tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/StatisticsFunctions/arm_max_q31.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_q31.c
   9 *
  10 * Description:  Maximum value of a Q31 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  * @addtogroup Max
  49  * @{
  50  */
  51
  52
  53 /**
  54  * @brief Maximum value of a Q31 vector.
  55  * @param[in]       *pSrc points to the input vector
  56  * @param[in]       blockSize length of the input vector
  57  * @param[out]      *pResult maximum value returned here
  58  * @param[out]      *pIndex index of maximum value returned here
  59  * @return none.
  60  */
  61
  62 void arm_max_q31(
  63   q31_t * pSrc,
  64   uint32_t blockSize,
  65   q31_t * pResult,
  66   uint32_t * pIndex)
  67 {
  68 #ifndef ARM_MATH_CM0_FAMILY
  69
  70   /* Run the below code for Cortex-M4 and Cortex-M3 */
  71   q31_t maxVal1, maxVal2, out;                   /* Temporary variables to store the output value. */
  72   uint32_t blkCnt, outIndex, count;              /* loop counter */
  73
  74   /* Initialise the count value. */
  75   count = 0u;
  76   /* Initialise the index value to zero. */
  77   outIndex = 0u;
  78   /* Load first input value that act as reference value for comparision */
  79   out = *pSrc++;
  80
  81   /* Loop unrolling */
  82   blkCnt = (blockSize - 1u) >> 2u;
  83
  84   /* Run the below code for Cortex-M4 and Cortex-M3 */
  85   while(blkCnt > 0u)
  86   {
  87     /* Initialize maxVal to the next consecutive values one by one */
  88     maxVal1 = *pSrc++;
  89
  90     maxVal2 = *pSrc++;
  91
  92     /* compare for the maximum value */
  93     if(out < maxVal1)
  94     {
  95       /* Update the maximum value and its index */
  96       out = maxVal1;
  97       outIndex = count + 1u;
  98     }
  99
 100     maxVal1 = *pSrc++;
 101
 102     /* compare for the maximum value */
 103     if(out < maxVal2)
 104     {
 105       /* Update the maximum value and its index */
 106       out = maxVal2;
 107       outIndex = count + 2u;
 108     }
 109
 110     maxVal2 = *pSrc++;
 111
 112     /* compare for the maximum value */
 113     if(out < maxVal1)
 114     {
 115       /* Update the maximum value and its index */
 116       out = maxVal1;
 117       outIndex = count + 3u;
 118     }
 119
 120     /* compare for the maximum value */
 121     if(out < maxVal2)
 122     {
 123       /* Update the maximum value and its index */
 124       out = maxVal2;
 125       outIndex = count + 4u;
 126     }
 127
 128     count += 4u;
 129
 130     /* Decrement the loop counter */
 131     blkCnt--;
 132   }
 133
 134   /* if (blockSize - 1u) is not multiple of 4 */
 135   blkCnt = (blockSize - 1u) % 4u;
 136
 137 #else
 138
 139   /* Run the below code for Cortex-M0 */
 140   q31_t maxVal1, out;                            /* Temporary variables to store the output value. */
 141   uint32_t blkCnt, outIndex;                     /* loop counter */
 142
 143   /* Initialise the index value to zero. */
 144   outIndex = 0u;
 145   /* Load first input value that act as reference value for comparision */
 146   out = *pSrc++;
 147
 148   blkCnt = (blockSize - 1u);
 149
 150 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
 151
 152   while(blkCnt > 0u)
 153   {
 154     /* Initialize maxVal to the next consecutive values one by one */
 155     maxVal1 = *pSrc++;
 156
 157     /* compare for the maximum value */
 158     if(out < maxVal1)
 159     {
 160       /* Update the maximum value and it's index */
 161       out = maxVal1;
 162       outIndex = blockSize - blkCnt;
 163     }
 164
 165     /* Decrement the loop counter */
 166     blkCnt--;
 167
 168   }
 169
 170   /* Store the maximum value and its index into destination pointers */
 171   *pResult = out;
 172   *pIndex = outIndex;
 173 }
 174
 175 /**
 176  * @} end of Max group
 177  */