1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
|
/*
ChibiOS/RT - Copyright (C) 2006-2007 Giovanni Di Sirio.
This file is part of ChibiOS/RT.
ChibiOS/RT is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
ChibiOS/RT is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/**
* @addtogroup Scheduler
* @{
*/
#include <ch.h>
/** @cond never */
ReadyList rlist;
/** @endcond */
/**
* @brief Scheduler initialization.
* @note Internally invoked by the @p chSysInit().
*/
void chSchInit(void) {
queue_init(&rlist);
rlist.r_prio = NOPRIO;
#ifdef CH_USE_ROUNDROBIN
rlist.r_preempt = CH_TIME_QUANTUM;
#endif
}
/**
* @brief Inserts a thread in the Ready List.
*
* @param tp the Thread to be made ready
* @return The Thread pointer.
* @note The function must be called in the system mutex zone.
* @note The function does not reschedule, the @p chSchRescheduleS() should
* be called soon after.
* @note The function is not meant to be used in the user code directly.
*/
#ifdef CH_OPTIMIZE_SPEED
/* NOTE: it is inlined in this module only.*/
INLINE Thread *chSchReadyI(Thread *tp) {
#else
Thread *chSchReadyI(Thread *tp) {
#endif
Thread *cp;
tp->p_state = PRREADY;
cp = rlist.p_next;
while (cp->p_prio >= tp->p_prio)
cp = cp->p_next;
/* Insertion on p_prev.*/
tp->p_prev = (tp->p_next = cp)->p_prev;
tp->p_prev->p_next = cp->p_prev = tp;
return tp;
}
/**
* @brief Puts the current thread to sleep into the specified state.
* @details The next highest priority thread becomes running. The threads
* states are described into @p threads.h.
*
* @param newstate the new thread state
* @note The function must be called in the system mutex zone.
* @note The function is not meant to be used in the user code directly.
*/
void chSchGoSleepS(tstate_t newstate) {
Thread *otp;
(otp = currp)->p_state = newstate;
(currp = fifo_remove((void *)&rlist))->p_state = PRCURR;
#ifdef CH_USE_ROUNDROBIN
rlist.r_preempt = CH_TIME_QUANTUM;
#endif
#ifdef CH_USE_TRACE
chDbgTrace(otp, currp);
#endif
chSysSwitchI(otp, currp);
}
/*
* Timeout wakeup callback.
*/
static void wakeup(void *p) {
Thread *tp = (Thread *)p;
switch (tp->p_state) {
#ifdef CH_USE_SEMAPHORES
case PRWTSEM:
chSemFastSignalI(tp->p_wtsemp);
/* Falls into, intentional. */
#endif
case PRWTCOND:
case PRWTMTX:
/* States requiring dequeuing. */
dequeue(tp);
/* Falls into, intentional. */
default:
chSchReadyI(tp)->p_rdymsg = RDY_TIMEOUT;
}
}
/**
* @brief Puts the current thread to sleep into the specified state.
* @details The next highest priority thread becomes running. The thread put
* to sleep is awakened after the specified time has elapsed.
*
* @param newstate the new thread state
* @param time the number of ticks before the operation timeouts. the value
* zero (@p TIME_INFINITE) is allowed.
* @return The wakeup message.
* @retval RDY_TIMEOUT if a timeout occurs.
* @note The function must be called in the system mutex zone.
* @note The function is not meant to be used in the user code directly.
*/
msg_t chSchGoSleepTimeoutS(tstate_t newstate, systime_t time) {
if (TIME_INFINITE != time) {
VirtualTimer vt;
chVTSetI(&vt, time, wakeup, currp);
chSchGoSleepS(newstate);
if (chVTIsArmedI(&vt))
chVTResetI(&vt);
}
else
chSchGoSleepS(newstate);
return currp->p_rdymsg;
}
/**
* @brief Wakes up a thread.
* @details The thread is inserted into the ready list or immediately made
* running depending on its relative priority compared to the current thread.
*
* @param ntp the Thread to be made ready
* @param msg message to the awakened thread
* @note The function must be called in the system mutex zone.
* @note The function is not meant to be used in the user code directly.
* @note It is equivalent to a @p chSchReadyI() followed by a
* @p chSchRescheduleS() but much more efficient.
*/
void chSchWakeupS(Thread *ntp, msg_t msg) {
ntp->p_rdymsg = msg;
if (ntp->p_prio <= currp->p_prio)
/* the woken thread has equal or lower priority than the running thread */
chSchReadyI(ntp);
else {
/* the woken thread has higher priority than the running thread and thus
* preempts the currently running thread. */
Thread *otp = currp;
chSchReadyI(otp);
/* change the to-be-run thread to running state */
(currp = ntp)->p_state = PRCURR;
#ifdef CH_USE_ROUNDROBIN
rlist.r_preempt = CH_TIME_QUANTUM;
#endif
#ifdef CH_USE_TRACE
/* trace the context switch */
chDbgTrace(otp, ntp);
#endif
/* switch the thread context */
chSysSwitchI(otp, ntp);
}
}
/**
* @brief Switches to the first thread on the runnable queue.
*
* @note It is intended to be called if @p chSchRescRequiredI() evaluates to @p TRUE.
*/
void chSchDoRescheduleI(void) {
Thread *otp = currp;
/* pick the first thread from the ready queue and makes it current */
(currp = fifo_remove((void *)&rlist))->p_state = PRCURR;
chSchReadyI(otp);
#ifdef CH_USE_ROUNDROBIN
rlist.r_preempt = CH_TIME_QUANTUM;
#endif
#ifdef CH_USE_TRACE
chDbgTrace(otp, currp);
#endif
chSysSwitchI(otp, currp);
}
/**
* @brief Performs a reschedulation if a higher priority thread is runnable.
* @details If a thread with a higher priority than the current thread is in
* the ready list then make the higher priority thread running.
*
* @note The function must be called in the system mutex zone.
*/
void chSchRescheduleS(void) {
/* first thread in the runnable queue has higher priority than the running
* thread? */
if (firstprio(&rlist) > currp->p_prio)
chSchDoRescheduleI();
}
/**
* @brief Evaluates if a reschedulation is required.
*
* @retval TRUE if there is a thread that should go in running state.
* @retval FALSE if a reschedulation is not required.
*/
bool_t chSchRescRequiredI(void) {
tprio_t p1 = firstprio(&rlist);
tprio_t p2 = currp->p_prio;
#ifdef CH_USE_ROUNDROBIN
/* If the running thread has not reached its time quantum, reschedule only
* if the first thread on the ready queue has a higher priority.
* Otherwise, if the running thread has used up its time quantum, reschedule
* if the first thread on the ready queue has equal or higher priority.
*/
return rlist.r_preempt ? p1 > p2 : p1 >= p2;
#else
return p1 > p2;
#endif
}
/** @} */
|
