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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_q15.c
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9 *
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10 * Description: Maximum value of a Q15 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 * @addtogroup Max
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49 * @{
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50 */
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51
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52
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53 /**
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54 * @brief Maximum value of a Q15 vector.
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55 * @param[in] *pSrc points to the input vector
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56 * @param[in] blockSize length of the input vector
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57 * @param[out] *pResult maximum value returned here
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58 * @param[out] *pIndex index of maximum value returned here
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59 * @return none.
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60 */
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61
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62 void arm_max_q15(
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63 q15_t * pSrc,
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64 uint32_t blockSize,
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65 q15_t * pResult,
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66 uint32_t * pIndex)
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67 {
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68 #ifndef ARM_MATH_CM0_FAMILY
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69
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70 /* Run the below code for Cortex-M4 and Cortex-M3 */
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71 q15_t maxVal1, maxVal2, out; /* Temporary variables to store the output value. */
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72 uint32_t blkCnt, outIndex, count; /* loop counter */
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73
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74 /* Initialise the count value. */
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75 count = 0u;
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76 /* Initialise the index value to zero. */
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77 outIndex = 0u;
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78 /* Load first input value that act as reference value for comparision */
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79 out = *pSrc++;
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80
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81 /* Loop unrolling */
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82 blkCnt = (blockSize - 1u) >> 2u;
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83
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84 /* Run the below code for Cortex-M4 and Cortex-M3 */
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85 while(blkCnt > 0u)
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86 {
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87 /* Initialize maxVal to the next consecutive values one by one */
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88 maxVal1 = *pSrc++;
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89
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90 maxVal2 = *pSrc++;
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91
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92 /* compare for the maximum value */
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93 if(out < maxVal1)
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94 {
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95 /* Update the maximum value and its index */
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96 out = maxVal1;
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97 outIndex = count + 1u;
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98 }
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99
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100 maxVal1 = *pSrc++;
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101
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102 /* compare for the maximum value */
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103 if(out < maxVal2)
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104 {
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105 /* Update the maximum value and its index */
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106 out = maxVal2;
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107 outIndex = count + 2u;
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108 }
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109
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110 maxVal2 = *pSrc++;
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111
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112 /* compare for the maximum value */
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113 if(out < maxVal1)
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114 {
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115 /* Update the maximum value and its index */
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116 out = maxVal1;
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117 outIndex = count + 3u;
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118 }
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119
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120 /* compare for the maximum value */
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121 if(out < maxVal2)
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122 {
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123 /* Update the maximum value and its index */
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124 out = maxVal2;
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125 outIndex = count + 4u;
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126 }
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127
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128 count += 4u;
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129
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130 /* Decrement the loop counter */
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131 blkCnt--;
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132 }
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133
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134 /* if (blockSize - 1u) is not multiple of 4 */
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135 blkCnt = (blockSize - 1u) % 4u;
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136
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137 #else
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138
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139 /* Run the below code for Cortex-M0 */
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140 q15_t maxVal1, out; /* Temporary variables to store the output value. */
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141 uint32_t blkCnt, outIndex; /* loop counter */
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142
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143 blkCnt = (blockSize - 1u);
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144
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145 /* Initialise the index value to zero. */
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146 outIndex = 0u;
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147 /* Load first input value that act as reference value for comparision */
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148 out = *pSrc++;
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149
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150 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
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151
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152 while(blkCnt > 0u)
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153 {
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154 /* Initialize maxVal to the next consecutive values one by one */
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155 maxVal1 = *pSrc++;
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156
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157 /* compare for the maximum value */
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158 if(out < maxVal1)
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159 {
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160 /* Update the maximum value and it's index */
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161 out = maxVal1;
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162 outIndex = blockSize - blkCnt;
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163 }
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164 /* Decrement the loop counter */
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165 blkCnt--;
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166
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167 }
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168
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169 /* Store the maximum value and its index into destination pointers */
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170 *pResult = out;
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171 *pIndex = outIndex;
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172 }
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173
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174 /**
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175 * @} end of Max group
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176 */
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