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  1. /* ----------------------------------------------------------------------
  2.  * Project:      CMSIS DSP Library
  3.  * Title:        arm_dot_prod_q15.c
  4.  * Description:  Q15 dot product
  5.  *
  6.  * $Date:        27. January 2017
  7.  * $Revision:    V.1.5.1
  8.  *
  9.  * Target Processor: Cortex-M cores
  10.  * -------------------------------------------------------------------- */
  11. /*
  12.  * Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved.
  13.  *
  14.  * SPDX-License-Identifier: Apache-2.0
  15.  *
  16.  * Licensed under the Apache License, Version 2.0 (the License); you may
  17.  * not use this file except in compliance with the License.
  18.  * You may obtain a copy of the License at
  19.  *
  20.  * www.apache.org/licenses/LICENSE-2.0
  21.  *
  22.  * Unless required by applicable law or agreed to in writing, software
  23.  * distributed under the License is distributed on an AS IS BASIS, WITHOUT
  24.  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  25.  * See the License for the specific language governing permissions and
  26.  * limitations under the License.
  27.  */
  28.  
  29. #include "arm_math.h"
  30.  
  31. /**
  32.  * @ingroup groupMath
  33.  */
  34.  
  35. /**
  36.  * @addtogroup dot_prod
  37.  * @{
  38.  */
  39.  
  40. /**
  41.  * @brief Dot product of Q15 vectors.
  42.  * @param[in]       *pSrcA points to the first input vector
  43.  * @param[in]       *pSrcB points to the second input vector
  44.  * @param[in]       blockSize number of samples in each vector
  45.  * @param[out]      *result output result returned here
  46.  * @return none.
  47.  *
  48.  * <b>Scaling and Overflow Behavior:</b>
  49.  * \par
  50.  * The intermediate multiplications are in 1.15 x 1.15 = 2.30 format and these
  51.  * results are added to a 64-bit accumulator in 34.30 format.
  52.  * Nonsaturating additions are used and given that there are 33 guard bits in the accumulator
  53.  * there is no risk of overflow.
  54.  * The return result is in 34.30 format.
  55.  */
  56.  
  57. void arm_dot_prod_q15(
  58.   q15_t * pSrcA,
  59.   q15_t * pSrcB,
  60.   uint32_t blockSize,
  61.   q63_t * result)
  62. {
  63.   q63_t sum = 0;                                 /* Temporary result storage */
  64.   uint32_t blkCnt;                               /* loop counter */
  65.  
  66. #if defined (ARM_MATH_DSP)
  67.  
  68. /* Run the below code for Cortex-M4 and Cortex-M3 */
  69.  
  70.  
  71.   /*loop Unrolling */
  72.   blkCnt = blockSize >> 2U;
  73.  
  74.   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
  75.    ** a second loop below computes the remaining 1 to 3 samples. */
  76.   while (blkCnt > 0U)
  77.   {
  78.     /* C = A[0]* B[0] + A[1]* B[1] + A[2]* B[2] + .....+ A[blockSize-1]* B[blockSize-1] */
  79.     /* Calculate dot product and then store the result in a temporary buffer. */
  80.     sum = __SMLALD(*__SIMD32(pSrcA)++, *__SIMD32(pSrcB)++, sum);
  81.     sum = __SMLALD(*__SIMD32(pSrcA)++, *__SIMD32(pSrcB)++, sum);
  82.  
  83.     /* Decrement the loop counter */
  84.     blkCnt--;
  85.   }
  86.  
  87.   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
  88.    ** No loop unrolling is used. */
  89.   blkCnt = blockSize % 0x4U;
  90.  
  91.   while (blkCnt > 0U)
  92.   {
  93.     /* C = A[0]* B[0] + A[1]* B[1] + A[2]* B[2] + .....+ A[blockSize-1]* B[blockSize-1] */
  94.     /* Calculate dot product and then store the results in a temporary buffer. */
  95.     sum = __SMLALD(*pSrcA++, *pSrcB++, sum);
  96.  
  97.     /* Decrement the loop counter */
  98.     blkCnt--;
  99.   }
  100.  
  101.  
  102. #else
  103.  
  104.   /* Run the below code for Cortex-M0 */
  105.  
  106.   /* Initialize blkCnt with number of samples */
  107.   blkCnt = blockSize;
  108.  
  109.   while (blkCnt > 0U)
  110.   {
  111.     /* C = A[0]* B[0] + A[1]* B[1] + A[2]* B[2] + .....+ A[blockSize-1]* B[blockSize-1] */
  112.     /* Calculate dot product and then store the results in a temporary buffer. */
  113.     sum += (q63_t) ((q31_t) * pSrcA++ * *pSrcB++);
  114.  
  115.     /* Decrement the loop counter */
  116.     blkCnt--;
  117.   }
  118.  
  119. #endif /* #if defined (ARM_MATH_DSP) */
  120.  
  121.   /* Store the result in the destination buffer in 34.30 format */
  122.   *result = sum;
  123.  
  124. }
  125.  
  126. /**
  127.  * @} end of dot_prod group
  128.  */
  129.