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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_dot_prod_q31.c
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*
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* Description: Q31 dot product.
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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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* Version 0.0.7 2010/06/10
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* Misra-C changes done
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* -------------------------------------------------------------------- */
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#include "arm_math.h"
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/**
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* @ingroup groupMath
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*/
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/**
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* @addtogroup dot_prod
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* @{
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*/
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/**
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* @brief Dot product of Q31 vectors.
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* @param[in] *pSrcA points to the first input vector
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* @param[in] *pSrcB points to the second input vector
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* @param[in] blockSize number of samples in each vector
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* @param[out] *result output result returned here
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* @return none.
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*
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* <b>Scaling and Overflow Behavior:</b>
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* \par
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* The intermediate multiplications are in 1.31 x 1.31 = 2.62 format and these
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* are truncated to 2.48 format by discarding the lower 14 bits.
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* The 2.48 result is then added without saturation to a 64-bit accumulator in 16.48 format.
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* There are 15 guard bits in the accumulator and there is no risk of overflow as long as
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* the length of the vectors is less than 2^16 elements.
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* The return result is in 16.48 format.
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*/
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void arm_dot_prod_q31(
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q31_t * pSrcA,
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q31_t * pSrcB,
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uint32_t blockSize,
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q63_t * result)
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{
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q63_t sum = 0; /* Temporary result storage */
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uint32_t blkCnt; /* loop counter */
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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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/*loop Unrolling */
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blkCnt = blockSize >> 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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/* C = A[0]* B[0] + A[1]* B[1] + A[2]* B[2] + .....+ A[blockSize-1]* B[blockSize-1] */
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/* Calculate dot product and then store the result in a temporary buffer. */
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sum += ((q63_t) * pSrcA++ * *pSrcB++) >> 14u;
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sum += ((q63_t) * pSrcA++ * *pSrcB++) >> 14u;
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sum += ((q63_t) * pSrcA++ * *pSrcB++) >> 14u;
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sum += ((q63_t) * pSrcA++ * *pSrcB++) >> 14u;
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/* Decrement the loop counter */
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blkCnt--;
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}
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/* If the blockSize 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 % 0x4u;
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#else
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/* Run the below code for Cortex-M0 */
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/* Initialize blkCnt with number of samples */
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blkCnt = blockSize;
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#endif /* #ifndef ARM_MATH_CM0 */
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while(blkCnt > 0u)
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{
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/* C = A[0]* B[0] + A[1]* B[1] + A[2]* B[2] + .....+ A[blockSize-1]* B[blockSize-1] */
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/* Calculate dot product and then store the result in a temporary buffer. */
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sum += ((q63_t) * pSrcA++ * *pSrcB++) >> 14u;
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/* Decrement the loop counter */
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blkCnt--;
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}
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/* Store the result in the destination buffer in 16.48 format */
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*result = sum;
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}
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/**
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* @} end of dot_prod group
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*/
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