arm_cmplx_mag_q31.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_mag_q31.c    
*    
* Description:	Q31 complex magnitude    
*    
* 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;
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* POSSIBILITY OF SUCH DAMAGE.  
* ---------------------------------------------------------------------------- */

#include "arm_math.h"

/**        
 * @ingroup groupCmplxMath        
 */

/**        
 * @addtogroup cmplx_mag        
 * @{        
 */

/**        
 * @brief  Q31 complex magnitude        
 * @param  *pSrc points to the complex input vector        
 * @param  *pDst points to the real output vector        
 * @param  numSamples number of complex samples in the input vector        
 * @return none.        
 *        
 * <b>Scaling and Overflow Behavior:</b>        
 * \par        
 * The function implements 1.31 by 1.31 multiplications and finally output is converted into 2.30 format.        
 * Input down scaling is not required.        
 */

void arm_cmplx_mag_q31(
  q31_t * pSrc,
  q31_t * pDst,
  uint32_t numSamples)
{
  q31_t real, imag;                              /* Temporary variables to hold input values */
  q31_t acc0, acc1;                              /* Accumulators */
  uint32_t blkCnt;                               /* loop counter */

#ifndef ARM_MATH_CM0_FAMILY

  /* Run the below code for Cortex-M4 and Cortex-M3 */
  q31_t real1, real2, imag1, imag2;              /* Temporary variables to hold input values */
  q31_t out1, out2, out3, out4;                  /* Accumulators */
  q63_t mul1, mul2, mul3, mul4;                  /* Temporary variables */


  /*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)
  {
    /* read complex input from source buffer */
    real1 = pSrc[0];
    imag1 = pSrc[1];
    real2 = pSrc[2];
    imag2 = pSrc[3];

    /* calculate power of input values */
    mul1 = (q63_t) real1 *real1;
    mul2 = (q63_t) imag1 *imag1;
    mul3 = (q63_t) real2 *real2;
    mul4 = (q63_t) imag2 *imag2;

    /* get the result to 3.29 format */
    out1 = (q31_t) (mul1 >> 33);
    out2 = (q31_t) (mul2 >> 33);
    out3 = (q31_t) (mul3 >> 33);
    out4 = (q31_t) (mul4 >> 33);

    /* add real and imaginary accumulators */
    out1 = out1 + out2;
    out3 = out3 + out4;

    /* read complex input from source buffer */
    real1 = pSrc[4];
    imag1 = pSrc[5];
    real2 = pSrc[6];
    imag2 = pSrc[7];

    /* calculate square root */
    arm_sqrt_q31(out1, &pDst[0]);

    /* calculate power of input values */
    mul1 = (q63_t) real1 *real1;

    /* calculate square root */
    arm_sqrt_q31(out3, &pDst[1]);

    /* calculate power of input values */
    mul2 = (q63_t) imag1 *imag1;
    mul3 = (q63_t) real2 *real2;
    mul4 = (q63_t) imag2 *imag2;

    /* get the result to 3.29 format */
    out1 = (q31_t) (mul1 >> 33);
    out2 = (q31_t) (mul2 >> 33);
    out3 = (q31_t) (mul3 >> 33);
    out4 = (q31_t) (mul4 >> 33);

    /* add real and imaginary accumulators */
    out1 = out1 + out2;
    out3 = out3 + out4;

    /* calculate square root */
    arm_sqrt_q31(out1, &pDst[2]);

    /* increment destination by 8 to process next samples */
    pSrc += 8u;

    /* calculate square root */
    arm_sqrt_q31(out3, &pDst[3]);

    /* increment destination by 4 to process next samples */
    pDst += 4u;

    /* 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;

#else

  /* Run the below code for Cortex-M0 */
  blkCnt = numSamples;

#endif /* #ifndef ARM_MATH_CM0_FAMILY */

  while(blkCnt > 0u)
  {
    /* C[0] = sqrt(A[0] * A[0] + A[1] * A[1]) */
    real = *pSrc++;
    imag = *pSrc++;
    acc0 = (q31_t) (((q63_t) real * real) >> 33);
    acc1 = (q31_t) (((q63_t) imag * imag) >> 33);
    /* store the result in 2.30 format in the destination buffer. */
    arm_sqrt_q31(acc0 + acc1, pDst++);

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

/**        
 * @} end of cmplx_mag group        
 */