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/* ----------------------------------------------------------------------
* Project: CMSIS DSP Library
* Title: arm_max_f16.c
* Description: Maximum value of a floating-point vector
*
* $Date: 23 April 2021
* $Revision: V1.9.0
*
* Target Processor: Cortex-M and Cortex-A cores
* -------------------------------------------------------------------- */
/*
* Copyright (C) 2010-2021 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 "dsp/statistics_functions_f16.h"
#if defined(ARM_FLOAT16_SUPPORTED)
#if (defined(ARM_MATH_NEON) || defined(ARM_MATH_MVEF)) && !defined(ARM_MATH_AUTOVECTORIZE)
#include <limits.h>
#endif
/**
@ingroup groupStats
*/
/**
@addtogroup Max
@{
*/
/**
@brief Maximum value of a floating-point 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
*/
#if defined(ARM_MATH_MVE_FLOAT16) && !defined(ARM_MATH_AUTOVECTORIZE)
void arm_max_f16(
const float16_t * pSrc,
uint32_t blockSize,
float16_t * pResult,
uint32_t * pIndex)
{
int32_t blkCnt;
f16x8_t vecSrc;
f16x8_t curExtremValVec = vdupq_n_f16(F16_MIN);
float16_t maxValue = F16_MIN;
uint32_t idx = blockSize;
uint16x8_t indexVec;
uint16x8_t curExtremIdxVec;
uint32_t curIdx = 0;
mve_pred16_t p0;
float16_t tmp;
indexVec = vidupq_wb_u16(&curIdx, 1);
curExtremIdxVec = vdupq_n_u16(0);
/* Compute 4 outputs at a time */
blkCnt = blockSize >> 3;
while (blkCnt > 0)
{
vecSrc = vldrhq_f16(pSrc);
/*
* Get current max per lane and current index per lane
* when a max is selected
*/
p0 = vcmpgeq(vecSrc, curExtremValVec);
curExtremValVec = vpselq(vecSrc, curExtremValVec, p0);
curExtremIdxVec = vpselq(indexVec, curExtremIdxVec, p0);
indexVec = vidupq_wb_u16(&curIdx, 1);
pSrc += 8;
/* Decrement the loop counter */
blkCnt--;
}
/*
* Get max value across the vector
*/
maxValue = vmaxnmvq(maxValue, curExtremValVec);
/*
* set index for lower values to max possible index
*/
p0 = vcmpgeq(curExtremValVec, maxValue);
indexVec = vpselq(curExtremIdxVec, vdupq_n_u16(blockSize), p0);
/*
* Get min index which is thus for a max value
*/
idx = vminvq(idx, indexVec);
/* Tail */
blkCnt = blockSize & 7;
while (blkCnt > 0)
{
/* Initialize tmp to the next consecutive values one by one */
tmp = *pSrc++;
/* compare for the maximum value */
if ((_Float16)maxValue < (_Float16)tmp)
{
/* Update the maximum value and it's index */
maxValue = tmp;
idx = blockSize - blkCnt;
}
/* Decrement loop counter */
blkCnt--;
}
/*
* Save result
*/
*pIndex = idx;
*pResult = maxValue;
}
#else
void arm_max_f16(
const float16_t * pSrc,
uint32_t blockSize,
float16_t * pResult,
uint32_t * pIndex)
{
float16_t maxVal, out; /* Temporary variables to store the output value. */
uint32_t blkCnt, outIndex; /* Loop counter */
#if defined (ARM_MATH_LOOPUNROLL) && !defined(ARM_MATH_AUTOVECTORIZE)
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) && !defined(ARM_MATH_AUTOVECTORIZE)
/* 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 ((_Float16)out < (_Float16)maxVal)
{
/* Update the maximum value and it's index */
out = maxVal;
outIndex = index + 1U;
}
maxVal = *pSrc++;
if ((_Float16)out < (_Float16)maxVal)
{
out = maxVal;
outIndex = index + 2U;
}
maxVal = *pSrc++;
if ((_Float16)out < (_Float16)maxVal)
{
out = maxVal;
outIndex = index + 3U;
}
maxVal = *pSrc++;
if ((_Float16)out < (_Float16)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 ((_Float16)out < (_Float16)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;
}
#endif /* defined(ARM_MATH_MVEF) && !defined(ARM_MATH_AUTOVECTORIZE) */
/**
@} end of Max group
*/
#endif /* #if defined(ARM_FLOAT16_SUPPORTED) */
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