| /* ---------------------------------------------------------------------- |
| * Project: CMSIS DSP Library |
| * Title: arm_dot_prod_q31.c |
| * Description: Q31 dot product |
| * |
| * $Date: 18. March 2019 |
| * $Revision: V1.6.0 |
| * |
| * Target Processor: Cortex-M cores |
| * -------------------------------------------------------------------- */ |
| /* |
| * Copyright (C) 2010-2019 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 BasicDotProd |
| @{ |
| */ |
| |
| /** |
| @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 |
| |
| @par Scaling and Overflow Behavior |
| 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( |
| const q31_t * pSrcA, |
| const q31_t * pSrcB, |
| uint32_t blockSize, |
| q63_t * result) |
| { |
| uint32_t blkCnt; /* Loop counter */ |
| q63_t sum = 0; /* Temporary return variable */ |
| |
| #if defined (ARM_MATH_LOOPUNROLL) |
| |
| /* Loop unrolling: Compute 4 outputs at a time */ |
| blkCnt = blockSize >> 2U; |
| |
| 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 store result in a temporary buffer. */ |
| sum += ((q63_t) *pSrcA++ * *pSrcB++) >> 14U; |
| |
| sum += ((q63_t) *pSrcA++ * *pSrcB++) >> 14U; |
| |
| sum += ((q63_t) *pSrcA++ * *pSrcB++) >> 14U; |
| |
| sum += ((q63_t) *pSrcA++ * *pSrcB++) >> 14U; |
| |
| /* Decrement loop counter */ |
| blkCnt--; |
| } |
| |
| /* Loop unrolling: Compute remaining outputs */ |
| blkCnt = blockSize % 0x4U; |
| |
| #else |
| |
| /* Initialize blkCnt with number of samples */ |
| blkCnt = blockSize; |
| |
| #endif /* #if defined (ARM_MATH_LOOPUNROLL) */ |
| |
| 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 store result in a temporary buffer. */ |
| sum += ((q63_t) *pSrcA++ * *pSrcB++) >> 14U; |
| |
| /* Decrement loop counter */ |
| blkCnt--; |
| } |
| |
| /* Store result in destination buffer in 16.48 format */ |
| *result = sum; |
| } |
| |
| /** |
| @} end of BasicDotProd group |
| */ |