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/* ----------------------------------------------------------------------
* Project: CMSIS DSP Library
* Title: arm_logsumexp_f16.c
* Description: LogSumExp
*
* $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)
#include <limits.h>
#include <math.h>
/**
@ingroup groupStats
*/
/**
@defgroup Entropy Entropy
Computes the entropy of a distribution
*/
/**
* @addtogroup Entropy
* @{
*/
/**
* @brief Entropy
*
* @param[in] pSrcA Array of input values.
* @param[in] blockSize Number of samples in the input array.
* @return Entropy -Sum(p ln p)
*
*/
#if defined(ARM_MATH_MVE_FLOAT16) && !defined(ARM_MATH_AUTOVECTORIZE)
#include "arm_helium_utils.h"
#include "arm_vec_math_f16.h"
float16_t arm_entropy_f16(const float16_t * pSrcA,uint32_t blockSize)
{
uint32_t blkCnt;
_Float16 accum=0.0f16,p;
blkCnt = blockSize;
f16x8_t vSum = vdupq_n_f16(0.0f);
/* Compute 4 outputs at a time */
blkCnt = blockSize >> 3U;
while (blkCnt > 0U)
{
f16x8_t vecIn = vld1q(pSrcA);
vSum = vaddq_f16(vSum, vmulq(vecIn, vlogq_f16(vecIn)));
/*
* Decrement the blockSize loop counter
* Advance vector source and destination pointers
*/
pSrcA += 8;
blkCnt --;
}
accum = vecAddAcrossF16Mve(vSum);
/* Tail */
blkCnt = blockSize & 0x7;
while(blkCnt > 0)
{
p = *pSrcA++;
accum += p * (_Float16)logf((float32_t)p);
blkCnt--;
}
return (-accum);
}
#else
float16_t arm_entropy_f16(const float16_t * pSrcA,uint32_t blockSize)
{
const float16_t *pIn;
uint32_t blkCnt;
_Float16 accum, p;
pIn = pSrcA;
blkCnt = blockSize;
accum = 0.0f;
while(blkCnt > 0)
{
p = *pIn++;
accum += p * (_Float16)logf((float32_t)p);
blkCnt--;
}
return(-accum);
}
#endif /* defined(ARM_MATH_MVEF) && !defined(ARM_MATH_AUTOVECTORIZE) */
/**
* @} end of Entropy group
*/
#endif /* #if defined(ARM_FLOAT16_SUPPORTED) */
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