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/*
* This file is subject to the terms of the GFX License. If a copy of
* the license was not distributed with this file, you can obtain one at:
*
* http://ugfx.org/license.html
*/
#include "../../gfx.h"
#if GFX_USE_GEVENT || defined(__DOXYGEN__)
#if GEVENT_ASSERT_NO_RESOURCE
#define GEVENT_ASSERT(x) assert(x)
#else
#define GEVENT_ASSERT(x)
#endif
/* Flags in the listener structure */
#define GLISTENER_WITHLISTENER 0x0001 // The listener is current using the buffer
#define GLISTENER_WITHSOURCE 0x0002 // The source is currently using the buffer
/* This mutex protects access to our tables */
static gfxMutex geventMutex;
/* Our table of listener/source pairs */
static GSourceListener Assignments[GEVENT_MAX_SOURCE_LISTENERS];
/* Send an exit event if possible. */
/* We already have the geventMutex */
static void doExitEvent(GListener *pl) {
// Don't do the exit if someone else currently is using the buffer
if (!(pl->flags & GLISTENER_WITHLISTENER)) {
pl->event.type = GEVENT_EXIT; // Set up the EXIT event
pl->flags = GLISTENER_WITHLISTENER; // Event buffer is now in use by the listener
gfxSemSignal(&pl->waitqueue);
}
}
/* Loop through the assignment table deleting this listener/source pair. */
/* Null is treated as a wildcard. */
/* We already have the geventMutex */
static void deleteAssignments(GListener *pl, GSourceHandle gsh) {
GSourceListener *psl;
for(psl = Assignments; psl < Assignments+GEVENT_MAX_SOURCE_LISTENERS; psl++) {
if ((!pl || psl->pListener == pl) && (!gsh || psl->pSource == gsh)) {
doExitEvent(psl->pListener);
psl->pListener = 0;
psl->pSource = 0;
}
}
}
void _geventInit(void)
{
gfxMutexInit(&geventMutex);
}
void _geventDeinit(void)
{
gfxMutexDestroy(&geventMutex);
}
void geventListenerInit(GListener *pl) {
gfxSemInit(&pl->waitqueue, 0, MAX_SEMAPHORE_COUNT); // Next wait'er will block
pl->callback = 0; // No callback active
pl->event.type = GEVENT_NULL; // Always safety
pl->flags = 0;
}
gBool geventAttachSource(GListener *pl, GSourceHandle gsh, uint32_t flags) {
GSourceListener *psl, *pslfree;
// Safety first
if (!pl || !gsh) {
GEVENT_ASSERT(gFalse);
return gFalse;
}
gfxMutexEnter(&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+GEVENT_MAX_SOURCE_LISTENERS; psl++) {
if (pl == psl->pListener && gsh == psl->pSource) {
// Just update the flags
psl->listenflags = flags;
gfxMutexExit(&geventMutex);
return gTrue;
}
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;
}
gfxMutexExit(&geventMutex);
GEVENT_ASSERT(pslfree != 0);
return pslfree != 0;
}
void geventDetachSource(GListener *pl, GSourceHandle gsh) {
if (pl) {
gfxMutexEnter(&geventMutex);
deleteAssignments(pl, gsh);
if (!gsh)
doExitEvent(pl);
gfxMutexExit(&geventMutex);
}
}
GEvent *geventEventWait(GListener *pl, delaytime_t timeout) {
/* NOTE:
We no longer try to protect against two threads trying to listen on the
one listener. This was never allowed, it makes little sense to try to do so,
and the testing caused strange multi-thread windows of opportunity.
In practice it is probably safer than it used to be - the only potential
issue is that the buffer may be prematurely marked as not in use by the listener.
If the calling code can guarantee that the event buffer is free when either thread
calls the event wait - it is now safe for them to do so.
ie. it is the implicit geventEventComplete() that is the only thing that now raises
possible multi-thread issues.
*/
// Don't allow waiting if we are on callbacks
if (pl->callback)
return 0;
// Event buffer is not in use by the listener - this is an implicit geventEventComplete() call
pl->flags &= ~GLISTENER_WITHLISTENER;
// Wait for an event
if (!gfxSemWait(&pl->waitqueue, timeout))
return 0; // Timeout
return &pl->event;
}
void geventEventComplete(GListener *pl) {
// The listener is done with the buffer
pl->flags &= ~GLISTENER_WITHLISTENER;
}
void geventRegisterCallback(GListener *pl, GEventCallbackFn fn, void *param) {
if (pl) {
gfxMutexEnter(&geventMutex);
doExitEvent(pl);
pl->param = param; // Set the param
pl->callback = fn; // Set the callback function
if (fn)
pl->flags &= ~GLISTENER_WITHLISTENER; // The event buffer is immediately available
gfxMutexExit(&geventMutex);
}
}
GSourceListener *geventGetSourceListener(GSourceHandle gsh, GSourceListener *lastlr) {
GSourceListener *psl;
// Safety first
if (!gsh)
return 0;
gfxMutexEnter(&geventMutex);
// Unlock the last listener event buffer if it wasn't used.
if (lastlr && lastlr->pListener && (lastlr->pListener->flags & GLISTENER_WITHSOURCE))
lastlr->pListener->flags &= ~GLISTENER_WITHSOURCE;
// Loop through the table looking for attachments to this source
for(psl = lastlr ? (lastlr+1) : Assignments; psl < Assignments+GEVENT_MAX_SOURCE_LISTENERS; psl++) {
if (gsh == psl->pSource) {
gfxMutexExit(&geventMutex);
return psl;
}
}
gfxMutexExit(&geventMutex);
return 0;
}
GEvent *geventGetEventBuffer(GSourceListener *psl) {
gfxMutexEnter(&geventMutex);
if ((psl->pListener->flags & (GLISTENER_WITHLISTENER|GLISTENER_WITHSOURCE))) {
gfxMutexExit(&geventMutex);
return 0;
}
// Allocate the event buffer to the source
psl->pListener->flags |= GLISTENER_WITHSOURCE;
gfxMutexExit(&geventMutex);
return &psl->pListener->event;
}
void geventSendEvent(GSourceListener *psl) {
gfxMutexEnter(&geventMutex);
if (psl->pListener->callback) {
// Mark it back as free and as sent. This is early to be marking as free but it protects
// if the callback alters the listener in any way
psl->pListener->flags = 0;
gfxMutexExit(&geventMutex);
// Do the callback
psl->pListener->callback(psl->pListener->param, &psl->pListener->event);
} else {
// Wake up the listener
psl->pListener->flags = GLISTENER_WITHLISTENER;
gfxSemSignal(&psl->pListener->waitqueue);
gfxMutexExit(&geventMutex);
}
}
void geventDetachSourceListeners(GSourceHandle gsh) {
gfxMutexEnter(&geventMutex);
deleteAssignments(0, gsh);
gfxMutexExit(&geventMutex);
}
#endif /* GFX_USE_GEVENT */
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