text: /* ----------------------------------------------------------------------    
  * Copyright (C) 2010-2014 ARM Limited. All rights reserved.    
  *    
  * $Date: 16/06/16 3:44p $Revision: 	V.1.4.5
  *    
  * 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
  *  
  * Redistribution and use in source and binary forms, with or without 
  * modification, are permitted provided that the following conditions
  * are met:
  *   - Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  *   - Redistributions in binary form must reproduce the above copyright
  *     notice, this list of conditions and the following disclaimer in
  *     the documentation and/or other materials provided with the 
  *     distribution.
  *   - Neither the name of ARM LIMITED nor the names of its contributors
  *     may be used to endorse or promote products derived from this
  *     software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 
  * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  * POSSIBILITY OF SUCH DAMAGE.   
  * -------------------------------------------------------------------- */
  
  #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_FAMILY
  
    /* 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_FAMILY */
  
  }
  
  /**    
   * @} end of CmplxByCmplxMult group    
   */
  