initial commit of lk (little kernel) project
diff --git a/kernel/event.c b/kernel/event.c
new file mode 100644
index 0000000..bd71e75
--- /dev/null
+++ b/kernel/event.c
@@ -0,0 +1,132 @@
+/*
+ * Copyright (c) 2008 Travis Geiselbrecht
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files
+ * (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge,
+ * publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+#include <debug.h>
+#include <err.h>
+#include <kernel/event.h>
+
+#if DEBUGLEVEL > 1
+#define EVENT_CHECK 1
+#endif
+
+void event_init(event_t *e, bool initial, uint flags)
+{
+#if EVENT_CHECK
+// ASSERT(e->magic != EVENT_MAGIC);
+#endif
+
+ e->magic = EVENT_MAGIC;
+ e->signalled = initial;
+ e->flags = flags;
+ wait_queue_init(&e->wait);
+}
+
+void event_destroy(event_t *e)
+{
+ enter_critical_section();
+
+#if EVENT_CHECK
+ ASSERT(e->magic == EVENT_MAGIC);
+#endif
+
+ e->magic = 0;
+ e->signalled = false;
+ e->flags = 0;
+ wait_queue_destroy(&e->wait, true);
+
+ exit_critical_section();
+}
+
+status_t event_wait_timeout(event_t *e, time_t timeout)
+{
+ status_t ret = NO_ERROR;
+
+ enter_critical_section();
+
+#if EVENT_CHECK
+ ASSERT(e->magic == EVENT_MAGIC);
+#endif
+
+ if (e->signalled) {
+ /* signalled, we're going to fall through */
+ if (e->flags & EVENT_FLAG_AUTOUNSIGNAL) {
+ /* autounsignal flag lets one thread fall through before unsignalling */
+ e->signalled = false;
+ }
+ } else {
+ /* unsignalled, block here */
+ ret = wait_queue_block(&e->wait, timeout);
+ if (ret < 0)
+ goto err;
+ }
+
+err:
+ exit_critical_section();
+
+ return ret;
+}
+
+status_t event_wait(event_t *e)
+{
+ return event_wait_timeout(e, INFINITE_TIME);
+}
+
+status_t event_signal(event_t *e, bool reschedule)
+{
+ enter_critical_section();
+
+#if EVENT_CHECK
+ ASSERT(e->magic == EVENT_MAGIC);
+#endif
+
+ if (!e->signalled) {
+ e->signalled = true;
+ if (e->flags & EVENT_FLAG_AUTOUNSIGNAL) {
+ /* release one thread and unsignal again */
+ wait_queue_wake_one(&e->wait, reschedule, NO_ERROR);
+ e->signalled = false;
+ } else {
+ /* relase all threads and remain signalled */
+ wait_queue_wake_all(&e->wait, reschedule, NO_ERROR);
+ }
+ }
+
+ exit_critical_section();
+
+ return NO_ERROR;
+}
+
+status_t event_unsignal(event_t *e)
+{
+ enter_critical_section();
+
+#if EVENT_CHECK
+ ASSERT(e->magic == EVENT_MAGIC);
+#endif
+
+ e->signalled = false;
+
+ exit_critical_section();
+
+ return NO_ERROR;
+}
+