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1 //================================================================= |
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2 // |
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3 // rand3.c |
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4 // |
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5 // Testcase for C library rand() |
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6 // |
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7 //================================================================= |
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8 //####COPYRIGHTBEGIN#### |
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9 // |
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10 // ------------------------------------------- |
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11 // The contents of this file are subject to the Cygnus eCos Public License |
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12 // Version 1.0 (the "License"); you may not use this file except in |
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13 // compliance with the License. You may obtain a copy of the License at |
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14 // http://sourceware.cygnus.com/ecos |
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15 // |
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16 // Software distributed under the License is distributed on an "AS IS" |
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17 // basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the |
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18 // License for the specific language governing rights and limitations under |
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19 // the License. |
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20 // |
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21 // The Original Code is eCos - Embedded Cygnus Operating System, released |
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22 // September 30, 1998. |
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23 // |
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24 // The Initial Developer of the Original Code is Cygnus. Portions created |
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25 // by Cygnus are Copyright (C) 1998,1999 Cygnus Solutions. All Rights Reserved. |
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26 // ------------------------------------------- |
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27 // |
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28 //####COPYRIGHTEND#### |
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29 //================================================================= |
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30 //#####DESCRIPTIONBEGIN#### |
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31 // |
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32 // Author(s): ctarpy, jlarmour |
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33 // Contributors: ctarpy, jlarmour |
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34 // Date: 1999-03-23 |
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35 // Description: Contains testcode for C library rand() function. This tests |
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36 // that random numbers are distributed well between 0 and |
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37 // RAND_MAX |
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38 // |
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39 // |
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40 //####DESCRIPTIONEND#### |
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41 |
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42 |
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43 // CONFIGURATION |
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44 |
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45 #include <pkgconf/libc.h> // Configuration header |
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46 |
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47 |
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48 // INCLUDES |
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49 |
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50 #include <stdlib.h> |
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51 #include <cyg/infra/testcase.h> |
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52 #include <sys/cstartup.h> // C library initialisation |
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53 |
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54 |
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55 // CONSTANTS |
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56 |
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57 #define NUM_BUCKETS 1000 // how many categories to define |
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58 #define TEST_LENGTH 200000 // how many samples to take - careful |
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59 // when reducing this since it also reduces |
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60 // BUCKET_DIFF_TOLERANCE below. If you reduce |
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61 // it too low, BUCKET_DIFF_TOLERANCE will need |
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62 // a fudge factor |
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63 |
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64 #define BUCKET_SIZE (RAND_MAX / NUM_BUCKETS) // number space allocated |
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65 // to bucket from 0..RAND_MAX |
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66 #define NUM_PER_BUCKET (TEST_LENGTH/NUM_BUCKETS) // Expected number that went |
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67 // into each bucket at end |
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68 |
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69 // how much the buckets can vary at the end. |
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70 #define BUCKET_DIFF_TOLERANCE (NUM_PER_BUCKET/4) // allowed to vary 25% |
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71 |
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72 |
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73 |
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74 // FUNCTIONS |
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75 |
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76 |
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77 externC void |
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78 cyg_package_start( void ) |
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79 { |
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80 cyg_iso_c_start(); |
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81 } // cyg_package_start() |
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82 |
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83 |
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84 static __inline__ int |
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85 my_abs(int i) |
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86 { |
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87 return (i < 0) ? -i : i; |
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88 } // my_abs() |
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89 |
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90 int |
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91 main(int argc, char *argv[]) |
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92 { |
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93 // divide the space from 0..RAND_MAX into NUM_BUCKETS categories *BUT* |
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94 // RAND_MAX / NUM_BUCKETS may not divide exactly so we leave space for |
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95 // the bits left over, in case there are any! So we add 1. |
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96 |
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97 static cyg_uint8 rand_bucket[NUM_BUCKETS+1]; |
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98 cyg_ucount32 count; // loop variable |
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99 int r; // temp for rand() variable |
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100 |
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101 CYG_TEST_INIT(); |
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102 |
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103 CYG_TEST_INFO("Starting tests from testcase " __FILE__ " for C library " |
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104 "rand() function"); |
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105 |
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106 CYG_TEST_INFO("This test tests the distribution of random numbers and"); |
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107 CYG_TEST_INFO("may take some time"); |
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108 |
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109 for ( count=0; count < TEST_LENGTH; ++count ) { |
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110 r = rand(); |
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111 ++rand_bucket[ r / BUCKET_SIZE ]; |
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112 if ((count%10000)==0) |
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113 CYG_TEST_STILL_ALIVE(count, "Still testing..."); |
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114 } // for |
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115 |
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116 for ( count=0; count < NUM_BUCKETS; ++count ) { |
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117 cyg_ucount32 diff; |
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118 |
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119 diff = my_abs( rand_bucket[count] - NUM_PER_BUCKET ); |
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120 if ( diff > BUCKET_DIFF_TOLERANCE ) |
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121 break; |
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122 } // for |
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123 |
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124 // if the previous loop completed, we may want to check the "extra" |
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125 // bucket (see the comment at the top) that may have some bits in if |
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126 // RAND_MAX doesn't split into NUM_BUCKETS evenly. The number of random |
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127 // digits that fell into that bucket would be expected to be proportional |
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128 // to the ratio of the remainder of (RAND_MAX % NUM_BUCKETS) to |
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129 // NUM_BUCKETS. |
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130 if (count == NUM_BUCKETS) { |
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131 cyg_ucount32 rem; |
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132 cyg_ucount32 last_bucket_expected; |
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133 cyg_ucount32 diff; |
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134 |
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135 rem = RAND_MAX % NUM_BUCKETS; |
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136 |
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137 last_bucket_expected = (rem * NUM_PER_BUCKET) / BUCKET_SIZE; |
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138 |
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139 diff = my_abs(last_bucket_expected - rand_bucket[count]); |
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140 CYG_TEST_PASS_FAIL(diff <= BUCKET_DIFF_TOLERANCE, |
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141 "Upper bound fencepost test"); |
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142 } |
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143 CYG_TEST_PASS_FAIL( (count >= NUM_BUCKETS), |
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144 "even distribution of rand()"); |
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145 |
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146 CYG_TEST_FINISH("Finished tests from testcase " __FILE__ " for " |
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147 "C library rand() function"); |
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148 } // main() |
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149 |
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150 |
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151 // EOF rand3.c |
