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
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
|
/*
ChibiOS/GFX - Copyright (C) 2012
Joel Bodenmann aka Tectu <joel@unormal.org>
This file is part of ChibiOS/GFX.
ChibiOS/GFX 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/GFX 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/>.
*/
/**
* @file src/gevent.c
* @brief GEVENT Driver code.
*
* @addtogroup GEVENT
* @{
*/
#include "ch.h"
#include "hal.h"
#include "gevent.h"
#if GFX_USE_GEVENT || defined(__DOXYGEN__)
#if GEVENT_ASSERT_NO_RESOURCE
#define GEVENT_ASSERT(x) assert(x)
#else
#define GEVENT_ASSERT(x)
#endif
/* This mutex protects access to our tables */
static MUTEX_DECL(geventMutex);
/* Our table of listener/source pairs */
static GSourceListener Assignments[MAX_SOURCE_LISTENERS];
/* Loop through the assignment table deleting this listener/source pair. */
/* Null is treated as a wildcard. */
static void deleteAssignments(GListener *pl, GSourceHandle gsh) {
GSourceListener *psl;
for(psl = Assignments; psl < Assignments+MAX_SOURCE_LISTENERS; psl++) {
if ((!pl || psl->pListener == pl) && (!gsh || psl->pSource == gsh)) {
if (chSemGetCounterI(&psl->pListener->waitqueue) < 0) {
chBSemWait(&psl->pListener->eventlock); // Obtain the buffer lock
psl->pListener->event.type = GEVENT_EXIT; // Set up the EXIT event
chSemSignal(&psl->pListener->waitqueue); // Wake up the listener
chBSemSignal(&psl->pListener->eventlock); // Release the buffer lock
}
psl->pListener = 0;
}
}
}
/**
* @brief Create a Listener
* @details If insufficient resources are available it will either assert or return NULL
* depending on the value of GEVENT_ASSERT_NO_RESOURCE.
*
* @param[in] pl A listener
*/
void geventListenerInit(GListener *pl) {
chSemInit(&pl->waitqueue, 0); // Next wait'er will block
chBSemInit(&pl->eventlock, FALSE); // Only one thread at a time looking at the event buffer
pl->callback = 0; // No callback active
pl->event.type = GEVENT_NULL; // Always safety
}
/**
* @brief Attach a source to a listener
* @details Flags are interpreted by the source when generating events for each listener.
* If this source is already assigned to the listener it will update the flags.
* If insufficient resources are available it will either assert or return FALSE
* depending on the value of GEVENT_ASSERT_NO_RESOURCE.
*
* @param[in] pl The listener
* @param[in] gsh The source which has to be attached to the listener
* @param[in] flags The flags
*
* @return TRUE if succeeded, FALSE otherwise
*/
bool_t geventAttachSource(GListener *pl, GSourceHandle gsh, unsigned flags) {
GSourceListener *psl, *pslfree;
// Safety first
if (!pl || !gsh) {
GEVENT_ASSERT(FALSE);
return FALSE;
}
chMtxLock(&geventMutex);
// Check if this pair is already in the table (scan for a free slot at the same time)
pslfree = 0;
for(psl = Assignments; psl < Assignments+MAX_SOURCE_LISTENERS; psl++) {
if (pl == psl->pListener && gsh == psl->pSource) {
// Just update the flags
chBSemWait(&pl->eventlock); // Safety first - just in case a source is using it
psl->listenflags = flags;
chBSemSignal(&pl->eventlock); // Release this lock
chMtxUnlock();
return TRUE;
}
if (!pslfree && !psl->pListener)
pslfree = psl;
}
// A free slot was found - allocate it
if (pslfree) {
pslfree->pListener = pl;
pslfree->pSource = gsh;
pslfree->listenflags = flags;
pslfree->srcflags = 0;
}
chMtxUnlock();
GEVENT_ASSERT(pslfree != 0);
return pslfree != 0;
}
/**
* @brief Detach a source from a listener
* @details If gsh is NULL detach all sources from this listener and if there is still
* a thread waiting for events on this listener, it is sent the exit event.
*
* @param[in] pl The listener
* @param[in] gsh The source
*/
void geventDetachSource(GListener *pl, GSourceHandle gsh) {
if (pl && gsh) {
chMtxLock(&geventMutex);
deleteAssignments(pl, gsh);
if (!gsh && chSemGetCounterI(&pl->waitqueue) < 0) {
chBSemWait(&pl->eventlock); // Obtain the buffer lock
pl->event.type = GEVENT_EXIT; // Set up the EXIT event
chSemSignal(&pl->waitqueue); // Wake up the listener
chBSemSignal(&pl->eventlock); // Release the buffer lock
}
chMtxUnlock();
}
}
/**
* @brief Wait for an event on a listener from an assigned source.
* @details The type of the event should be checked (pevent->type) and then pevent should
* be typecast to the actual event type if it needs to be processed.
* timeout specifies the time to wait in system ticks.
