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1 //========================================================================== |
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2 // |
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3 // bin_sem2.cxx |
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4 // |
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5 // Binary semaphore test 2 |
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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): nickg,dsm |
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33 // Contributors: dsm |
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34 // Date: 1998-03-10 |
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35 // Description: |
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36 // Dining philosophers test. Based on philo.cxx |
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37 //####DESCRIPTIONEND#### |
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38 |
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39 #include <pkgconf/kernel.h> |
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40 |
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41 #include <cyg/kernel/sched.hxx> |
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42 #include <cyg/kernel/thread.hxx> |
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43 #include <cyg/kernel/thread.inl> |
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44 #include <cyg/kernel/mutex.hxx> |
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45 |
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46 #include <cyg/kernel/sema.hxx> |
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47 |
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48 #include <cyg/infra/testcase.h> |
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49 |
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50 #include <cyg/kernel/sched.inl> |
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51 |
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52 static cyg_ucount16 PHILO_LOOPS = 1000; |
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53 |
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54 #define PHILOSOPHERS 15 |
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55 #define NTHREADS PHILOSOPHERS |
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56 #include "testaux.hxx" |
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57 |
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58 static Cyg_Binary_Semaphore chopstick[PHILOSOPHERS]; |
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59 |
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60 static char pstate[PHILOSOPHERS+1]; // state of each philosopher |
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61 |
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62 static cyg_ucount16 state_changes = 0; |
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63 // state_changes keep track of number of changes to pstate so |
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64 // we can exit after we've seen enough. |
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65 |
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66 |
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67 static Cyg_Mutex pstate_mutex; |
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68 static Cyg_Mutex cycle_mutex; |
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69 |
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70 static inline int left(cyg_count8 i) |
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71 { |
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72 return (0 == i) ? PHILOSOPHERS-1 : i-1 ; |
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73 } |
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74 static inline int right(cyg_count8 i) |
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75 { |
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76 return (PHILOSOPHERS == i+1) ? 0 : i+1 ; |
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77 } |
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78 |
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79 void change_state(int id, char newstate) |
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80 { |
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81 if (PHILO_LOOPS == state_changes++) |
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82 CYG_TEST_PASS_FINISH("Binary Semaphore 2 OK"); |
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83 |
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84 |
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85 pstate_mutex.lock(); { |
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86 pstate[id] = newstate; |
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87 bool all_hungry = true; // until proved otherwise |
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88 for(cyg_ucount8 i=0; i < PHILOSOPHERS; i++) { |
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89 if('E' == pstate[i]) { |
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90 CHECK('E' != pstate[left(i)]); |
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91 CHECK('E' != pstate[right(i)]); |
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92 } |
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93 if('H' != pstate[i]) { |
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94 all_hungry = false; |
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95 } |
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96 } |
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97 // Theoretically it is possible for all the philosophers to be |
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98 // hungry but not waiting on semaphores. But in practice this |
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99 // means something is wrong. |
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100 CHECK(false == all_hungry); |
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101 } pstate_mutex.unlock(); |
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102 } |
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103 |
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104 char get_state(int id) |
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105 { |
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106 pstate_mutex.lock(); |
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107 |
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108 char s = pstate[id]; |
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109 |
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110 pstate_mutex.unlock(); |
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111 |
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112 return s; |
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113 } |
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114 |
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115 // ------------------------------------------------------------------------- |
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116 // Thread to behave like a philosopher |
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117 |
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118 void Philosopher( CYG_ADDRESS id ) |
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119 { |
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120 Cyg_Thread *self = Cyg_Thread::self(); |
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121 Cyg_Binary_Semaphore *first_stick = &chopstick[id]; |
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122 Cyg_Binary_Semaphore *second_stick = &chopstick[(id+1)%PHILOSOPHERS]; |
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123 |
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124 CHECK( id >= 0 && id < PHILOSOPHERS); |
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125 |
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126 // Deadlock avoidance. The easiest way to make the philosophers |
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127 // behave is to make each pick up the lowest numbered stick |
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128 // first. This is how it works out anyway for all the philosophers |
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129 // except the last, who must have his sticks swapped. |
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130 |
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131 if( id == PHILOSOPHERS-1 ) |
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132 { |
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133 Cyg_Binary_Semaphore *t = first_stick; |
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134 first_stick = second_stick; |
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135 second_stick = t; |
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136 } |
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137 |
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138 |
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139 // The following variable is shared by all philosophers. |
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140 // It is incremented unprotected, but this does not matter |
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141 // since it is only present to introduce a little variability |
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142 // into the think and eat times. |
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143 |
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144 static int cycle = 0; |
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145 |
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146 for(;;) |
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147 { |
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148 // Think for a bit |
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149 |
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150 self->delay((id+cycle++)%12); // Cogito ergo sum... |
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151 |
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152 // I am now hungry, try to get the chopsticks |
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153 change_state(id,'H'); |
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154 |
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155 // Get the sticks |
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156 first_stick->wait(); |
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157 second_stick->wait(); |
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158 |
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159 // Got them, now eat |
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160 change_state(id,'E'); |
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161 |
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162 // Check that the world is as I think it is... |
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163 CYG_TEST_CHECK( !first_stick->posted(), |
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164 "Not got first stick"); |
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165 CYG_TEST_CHECK( !second_stick->posted(), |
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166 "Not got second stick"); |
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167 CYG_TEST_CHECK( get_state(left(id)) != 'E', |
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168 "Left neighbour also eating!!"); |
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169 CYG_TEST_CHECK( get_state(right(id)) != 'E', |
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170 "Right neighbour also eating!!"); |
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171 |
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172 self->delay((id+cycle++)%6); // munch munch |
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173 |
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174 // Finished eating, put down sticks. |
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175 |
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176 change_state(id,'T'); |
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177 |
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178 // put sticks back on table |
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179 first_stick->post(); |
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180 second_stick->post(); |
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181 } |
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182 } |
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183 |
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184 // ------------------------------------------------------------------------- |
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185 |
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186 void bin_sem2_main( void ) |
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187 { |
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188 CYG_TEST_INIT(); |
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189 |
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190 if (cyg_test_is_simulator) |
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191 PHILO_LOOPS = 100; |
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192 |
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193 for( int i = 0; i < PHILOSOPHERS; i++ ) |
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194 { |
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195 pstate[i] = 'T'; // starting state |
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196 new_thread(Philosopher, i); |
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197 |
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198 // make the matching chopstick present |
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199 chopstick[i].post(); |
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200 } |
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201 |
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202 Cyg_Scheduler::scheduler.start(); |
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203 } |
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204 |
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205 externC void |
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206 cyg_start( void ) |
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207 { |
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208 bin_sem2_main(); |
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209 } |
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210 // EOF bin_sem2.cxx |
