CMSIS-DSP/Source/StatisticsFunctions/arm_absmax_q31.c

/* ----------------------------------------------------------------------
 * Project:      CMSIS DSP Library
 * Title:        arm_absmax_q31.c
 * Description:  Maximum value of absolute values of a Q31 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
 */

/**
  @addtogroup AbsMax
  @{
 */

/**
  @brief         Maximum value of absolute values of a Q31 vector.
  @param[in]     pSrc       points to the input vector
  @param[in]     blockSize  number of samples in input vector
  @param[out]    pResult    maximum value returned here
  @param[out]    pIndex     index of maximum value returned here
 */

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

#include "arm_helium_utils.h"
void arm_absmax_q31(
  const q31_t * pSrc,
        uint32_t blockSize,
        q31_t * pResult,
        uint32_t * pIndex)
{
    int32_t         blkCnt;     /* loop counters */
    q31x4_t         extremValVec = vdupq_n_s32(Q31_ABSMIN);
    q31_t           maxValue = Q31_ABSMIN;
    uint32x4_t      indexVec;
    uint32x4_t      extremIdxVec;
    mve_pred16_t    p0;
    uint32_t        extremIdxArr[4];

    indexVec = vidupq_u32(0U, 1);

    blkCnt = blockSize;
    do {
        mve_pred16_t    p = vctp32q(blkCnt);
        q31x4_t         extremIdxVal = vld1q_z_s32(pSrc, p);

        extremIdxVal = vqabsq(extremIdxVal);
        /*
         * Get current max per lane and current index per lane
         * when a max is selected
         */
        p0 = vcmpgtq_m(extremIdxVal, extremValVec, p);

        extremValVec = vorrq_m(extremValVec, extremIdxVal, extremIdxVal, p0);
        /* store per-lane extrema indexes */
        vst1q_p_u32(extremIdxArr, indexVec, p0);

        indexVec += 4;
        pSrc += 4;
        blkCnt -= 4;
    }
    while (blkCnt > 0);


    /* Get max value across the vector   */
    maxValue = vmaxvq(maxValue, extremValVec);

    /* set index for lower values to max possible index   */
    p0 = vcmpgeq(extremValVec, maxValue);
    extremIdxVec = vld1q_u32(extremIdxArr);

