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Initial commit of eCos version 1.1
author jlarmour
date Tue, 11 May 1999 11:16:07 +0000
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children 443894e2e912
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-1:000000000000 0:3111d98ba7b3
1 #ifndef CYGONCE_KERNEL_MLQUEUE_HXX
2 #define CYGONCE_KERNEL_MLQUEUE_HXX
3
4 //==========================================================================
5 //
6 // mlqueue.hxx
7 //
8 // Multi-Level Queue scheduler class declarations
9 //
10 //==========================================================================
11 //####COPYRIGHTBEGIN####
12 //
13 // -------------------------------------------
14 // The contents of this file are subject to the Cygnus eCos Public License
15 // Version 1.0 (the "License"); you may not use this file except in
16 // compliance with the License. You may obtain a copy of the License at
17 // http://sourceware.cygnus.com/ecos
18 //
19 // Software distributed under the License is distributed on an "AS IS"
20 // basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
21 // License for the specific language governing rights and limitations under
22 // the License.
23 //
24 // The Original Code is eCos - Embedded Cygnus Operating System, released
25 // September 30, 1998.
26 //
27 // The Initial Developer of the Original Code is Cygnus. Portions created
28 // by Cygnus are Copyright (C) 1998 Cygnus Solutions. All Rights Reserved.
29 // -------------------------------------------
30 //
31 //####COPYRIGHTEND####
32 //==========================================================================
33 //#####DESCRIPTIONBEGIN####
34 //
35 // Author(s): nickg
36 // Contributors: nickg
37 // Date: 1997-09-10
38 // Purpose: Define multilevel queue scheduler implementation
39 // Description: The classes defined here are used as base classes
40 // by the common classes that define schedulers and thread
41 // things. The MLQ scheduler in various configurations
42 // provides standard FIFO, round-robin and single priority
43 // schedulers.
44 // Usage: Included according to configuration by
45 // <cyg/kernel/sched.hxx>
46 //
47 //####DESCRIPTIONEND####
48 //
49 //==========================================================================
50
51 #include <cyg/kernel/ktypes.h>
52
53 // -------------------------------------------------------------------------
54 // The macro CYGNUM_KERNEL_SCHED_PRIORITIES contains the number of priorities
55 // supported by the scheduler.
56
57 #ifndef CYGNUM_KERNEL_SCHED_PRIORITIES
58 #define CYGNUM_KERNEL_SCHED_PRIORITIES 32 // define a default
59 #endif
60
61 // set bitmap size
62 #define CYGNUM_KERNEL_SCHED_BITMAP_SIZE CYGNUM_KERNEL_SCHED_PRIORITIES
63
64 // -------------------------------------------------------------------------
65 // The macro CYGNUM_KERNEL_SCHED_BITMAP_SIZE contains the number of bits that the
66 // scheduler bitmap should contain. It is derived from the number of prioirity
67 // levels defined by the configuration.
68
69 #if CYGNUM_KERNEL_SCHED_BITMAP_SIZE <= 8
70 typedef cyg_ucount8 cyg_sched_bitmap;
71 #elif CYGNUM_KERNEL_SCHED_BITMAP_SIZE <= 16
72 typedef cyg_ucount16 cyg_sched_bitmap;
73 #elif CYGNUM_KERNEL_SCHED_BITMAP_SIZE <= 32
74 typedef cyg_ucount32 cyg_sched_bitmap;
75 #else
76 #error Bitmaps greater than 32 bits not currently allowed
77 #endif
78
79 // -------------------------------------------------------------------------
80 // Customize the scheduler
81
82 #define CYGIMP_THREAD_PRIORITY 1 // Threads have changable priorities
83 #define CYG_SCHED_UNIQUE_PRIORITIES 0 // Threads don't have unique priorities
84
85 #define CYG_THREAD_MIN_PRIORITY (CYGNUM_KERNEL_SCHED_PRIORITIES-1)
86 #define CYG_THREAD_MAX_PRIORITY 0
87
88 // set default scheduling info value for thread constructors.
89 #define CYG_SCHED_DEFAULT_INFO CYG_THREAD_MAX_PRIORITY
90
91 // -------------------------------------------------------------------------
92 // Thread queue implementation.
93 // This class provides the (scheduler specific) implementation of the
94 // thread queue class.
