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1 #ifndef CYGONCE_KERNEL_SCHED_HXX |
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2 #define CYGONCE_KERNEL_SCHED_HXX |
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3 |
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4 //========================================================================== |
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5 // |
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6 // sched.hxx |
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7 // |
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8 // Scheduler class declaration(s) |
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9 // |
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10 //========================================================================== |
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11 //####COPYRIGHTBEGIN#### |
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12 // |
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13 // ------------------------------------------- |
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14 // The contents of this file are subject to the Cygnus eCos Public License |
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15 // Version 1.0 (the "License"); you may not use this file except in |
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16 // compliance with the License. You may obtain a copy of the License at |
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17 // http://sourceware.cygnus.com/ecos |
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18 // |
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19 // Software distributed under the License is distributed on an "AS IS" |
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20 // basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the |
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21 // License for the specific language governing rights and limitations under |
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22 // the License. |
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23 // |
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24 // The Original Code is eCos - Embedded Cygnus Operating System, released |
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25 // September 30, 1998. |
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26 // |
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27 // The Initial Developer of the Original Code is Cygnus. Portions created |
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28 // by Cygnus are Copyright (C) 1998 Cygnus Solutions. All Rights Reserved. |
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29 // ------------------------------------------- |
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30 // |
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31 //####COPYRIGHTEND#### |
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32 //========================================================================== |
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33 //#####DESCRIPTIONBEGIN#### |
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34 // |
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35 // Author(s): nickg |
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36 // Contributors: nickg |
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37 // Date: 1997-09-09 |
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38 // Purpose: Define Scheduler class interfaces |
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39 // Description: These class definitions supply the internal API |
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40 // used to scheduler threads. |
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41 // Usage: #include <cyg/kernel/sched.hxx> |
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42 // |
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43 //####DESCRIPTIONEND#### |
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44 // |
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45 //========================================================================== |
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46 |
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47 #include <cyg/kernel/ktypes.h> |
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48 #include <cyg/infra/cyg_ass.h> // assertion macros |
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49 |
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50 // ------------------------------------------------------------------------- |
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51 // Scheduler base class. This defines stuff that is needed by the |
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52 // specific scheduler implementation. Each scheduler comprises three |
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53 // classes: Cyg_Scheduler_Base, Cyg_Scheduler_Implementation which |
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54 // inherits from it and Cyg_Scheduler which inherits from _it_ in turn. |
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55 |
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56 class Cyg_Scheduler_Base |
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57 { |
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58 friend class Cyg_HardwareThread; |
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59 friend class Cyg_SchedThread; |
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60 |
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61 protected: |
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62 // The following variables are implicit in the API, but are |
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63 // not publically visible. |
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64 |
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65 static volatile cyg_ucount32 sched_lock; // lock counter |
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66 |
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67 static Cyg_Thread *current_thread; // current running thread |
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68 |
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69 static cyg_bool need_reschedule; // set when schedule needed |
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70 |
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71 static cyg_ucount32 thread_switches; // count of number of thread switches |
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72 }; |
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73 |
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74 // ------------------------------------------------------------------------- |
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75 // Include the scheduler implementation header |
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76 |
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77 #include CYGPRI_KERNEL_SCHED_IMPL_HXX |
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78 |
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79 // Do some checking that we have a consistent universe. |
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80 |
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81 #ifdef CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INHERITANCE |
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82 # ifndef CYGIMP_THREAD_PRIORITY |
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83 # error Priority inheritance will not work without priorities!!! |
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84 # endif |
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85 # if CYG_SCHED_UNIQUE_PRIORITIES |
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86 # error Priority inheritance needs non-unique priorities!!! |
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87 # endif |
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88 #endif |
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89 |
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90 // ------------------------------------------------------------------------- |
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91 // Scheduler class. This is the public scheduler interface seen by the |
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92 // rest of the kernel. |
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93 |
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94 class Cyg_Scheduler |
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95 : public Cyg_Scheduler_Implementation |
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96 { |
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97 friend class Cyg_Thread; |
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98 |
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99 // This function is the actual implementation of the unlock |
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100 // function. The unlock() later is an inline shell that deals |
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101 // with the common case. |
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102 |
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103 static void unlock_inner(); |
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104 |
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105 public: |
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106 |
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107 CYGDBG_DEFINE_CHECK_THIS |
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108 |
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109 // The following API functions are common to all scheduler |
