From: Philip Chimento Date: Sat, 13 Jun 2009 14:46:17 +0000 (+0000) Subject: Implemented glk_select_poll() (Fix #18) X-Git-Url: https://git.stderr.nl/gitweb?a=commitdiff_plain;h=634959c3b160ea688522577e5e55e05686fd57d4;p=rodin%2Fchimara.git Implemented glk_select_poll() (Fix #18) git-svn-id: http://lassie.dyndns-server.com/svn/gargoyle-gtk@105 ddfedd41-794f-dd11-ae45-00112f111e67 --- diff --git a/libchimara/event.c b/libchimara/event.c index d7cb659..1a24f28 100644 --- a/libchimara/event.c +++ b/libchimara/event.c @@ -92,3 +92,95 @@ glk_select(event_t *event) g_assert(event->type != evtype_Abort); } +/** + * glk_select_poll: + * @event: Return location for an event. + * + * You can also inquire if an event is available, without stopping to wait for + * one to occur. + * + * This checks if an internally-spawned event is available. If so, it stores it + * in the structure pointed to by @event. If not, it sets + * @event->type to %evtype_None. Either way, it returns almost + * immediately. + * + * The first question you now ask is, what is an internally-spawned event? + * glk_select_poll() does not check for or return %evtype_CharInput, + * %evtype_LineInput, %evtype_MouseInput, or %evtype_Hyperlink events. It is + * intended for you to test conditions which may have occurred while you are + * computing, and not interfacing with the player. For example, time may pass + * during slow computations; you can use glk_select_poll() to see if a + * %evtype_Timer event has occured. (See Timer Events.) + * + * At the moment, glk_select_poll() checks for %evtype_Timer, %evtype_Arrange, + * %evtype_Redraw and %evtype_SoundNotify events. But see Other Events. + * + * The second question is, what does it mean that glk_select_poll() returns + * almost immediately? In some Glk libraries, text that you send + * to a window is buffered; it does not actually appear until you request player + * input with glk_select(). glk_select_poll() attends to this buffer-flushing + * task in the same way. (Although it does not do the Hit + * any key to scroll down waiting which may be done in + * glk_select(); that's a player-input task.) + * + * Similarly, on multitasking platforms, glk_select() may yield time to other + * processes; and glk_select_poll() does this as well. + * + * The upshot of this is that you should not call glk_select_poll() very often. + * If you are not doing much work between player inputs, you should not need to + * call it at all. + * + * + * For example, in a virtual machine interpreter, you should not call + * glk_select_poll() after every opcode. + * + * + * However, if you are doing intense computation, you may wish to call + * glk_select_poll() every so often to yield time to other processes. And if you + * are printing intermediate results during this computation, you should + * glk_select_poll() every so often, so that you can be certain your output will + * be displayed before the next glk_select(). + * + * + * However, you should call glk_tick() often — once per opcode in a VM + * interpreter. See The Tick + * Thing. + * + */ +void +glk_select_poll(event_t *event) +{ + g_return_if_fail(event != NULL); + + event->type = evtype_None; + + g_mutex_lock(glk_data->event_lock); + + if( !g_queue_is_empty(glk_data->event_queue) ) + { + GList *link; + int count; + for(count = 0; (link = g_queue_peek_nth_link(glk_data->event_queue, count)) != NULL; count++) + { + glui32 type = ((event_t *)link->data)->type; + if(type != evtype_CharInput && type != evtype_LineInput && type != evtype_MouseInput && type != evtype_Hyperlink) + { + memcpy(event, link->data, sizeof(event_t)); + g_free(link->data); + g_queue_delete_link(glk_data->event_queue, link); + g_cond_signal(glk_data->event_queue_not_full); + break; + } + } + } + + g_mutex_unlock(glk_data->event_lock); + + /* Check for interrupt */ + glk_tick(); + + /* If an abort event was generated, the thread should have exited by now */ + g_assert(event->type != evtype_Abort); +} \ No newline at end of file