msts/Drivers/CMSIS/DSP/Source/ComplexMathFunctions/arm_cmplx_mag_squared_f32.c

/* ----------------------------------------------------------------------
 * Project:      CMSIS DSP Library
 * Title:        arm_cmplx_mag_squared_f32.c
 * Description:  Floating-point complex magnitude squared
 *
 * $Date:        27. January 2017
 * $Revision:    V.1.5.1
 *
 * Target Processor: Cortex-M cores
 * -------------------------------------------------------------------- */
/*
 * Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved.
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Licensed under the Apache License, Version 2.0 (the License); you may
 * not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an AS IS BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "arm_math.h"

/**
 * @ingroup groupCmplxMath
 */

/**
 * @defgroup cmplx_mag_squared Complex Magnitude Squared
 *
 * Computes the magnitude squared of the elements of a complex data vector.
 *
 * The <code>pSrc</code> points to the source data and
 * <code>pDst</code> points to the where the result should be written.
 * <code>numSamples</code> specifies the number of complex samples
 * in the input array and the data is stored in an interleaved fashion
 * (real, imag, real, imag, ...).
 * The input array has a total of <code>2*numSamples</code> values;
 * the output array has a total of <code>numSamples</code> values.
 *
 * The underlying algorithm is used:
 *
 * <pre>
 * for(n=0; n<numSamples; n++) {
 *     pDst[n] = pSrc[(2*n)+0]^2 + pSrc[(2*n)+1]^2;
 * }
 * </pre>
 *
 * There are separate functions for floating-point, Q15, and Q31 data types.
 */

/**
 * @addtogroup cmplx_mag_squared
 * @{
 */


/**
 * @brief  Floating-point complex magnitude squared
 * @param[in]  *pSrc points to the complex input vector
 * @param[out]  *pDst points to the real output vector
 * @param[in]  numSamples number of complex samples in the input vector
 * @return none.
 */

void arm_cmplx_mag_squared_f32(
  float32_t * pSrc,
  float32_t * pDst,
  uint32_t numSamples)
{
  float32_t real, imag;                          /* Temporary variables to store real and imaginary values */
  uint32_t blkCnt;                               /* loop counter */

#if defined (ARM_MATH_DSP)
  float32_t real1, real2, real3, real4;          /* Temporary variables to hold real values */
  float32_t imag1, imag2, imag3, imag4;          /* Temporary variables to hold imaginary values */
  float32_t mul1, mul2, mul3, mul4;              /* Temporary variables */
  float32_t mul5, mul6, mul7, mul8;              /* Temporary variables */
  float32_t out1, out2, out3, out4;              /* Temporary variables to hold output values */

  /*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[0] = (A[0] * A[0] + A[1] * A[1]) */
    /* read real input sample from source buffer */
    real1 = pSrc[0];
    /* read imaginary input sample from source buffer */
    imag1 = pSrc[1];

    /* calculate power of real value */
    mul1 = real1 * real1;

    /* read real input sample from source buffer */
    real2 = pSrc[2];

    /* calculate power of imaginary value */
    mul2 = imag1 * imag1;

    /* read imaginary input sample from source buffer */
    imag2 = pSrc[3];

    /* calculate power of real value */
    mul3 = real2 * real2;

    /* read real input sample from source buffer */
    real3 = pSrc[4];

    /* calculate power of imaginary value */
    mul4 = imag2 * imag2;

    /* read imaginary input sample from source buffer */
    imag3 = pSrc[5];

    /* calculate power of real value */
    mul5 = real3 * real3;
    /* calculate power of imaginary value */
    mul6 = imag3 * imag3;

    /* read real input sample from source buffer */
    real4 = pSrc[6];

    /* accumulate real and imaginary powers */
    out1 = mul1 + mul2;

    /* read imaginary input sample from source buffer */
    imag4 = pSrc[7];

    /* accumulate real and imaginary powers */
    out2 = mul3 + mul4;

    /* calculate power of real value */
    mul7 = real4 * real4;
    /* calculate power of imaginary value */
    mul8 = imag4 * imag4;

    /* store output to destination */
    pDst[0] = out1;

    /* accumulate real and imaginary powers */
    out3 = mul5 + mul6;

    /* store output to destination */
    pDst[1] = out2;

    /* accumulate real and imaginary powers */
    out4 = mul7 + mul8;

    /* store output to destination */
    pDst[2] = out3;

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

    /* store output to destination */
    pDst[3] = out4;

    /* increment destination pointer 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 /* #if defined (ARM_MATH_DSP) */

  while (blkCnt > 0U)
  {
    /* C[0] = (A[0] * A[0] + A[1] * A[1]) */
    real = *pSrc++;
    imag = *pSrc++;

    /* out = (real * real) + (imag * imag) */
    /* store the result in the destination buffer. */
    *pDst++ = (real * real) + (imag * imag);

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

/**
 * @} end of cmplx_mag_squared group
 */