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/* ----------------------------------------------------------------------    
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* Copyright (C) 2010-2014 ARM Limited. All rights reserved.    
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*    
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* $Date:        19. March 2015
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* $Revision:    V.1.4.5
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*    
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* Project:          CMSIS DSP Library    
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* Title:                arm_dot_prod_q31.c    
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*    
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* Description:  Q31 dot product.    
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*    
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* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
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*  
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*   - Redistributions of source code must retain the above copyright
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*     notice, this list of conditions and the following disclaimer.
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*   - Redistributions in binary form must reproduce the above copyright
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*     notice, this list of conditions and the following disclaimer in
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*     the documentation and/or other materials provided with the
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*     distribution.
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*   - Neither the name of ARM LIMITED nor the names of its contributors
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*     may be used to endorse or promote products derived from this
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*     software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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* -------------------------------------------------------------------- */
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#include "arm_math.h"
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/**    
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 * @ingroup groupMath    
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 */
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/**    
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 * @addtogroup dot_prod    
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 * @{    
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 */
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/**    
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 * @brief Dot product of Q31 vectors.    
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 * @param[in]       *pSrcA points to the first input vector    
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 * @param[in]       *pSrcB points to the second input vector    
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 * @param[in]       blockSize number of samples in each vector    
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 * @param[out]      *result output result returned here    
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 * @return none.    
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 *    
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 * <b>Scaling and Overflow Behavior:</b>    
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 * \par    
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 * The intermediate multiplications are in 1.31 x 1.31 = 2.62 format and these    
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 * are truncated to 2.48 format by discarding the lower 14 bits.    
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 * The 2.48 result is then added without saturation to a 64-bit accumulator in 16.48 format.    
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 * There are 15 guard bits in the accumulator and there is no risk of overflow as long as    
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 * the length of the vectors is less than 2^16 elements.    
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 * The return result is in 16.48 format.    
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 */
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void arm_dot_prod_q31(
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  q31_t * pSrcA,
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  q31_t * pSrcB,
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  uint32_t blockSize,
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  q63_t * result)
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{
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  q63_t sum = 0;                                 /* Temporary result storage */
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  uint32_t blkCnt;                               /* loop counter */
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#ifndef ARM_MATH_CM0_FAMILY
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/* Run the below code for Cortex-M4 and Cortex-M3 */
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  q31_t inA1, inA2, inA3, inA4;
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  q31_t inB1, inB2, inB3, inB4;
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  /*loop Unrolling */
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  blkCnt = blockSize >> 2u;
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  /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.    
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   ** a second loop below computes the remaining 1 to 3 samples. */
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  while(blkCnt > 0u)
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  {
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    /* C = A[0]* B[0] + A[1]* B[1] + A[2]* B[2] + .....+ A[blockSize-1]* B[blockSize-1] */
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    /* Calculate dot product and then store the result in a temporary buffer. */
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    inA1 = *pSrcA++;
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    inA2 = *pSrcA++;
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    inA3 = *pSrcA++;
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    inA4 = *pSrcA++;
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    inB1 = *pSrcB++;
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    inB2 = *pSrcB++;
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    inB3 = *pSrcB++;
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    inB4 = *pSrcB++;
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    sum += ((q63_t) inA1 * inB1) >> 14u;
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    sum += ((q63_t) inA2 * inB2) >> 14u;
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    sum += ((q63_t) inA3 * inB3) >> 14u;
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    sum += ((q63_t) inA4 * inB4) >> 14u;
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    /* Decrement the loop counter */
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    blkCnt--;
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  }
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  /* If the blockSize is not a multiple of 4, compute any remaining output samples here.    
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   ** No loop unrolling is used. */
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  blkCnt = blockSize % 0x4u;
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#else
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  /* Run the below code for Cortex-M0 */
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  /* Initialize blkCnt with number of samples */
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  blkCnt = blockSize;
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#endif /* #ifndef ARM_MATH_CM0_FAMILY */
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  while(blkCnt > 0u)
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  {
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    /* C = A[0]* B[0] + A[1]* B[1] + A[2]* B[2] + .....+ A[blockSize-1]* B[blockSize-1] */
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    /* Calculate dot product and then store the result in a temporary buffer. */
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    sum += ((q63_t) * pSrcA++ * *pSrcB++) >> 14u;
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    /* Decrement the loop counter */
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    blkCnt--;
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  }
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  /* Store the result in the destination buffer in 16.48 format */
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  *result = sum;
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}
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/**    
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 * @} end of dot_prod group    
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 */