tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/BasicMathFunctions/arm_dot_prod_q31.c

   1 /* ----------------------------------------------------------------------
   2 * Copyright (C) 2010-2013 ARM Limited. All rights reserved.
   3 *
   4 * $Date:        17. January 2013
   5 * $Revision:    V1.4.1
   6 *
   7 * Project:          CMSIS DSP Library
   8 * Title:                arm_dot_prod_q31.c
   9 *
  10 * Description:  Q31 dot product.
  11 *
  12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
  13 *
  14 * Redistribution and use in source and binary forms, with or without
  15 * modification, are permitted provided that the following conditions
  16 * are met:
  17 *   - Redistributions of source code must retain the above copyright
  18 *     notice, this list of conditions and the following disclaimer.
  19 *   - Redistributions in binary form must reproduce the above copyright
  20 *     notice, this list of conditions and the following disclaimer in
  21 *     the documentation and/or other materials provided with the
  22 *     distribution.
  23 *   - Neither the name of ARM LIMITED nor the names of its contributors
  24 *     may be used to endorse or promote products derived from this
  25 *     software without specific prior written permission.
  26 *
  27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  29 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  30 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  31 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  33 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  34 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  35 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  37 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  38 * POSSIBILITY OF SUCH DAMAGE.
  39 * -------------------------------------------------------------------- */
  40
  41 #include "arm_math.h"
  42
  43 /**
  44  * @ingroup groupMath
  45  */
  46
  47 /**
  48  * @addtogroup dot_prod
  49  * @{
  50  */
  51
  52 /**
  53  * @brief Dot product of Q31 vectors.
  54  * @param[in]       *pSrcA points to the first input vector
  55  * @param[in]       *pSrcB points to the second input vector
  56  * @param[in]       blockSize number of samples in each vector
  57  * @param[out]      *result output result returned here
  58  * @return none.
  59  *
  60  * <b>Scaling and Overflow Behavior:</b>
  61  * \par
  62  * The intermediate multiplications are in 1.31 x 1.31 = 2.62 format and these
  63  * are truncated to 2.48 format by discarding the lower 14 bits.
  64  * The 2.48 result is then added without saturation to a 64-bit accumulator in 16.48 format.
  65  * There are 15 guard bits in the accumulator and there is no risk of overflow as long as
  66  * the length of the vectors is less than 2^16 elements.
  67  * The return result is in 16.48 format.
  68  */
  69
  70 void arm_dot_prod_q31(
  71   q31_t * pSrcA,
  72   q31_t * pSrcB,
  73   uint32_t blockSize,
  74   q63_t * result)
  75 {
  76   q63_t sum = 0;                                 /* Temporary result storage */
  77   uint32_t blkCnt;                               /* loop counter */
  78
  79
  80 #ifndef ARM_MATH_CM0_FAMILY
  81
  82 /* Run the below code for Cortex-M4 and Cortex-M3 */
  83   q31_t inA1, inA2, inA3, inA4;
  84   q31_t inB1, inB2, inB3, inB4;
  85
  86   /*loop Unrolling */
  87   blkCnt = blockSize >> 2u;
  88
  89   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
  90    ** a second loop below computes the remaining 1 to 3 samples. */
  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 result in a temporary buffer. */
  95     inA1 = *pSrcA++;
  96     inA2 = *pSrcA++;
  97     inA3 = *pSrcA++;
  98     inA4 = *pSrcA++;
  99     inB1 = *pSrcB++;
 100     inB2 = *pSrcB++;
 101     inB3 = *pSrcB++;
 102     inB4 = *pSrcB++;
 103
 104     sum += ((q63_t) inA1 * inB1) >> 14u;
 105     sum += ((q63_t) inA2 * inB2) >> 14u;
 106     sum += ((q63_t) inA3 * inB3) >> 14u;
 107     sum += ((q63_t) inA4 * inB4) >> 14u;
 108
 109     /* Decrement the loop counter */
 110     blkCnt--;
 111   }
 112
 113   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
 114    ** No loop unrolling is used. */
 115   blkCnt = blockSize % 0x4u;
 116
 117 #else
 118
 119   /* Run the below code for Cortex-M0 */
 120
 121   /* Initialize blkCnt with number of samples */
 122   blkCnt = blockSize;
 123
 124 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
 125
 126
 127   while(blkCnt > 0u)
 128   {
 129     /* C = A[0]* B[0] + A[1]* B[1] + A[2]* B[2] + .....+ A[blockSize-1]* B[blockSize-1] */
 130     /* Calculate dot product and then store the result in a temporary buffer. */
 131     sum += ((q63_t) * pSrcA++ * *pSrcB++) >> 14u;
 132
 133     /* Decrement the loop counter */
 134     blkCnt--;
 135   }
 136
 137   /* Store the result in the destination buffer in 16.48 format */
 138   *result = sum;
 139 }
 140
 141 /**
 142  * @} end of dot_prod group
 143  */