lib/main/CMSIS/DSP/Source/StatisticsFunctions/arm_min_q31.c

   1 /* ----------------------------------------------------------------------
   2  * Project:      CMSIS DSP Library
   3  * Title:        arm_min_q31.c
   4  * Description:  Minimum value of a Q31 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 /**
  37  * @addtogroup Min
  38  * @{
  39  */
  40
  41
  42 /**
  43  * @brief Minimum value of a Q31 vector.
  44  * @param[in]       *pSrc points to the input vector
  45  * @param[in]       blockSize length of the input vector
  46  * @param[out]      *pResult minimum value returned here
  47  * @param[out]      *pIndex index of minimum value returned here
  48  * @return none.
  49  */
  50
  51 void arm_min_q31(
  52   q31_t * pSrc,
  53   uint32_t blockSize,
  54   q31_t * pResult,
  55   uint32_t * pIndex)
  56 {
  57 #if defined (ARM_MATH_DSP)
  58   /* Run the below code for Cortex-M4 and Cortex-M3 */
  59
  60   q31_t minVal1, minVal2, out;                   /* Temporary variables to store the output value. */
  61   uint32_t blkCnt, outIndex, count;              /* loop counter */
  62
  63   /* Initialise the count value. */
  64   count = 0U;
  65   /* Initialise the index value to zero. */
  66   outIndex = 0U;
  67   /* Load first input value that act as reference value for comparision */
  68   out = *pSrc++;
  69
  70   /* Loop unrolling */
  71   blkCnt = (blockSize - 1U) >> 2U;
  72
  73   while (blkCnt > 0U)
  74   {
  75     /* Initialize minVal to the next consecutive values one by one */
  76     minVal1 = *pSrc++;
  77     minVal2 = *pSrc++;
  78
  79     /* compare for the minimum value */
  80     if (out > minVal1)
  81     {
  82       /* Update the minimum value and its index */
  83       out = minVal1;
  84       outIndex = count + 1U;
  85     }
  86
  87     /* compare for the minimum value */
  88     if (out > minVal2)
  89     {
  90       /* Update the minimum value and its index */
  91       out = minVal2;
  92       outIndex = count + 2U;
  93     }
  94
  95     /* Initialize minVal to the next consecutive values one by one */
  96     minVal1 = *pSrc++;
  97     minVal2 = *pSrc++;
  98
  99     /* compare for the minimum value */
 100     if (out > minVal1)
 101     {
 102       /* Update the minimum value and its index */
 103       out = minVal1;
 104       outIndex = count + 3U;
 105     }
 106
 107     /* compare for the minimum value */
 108     if (out > minVal2)
 109     {
 110       /* Update the minimum value and its index */
 111       out = minVal2;
 112       outIndex = count + 4U;
 113     }
 114
 115     count += 4U;
 116
 117     /* Decrement the loop counter */
 118     blkCnt--;
 119   }
 120
 121   /* if (blockSize - 1U) is not multiple of 4 */
 122   blkCnt = (blockSize - 1U) % 4U;
 123
 124 #else
 125   /* Run the below code for Cortex-M0 */
 126
 127   q31_t minVal1, out;                            /* Temporary variables to store the output value. */
 128   uint32_t blkCnt, outIndex;                     /* loop counter */
 129
 130   /* Initialise the index value to zero. */
 131   outIndex = 0U;
 132   /* Load first input value that act as reference value for comparision */
 133   out = *pSrc++;
 134
 135   blkCnt = (blockSize - 1U);
 136
 137 #endif /* #if defined (ARM_MATH_DSP) */
 138
 139   while (blkCnt > 0U)
 140   {
 141     /* Initialize minVal to the next consecutive values one by one */
 142     minVal1 = *pSrc++;
 143
 144     /* compare for the minimum value */
 145     if (out > minVal1)
 146     {
 147       /* Update the minimum value and it's index */
 148       out = minVal1;
 149       outIndex = blockSize - blkCnt;
 150     }
 151
 152     /* Decrement the loop counter */
 153     blkCnt--;
 154   }
 155
 156   /* Store the minimum value and it's index into destination pointers */
 157   *pResult = out;
 158   *pIndex = outIndex;
 159 }
 160
 161 /**
 162  * @} end of Min group
 163  */