/* ----------------------------------------------------------------------   
* Copyright (C) 2010 ARM Limited. All rights reserved.   
*   
* $Date:        15. July 2011  
* $Revision: 	V1.0.10  
*   
* Project: 	    CMSIS DSP Library   
* Title:	    arm_cmplx_mult_cmplx_q15.c   
*   
* Description:	Q15 complex-by-complex multiplication   
*   
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
*  
* Version 1.0.10 2011/7/15 
*    Big Endian support added and Merged M0 and M3/M4 Source code.  
*   
* 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 CmplxByCmplxMult   
 * @{   
 */

/**   
 * @brief  Q15 complex-by-complex multiplication   
 * @param[in]  *pSrcA points to the first input vector   
 * @param[in]  *pSrcB points to the second input vector   
 * @param[out]  *pDst  points to the output vector   
 * @param[in]  numSamples number of complex samples in each vector   
 * @return none.   
 *   
 * <b>Scaling and Overflow Behavior:</b>   
 * \par   
 * The function implements 1.15 by 1.15 multiplications and finally output is converted into 3.13 format.   
 */

void arm_cmplx_mult_cmplx_q15(
  q15_t * pSrcA,
  q15_t * pSrcB,
  q15_t * pDst,
  uint32_t numSamples)
{
  q15_t a, b, c, d;                              /* Temporary variables to store real and imaginary values */

#ifndef ARM_MATH_CM0

  /* Run the below code for Cortex-M4 and Cortex-M3 */
  uint32_t blkCnt;                               /* loop counters */

  /* 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)
  {
    /* C[2 * i] = A[2 * i] * B[2 * i] - A[2 * i + 1] * B[2 * i + 1].  */
    /* C[2 * i + 1] = A[2 * i] * B[2 * i + 1] + A[2 * i + 1] * B[2 * i].  */
    a = *pSrcA++;
    b = *pSrcA++;
    c = *pSrcB++;
    d = *pSrcB++;

    /* store the result in 3.13 format in the destination buffer. */
    *pDst++ =
      (q15_t) (q31_t) (((q31_t) a * c) >> 17) - (((q31_t) b * d) >> 17);
    /* store the result in 3.13 format in the destination buffer. */
    *pDst++ =
      (q15_t) (q31_t) (((q31_t) a * d) >> 17) + (((q31_t) b * c) >> 17);

    a = *pSrcA++;
    b = *pSrcA++;
    c = *pSrcB++;
    d = *pSrcB++;

    /* store the result in 3.13 format in the destination buffer. */
    *pDst++ =
      (q15_t) (q31_t) (((q31_t) a * c) >> 17) - (((q31_t) b * d) >> 17);
    /* store the result in 3.13 format in the destination buffer. */
    *pDst++ =
      (q15_t) (q31_t) (((q31_t) a * d) >> 17) + (((q31_t) b * c) >> 17);

    a = *pSrcA++;
    b = *pSrcA++;
    c = *pSrcB++;
    d = *pSrcB++;

    /* store the result in 3.13 format in the destination buffer. */
    *pDst++ =
      (q15_t) (q31_t) (((q31_t) a * c) >> 17) - (((q31_t) b * d) >> 17);
    /* store the result in 3.13 format in the destination buffer. */
    *pDst++ =
      (q15_t) (q31_t) (((q31_t) a * d) >> 17) + (((q31_t) b * c) >> 17);

    a = *pSrcA++;
    b = *pSrcA++;
    c = *pSrcB++;
    d = *pSrcB++;

    /* store the result in 3.13 format in the destination buffer. */
    *pDst++ =
      (q15_t) (q31_t) (((q31_t) a * c) >> 17) - (((q31_t) b * d) >> 17);
    /* store the result in 3.13 format in the destination buffer. */
    *pDst++ =
      (q15_t) (q31_t) (((q31_t) a * d) >> 17) + (((q31_t) b * c) >> 17);

    /* Decrement the blockSize loop counter */
    blkCnt--;
  }

  /* If the blockSize is not a multiple of 4, compute any remaining output samples here.   
   ** No loop unrolling is used. */
  blkCnt = numSamples % 0x4u;

  while(blkCnt > 0u)
  {
    /* C[2 * i] = A[2 * i] * B[2 * i] - A[2 * i + 1] * B[2 * i + 1].  */
    /* C[2 * i + 1] = A[2 * i] * B[2 * i + 1] + A[2 * i + 1] * B[2 * i].  */
    a = *pSrcA++;
    b = *pSrcA++;
    c = *pSrcB++;
    d = *pSrcB++;

    /* store the result in 3.13 format in the destination buffer. */
    *pDst++ =
      (q15_t) (q31_t) (((q31_t) a * c) >> 17) - (((q31_t) b * d) >> 17);
    /* store the result in 3.13 format in the destination buffer. */
    *pDst++ =
      (q15_t) (q31_t) (((q31_t) a * d) >> 17) + (((q31_t) b * c) >> 17);

    /* Decrement the blockSize loop counter */
    blkCnt--;
  }

#else

  /* Run the below code for Cortex-M0 */

  while(numSamples > 0u)
  {
    /* C[2 * i] = A[2 * i] * B[2 * i] - A[2 * i + 1] * B[2 * i + 1].  */
    /* C[2 * i + 1] = A[2 * i] * B[2 * i + 1] + A[2 * i + 1] * B[2 * i].  */
    a = *pSrcA++;
    b = *pSrcA++;
    c = *pSrcB++;
    d = *pSrcB++;

    /* store the result in 3.13 format in the destination buffer. */
    *pDst++ =
      (q15_t) (q31_t) (((q31_t) a * c) >> 17) - (((q31_t) b * d) >> 17);
    /* store the result in 3.13 format in the destination buffer. */
    *pDst++ =
      (q15_t) (q31_t) (((q31_t) a * d) >> 17) + (((q31_t) b * c) >> 17);

    /* Decrement the blockSize loop counter */
    numSamples--;
  }

#endif /* #ifndef ARM_MATH_CM0 */

}

/**   
 * @} end of CmplxByCmplxMult group   
 */
