1 | /* |
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2 | * COPYRIGHT (c) 1989-2009. |
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3 | * On-Line Applications Research Corporation (OAR). |
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4 | * |
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5 | * The license and distribution terms for this file may be |
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6 | * found in the file LICENSE in this distribution or at |
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7 | * http://www.rtems.org/license/LICENSE. |
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8 | */ |
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9 | |
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10 | #ifdef HAVE_CONFIG_H |
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11 | #include "config.h" |
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12 | #endif |
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13 | |
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14 | #include <tmacros.h> |
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15 | #include <intrcritical.h> |
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16 | |
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17 | #define INTERRUPT_CRITICAL_NAME rtems_build_name( 'I', 'C', 'R', 'I' ) |
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18 | |
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19 | typedef struct { |
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20 | rtems_interval minimum; |
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21 | rtems_interval maximum; |
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22 | rtems_interval maximum_current; |
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23 | rtems_timer_service_routine_entry tsr; |
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24 | rtems_id timer; |
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25 | uint64_t t0; |
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26 | uint64_t t1; |
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27 | } interrupt_critical_control; |
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28 | |
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29 | static interrupt_critical_control interrupt_critical; |
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30 | |
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31 | static rtems_interval estimate_busy_loop_maximum( void ) |
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32 | { |
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33 | rtems_interval units = 0; |
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34 | rtems_interval initial = rtems_clock_get_ticks_since_boot(); |
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35 | |
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36 | while ( initial == rtems_clock_get_ticks_since_boot() ) { |
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37 | ++units; |
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38 | } |
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39 | |
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40 | return units; |
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41 | } |
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42 | |
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43 | static rtems_interval wait_for_tick_change( void ) |
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44 | { |
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45 | rtems_interval initial = rtems_clock_get_ticks_since_boot(); |
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46 | rtems_interval now; |
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47 | |
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48 | do { |
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49 | now = rtems_clock_get_ticks_since_boot(); |
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50 | } while ( now == initial ); |
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51 | |
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52 | return now; |
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53 | } |
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54 | |
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55 | /* |
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56 | * It is important that we use actually use the same busy() function at the |
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57 | * various places, since otherwise the obtained maximum value might be wrong. |
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58 | * So the compiler must not inline this function. |
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59 | */ |
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60 | static __attribute__( ( noinline ) ) void busy( rtems_interval max ) |
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61 | { |
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62 | rtems_interval i = 0; |
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63 | |
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64 | do { |
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65 | __asm__ volatile (""); |
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66 | ++i; |
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67 | } while ( i < max ); |
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68 | } |
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69 | |
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70 | static bool interrupt_critical_busy_wait( void ) |
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71 | { |
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72 | rtems_interval max = interrupt_critical.maximum_current; |
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73 | bool reset = max <= interrupt_critical.minimum; |
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74 | |
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75 | if ( reset ) { |
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76 | interrupt_critical.maximum_current = interrupt_critical.maximum; |
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77 | } else { |
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78 | interrupt_critical.maximum_current = max - 1; |
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79 | } |
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80 | |
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81 | busy( max ); |
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82 | |
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83 | return reset; |
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84 | } |
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85 | |
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86 | void interrupt_critical_section_test_support_initialize( |
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87 | rtems_timer_service_routine_entry tsr |
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88 | ) |
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89 | { |
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90 | rtems_interval last; |
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91 | rtems_interval now; |
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92 | rtems_interval a; |
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93 | rtems_interval b; |
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94 | rtems_interval m; |
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95 | |
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96 | interrupt_critical.tsr = tsr; |
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97 | |
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98 | if ( tsr != NULL && interrupt_critical.timer == 0 ) { |
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99 | rtems_status_code sc = rtems_timer_create( |
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100 | INTERRUPT_CRITICAL_NAME, |
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101 | &interrupt_critical.timer |
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102 | ); |
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103 | rtems_test_assert( sc == RTEMS_SUCCESSFUL ); |
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104 | } |
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105 | |
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106 | /* Choose a lower bound */ |
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107 | a = 1; |
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108 | |
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109 | /* Estimate an upper bound */ |
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110 | |
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111 | wait_for_tick_change(); |
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112 | b = 2 * estimate_busy_loop_maximum(); |
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113 | |
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114 | while ( true ) { |
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115 | last = wait_for_tick_change(); |
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116 | busy( b ); |
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117 | now = rtems_clock_get_ticks_since_boot(); |
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118 | |
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119 | if ( now != last ) { |
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120 | break; |
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121 | } |
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122 | |
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123 | b *= 2; |
