arm_cmplx_dot_prod_f32.c

/* ----------------------------------------------------------------------    
* Copyright (C) 2010-2014 ARM Limited. All rights reserved.    
*    
* $Date:        19. March 2015
* $Revision: 	V.1.4.5
*    
* Project: 	    CMSIS DSP Library    
* Title:		arm_cmplx_dot_prod_f32.c    
*    
* Description:	Floating-point complex dot product    
*    
* 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
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*   - 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,
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* ---------------------------------------------------------------------------- */

#include "arm_math.h"

/**    
 * @ingroup groupCmplxMath    
 */

/**    
 * @defgroup cmplx_dot_prod Complex Dot Product    
 *    
 * Computes the dot product of two complex vectors.    
 * The vectors are multiplied element-by-element and then summed.    
 *   
 * The <code>pSrcA</code> points to the first complex input vector and    
 * <code>pSrcB</code> points to the second complex input vector.    
 * <code>numSamples</code> specifies the number of complex samples    
 * and the data in each array is stored in an interleaved fashion    
 * (real, imag, real, imag, ...).    
 * Each array has a total of <code>2*numSamples</code> values.    
 *    
 * The underlying algorithm is used:    
 * <pre>    
 * realResult=0;    
 * imagResult=0;    
 * for(n=0; n<numSamples; n++) {    
 *     realResult += pSrcA[(2*n)+0]*pSrcB[(2*n)+0] - pSrcA[(2*n)+1]*pSrcB[(2*n)+1];    
 *     imagResult += pSrcA[(2*n)+0]*pSrcB[(2*n)+1] + pSrcA[(2*n)+1]*pSrcB[(2*n)+0];    
 * }    
 * </pre>    
 *    
 * There are separate functions for floating-point, Q15, and Q31 data types.    
 */

/**    
 * @addtogroup cmplx_dot_prod    
 * @{    
 */

/**    
 * @brief  Floating-point 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.    
 */

void arm_cmplx_dot_prod_f32(
  float32_t * pSrcA,
  float32_t * pSrcB,
  uint32_t numSamples,
  float32_t * realResult,
  float32_t * imagResult)
{
  float32_t real_sum = 0.0f, imag_sum = 0.0f;    /* Temporary result storage */
  float32_t a0,b0,c0,d0;

#ifndef ARM_MATH_CM0_FAMILY

  /* Run the below code for Cortex-M4 and Cortex-M3 */
  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)
  {
      a0 = *pSrcA++;
      b0 = *pSrcA++;
      c0 = *pSrcB++;
      d0 = *pSrcB++;  
  
      real_sum += a0 * c0;
      imag_sum += a0 * d0;
      real_sum -= b0 * d0;
      imag_sum += b0 * c0;
    
      a0 = *pSrcA++;
      b0 = *pSrcA++;
      c0 = *pSrcB++;
      d0 = *pSrcB++; 
  
      real_sum += a0 * c0;
      imag_sum += a0 * d0;
      real_sum -= b0 * d0;
      imag_sum += b0 * c0;
      
      a0 = *pSrcA++;
      b0 = *pSrcA++;
      c0 = *pSrcB++;
      d0 = *pSrcB++;  
  
      real_sum += a0 * c0;
      imag_sum += a0 * d0;
      real_sum -= b0 * d0;
      imag_sum += b0 * c0;
    
      a0 = *pSrcA++;
      b0 = *pSrcA++;
      c0 = *pSrcB++;
      d0 = *pSrcB++; 
  
      real_sum += a0 * c0;
      imag_sum += a0 * d0;
      real_sum -= b0 * d0;
      imag_sum += b0 * c0;

      /* 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 & 0x3u;

  while(blkCnt > 0u)
  {
      a0 = *pSrcA++;
      b0 = *pSrcA++;
      c0 = *pSrcB++;
      d0 = *pSrcB++;  
  
      real_sum += a0 * c0;
      imag_sum += a0 * d0;
      real_sum -= b0 * d0;
      imag_sum += b0 * c0;

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

#else

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

  while(numSamples > 0u)
  {
      a0 = *pSrcA++;
      b0 = *pSrcA++;
      c0 = *pSrcB++;
      d0 = *pSrcB++;  
  
      real_sum += a0 * c0;
      imag_sum += a0 * d0;
      real_sum -= b0 * d0;
      imag_sum += b0 * c0;

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

#endif /* #ifndef ARM_MATH_CM0_FAMILY */

  /* Store the real and imaginary results in the destination buffers */
  *realResult = real_sum;
  *imagResult = imag_sum;
}

/**    
 * @} end of cmplx_dot_prod group    
 */