@{
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*/
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/**
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@brief Maximum value of a floating-point vector.
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@param[in] pSrc points to the input vector
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@param[in] blockSize number of samples in input vector
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@param[out] pResult maximum value returned here
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@param[out] pIndex index of maximum value returned here
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@return none
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*/
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void arm_max_f32(
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const float32_t * pSrc,
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uint32_t blockSize,
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float32_t * pResult,
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uint32_t * pIndex)
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{
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float32_t maxVal, out; /* Temporary variables to store the output value. */
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uint32_t blkCnt, outIndex; /* Loop counter */
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#if defined (ARM_MATH_LOOPUNROLL)
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uint32_t index; /* index of maximum value */
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#endif
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/* Initialise index value to zero. */
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outIndex = 0U;
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/* Load first input value that act as reference value for comparision */
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out = *pSrc++;
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#if defined (ARM_MATH_LOOPUNROLL)
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/* Initialise index of maximum value. */
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index = 0U;
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/* Loop unrolling: Compute 4 outputs at a time */
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blkCnt = (blockSize - 1U) >> 2U;
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while (blkCnt > 0U)
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{
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/* Initialize maxVal to next consecutive values one by one */
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maxVal = *pSrc++;
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/* compare for the maximum value */
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if (out < maxVal)
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{
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/* Update the maximum value and it's index */
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out = maxVal;
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outIndex = index + 1U;
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}
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maxVal = *pSrc++;
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if (out < maxVal)
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{
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out = maxVal;
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outIndex = index + 2U;
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}
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maxVal = *pSrc++;
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if (out < maxVal)
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{
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out = maxVal;
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outIndex = index + 3U;
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}
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maxVal = *pSrc++;
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if (out < maxVal)
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{
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out = maxVal;
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outIndex = index + 4U;
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}
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index += 4U;
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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 - 1U) % 4U;
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#else
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/* Initialize blkCnt with number of samples */
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blkCnt = (blockSize - 1U);
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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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/* Initialize maxVal to the next consecutive values one by one */
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maxVal = *pSrc++;
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/* compare for the maximum value */
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if (out < maxVal)
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{
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/* Update the maximum value and it's index */
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out = maxVal;
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outIndex = blockSize - blkCnt;
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}
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/* Decrement loop counter */
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blkCnt--;
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}
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/* Store the maximum value and it's index into destination pointers */
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*pResult = out;
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*pIndex = outIndex;
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}
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/**
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@} end of Max group
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*/
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