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/* ----------------------------------------------------------------------
* Project: CMSIS DSP Library
* Title: arm_max_q7.c
* Description: Maximum value of a Q7 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.h"
/**
@ingroup groupStats
*/
/**
@addtogroup Max
@{
*/
/**
@brief Maximum value of a Q7 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_MVEI) && !defined(ARM_MATH_AUTOVECTORIZE)
#include "arm_helium_utils.h"
static void arm_small_blk_max_q7(
const q7_t * pSrc,
uint16_t blockSize,
q7_t * pResult,
uint32_t * pIndex)
{
int32_t blkCnt; /* loop counters */
q7x16_t extremValVec = vdupq_n_s8(Q7_MIN);
q7_t maxValue = Q7_MIN;
uint8x16_t indexVec;
uint8x16_t extremIdxVec;
mve_pred16_t p0;
uint8_t extremIdxArr[16];
indexVec = vidupq_u8(0U, 1);
blkCnt = blockSize;
do {
mve_pred16_t p = vctp8q(blkCnt);
q7x16_t extremIdxVal = vld1q_z_s8(pSrc, p);
/*
* Get current max per lane and current index per lane
* when a max is selected
*/
p0 = vcmpgeq_m(extremIdxVal, extremValVec, p);
extremValVec = vorrq_m(extremValVec, extremIdxVal, extremIdxVal, p0);
/* store per-lane extrema indexes */
vst1q_p_u8(extremIdxArr, indexVec, p0);
indexVec += 16;
pSrc += 16;
blkCnt -= 16;
}
while (blkCnt > 0);
/* Get max value across the vector */
maxValue = vmaxvq(maxValue, extremValVec);
/* set index for lower values to max possible index */
p0 = vcmpgeq(extremValVec, maxValue);
extremIdxVec = vld1q_u8(extremIdxArr);
indexVec = vpselq(extremIdxVec, vdupq_n_u8(blockSize - 1), p0);
*pIndex = vminvq_u8(blockSize - 1, indexVec);
*pResult = maxValue;
}
void arm_max_q7(
const q7_t * pSrc,
uint32_t blockSize,
q7_t * pResult,
uint32_t * pIndex)
{
int32_t totalSize = blockSize;
const uint16_t sub_blk_sz = UINT8_MAX + 1;
if (totalSize <= sub_blk_sz)
{
arm_small_blk_max_q7(pSrc, blockSize, pResult, pIndex);
}
else
{
uint32_t curIdx = 0;
q7_t curBlkExtr = Q7_MIN;
uint32_t curBlkPos = 0;
uint32_t curBlkIdx = 0;
/*
* process blocks of 255 elts
*/
while (totalSize >= sub_blk_sz)
{
const q7_t *curSrc = pSrc;
arm_small_blk_max_q7(curSrc, sub_blk_sz, pResult, pIndex);
if (*pResult > curBlkExtr)
{
/*
* update partial extrema
*/
curBlkExtr = *pResult;
curBlkPos = *pIndex;
curBlkIdx = curIdx;
}
curIdx++;
pSrc += sub_blk_sz;
totalSize -= sub_blk_sz;
}
/*
* remainder
*/
arm_small_blk_max_q7(pSrc, totalSize, pResult, pIndex);
if (*pResult > curBlkExtr)
{
curBlkExtr = *pResult;
curBlkPos = *pIndex;
curBlkIdx = curIdx;
}
*pIndex = curBlkIdx * sub_blk_sz + curBlkPos;
*pResult = curBlkExtr;
}
}
#else
void arm_max_q7(
const q7_t * pSrc,
uint32_t blockSize,
q7_t * pResult,
uint32_t * pIndex)
{
q7_t maxVal, out; /* Temporary variables to store the output value. */
uint32_t blkCnt, outIndex; /* Loop counter */
#if defined (ARM_MATH_LOOPUNROLL)
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)
/* 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 (out < maxVal)
{
/* Update the maximum value and it's index */
out = maxVal;
outIndex = index + 1U;
}
maxVal = *pSrc++;
if (out < maxVal)
{
out = maxVal;
outIndex = index + 2U;
}
maxVal = *pSrc++;
if (out < maxVal)
{
out = maxVal;
outIndex = index + 3U;
}
maxVal = *pSrc++;
if (out < 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 (out < 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_MVEI) */
/**
@} end of Max group
*/
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