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  1. /* ----------------------------------------------------------------------
  2.  * Project:      CMSIS DSP Library
  3.  * Title:        arm_cmplx_mag_squared_q31.c
  4.  * Description:  Q31 complex magnitude squared
  5.  *
  6.  * $Date:        27. January 2017
  7.  * $Revision:    V.1.5.1
  8.  *
  9.  * Target Processor: Cortex-M cores
  10.  * -------------------------------------------------------------------- */
  11. /*
  12.  * Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved.
  13.  *
  14.  * SPDX-License-Identifier: Apache-2.0
  15.  *
  16.  * Licensed under the Apache License, Version 2.0 (the License); you may
  17.  * not use this file except in compliance with the License.
  18.  * You may obtain a copy of the License at
  19.  *
  20.  * www.apache.org/licenses/LICENSE-2.0
  21.  *
  22.  * Unless required by applicable law or agreed to in writing, software
  23.  * distributed under the License is distributed on an AS IS BASIS, WITHOUT
  24.  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  25.  * See the License for the specific language governing permissions and
  26.  * limitations under the License.
  27.  */
  28.  
  29. #include "arm_math.h"
  30.  
  31. /**
  32.  * @ingroup groupCmplxMath
  33.  */
  34.  
  35. /**
  36.  * @addtogroup cmplx_mag_squared
  37.  * @{
  38.  */
  39.  
  40.  
  41. /**
  42.  * @brief  Q31 complex magnitude squared
  43.  * @param  *pSrc points to the complex input vector
  44.  * @param  *pDst points to the real output vector
  45.  * @param  numSamples number of complex samples in the input vector
  46.  * @return none.
  47.  *
  48.  * <b>Scaling and Overflow Behavior:</b>
  49.  * \par
  50.  * The function implements 1.31 by 1.31 multiplications and finally output is converted into 3.29 format.
  51.  * Input down scaling is not required.
  52.  */
  53.  
  54. void arm_cmplx_mag_squared_q31(
  55.   q31_t * pSrc,
  56.   q31_t * pDst,
  57.   uint32_t numSamples)
  58. {
  59.   q31_t real, imag;                              /* Temporary variables to store real and imaginary values */
  60.   q31_t acc0, acc1;                              /* Accumulators */
  61.  
  62. #if defined (ARM_MATH_DSP)
  63.  
  64.   /* Run the below code for Cortex-M4 and Cortex-M3 */
  65.   uint32_t blkCnt;                               /* loop counter */
  66.  
  67.   /* loop Unrolling */
  68.   blkCnt = numSamples >> 2U;
  69.  
  70.   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
  71.    ** a second loop below computes the remaining 1 to 3 samples. */
  72.   while (blkCnt > 0U)
  73.   {
  74.     /* C[0] = (A[0] * A[0] + A[1] * A[1]) */
  75.     real = *pSrc++;
  76.     imag = *pSrc++;
  77.     acc0 = (q31_t) (((q63_t) real * real) >> 33);
  78.     acc1 = (q31_t) (((q63_t) imag * imag) >> 33);
  79.     /* store the result in 3.29 format in the destination buffer. */
  80.     *pDst++ = acc0 + acc1;
  81.  
  82.     real = *pSrc++;
  83.     imag = *pSrc++;
  84.     acc0 = (q31_t) (((q63_t) real * real) >> 33);
  85.     acc1 = (q31_t) (((q63_t) imag * imag) >> 33);
  86.     /* store the result in 3.29 format in the destination buffer. */
  87.     *pDst++ = acc0 + acc1;
  88.  
  89.     real = *pSrc++;
  90.     imag = *pSrc++;
  91.     acc0 = (q31_t) (((q63_t) real * real) >> 33);
  92.     acc1 = (q31_t) (((q63_t) imag * imag) >> 33);
  93.     /* store the result in 3.29 format in the destination buffer. */
  94.     *pDst++ = acc0 + acc1;
  95.  
  96.     real = *pSrc++;
  97.     imag = *pSrc++;
  98.     acc0 = (q31_t) (((q63_t) real * real) >> 33);
  99.     acc1 = (q31_t) (((q63_t) imag * imag) >> 33);
  100.     /* store the result in 3.29 format in the destination buffer. */
  101.     *pDst++ = acc0 + acc1;
  102.  
  103.     /* Decrement the loop counter */
  104.     blkCnt--;
  105.   }
  106.  
  107.   /* If the numSamples is not a multiple of 4, compute any remaining output samples here.
  108.    ** No loop unrolling is used. */
  109.   blkCnt = numSamples % 0x4U;
  110.  
  111.   while (blkCnt > 0U)
  112.   {
  113.     /* C[0] = (A[0] * A[0] + A[1] * A[1]) */
  114.     real = *pSrc++;
  115.     imag = *pSrc++;
  116.     acc0 = (q31_t) (((q63_t) real * real) >> 33);
  117.     acc1 = (q31_t) (((q63_t) imag * imag) >> 33);
  118.     /* store the result in 3.29 format in the destination buffer. */
  119.     *pDst++ = acc0 + acc1;
  120.  
  121.     /* Decrement the loop counter */
  122.     blkCnt--;
  123.   }
  124.  
  125. #else
  126.  
  127.   /* Run the below code for Cortex-M0 */
  128.  
  129.   while (numSamples > 0U)
  130.   {
  131.     /* out = ((real * real) + (imag * imag)) */
  132.     real = *pSrc++;
  133.     imag = *pSrc++;
  134.     acc0 = (q31_t) (((q63_t) real * real) >> 33);
  135.     acc1 = (q31_t) (((q63_t) imag * imag) >> 33);
  136.     /* store the result in 3.29 format in the destination buffer. */
  137.     *pDst++ = acc0 + acc1;
  138.  
  139.     /* Decrement the loop counter */
  140.     numSamples--;
  141.   }
  142.  
  143. #endif /* #if defined (ARM_MATH_DSP) */
  144.  
  145. }
  146.  
  147. /**
  148.  * @} end of cmplx_mag_squared group
  149.  */
  150.