lib/main/CMSIS/DSP/Source/BasicMathFunctions/arm_dot_prod_q15.c

   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  */