lib/main/CMSIS/DSP/Source/StatisticsFunctions/arm_max_f32.c

   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  */