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  1. /* ----------------------------------------------------------------------
  2.  * Project:      CMSIS DSP Library
  3.  * Title:        arm_max_f32.c
  4.  * Description:  Maximum value 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 Max Maximum
  37.  *
  38.  * Computes the maximum value of an array of data.
  39.  * The function returns both the maximum value and its position within the array.
  40.  * There are separate functions for floating-point, Q31, Q15, and Q7 data types.
  41.  */
  42.  
  43. /**
  44.  * @addtogroup Max
  45.  * @{
  46.  */
  47.  
  48.  
  49. /**
  50.  * @brief Maximum value of a floating-point vector.
  51.  * @param[in]       *pSrc points to the input vector
  52.  * @param[in]       blockSize length of the input vector
  53.  * @param[out]      *pResult maximum value returned here
  54.  * @param[out]      *pIndex index of maximum value returned here
  55.  * @return none.
  56.  */
  57.  
  58. void arm_max_f32(
  59.   float32_t * pSrc,
  60.   uint32_t blockSize,
  61.   float32_t * pResult,
  62.   uint32_t * pIndex)
  63. {
  64. #if defined (ARM_MATH_DSP)
  65.   /* Run the below code for Cortex-M4 and Cortex-M3 */
  66.  
  67.   float32_t maxVal1, maxVal2, out;               /* Temporary variables to store the output value. */
  68.   uint32_t blkCnt, outIndex, count;              /* loop counter */
  69.  
  70.   /* Initialise the count value. */
  71.   count = 0U;
  72.   /* Initialise the index value to zero. */
  73.   outIndex = 0U;
  74.   /* Load first input value that act as reference value for comparision */
  75.   out = *pSrc++;
  76.  
  77.   /* Loop unrolling */
  78.   blkCnt = (blockSize - 1U) >> 2U;
  79.  
  80.   while (blkCnt > 0U)
  81.   {
  82.     /* Initialize maxVal to the next consecutive values one by one */
  83.     maxVal1 = *pSrc++;
  84.     maxVal2 = *pSrc++;
  85.  
  86.     /* compare for the maximum value */
  87.     if (out < maxVal1)
  88.     {
  89.       /* Update the maximum value and its index */
  90.       out = maxVal1;
  91.       outIndex = count + 1U;
  92.     }
  93.  
  94.     /* compare for the maximum value */
  95.     if (out < maxVal2)
  96.     {
  97.       /* Update the maximum value and its index */
  98.       out = maxVal2;
  99.       outIndex = count + 2U;
  100.     }
  101.  
  102.     /* Initialize maxVal to the next consecutive values one by one */
  103.     maxVal1 = *pSrc++;
  104.     maxVal2 = *pSrc++;
  105.  
  106.     /* compare for the maximum value */
  107.     if (out < maxVal1)
  108.     {
  109.       /* Update the maximum value and its index */
  110.       out = maxVal1;
  111.       outIndex = count + 3U;
  112.     }
  113.  
  114.     /* compare for the maximum value */
  115.     if (out < maxVal2)
  116.     {
  117.       /* Update the maximum value and its index */
  118.       out = maxVal2;
  119.       outIndex = count + 4U;
  120.     }
  121.  
  122.     count += 4U;
  123.  
  124.     /* Decrement the loop counter */
  125.     blkCnt--;
  126.   }
  127.  
  128.   /* if (blockSize - 1U) is not multiple of 4 */
  129.   blkCnt = (blockSize - 1U) % 4U;
  130.  
  131. #else
  132.   /* Run the below code for Cortex-M0 */
  133.  
  134.   float32_t maxVal1, out;                        /* Temporary variables to store the output value. */
  135.   uint32_t blkCnt, outIndex;                     /* loop counter */
  136.  
  137.   /* Initialise the index value to zero. */
  138.   outIndex = 0U;
  139.   /* Load first input value that act as reference value for comparision */
  140.   out = *pSrc++;
  141.  
  142.   blkCnt = (blockSize - 1U);
  143.  
  144. #endif /* #if defined (ARM_MATH_DSP) */
  145.  
  146.   while (blkCnt > 0U)
  147.   {
  148.     /* Initialize maxVal to the next consecutive values one by one */
  149.     maxVal1 = *pSrc++;
  150.  
  151.     /* compare for the maximum value */
  152.     if (out < maxVal1)
  153.     {
  154.       /* Update the maximum value and it's index */
  155.       out = maxVal1;
  156.       outIndex = blockSize - blkCnt;
  157.     }
  158.  
  159.     /* Decrement the loop counter */
  160.     blkCnt--;
  161.   }
  162.  
  163.   /* Store the maximum value and it's index into destination pointers */
  164.   *pResult = out;
  165.   *pIndex = outIndex;
  166. }
  167.  
  168. /**
  169.  * @} end of Max group
  170.  */
  171.