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/* ----------------------------------------------------------------------
* Project: CMSIS DSP Library
* Title: arm_chebyshev_distance_f16.c
* Description: Chebyshev distance between two vectors
*
* $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/distance_functions_f16.h"
#if defined(ARM_FLOAT16_SUPPORTED)
#include <limits.h>
#include <math.h>
/**
@ingroup FloatDist
*/
/**
@defgroup Chebyshev Chebyshev distance
Chebyshev distance
*/
/**
@addtogroup Chebyshev
@{
*/
/**
* @brief Chebyshev distance between two vectors
* @param[in] pA First vector
* @param[in] pB Second vector
* @param[in] blockSize vector length
* @return distance
*
*/
#if defined(ARM_MATH_MVE_FLOAT16) && !defined(ARM_MATH_AUTOVECTORIZE)
#include "arm_helium_utils.h"
#include "arm_vec_math.h"
float16_t arm_chebyshev_distance_f16(const float16_t *pA,const float16_t *pB, uint32_t blockSize)
{
uint32_t blkCnt; /* loop counters */
f16x8_t vecA, vecB;
f16x8_t vecDiff = vdupq_n_f16(0.0);
float16_t maxValue = 0.0f16;
blkCnt = blockSize >> 3;
while (blkCnt > 0U) {
vecA = vld1q(pA);
pA += 8;
vecB = vld1q(pB);
pB += 8;
/*
* update per-lane max.
*/
vecDiff = vmaxnmaq(vsubq(vecA, vecB), vecDiff);
/*
* Decrement the blockSize loop counter
*/
blkCnt--;
}
/*
* tail
* (will be merged thru tail predication)
*/
blkCnt = blockSize & 7;
if (blkCnt > 0U) {
mve_pred16_t p0 = vctp16q(blkCnt);
vecA = vldrhq_z_f16(pA, p0);
vecB = vldrhq_z_f16(pB, p0);
/*
* Get current max per lane and current index per lane
* when a max is selected
*/
vecDiff = vmaxnmaq_m(vecDiff, vsubq(vecA, vecB), p0);
}
/*
* Get max value across the vector
*/
return vmaxnmavq(maxValue, vecDiff);
}
#else
float16_t arm_chebyshev_distance_f16(const float16_t *pA,const float16_t *pB, uint32_t blockSize)
{
_Float16 diff=0.0f, maxVal,tmpA, tmpB;
tmpA = *pA++;
tmpB = *pB++;
diff = (_Float16)fabsf((float32_t)((_Float16)tmpA - (_Float16)tmpB));
maxVal = diff;
blockSize--;
while(blockSize > 0)
{
tmpA = *pA++;
tmpB = *pB++;
diff = (_Float16)fabsf((float32_t)((_Float16)tmpA - (_Float16)tmpB));
if ((_Float16)diff > (_Float16)maxVal)
{
maxVal = diff;
}
blockSize --;
}
return(maxVal);
}
#endif /* defined(ARM_MATH_MVEF) && !defined(ARM_MATH_AUTOVECTORIZE) */
/**
* @} end of Chebyshev group
*/
#endif /* #if defined(ARM_FLOAT16_SUPPORTED) */
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