116 lines
3.4 KiB
C
116 lines
3.4 KiB
C
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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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* Description: Q31 dot product
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*
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* $Date: 18. March 2019
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* $Revision: V1.6.0
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*
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* Target Processor: Cortex-M cores
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* -------------------------------------------------------------------- */
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/*
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* Copyright (C) 2010-2019 ARM Limited or its affiliates. All rights reserved.
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 (the License); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an AS IS BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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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 BasicDotProd
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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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@par Scaling and Overflow Behavior
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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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const q31_t * pSrcA,
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const 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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uint32_t blkCnt; /* Loop counter */
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q63_t sum = 0; /* Temporary return variable */
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#if defined (ARM_MATH_LOOPUNROLL)
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/* Loop unrolling: Compute 4 outputs at a time */
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blkCnt = blockSize >> 2U;
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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 store 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 loop counter */
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blkCnt--;
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}
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/* Loop unrolling: Compute remaining outputs */
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blkCnt = blockSize % 0x4U;
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#else
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/* Initialize blkCnt with number of samples */
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blkCnt = blockSize;
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#endif /* #if defined (ARM_MATH_LOOPUNROLL) */
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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 store result in a temporary buffer. */
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sum += ((q63_t) *pSrcA++ * *pSrcB++) >> 14U;
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/* Decrement loop counter */
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blkCnt--;
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}
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/* Store result in 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 BasicDotProd group
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*/
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