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/* ----------------------------------------------------------------------
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* Copyright (C) 2010 ARM Limited. All rights reserved.
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*
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* $Date: 15. July 2011
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* $Revision: V1.0.10
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*
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* Project: CMSIS DSP Library
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* Title: arm_max_q7.c
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*
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* Description: Maximum value of a Q7 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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* Version 1.0.10 2011/7/15
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* Big Endian support added and Merged M0 and M3/M4 Source code.
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*
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* Version 1.0.3 2010/11/29
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* Re-organized the CMSIS folders and updated documentation.
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*
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* Version 1.0.2 2010/11/11
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* Documentation updated.
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*
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* Version 1.0.1 2010/10/05
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* Production release and review comments incorporated.
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*
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* Version 1.0.0 2010/09/20
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* Production release and review comments incorporated.
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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 Q7 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_q7(
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q7_t * pSrc,
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uint32_t blockSize,
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q7_t * pResult,
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uint32_t * pIndex)
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{
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#ifndef ARM_MATH_CM0
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/* Run the below code for Cortex-M4 and Cortex-M3 */
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q7_t res, maxVal, x0, x1, maxVal2, maxVal1; /* Temporary variables to store the output value. */
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uint32_t blkCnt, index1, index2, index3, indx, indxMod; /* loop counter */
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/* Initialise the index value to zero. */
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indx = 0u;
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/* Load first input value that act as reference value for comparision */
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res = *pSrc++;
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/* Loop unrolling */
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blkCnt = (blockSize - 1u) >> 2u;
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/* First part of the processing with loop unrolling. Compute 4 outputs at a time.
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** a second loop below computes the remaining 1 to 3 samples. */
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while(blkCnt > 0u)
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{
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indxMod = blockSize - (blkCnt * 4u);
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/* Load two input values for comparision */
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x0 = *pSrc++;
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x1 = *pSrc++;
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if(x0 < x1)
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{
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/* Update the maximum value and its index */
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maxVal1 = x1;
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index1 = indxMod + 1u;
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}
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else
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{
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/* Update the maximum value and its index */
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maxVal1 = x0;
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index1 = indxMod;
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}
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/* Load two input values for comparision */
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x0 = *pSrc++;
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x1 = *pSrc++;
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if(x0 < x1)
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{
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/* Update the maximum value and its index */
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maxVal2 = x1;
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index2 = indxMod + 3u;
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}
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else
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{
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/* Update the maximum value and its index */
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maxVal2 = x0;
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index2 = indxMod + 2u;
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}
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if(maxVal1 < maxVal2)
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{
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/* Update the maximum value and its index */
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maxVal = maxVal2;
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index3 = index2;
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}
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else
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{
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/* Update the maximum value and its index */
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maxVal = maxVal1;
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index3 = index1;
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}
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if(res < maxVal)
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{
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/* Update the maximum value and its index */
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res = maxVal;
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indx = index3;
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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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/* If the blockSize - 1 is not a multiple of 4, compute any remaining output samples here.
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** No loop unrolling is used. */
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blkCnt = (blockSize - 1u) % 0x04u;
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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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maxVal = *pSrc++;
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/* compare for the maximum value */
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if(res < maxVal)
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{
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/* Update the maximum value and its index */
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res = maxVal;
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indx = 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 = res;
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*pIndex = indx;
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#else
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/* Run the below code for Cortex-M0 */
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q7_t maxVal, 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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/* Loop over blockSize - 1 number of values */
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blkCnt = (blockSize - 1u);
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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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maxVal = *pSrc++;
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/* compare for the maximum value */
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if(out < maxVal)
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{
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/* Update the maximum value and its index */
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out = maxVal;
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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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#endif /* #ifndef ARM_MATH_CM0 */
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}
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/**
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* @} end of Max group
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*/
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