tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/StatisticsFunctions/arm_max_f32.c

   1 /* ----------------------------------------------------------------------
   2 * Copyright (C) 2010-2013 ARM Limited. All rights reserved.
   3 *
   4 * $Date:        17. January 2013
   5 * $Revision:    V1.4.1
   6 *
   7 * Project:          CMSIS DSP Library
   8 * Title:                arm_max_f32.c
   9 *
  10 * Description:  Maximum value of a floating-point vector.
  11 *
  12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
  13 *
  14 * Redistribution and use in source and binary forms, with or without
  15 * modification, are permitted provided that the following conditions
  16 * are met:
  17 *   - Redistributions of source code must retain the above copyright
  18 *     notice, this list of conditions and the following disclaimer.
  19 *   - Redistributions in binary form must reproduce the above copyright
  20 *     notice, this list of conditions and the following disclaimer in
  21 *     the documentation and/or other materials provided with the
  22 *     distribution.
  23 *   - Neither the name of ARM LIMITED nor the names of its contributors
  24 *     may be used to endorse or promote products derived from this
  25 *     software without specific prior written permission.
  26 *
  27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  29 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  30 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  31 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  33 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  34 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  35 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  37 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  38 * POSSIBILITY OF SUCH DAMAGE.
  39 * ---------------------------------------------------------------------------- */
  40
  41 #include "arm_math.h"
  42
  43 /**
  44  * @ingroup groupStats
  45  */
  46
  47 /**
  48  * @defgroup Max Maximum
  49  *
  50  * Computes the maximum value of an array of data.
  51  * The function returns both the maximum value and its position within the array.
  52  * There are separate functions for floating-point, Q31, Q15, and Q7 data types.
  53  */
  54
  55 /**
  56  * @addtogroup Max
  57  * @{
  58  */
  59
  60
  61 /**
  62  * @brief Maximum value of a floating-point vector.
  63  * @param[in]       *pSrc points to the input vector
  64  * @param[in]       blockSize length of the input vector
  65  * @param[out]      *pResult maximum value returned here
  66  * @param[out]      *pIndex index of maximum value returned here
  67  * @return none.
  68  */
  69
  70 void arm_max_f32(
  71   float32_t * pSrc,
  72   uint32_t blockSize,
  73   float32_t * pResult,
  74   uint32_t * pIndex)
  75 {
  76 #ifndef ARM_MATH_CM0_FAMILY
  77
  78   /* Run the below code for Cortex-M4 and Cortex-M3 */
  79   float32_t maxVal1, maxVal2, out;               /* Temporary variables to store the output value. */
  80   uint32_t blkCnt, outIndex, count;              /* loop counter */
  81
  82   /* Initialise the count value. */
  83   count = 0u;
  84   /* Initialise the index value to zero. */
  85   outIndex = 0u;
  86   /* Load first input value that act as reference value for comparision */
  87   out = *pSrc++;
  88
  89   /* Loop unrolling */
  90   blkCnt = (blockSize - 1u) >> 2u;
  91
  92   /* Run the below code for Cortex-M4 and Cortex-M3 */
  93   while(blkCnt > 0u)
  94   {
  95     /* Initialize maxVal to the next consecutive values one by one */
  96     maxVal1 = *pSrc++;
  97
  98     maxVal2 = *pSrc++;
  99
 100     /* compare for the maximum value */
 101     if(out < maxVal1)
 102     {
 103       /* Update the maximum value and its index */
 104       out = maxVal1;
 105       outIndex = count + 1u;
 106     }
 107
 108     maxVal1 = *pSrc++;
 109
 110     /* compare for the maximum value */
 111     if(out < maxVal2)
 112     {
 113       /* Update the maximum value and its index */
 114       out = maxVal2;
 115       outIndex = count + 2u;
 116     }
 117
 118     maxVal2 = *pSrc++;
 119
 120     /* compare for the maximum value */
 121     if(out < maxVal1)
 122     {
 123       /* Update the maximum value and its index */
 124       out = maxVal1;
 125       outIndex = count + 3u;
 126     }
 127
 128     /* compare for the maximum value */
 129     if(out < maxVal2)
 130     {
 131       /* Update the maximum value and its index */
 132       out = maxVal2;
 133       outIndex = count + 4u;
 134     }
 135
 136     count += 4u;
 137
 138     /* Decrement the loop counter */
 139     blkCnt--;
 140   }
 141
 142   /* if (blockSize - 1u) is not multiple of 4 */
 143   blkCnt = (blockSize - 1u) % 4u;
 144
 145 #else
 146
 147   /* Run the below code for Cortex-M0 */
 148   float32_t maxVal1, out;                        /* Temporary variables to store the output value. */
 149   uint32_t blkCnt, outIndex;                     /* loop counter */
 150
 151   /* Initialise the index value to zero. */
 152   outIndex = 0u;
 153   /* Load first input value that act as reference value for comparision */
 154   out = *pSrc++;
 155
 156   blkCnt = (blockSize - 1u);
 157
 158 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
 159
 160   while(blkCnt > 0u)
 161   {
 162     /* Initialize maxVal to the next consecutive values one by one */
 163     maxVal1 = *pSrc++;
 164
 165     /* compare for the maximum value */
 166     if(out < maxVal1)
 167     {
 168       /* Update the maximum value and it's index */
 169       out = maxVal1;
 170       outIndex = blockSize - blkCnt;
 171     }
 172
 173
 174     /* Decrement the loop counter */
 175     blkCnt--;
 176
 177   }
 178
 179   /* Store the maximum value and it's index into destination pointers */
 180   *pResult = out;
 181   *pIndex = outIndex;
 182 }
 183
 184 /**
 185  * @} end of Max group
 186  */