    indexVec = vpselq(extremIdxVec, vdupq_n_u32(blockSize - 1), p0);
    *pIndex = vminvq(blockSize - 1, indexVec);
    *pResult = maxValue;  
}
#else
#if defined(ARM_MATH_DSP)
void arm_absmax_q31(
  const q31_t * pSrc,
        uint32_t blockSize,
        q31_t * pResult,
        uint32_t * pIndex)
{
        q31_t cur_absmax, out;                     /* Temporary variables to store the output value. */\
        uint32_t blkCnt, outIndex;                     /* Loop counter */                                   \
        uint32_t index;                                /* index of maximum value */                         \
                                                                                                            \
  /* Initialize index value to zero. */                                                                     \
  outIndex = 0U;                                                                                            \
  /* Load first input value that act as reference value for comparision */                                  \
  out = *pSrc++;                                                                                            \
  out = (out > 0) ? out : (q31_t)__QSUB(0, out);                                                                           \
  /* Initialize index of extrema value. */                                                                  \
  index = 0U;                                                                                               \
                                                                                                            \
  /* Loop unrolling: Compute 4 outputs at a time */                                                         \
  blkCnt = (blockSize - 1U) >> 2U;                                                                          \
                                                                                                            \
  while (blkCnt > 0U)                                                                                       \
  {                                                                                                         \
    /* Initialize cur_absmax to next consecutive values one by one */                                         \
    cur_absmax = *pSrc++;                                                                                     \
    cur_absmax = (cur_absmax > 0) ? cur_absmax : (q31_t)__QSUB(0, cur_absmax);                                                                \
    /* compare for the extrema value */                                                                     \
    if (cur_absmax > out)                                                                         \
    {                                                                                                       \
      /* Update the extrema value and it's index */                                                         \
      out = cur_absmax;                                                                                       \
      outIndex = index + 1U;                                                                                \
    }                                                                                                       \
                                                                                                            \
    cur_absmax = *pSrc++;                                                                                     \
    cur_absmax = (cur_absmax > 0) ? cur_absmax : (q31_t)__QSUB(0, cur_absmax);                                                                \
    if (cur_absmax > out)                                                                         \
    {                                                                                                       \
      out = cur_absmax;                                                                                       \
      outIndex = index + 2U;                                                                                \
    }                                                                                                       \
                                                                                                            \
    cur_absmax = *pSrc++;                                                                                     \
    cur_absmax = (cur_absmax > 0) ? cur_absmax : (q31_t)__QSUB(0, cur_absmax);                                                                \
    if (cur_absmax > out)                                                                          \
    {                                                                                                       \
      out = cur_absmax;                                                                                       \
      outIndex = index + 3U;                                                                                \
    }                                                                                                       \
                                                                                                            \
    cur_absmax = *pSrc++;                                                                                     \
    cur_absmax = (cur_absmax > 0) ? cur_absmax : (q31_t)__QSUB(0, cur_absmax);                                                                 \
    if (cur_absmax > out)                                                                          \
    {                                                                                                       \
      out = cur_absmax;                                                                                       \
      outIndex = index + 4U;                                                                                \
    }                                                                                                       \
                                                                                                            \
    index += 4U;                                                                                            \
                                                                                                            \
    /* Decrement loop counter */                                                                            \
    blkCnt--;                                                                                               \
  }                                                                                                         \
                                                                                                            \
  /* Loop unrolling: Compute remaining outputs */                                                           \
  blkCnt = (blockSize - 1U) % 4U;                                                                           \
                                                                                                            \
                                                                                                            \
  while (blkCnt > 0U)                                                                                       \
  {                                                                                                         \
    cur_absmax = *pSrc++;                                                                                     \
    cur_absmax = (cur_absmax > 0) ? cur_absmax : (q31_t)__QSUB(0, cur_absmax);                                                                 \
    if (cur_absmax > out)                                                                         \
    {                                                                                                       \
      out = cur_absmax;                                                                                       \
      outIndex = blockSize - blkCnt;                                                                        \
    }                                                                                                       \
                                                                                                            \
    /* Decrement loop counter */                                                                            \
    blkCnt--;                                                                                               \
  }                                                                                                         \
                                                                                                            \
  /* Store the extrema value and it's index into destination pointers */                                    \
  *pResult = out;                                                                                           \
  *pIndex = outIndex;  
}
#else
void arm_absmax_q31(
  const q31_t * pSrc,
        uint32_t blockSize,
        q31_t * pResult,
        uint32_t * pIndex)
{
        q31_t maxVal, out;                             /* Temporary variables to store the output value. */
        uint32_t blkCnt, outIndex;                     /* Loop counter */


  /* Initialise index value to zero. */
  outIndex = 0U;
  /* Load first input value that act as reference value for comparision */
  out = (*pSrc > 0) ? *pSrc : ((*pSrc == INT32_MIN) ? INT32_MAX : -*pSrc);
  pSrc++;

  /* Initialize blkCnt with number of samples */
  blkCnt = (blockSize - 1U);

  while (blkCnt > 0U)
  {
    /* Initialize maxVal to the next consecutive values one by one */
    maxVal = (*pSrc > 0) ? *pSrc : ((*pSrc == INT32_MIN) ? INT32_MAX : -*pSrc);
    pSrc++;

    /* compare for the maximum value */
    if (out < maxVal)
    {
      /* Update the maximum value and it's index */
      out = maxVal;
      outIndex = blockSize - blkCnt;
    }

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

  /* Store the maximum value and it's index into destination pointers */
  *pResult = out;
  *pIndex = outIndex;
}
#endif /* defined(ARM_MATH_DSP) */
#endif /* defined(ARM_MATH_MVEI) && !defined(ARM_MATH_AUTOVECTORIZE) */
/**
  @} end of AbsMax group
 */