95
96 class Cyg_ThreadQueue_Implementation
97 {
98 friend class Cyg_Scheduler_Implementation;
99 friend class Cyg_SchedThread_Implementation;
100
101 Cyg_Thread *queue;
102
103 protected:
104
105 // API used by Cyg_ThreadQueue
106
107 Cyg_ThreadQueue_Implementation(); // Constructor
108
109 // Add thread to queue
110 void enqueue(Cyg_Thread *thread);
111
112 // return first thread on queue
113 Cyg_Thread *highpri();
114
115 // remove first thread on queue
116 Cyg_Thread *dequeue();
117
118 // remove specified thread from queue
119 void remove(Cyg_Thread *thread);
120
121 // test if queue is empty
122 cyg_bool empty();
123
124 void rotate(); // Rotate the queue
125 };
126
127 inline cyg_bool Cyg_ThreadQueue_Implementation::empty()
128 {
129 return queue == NULL;
130 }
131
132 // -------------------------------------------------------------------------
133 // This class contains the implementation details of the scheduler, and
134 // provides a standard API for accessing it.
135
136 class Cyg_Scheduler_Implementation
137 : public Cyg_Scheduler_Base
138 {
139 friend class Cyg_ThreadQueue_Implementation;
140 friend class Cyg_SchedThread_Implementation;
141 friend class Cyg_HardwareThread;
142
143 // Mask of which run queues have ready threads
144 cyg_sched_bitmap queue_map;
145
146 // Each run queue is a double linked circular list of threads.
147 // These pointers point to the head element of each list.
148 Cyg_ThreadQueue_Implementation run_queue[CYGNUM_KERNEL_SCHED_PRIORITIES];
149
150 protected:
151
152 #ifdef CYGSEM_KERNEL_SCHED_TIMESLICE
153
154 // Timeslice counter. This is decremented on each
155 // clock tick, and a timeslice is performed each
156 // time it zeroes.
157
158 static cyg_ucount32 timeslice_count;
159
160 static void reset_timeslice_count();
161
162 #endif
163
164 Cyg_Scheduler_Implementation(); // Constructor
165
166 // The following functions provide the scheduler implementation
167 // interface to the Cyg_Scheduler class. These are protected
168 // so that only the scheduler can call them.
169
170 // choose a new thread
171 Cyg_Thread *schedule();
172
173 // make thread schedulable
174 void add_thread(Cyg_Thread *thread);
175
176 // make thread un-schedulable
177 void rem_thread(Cyg_Thread *thread);
178
179 // register thread with scheduler
180 void register_thread(Cyg_Thread *thread);
181
182 // deregister thread
183 void deregister_thread(Cyg_Thread *thread);
184
185 // Test the given priority for uniqueness
186 cyg_bool unique( cyg_priority priority);
187
188 #ifdef CYGSEM_KERNEL_SCHED_TIMESLICE
189
190 // If timeslicing is enbled, define a scheduler
191 // entry point to do timeslicing. This will be
192 // called from the RTC DSR.
193 public:
194 void timeslice();
195
196 #endif
197
198 };
199
200 // -------------------------------------------------------------------------
201 // Cyg_Scheduler_Implementation inlines
202
203 #ifdef CYGSEM_KERNEL_SCHED_TIMESLICE
204
205 inline void Cyg_Scheduler_Implementation::reset_timeslice_count()
206 {
207 timeslice_count = CYGNUM_KERNEL_SCHED_TIMESLICE_TICKS;
208 }
209
210 #endif
211
212 // -------------------------------------------------------------------------
213 // Scheduler thread implementation.
214 // This class provides the implementation of the scheduler specific parts
215 // of each thread.
216
217 class Cyg_SchedThread_Implementation
218 {
219 friend class Cyg_Scheduler_Implementation;
220 friend class Cyg_ThreadQueue_Implementation;
221
222 Cyg_Thread *next; // next thread in queue
223 Cyg_Thread *prev; // previous thread in queue
224
225 void insert( Cyg_Thread *thread ); // Insert thread in front of this
226
227 void remove(); // remove this from queue
228
229 protected:
230
231 cyg_priority priority; // current thread priority
232
233 Cyg_SchedThread_Implementation(CYG_ADDRWORD sched_info);
234
235 void yield(); // Yield CPU to next thread
236
237 static void rotate_queue( cyg_priority pri );
238 // Rotate that run queue
239 };
240
241 // -------------------------------------------------------------------------
242 #endif // ifndef CYGONCE_KERNEL_MLQUEUE_HXX
243 // EOF mlqueue.hxx