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1 #ifndef CYGONCE_KERNEL_MLQUEUE_HXX |
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2 #define CYGONCE_KERNEL_MLQUEUE_HXX |
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3 |
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4 //========================================================================== |
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5 // |
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6 // mlqueue.hxx |
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7 // |
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8 // Multi-Level Queue scheduler class declarations |
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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) 1998,1999 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: 1997-09-10 |
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38 // Purpose: Define multilevel queue scheduler implementation |
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39 // Description: The classes defined here are used as base classes |
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40 // by the common classes that define schedulers and thread |
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41 // things. The MLQ scheduler in various configurations |
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42 // provides standard FIFO, round-robin and single priority |
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43 // schedulers. |
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44 // Usage: Included according to configuration by |
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45 // <cyg/kernel/sched.hxx> |
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46 // |
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47 //####DESCRIPTIONEND#### |
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48 // |
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49 //========================================================================== |
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50 |
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51 #include <cyg/kernel/ktypes.h> |
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52 |
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53 // ------------------------------------------------------------------------- |
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54 // The macro CYGNUM_KERNEL_SCHED_PRIORITIES contains the number of priorities |
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55 // supported by the scheduler. |
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56 |
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57 #ifndef CYGNUM_KERNEL_SCHED_PRIORITIES |
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58 #define CYGNUM_KERNEL_SCHED_PRIORITIES 32 // define a default |
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59 #endif |
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60 |
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61 // set bitmap size |
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62 #define CYGNUM_KERNEL_SCHED_BITMAP_SIZE CYGNUM_KERNEL_SCHED_PRIORITIES |
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63 |
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64 // ------------------------------------------------------------------------- |
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65 // The macro CYGNUM_KERNEL_SCHED_BITMAP_SIZE contains the number of bits that the |
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66 // scheduler bitmap should contain. It is derived from the number of prioirity |
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67 // levels defined by the configuration. |
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68 |
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69 #if CYGNUM_KERNEL_SCHED_BITMAP_SIZE <= 8 |
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70 typedef cyg_ucount8 cyg_sched_bitmap; |
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71 #elif CYGNUM_KERNEL_SCHED_BITMAP_SIZE <= 16 |
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72 typedef cyg_ucount16 cyg_sched_bitmap; |
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73 #elif CYGNUM_KERNEL_SCHED_BITMAP_SIZE <= 32 |
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74 typedef cyg_ucount32 cyg_sched_bitmap; |
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75 #else |
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76 #error Bitmaps greater than 32 bits not currently allowed |
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77 #endif |
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78 |
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79 // ------------------------------------------------------------------------- |
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80 // Customize the scheduler |
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81 |
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82 #define CYGIMP_THREAD_PRIORITY 1 // Threads have changable priorities |
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83 #define CYG_SCHED_UNIQUE_PRIORITIES 0 // Threads don't have unique priorities |
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84 |
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85 #define CYG_THREAD_MIN_PRIORITY (CYGNUM_KERNEL_SCHED_PRIORITIES-1) |
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86 #define CYG_THREAD_MAX_PRIORITY 0 |
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87 |
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88 // set default scheduling info value for thread constructors. |
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89 #define CYG_SCHED_DEFAULT_INFO CYG_THREAD_MAX_PRIORITY |
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90 |
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91 // ------------------------------------------------------------------------- |
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92 // Thread queue implementation. |
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93 // This class provides the (scheduler specific) implementation of the |
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94 // thread queue class. |
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95 |
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96 class Cyg_ThreadQueue_Implementation |
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97 { |
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98 friend class Cyg_Scheduler_Implementation; |
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99 friend class Cyg_SchedThread_Implementation; |
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100 |
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101 Cyg_Thread *queue; |
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102 |
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103 protected: |
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104 |
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105 // API used by Cyg_ThreadQueue |
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106 |
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107 Cyg_ThreadQueue_Implementation(); // Constructor |
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108 |
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109 // Add thread to queue |
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110 void enqueue(Cyg_Thread *thread); |
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111 |
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112 // return first thread on queue |
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113 Cyg_Thread *highpri(); |
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114 |
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115 // remove first thread on queue |
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116 Cyg_Thread *dequeue(); |
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117 |
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118 // remove specified thread from queue |
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119 void remove(Cyg_Thread *thread); |
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120 |
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121 // test if queue is empty |
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122 cyg_bool empty(); |
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123 |
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124 void rotate(); // Rotate the queue |
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125 |
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126 void to_head(Cyg_Thread *thread); |
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127 |
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128 }; |
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129 |
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130 inline cyg_bool Cyg_ThreadQueue_Implementation::empty() |
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131 { |
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132 return queue == NULL; |
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133 } |
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134 |
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135 // ------------------------------------------------------------------------- |
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136 // This class contains the implementation details of the scheduler, and |