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124 | last = now; |
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125 | } |
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126 | |
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127 | /* Find a good value */ |
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128 | do { |
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129 | m = ( a + b ) / 2; |
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130 | |
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131 | last = wait_for_tick_change(); |
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132 | busy( m ); |
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133 | now = rtems_clock_get_ticks_since_boot(); |
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134 | |
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135 | if ( now != last ) { |
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136 | b = m; |
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137 | } else { |
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138 | a = m; |
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139 | } |
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140 | } while ( b - a > 1 ); |
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141 | |
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142 | interrupt_critical.minimum = 0; |
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143 | interrupt_critical.maximum = m; |
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144 | interrupt_critical.maximum_current = m; |
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145 | } |
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146 | |
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147 | static void timer_fire_after(void) |
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148 | { |
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149 | if ( interrupt_critical.tsr != NULL ) { |
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150 | rtems_status_code sc = rtems_timer_fire_after( |
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151 | interrupt_critical.timer, |
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152 | 1, |
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153 | interrupt_critical.tsr, |
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154 | NULL |
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155 | ); |
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156 | rtems_test_assert( sc == RTEMS_SUCCESSFUL ); |
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157 | } |
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158 | } |
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159 | |
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160 | bool interrupt_critical_section_test_support_delay(void) |
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161 | { |
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162 | timer_fire_after(); |
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163 | |
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164 | return interrupt_critical_busy_wait(); |
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165 | } |
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166 | |
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167 | static bool is_idle( const Thread_Control *thread ) |
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168 | { |
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169 | return thread->Start.entry_point |
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170 | == (Thread_Entry) rtems_configuration_get_idle_task(); |
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171 | } |
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172 | |
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173 | static void thread_switch( Thread_Control *executing, Thread_Control *heir ) |
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174 | { |
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175 | (void) executing; |
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176 | (void) heir; |
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177 | |
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178 | if ( interrupt_critical.t1 == 0 && is_idle( heir ) ) { |
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179 | interrupt_critical.t1 = rtems_clock_get_uptime_nanoseconds(); |
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180 | } |
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181 | } |
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182 | |
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183 | static const rtems_extensions_table extensions = { |
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184 | .thread_switch = thread_switch |
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185 | }; |
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186 | |
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187 | bool interrupt_critical_section_test( |
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188 | bool ( *test_body )( void * ), |
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189 | void *test_body_arg, |
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190 | rtems_timer_service_routine_entry tsr |
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191 | ) |
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192 | { |
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193 | bool done; |
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194 | rtems_status_code sc; |
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195 | rtems_id id; |
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196 | uint64_t delta; |
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197 | rtems_interval busy_delta; |
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198 | int retries = 3; |
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199 | |
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200 | interrupt_critical_section_test_support_initialize( tsr ); |
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201 | |
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202 | sc = rtems_extension_create( |
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203 | INTERRUPT_CRITICAL_NAME, |
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204 | &extensions, |
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205 | &id |
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206 | ); |
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207 | rtems_test_assert( sc == RTEMS_SUCCESSFUL ); |
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208 | |
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209 | wait_for_tick_change(); |
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210 | timer_fire_after(); |
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211 | |
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212 | /* Get estimate for test body duration */ |
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213 | interrupt_critical.t0 = rtems_clock_get_uptime_nanoseconds(); |
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214 | done = ( *test_body )( test_body_arg ); |
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215 | if ( interrupt_critical.t1 == 0 ) { |
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216 | interrupt_critical.t1 = rtems_clock_get_uptime_nanoseconds(); |
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217 | } |
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218 | |
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219 | /* Update minimum */ |
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220 | |
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221 | delta = interrupt_critical.t1 - interrupt_critical.t0; |
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222 | busy_delta = (rtems_interval) |
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223 | ( ( interrupt_critical.maximum * ( 2 * delta ) ) |
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224 | / rtems_configuration_get_nanoseconds_per_tick() ); |
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225 | |
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226 | if ( busy_delta < interrupt_critical.maximum ) { |
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227 | interrupt_critical.minimum = interrupt_critical.maximum - busy_delta; |
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228 | } |
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229 | |
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230 | sc = rtems_extension_delete( id ); |
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231 | rtems_test_assert( sc == RTEMS_SUCCESSFUL ); |
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232 | |
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233 | while ( !done && retries >= 0 ) { |
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234 | wait_for_tick_change(); |
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235 | |
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236 | if ( interrupt_critical_section_test_support_delay() ) { |
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237 | --retries; |
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238 | } |
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239 | |
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240 | done = ( *test_body )( test_body_arg ); |
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241 | } |
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242 | |
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243 | return done; |
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244 | } |
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