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1 /* ----------------------------------------------------------------------
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2 * Copyright (C) 2010-2014 ARM Limited. All rights reserved.
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3 *
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4 * $Date: 19. March 2015
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5 * $Revision: V.1.4.5
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6 *
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7 * Project: CMSIS DSP Library
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8 * Title: arm_max_f32.c
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9 *
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10 * Description: Maximum value of a floating-point vector.
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11 *
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12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
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13 *
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14 * Redistribution and use in source and binary forms, with or without
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15 * modification, are permitted provided that the following conditions
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16 * are met:
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17 * - Redistributions of source code must retain the above copyright
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18 * notice, this list of conditions and the following disclaimer.
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19 * - Redistributions in binary form must reproduce the above copyright
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20 * notice, this list of conditions and the following disclaimer in
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21 * the documentation and/or other materials provided with the
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22 * distribution.
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23 * - Neither the name of ARM LIMITED nor the names of its contributors
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24 * may be used to endorse or promote products derived from this
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25 * software without specific prior written permission.
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26 *
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27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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29 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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30 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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31 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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33 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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34 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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35 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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37 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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38 * POSSIBILITY OF SUCH DAMAGE.
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39 * ---------------------------------------------------------------------------- */
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40
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41 #include "arm_math.h"
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42
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43 /**
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44 * @ingroup groupStats
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45 */
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46
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47 /**
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48 * @defgroup Max Maximum
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49 *
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50 * Computes the maximum value of an array of data.
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51 * The function returns both the maximum value and its position within the array.
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52 * There are separate functions for floating-point, Q31, Q15, and Q7 data types.
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53 */
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54
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55 /**
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56 * @addtogroup Max
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57 * @{
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58 */
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59
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60
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61 /**
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62 * @brief Maximum value of a floating-point vector.
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63 * @param[in] *pSrc points to the input vector
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64 * @param[in] blockSize length of the input vector
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65 * @param[out] *pResult maximum value returned here
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66 * @param[out] *pIndex index of maximum value returned here
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67 * @return none.
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68 */
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69
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70 void arm_max_f32(
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71 float32_t * pSrc,
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72 uint32_t blockSize,
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73 float32_t * pResult,
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74 uint32_t * pIndex)
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75 {
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76 #ifndef ARM_MATH_CM0_FAMILY
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77
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78 /* Run the below code for Cortex-M4 and Cortex-M3 */
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79 float32_t maxVal1, maxVal2, out; /* Temporary variables to store the output value. */
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80 uint32_t blkCnt, outIndex, count; /* loop counter */
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81
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82 /* Initialise the count value. */
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83 count = 0u;
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84 /* Initialise the index value to zero. */
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85 outIndex = 0u;
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86 /* Load first input value that act as reference value for comparision */
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87 out = *pSrc++;
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88
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89 /* Loop unrolling */
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90 blkCnt = (blockSize - 1u) >> 2u;
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91
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92 /* Run the below code for Cortex-M4 and Cortex-M3 */
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93 while(blkCnt > 0u)
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94 {
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95 /* Initialize maxVal to the next consecutive values one by one */
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96 maxVal1 = *pSrc++;
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97
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98 maxVal2 = *pSrc++;
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99
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100 /* compare for the maximum value */
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101 if(out < maxVal1)
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102 {
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103 /* Update the maximum value and its index */
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104 out = maxVal1;
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105 outIndex = count + 1u;
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106 }
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107
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108 maxVal1 = *pSrc++;
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109
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110 /* compare for the maximum value */
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111 if(out < maxVal2)
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112 {
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113 /* Update the maximum value and its index */
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114 out = maxVal2;
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115 outIndex = count + 2u;
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116 }
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117
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118 maxVal2 = *pSrc++;
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119
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120 /* compare for the maximum value */
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121 if(out < maxVal1)
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122 {
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123 /* Update the maximum value and its index */
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124 out = maxVal1;
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125 outIndex = count + 3u;
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126 }
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127
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128 /* compare for the maximum value */
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129 if(out < maxVal2)
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130 {
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131 /* Update the maximum value and its index */
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132 out = maxVal2;
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133 outIndex = count + 4u;
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134 }
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135
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136 count += 4u;
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137
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138 /* Decrement the loop counter */
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139 blkCnt--;
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140 }
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141
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142 /* if (blockSize - 1u) is not multiple of 4 */
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143 blkCnt = (blockSize - 1u) % 4u;
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144
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145 #else
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146
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147 /* Run the below code for Cortex-M0 */
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148 float32_t maxVal1, out; /* Temporary variables to store the output value. */
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149 uint32_t blkCnt, outIndex; /* loop counter */
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150
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151 /* Initialise the index value to zero. */
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152 outIndex = 0u;
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153 /* Load first input value that act as reference value for comparision */
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154 out = *pSrc++;
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155
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156 blkCnt = (blockSize - 1u);
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157
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158 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
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159
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160 while(blkCnt > 0u)
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161 {
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162 /* Initialize maxVal to the next consecutive values one by one */
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163 maxVal1 = *pSrc++;
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164
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165 /* compare for the maximum value */
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166 if(out < maxVal1)
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167 {
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168 /* Update the maximum value and it's index */
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169 out = maxVal1;
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170 outIndex = blockSize - blkCnt;
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171 }
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172
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173
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174 /* Decrement the loop counter */
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175 blkCnt--;
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176
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177 }
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178
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179 /* Store the maximum value and it's index into destination pointers */
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180 *pResult = out;
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181 *pIndex = outIndex;
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182 }
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183
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184 /**
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185 * @} end of Max group
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186 */
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