CMSIS_5/CMSIS/DSP/Source/StatisticsFunctions/arm_power_f32.c

/* ----------------------------------------------------------------------
 * Project:      CMSIS DSP Library
 * Title:        arm_power_f32.c
 * Description:  Sum of the squares of the elements of a floating-point vector
 *
 * $Date:        23 April 2021
 * $Revision:    V1.9.0
 *
 * Target Processor: Cortex-M and Cortex-A cores
 * -------------------------------------------------------------------- */
/*
 * Copyright (C) 2010-2021 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 "dsp/statistics_functions.h"

/**
  @ingroup groupStats
 */

/**
  @defgroup power Power

  Calculates the sum of the squares of the elements in the input vector.
  The underlying algorithm is used:

  <pre>
      Result = pSrc[0] * pSrc[0] + pSrc[1] * pSrc[1] + pSrc[2] * pSrc[2] + ... + pSrc[blockSize-1] * pSrc[blockSize-1];
  </pre>

  There are separate functions for floating point, Q31, Q15, and Q7 data types.

  Since the result is not divided by the length, those functions are in fact computing
  something which is more an energy than a power.

 */

/**
  @addtogroup power
  @{
 */

/**
  @brief         Sum of the squares of the elements of a floating-point vector.
  @param[in]     pSrc       points to the input vector
  @param[in]     blockSize  number of samples in input vector
  @param[out]    pResult    sum of the squares value returned here
  @return        none
 */
#if defined(ARM_MATH_MVEF) && !defined(ARM_MATH_AUTOVECTORIZE)

#include "arm_helium_utils.h"

void arm_power_f32(
  const float32_t * pSrc,
  uint32_t blockSize,
  float32_t * pResult)
{
    uint32_t        blkCnt;     /* loop counters */
    f32x4_t         vecSrc;
    f32x4_t         sumVec = vdupq_n_f32(0.0f);
    float32_t       sum = 0.0f;
    float32_t in;

    /* Compute 4 outputs at a time */
    blkCnt = blockSize >> 2U;
    while (blkCnt > 0U)
    {
        vecSrc = vldrwq_f32(pSrc);
        /*
         * sum lanes
         */
        sumVec = vfmaq(sumVec, vecSrc, vecSrc);

        blkCnt --;
        pSrc += 4;
    }
    sum = vecAddAcrossF32Mve(sumVec);

    /*
     * tail
     */
    blkCnt = blockSize & 0x3;
    while (blkCnt > 0U)
    {
      /* C = A[0] * A[0] + A[1] * A[1] + ... + A[blockSize-1] * A[blockSize-1] */
  
      /* Compute Power and store result in a temporary variable, sum. */
      in = *pSrc++;
      sum += in * in;
  
      /* Decrement loop counter */
      blkCnt--;
    }

    *pResult = sum;
}
#else
#if defined(ARM_MATH_NEON) && !defined(ARM_MATH_AUTOVECTORIZE)
void arm_power_f32(
  const float32_t * pSrc,
  uint32_t blockSize,
  float32_t * pResult)
{
  float32_t sum = 0.0f;                          /* accumulator */
  float32_t in;                                  /* Temporary variable to store input value */
  uint32_t blkCnt;                               /* loop counter */

  float32x4_t sumV = vdupq_n_f32(0.0f);                          /* Temporary result storage */
  float32x2_t sumV2;
  float32x4_t inV;

  blkCnt = blockSize >> 2U;

  /* Compute 4 outputs at a time.
   ** a second loop below computes the remaining 1 to 3 samples. */
  while (blkCnt > 0U)
  {
    /* C = A[0] * A[0] + A[1] * A[1] + A[2] * A[2] + ... + A[blockSize-1] * A[blockSize-1] */
    /* Compute Power and then store the result in a temporary variable, sum. */
    inV = vld1q_f32(pSrc);
    sumV = vmlaq_f32(sumV, inV, inV);
    pSrc += 4;

    /* Decrement the loop counter */
    blkCnt--;
  }
  sumV2 = vpadd_f32(vget_low_f32(sumV),vget_high_f32(sumV));
  sum = vget_lane_f32(sumV2, 0) + vget_lane_f32(sumV2, 1);

  /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
   ** No loop unrolling is used. */
  blkCnt = blockSize % 0x4U;

  while (blkCnt > 0U)
  {
    /* C = A[0] * A[0] + A[1] * A[1] + A[2] * A[2] + ... + A[blockSize-1] * A[blockSize-1] */
    /* compute power and then store the result in a temporary variable, sum. */
    in = *pSrc++;
    sum += in * in;

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

  /* Store the result to the destination */
  *pResult = sum;
}
#else
void arm_power_f32(
  const float32_t * pSrc,
        uint32_t blockSize,
        float32_t * pResult)
{
        uint32_t blkCnt;                               /* Loop counter */
        float32_t sum = 0.0f;                          /* Temporary result storage */
        float32_t in;                                  /* Temporary variable to store input value */

#if defined (ARM_MATH_LOOPUNROLL) && !defined(ARM_MATH_AUTOVECTORIZE)

  /* Loop unrolling: Compute 4 outputs at a time */
  blkCnt = blockSize >> 2U;

  while (blkCnt > 0U)
  {
    /* C = A[0] * A[0] + A[1] * A[1] + ... + A[blockSize-1] * A[blockSize-1] */

    /* Compute Power and store result in a temporary variable, sum. */
    in = *pSrc++;
    sum += in * in;

    in = *pSrc++;
    sum += in * in;

    in = *pSrc++;
    sum += in * in;

    in = *pSrc++;
    sum += in * in;

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

  /* Loop unrolling: Compute remaining outputs */
  blkCnt = blockSize % 0x4U;

#else

  /* Initialize blkCnt with number of samples */
  blkCnt = blockSize;

#endif /* #if defined (ARM_MATH_LOOPUNROLL) */

  while (blkCnt > 0U)
  {
    /* C = A[0] * A[0] + A[1] * A[1] + ... + A[blockSize-1] * A[blockSize-1] */

    /* Compute Power and store result in a temporary variable, sum. */
    in = *pSrc++;
    sum += in * in;

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

  /* Store result to destination */
  *pResult = sum;
}
#endif /* #if defined(ARM_MATH_NEON) */
#endif /* defined(ARM_MATH_MVEF) && !defined(ARM_MATH_AUTOVECTORIZE) */

/**
  @} end of power group
 */