/* ----------------------------------------------------------------------  
* Copyright (C) 2010 ARM Limited. All rights reserved.  
*  
* $Date:        29. November 2010  
* $Revision: 	V1.0.3  
*  
* Project: 	    CMSIS DSP Library  
* Title:		arm_cmplx_dot_prod_q31.c  
*  
* Description:	Q31 complex dot product  
*  
* Target Processor: Cortex-M4/Cortex-M3
*  
* Version 1.0.3 2010/11/29 
*    Re-organized the CMSIS folders and updated documentation.  
*   
* Version 1.0.2 2010/11/11  
*    Documentation updated.   
*  
* Version 1.0.1 2010/10/05   
*    Production release and review comments incorporated.  
*  
* Version 1.0.0 2010/09/20   
*    Production release and review comments incorporated.  
* -------------------------------------------------------------------- */ 
 
#include "arm_math.h" 
 
/**  
 * @ingroup groupCmplxMath  
 */ 
 
/**  
 * @addtogroup cmplx_dot_prod  
 * @{  
 */ 
 
/**  
 * @brief  Q31 complex dot product  
 * @param  *pSrcA points to the first input vector  
 * @param  *pSrcB points to the second input vector  
 * @param  numSamples number of complex samples in each vector  
 * @param  *realResult real part of the result returned here  
 * @param  *imagResult imaginary part of the result returned here  
 * @return none.  
 *  
 * <b>Scaling and Overflow Behavior:</b>  
 * \par  
 * The function is implemented using an internal 64-bit accumulator.  
 * The intermediate 1.31 by 1.31 multiplications are performed with 64-bit precision and then shifted to 16.48 format.  
 * The internal real and imaginary accumulators are in 16.48 format and provide 15 guard bits.  
 * Additions are nonsaturating and no overflow will occur as long as <code>numSamples</code> is less than 32768.  
 * The return results <code>realResult</code> and <code>imagResult</code> are in 16.48 format.  
 * Input down scaling is not required.  
 */ 
 
void arm_cmplx_dot_prod_q31( 
  q31_t * pSrcA, 
  q31_t * pSrcB, 
  uint32_t numSamples, 
  q63_t * realResult, 
  q63_t * imagResult) 
{ 
  q63_t real_sum = 0, imag_sum = 0;              /* Temporary result storage */ 
  uint32_t blkCnt;                               /* loop counter */ 
 
 
  /*loop Unrolling */ 
  blkCnt = numSamples >> 2u; 
 
  /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.  
   ** a second loop below computes the remaining 1 to 3 samples. */ 
  while(blkCnt > 0u) 
  { 
    /* CReal = A[0]* B[0] + A[2]* B[2] + A[4]* B[4] + .....+ A[numSamples-2]* B[numSamples-2] */ 
    /* Convert real data in 2.62 to 16.48 by 14 right shifts */ 
    real_sum += (q63_t) * pSrcA++ * (*pSrcB++) >> 14; 
    /* CImag = A[1]* B[1] + A[3]* B[3] + A[5]* B[5] + .....+ A[numSamples-1]* B[numSamples-1] */ 
    /* Convert imag data in 2.62 to 16.48 by 14 right shifts */ 
    imag_sum += (q63_t) * pSrcA++ * (*pSrcB++) >> 14; 
 
    real_sum += (q63_t) * pSrcA++ * (*pSrcB++) >> 14; 
    imag_sum += (q63_t) * pSrcA++ * (*pSrcB++) >> 14; 
 
    real_sum += (q63_t) * pSrcA++ * (*pSrcB++) >> 14; 
    imag_sum += (q63_t) * pSrcA++ * (*pSrcB++) >> 14; 
 
    real_sum += (q63_t) * pSrcA++ * (*pSrcB++) >> 14; 
    imag_sum += (q63_t) * pSrcA++ * (*pSrcB++) >> 14; 
 
 
    /* Decrement the loop counter */ 
    blkCnt--; 
  } 
 
  /* If the numSamples  is not a multiple of 4, compute any remaining output samples here.  
   ** No loop unrolling is used. */ 
  blkCnt = numSamples % 0x4u; 
 
  while(blkCnt > 0u) 
  { 
    /* CReal = A[0]* B[0] + A[2]* B[2] + A[4]* B[4] + .....+ A[numSamples-2]* B[numSamples-2] */ 
    real_sum += (q63_t) * pSrcA++ * (*pSrcB++) >> 14; 
    /* CImag = A[1]* B[1] + A[3]* B[3] + A[5]* B[5] + .....+ A[numSamples-1]* B[numSamples-1] */ 
    imag_sum += (q63_t) * pSrcA++ * (*pSrcB++) >> 14; 
 
    /* Decrement the loop counter */ 
    blkCnt--; 
  } 
 
  /* Store the real and imaginary results in 16.48 format  */ 
  *realResult = real_sum; 
  *imagResult = imag_sum; 
} 
 
/**  
 * @} end of cmplx_dot_prod group  
 */