* TIME_INFINITE means no timeout - wait forever for an event.
* TIME_IMMEDIATE means return immediately
* @note The GEvent buffer is staticly allocated within the GListener so the event does not
* need to be dynamicly freed however it will get overwritten by the next call to
* this routine.
*
* @param[in] pl The listener
* @param[in] timeout The timeout
*
* @return NULL on timeout
*/
GEvent *geventEventWait(GListener *pl, systime_t timeout) {
if (pl->callback || chSemGetCounterI(&pl->waitqueue) < 0)
return 0;
return chSemWaitTimeout(&pl->waitqueue, timeout) == RDY_OK ? &pl->event : 0;
}
/* @brief Register a callback for an event on a listener from an assigned source.
* @details The type of the event should be checked (pevent->type) and then pevent should be typecast to the
* actual event type if it needs to be processed.
*
* @params[in] pl The Listener
* @params[in] fn The function to call back
* @params[in] param A parameter to pass the callback function
*
* @note The GEvent buffer is valid only during the time of the callback. The callback MUST NOT save
* a pointer to the buffer for use outside the callback.
* @note An existing callback function is de-registered by passing a NULL for 'fn'. Any existing
* callback function is replaced. Any thread currently waiting using geventEventWait will be sent the exit event.
* @note Callbacks occur in a thread context but stack space must be kept to a minumum and
* the callback must process quickly as all other events are performed on a single thread.
* @note In the callback function you should never call ANY event functions using your own GListener handle
* as it WILL create a deadlock and lock the system up.
* @note Applications should not use this call - geventEventWait() is the preferred mechanism for an
* application. This call is provided for GUI objects that may not have their own thread.
*/
void geventRegisterCallback(GListener *pl, GEventCallbackFn fn, void *param) {
if (pl) {
chMtxLock(&geventMutex);
chBSemWait(&pl->eventlock); // Obtain the buffer lock
pl->param = param; // Set the param
pl->callback = fn; // Set the callback function
if (chSemGetCounterI(&pl->waitqueue) < 0) {
pl->event.type = GEVENT_EXIT; // Set up the EXIT event
chSemSignal(&pl->waitqueue); // Wake up the listener
}
chBSemSignal(&pl->eventlock); // Release the buffer lock
chMtxUnlock();
}
}
/**
* @brief Called by a source with a possible event to get a listener record.
* @details @p lastlr should be NULL on the first call and thereafter the result of the previous call.
*
* @param[in] gsh The source handler
* @param[in] lastlr The source listener
*
* @return NULL when there are no more listeners for this source
*/
GSourceListener *geventGetSourceListener(GSourceHandle gsh, GSourceListener *lastlr) {
GSourceListener *psl;
// Safety first
if (!gsh)
return 0;
chMtxLock(&geventMutex);
// Unlock the last listener event buffer
if (lastlr)
chBSemSignal(&lastlr->pListener->eventlock);
// Loop through the table looking for attachments to this source
for(psl = lastlr ? (lastlr+1) : Assignments; psl < Assignments+MAX_SOURCE_LISTENERS; psl++) {
if (gsh == psl->pSource) {
chBSemWait(&psl->pListener->eventlock); // Obtain a lock on the listener event buffer
chMtxUnlock();
return psl;
}
}
chMtxUnlock();
return 0;
}
/**
* @brief Get the event buffer from the GSourceListener.
* @details A NULL return allows the source to record (perhaps in glr->scrflags) that the listener
* has missed events. This can then be notified as part of the next event for the listener.
* The buffer can only be accessed untill the next call to geventGetSourceListener
* or geventSendEvent
*
* @param[in] psl The source listener
*
* @return NULL if the listener is not currently listening.
*/
GEvent *geventGetEventBuffer(GSourceListener *psl) {
// We already know we have the event lock
return &psl->pListener->callback || chSemGetCounterI(&psl->pListener->waitqueue) < 0 ? &psl->pListener->event : 0;
}
/**
* @brief Called by a source to indicate the listener's event buffer has been filled.
* @details After calling this function the source must not reference in fields in the GSourceListener or the event buffer.
*
* @param[in] psl The source listener
*/
void geventSendEvent(GSourceListener *psl) {
chMtxLock(&geventMutex);
if (psl->pListener->callback) { // This test needs to be taken inside the mutex
chMtxUnlock();
// We already know we have the event lock
psl->pListener->callback(psl->pListener->param, &psl->pListener->event);
} else {
// Wake up the listener
if (chSemGetCounterI(&psl->pListener->waitqueue) < 0)
chSemSignal(&psl->pListener->waitqueue);
chMtxUnlock();
}
}
/**
* @brief Detach any listener that has this source attached
*
* @param[in] gsh The source handle
*/
void geventDetachSourceListeners(GSourceHandle gsh) {
chMtxLock(&geventMutex);
deleteAssignments(0, gsh);
chMtxUnlock();
}
#endif /* GFX_USE_GEVENT */
/** @} */
|