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110 // implementations. |
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111 |
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112 // claim the preemption lock |
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113 static void lock(); |
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114 |
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115 // release the preemption lock |
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116 static void unlock(); |
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117 |
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118 // return a pointer to the current thread |
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119 static Cyg_Thread *get_current_thread(); |
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120 |
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121 // Return current value of lock |
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122 static cyg_ucount32 get_sched_lock(); |
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123 |
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124 // Return current number of thread switches |
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125 static cyg_ucount32 get_thread_switches(); |
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126 |
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127 // Start execution of the scheduler |
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128 static void start() __attribute__ ((noreturn)); |
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129 |
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130 // The only scheduler instance should be this one... |
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131 static Cyg_Scheduler scheduler; |
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132 |
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133 }; |
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134 |
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135 // ------------------------------------------------------------------------- |
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136 // This class encapsulates the scheduling abstractions in a thread. |
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137 // Cyg_SchedThread is included as a base class of Cyg_Thread. The actual |
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138 // implementation of the abstractions is in Cyg_SchedThread_Implementation |
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139 // so this class has little to do. |
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140 |
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141 class Cyg_SchedThread |
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142 : public Cyg_SchedThread_Implementation |
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143 { |
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144 friend class Cyg_ThreadQueue_Implementation; |
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145 friend class Cyg_Scheduler_Implementation; |
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146 |
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147 Cyg_ThreadQueue *queue; |
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148 |
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149 |
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150 public: |
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151 |
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152 Cyg_SchedThread(Cyg_Thread *thread, CYG_ADDRWORD sched_info); |
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153 |
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154 // Return current queue pointer |
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155 |
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156 Cyg_ThreadQueue *get_current_queue(); |
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157 |
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158 // Remove this thread from current queue |
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159 void remove(); |
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160 |
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161 #ifdef CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INHERITANCE |
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162 |
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163 private: |
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164 |
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165 // For all priority inheritance mechanisms we need to |
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166 // keep track of how many mutexes we have locked. |
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167 cyg_count32 mutex_count; |
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168 |
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169 public: |
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170 // Count and uncount the number of mutexes held by |
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171 // this thread. |
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172 void count_mutex() { mutex_count++; }; |
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173 void uncount_mutex() { mutex_count--; }; |
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174 |
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175 protected: |
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176 #ifdef CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INHERITANCE_SIMPLE |
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177 |
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178 // The simple priority inheritance mechanism simply needs |
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179 // somewhere to store the base priority of the current thread. |
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180 |
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181 cyg_priority original_priority; // our original priority |
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182 |
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183 cyg_bool priority_inherited; // have we inherited? |
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184 |
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185 #endif |
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186 |
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187 public: |
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188 |
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189 // Inherit the priority of the provided thread if it |
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190 // has higher priority than this. |
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191 void inherit_priority( Cyg_Thread *thread); |
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192 |
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193 // Lose priority inheritance |
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194 void disinherit_priority(); |
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195 |
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196 #endif |
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197 |
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198 }; |
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199 |
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200 // ------------------------------------------------------------------------- |
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201 // Simple inline accessor functions |
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202 |
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203 inline Cyg_Thread *Cyg_Scheduler::get_current_thread() |
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204 { |
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205 return current_thread; |
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206 } |
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207 |
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208 // Return current value of lock |
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209 inline cyg_ucount32 Cyg_Scheduler::get_sched_lock() |
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210 { |
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211 return sched_lock; |
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212 } |
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213 |
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214 // Return current number of thread switches |
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215 inline cyg_ucount32 Cyg_Scheduler::get_thread_switches() |
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216 { |
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217 return thread_switches; |
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218 } |
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219 |
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220 // Return current queue pointer |
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221 inline Cyg_ThreadQueue *Cyg_SchedThread::get_current_queue() |
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222 { |
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223 return queue; |
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224 } |
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225 |
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226 // ------------------------------------------------------------------------- |
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227 #endif // ifndef __SCHED_HXX__ |
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228 // EOF sched.hxx |
