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/* ----------------------------------------------------------------------
* Project: CMSIS DSP Library
* Title: arm_dot_prod_q31.c
* Description: Q31 dot product
*
* $Date: 27. January 2017
* $Revision: V.1.5.1
*
* Target Processor: Cortex-M cores
* -------------------------------------------------------------------- */
/*
* Copyright (C) 2010-2017 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 "arm_math.h"
/**
* @ingroup groupMath
*/
/**
* @addtogroup dot_prod
* @{
*/
/**
* @brief Dot product of Q31 vectors.
* @param[in] *pSrcA points to the first input vector
* @param[in] *pSrcB points to the second input vector
* @param[in] blockSize number of samples in each vector
* @param[out] *result output result returned here
* @return none.
*
* <b>Scaling and Overflow Behavior:</b>
* \par
* The intermediate multiplications are in 1.31 x 1.31 = 2.62 format and these
* are truncated to 2.48 format by discarding the lower 14 bits.
* The 2.48 result is then added without saturation to a 64-bit accumulator in 16.48 format.
* There are 15 guard bits in the accumulator and there is no risk of overflow as long as
* the length of the vectors is less than 2^16 elements.
* The return result is in 16.48 format.
*/
void arm_dot_prod_q31(
q31_t * pSrcA,
q31_t * pSrcB,
uint32_t blockSize,
q63_t * result)
{
q63_t sum = 0; /* Temporary result storage */
uint32_t blkCnt; /* loop counter */
#if defined (ARM_MATH_DSP)
/* Run the below code for Cortex-M4 and Cortex-M3 */
q31_t inA1, inA2, inA3, inA4;
q31_t inB1, inB2, inB3, inB4;
/*loop Unrolling */
blkCnt = blockSize >> 2U;
/* First part of the processing with loop unrolling. Compute 4 outputs at a time.
** a second loop below computes the remaining 1 to 3 samples. */
while (blkCnt > 0U)
{
/* C = A[0]* B[0] + A[1]* B[1] + A[2]* B[2] + .....+ A[blockSize-1]* B[blockSize-1] */
/* Calculate dot product and then store the result in a temporary buffer. */
inA1 = *pSrcA++;
inA2 = *pSrcA++;
inA3 = *pSrcA++;
inA4 = *pSrcA++;
inB1 = *pSrcB++;
inB2 = *pSrcB++;
inB3 = *pSrcB++;
inB4 = *pSrcB++;
sum += ((q63_t) inA1 * inB1) >> 14U;
sum += ((q63_t) inA2 * inB2) >> 14U;
sum += ((q63_t) inA3 * inB3) >> 14U;
sum += ((q63_t) inA4 * inB4) >> 14U;
/* Decrement the loop counter */
blkCnt--;
}
/* If the blockSize is not a multiple of 4, compute any remaining output samples here.
** No loop unrolling is used. */
blkCnt = blockSize % 0x4U;
#else
/* Run the below code for Cortex-M0 */
/* Initialize blkCnt with number of samples */
blkCnt = blockSize;
#endif /* #if defined (ARM_MATH_DSP) */
while (blkCnt > 0U)
{
/* C = A[0]* B[0] + A[1]* B[1] + A[2]* B[2] + .....+ A[blockSize-1]* B[blockSize-1] */
/* Calculate dot product and then store the result in a temporary buffer. */
sum += ((q63_t) * pSrcA++ * *pSrcB++) >> 14U;
/* Decrement the loop counter */
blkCnt--;
}
/* Store the result in the destination buffer in 16.48 format */
*result = sum;
}
/**
* @} end of dot_prod group
*/
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