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137 // provides a standard API for accessing it. |
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138 |
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139 class Cyg_Scheduler_Implementation |
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140 : public Cyg_Scheduler_Base |
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141 { |
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142 friend class Cyg_ThreadQueue_Implementation; |
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143 friend class Cyg_SchedThread_Implementation; |
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144 friend class Cyg_HardwareThread; |
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145 |
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146 // Mask of which run queues have ready threads |
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147 cyg_sched_bitmap queue_map; |
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148 |
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149 // Each run queue is a double linked circular list of threads. |
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150 // These pointers point to the head element of each list. |
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151 Cyg_ThreadQueue_Implementation run_queue[CYGNUM_KERNEL_SCHED_PRIORITIES]; |
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152 |
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153 protected: |
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154 |
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155 #ifdef CYGSEM_KERNEL_SCHED_TIMESLICE |
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156 |
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157 // Timeslice counter. This is decremented on each |
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158 // clock tick, and a timeslice is performed each |
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159 // time it zeroes. |
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160 |
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161 static cyg_ucount32 timeslice_count; |
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162 |
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163 static void reset_timeslice_count(); |
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164 |
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165 #endif |
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166 |
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167 Cyg_Scheduler_Implementation(); // Constructor |
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168 |
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169 // The following functions provide the scheduler implementation |
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170 // interface to the Cyg_Scheduler class. These are protected |
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171 // so that only the scheduler can call them. |
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172 |
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173 // choose a new thread |
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174 Cyg_Thread *schedule(); |
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175 |
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176 // make thread schedulable |
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177 void add_thread(Cyg_Thread *thread); |
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178 |
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179 // make thread un-schedulable |
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180 void rem_thread(Cyg_Thread *thread); |
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181 |
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182 // register thread with scheduler |
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183 void register_thread(Cyg_Thread *thread); |
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184 |
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185 // deregister thread |
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186 void deregister_thread(Cyg_Thread *thread); |
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187 |
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188 // Test the given priority for uniqueness |
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189 cyg_bool unique( cyg_priority priority); |
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190 |
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191 #ifdef CYGSEM_KERNEL_SCHED_TIMESLICE |
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192 |
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193 // If timeslicing is enbled, define a scheduler |
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194 // entry point to do timeslicing. This will be |
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195 // called from the RTC DSR. |
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196 public: |
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197 void timeslice(); |
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198 |
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199 #endif |
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200 |
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201 }; |
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202 |
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203 // ------------------------------------------------------------------------- |
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204 // Cyg_Scheduler_Implementation inlines |
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205 |
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206 #ifdef CYGSEM_KERNEL_SCHED_TIMESLICE |
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207 |
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208 inline void Cyg_Scheduler_Implementation::reset_timeslice_count() |
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209 { |
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210 timeslice_count = CYGNUM_KERNEL_SCHED_TIMESLICE_TICKS; |
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211 } |
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212 |
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213 #endif |
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214 |
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215 // ------------------------------------------------------------------------- |
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216 // Scheduler thread implementation. |
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217 // This class provides the implementation of the scheduler specific parts |
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218 // of each thread. |
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219 |
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220 class Cyg_SchedThread_Implementation |
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221 { |
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222 friend class Cyg_Scheduler_Implementation; |
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223 friend class Cyg_ThreadQueue_Implementation; |
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224 |
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225 Cyg_Thread *next; // next thread in queue |
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226 Cyg_Thread *prev; // previous thread in queue |
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227 |
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228 void insert( Cyg_Thread *thread ); // Insert thread in front of this |
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229 |
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230 void remove(); // remove this from queue |
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231 |
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232 protected: |
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233 |
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234 cyg_priority priority; // current thread priority |
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235 |
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236 Cyg_SchedThread_Implementation(CYG_ADDRWORD sched_info); |
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237 |
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238 void yield(); // Yield CPU to next thread |
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239 |
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240 static void rotate_queue( cyg_priority pri ); |
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241 // Rotate that run queue |
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242 |
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243 void to_queue_head( void ); // Move this thread to the head |
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244 // of its queue (not necessarily |
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245 // a scheduler queue) |
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246 }; |
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247 |
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248 // ------------------------------------------------------------------------- |
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249 #endif // ifndef CYGONCE_KERNEL_MLQUEUE_HXX |
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250 // EOF mlqueue.hxx |
