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  1. /* ----------------------------------------------------------------------
  2.  * Project:      CMSIS DSP Library
  3.  * Title:        arm_power_f32.c
  4.  * Description:  Sum of the squares of the elements of a floating-point vector
  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 groupStats
  33.  */
  34.  
  35. /**
  36.  * @defgroup power Power
  37.  *
  38.  * Calculates the sum of the squares of the elements in the input vector.
  39.  * The underlying algorithm is used:
  40.  *
  41.  * <pre>
  42.  *      Result = pSrc[0] * pSrc[0] + pSrc[1] * pSrc[1] + pSrc[2] * pSrc[2] + ... + pSrc[blockSize-1] * pSrc[blockSize-1];
  43.  * </pre>
  44.  *
  45.  * There are separate functions for floating point, Q31, Q15, and Q7 data types.
  46.  */
  47.  
  48. /**
  49.  * @addtogroup power
  50.  * @{
  51.  */
  52.  
  53.  
  54. /**
  55.  * @brief Sum of the squares of the elements of a floating-point vector.
  56.  * @param[in]       *pSrc points to the input vector
  57.  * @param[in]       blockSize length of the input vector
  58.  * @param[out]      *pResult sum of the squares value returned here
  59.  * @return none.
  60.  *
  61.  */
  62.  
  63.  
  64. void arm_power_f32(
  65.   float32_t * pSrc,
  66.   uint32_t blockSize,
  67.   float32_t * pResult)
  68. {
  69.   float32_t sum = 0.0f;                          /* accumulator */
  70.   float32_t in;                                  /* Temporary variable to store input value */
  71.   uint32_t blkCnt;                               /* loop counter */
  72.  
  73. #if defined (ARM_MATH_DSP)
  74.   /* Run the below code for Cortex-M4 and Cortex-M3 */
  75.  
  76.   /*loop Unrolling */
  77.   blkCnt = blockSize >> 2U;
  78.  
  79.   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
  80.    ** a second loop below computes the remaining 1 to 3 samples. */
  81.   while (blkCnt > 0U)
  82.   {
  83.     /* C = A[0] * A[0] + A[1] * A[1] + A[2] * A[2] + ... + A[blockSize-1] * A[blockSize-1] */
  84.     /* Compute Power and then store the result in a temporary variable, sum. */
  85.     in = *pSrc++;
  86.     sum += in * in;
  87.     in = *pSrc++;
  88.     sum += in * in;
  89.     in = *pSrc++;
  90.     sum += in * in;
  91.     in = *pSrc++;
  92.     sum += in * in;
  93.  
  94.     /* Decrement the loop counter */
  95.     blkCnt--;
  96.   }
  97.  
  98.   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
  99.    ** No loop unrolling is used. */
  100.   blkCnt = blockSize % 0x4U;
  101.  
  102.  
  103. #else
  104.   /* Run the below code for Cortex-M0 */
  105.  
  106.   /* Loop over blockSize number of values */
  107.   blkCnt = blockSize;
  108.  
  109. #endif /* #if defined (ARM_MATH_DSP) */
  110.  
  111.  
  112.   while (blkCnt > 0U)
  113.   {
  114.     /* C = A[0] * A[0] + A[1] * A[1] + A[2] * A[2] + ... + A[blockSize-1] * A[blockSize-1] */
  115.     /* compute power and then store the result in a temporary variable, sum. */
  116.     in = *pSrc++;
  117.     sum += in * in;
  118.  
  119.     /* Decrement the loop counter */
  120.     blkCnt--;
  121.   }
  122.  
  123.   /* Store the result to the destination */
  124.   *pResult = sum;
  125. }
  126.  
  127. /**
  128.  * @} end of power group
  129.  */
  130.