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177 lines
5.0 KiB
177 lines
5.0 KiB
/* ----------------------------------------------------------------------
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* Copyright (C) 2010-2014 ARM Limited. All rights reserved.
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*
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* $Date: 12. March 2014
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* $Revision: V1.4.4
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*
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* Project: CMSIS DSP Library
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* Title: arm_max_q31.c
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*
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* Description: Maximum value of a Q31 vector.
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*
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* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* - Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* - Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* - Neither the name of ARM LIMITED nor the names of its contributors
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* may be used to endorse or promote products derived from this
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* software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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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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* @addtogroup Max
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* @{
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*/
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/**
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* @brief Maximum value of a Q31 vector.
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* @param[in] *pSrc points to the input vector
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* @param[in] blockSize length of the 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_q31(
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q31_t * pSrc,
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uint32_t blockSize,
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q31_t * pResult,
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uint32_t * pIndex)
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{
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#ifndef ARM_MATH_CM0_FAMILY
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/* Run the below code for Cortex-M4 and Cortex-M3 */
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q31_t maxVal1, maxVal2, out; /* Temporary variables to store the output value. */
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uint32_t blkCnt, outIndex, count; /* loop counter */
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/* Initialise the count value. */
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count = 0u;
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/* Initialise the 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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/* Loop unrolling */
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blkCnt = (blockSize - 1u) >> 2u;
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/* Run the below code for Cortex-M4 and Cortex-M3 */
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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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maxVal1 = *pSrc++;
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maxVal2 = *pSrc++;
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/* compare for the maximum value */
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if(out < maxVal1)
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{
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/* Update the maximum value and its index */
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out = maxVal1;
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outIndex = count + 1u;
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}
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maxVal1 = *pSrc++;
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/* compare for the maximum value */
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if(out < maxVal2)
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{
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/* Update the maximum value and its index */
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out = maxVal2;
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outIndex = count + 2u;
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}
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maxVal2 = *pSrc++;
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/* compare for the maximum value */
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if(out < maxVal1)
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{
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/* Update the maximum value and its index */
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out = maxVal1;
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outIndex = count + 3u;
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}
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/* compare for the maximum value */
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if(out < maxVal2)
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{
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/* Update the maximum value and its index */
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out = maxVal2;
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outIndex = count + 4u;
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}
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count += 4u;
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/* Decrement the loop counter */
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blkCnt--;
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}
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/* if (blockSize - 1u) is not multiple of 4 */
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blkCnt = (blockSize - 1u) % 4u;
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#else
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/* Run the below code for Cortex-M0 */
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q31_t maxVal1, out; /* Temporary variables to store the output value. */
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uint32_t blkCnt, outIndex; /* loop counter */
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/* Initialise the 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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blkCnt = (blockSize - 1u);
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#endif /* #ifndef ARM_MATH_CM0_FAMILY */
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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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maxVal1 = *pSrc++;
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/* compare for the maximum value */
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if(out < maxVal1)
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{
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/* Update the maximum value and it's index */
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out = maxVal1;
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outIndex = blockSize - blkCnt;
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}
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/* Decrement the loop counter */
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blkCnt--;
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}
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/* Store the maximum value and its 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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