1 files changed, 97 insertions, 0 deletions
diff --git a/firmware/kernel/timeout.c b/firmware/kernel/timeout.c
new file mode 100644
index 0000000..8039e56
--- /dev/null
+++ b/firmware/kernel/timeout.c
@@ -0,0 +1,97 @@
+
+/****************************************************************************
+ * Tick-based interval timers/one-shots - be mindful this is not really
+ * intended for continuous timers but for events that need to run for a short
+ * time and be cancelled without further software intervention.
+ ****************************************************************************/
+
+#include "config.h"
+#include "system.h" /* TIME_AFTER */
+#include "kernel.h"
+#include "timeout.h"
+#include "general.h"
+
+/* list of active timeout events */
+static struct timeout *tmo_list[MAX_NUM_TIMEOUTS+1];
+
+/* timeout tick task - calls event handlers when they expire
+ * Event handlers may alter expiration, callback and data during operation.
+ */
+static void timeout_tick(void)
+{
+    unsigned long tick = current_tick;
+    struct timeout **p = tmo_list;
+    struct timeout *curr;
+
+    for(curr = *p; curr != NULL; curr = *(++p))
+    {
+        int ticks;
+
+        if(TIME_BEFORE(tick, curr->expires))
+            continue;
+
+        /* this event has expired - call callback */
+        ticks = curr->callback(curr);
+        if(ticks > 0)
+        {
+            curr->expires = tick + ticks; /* reload */
+        }
+        else
+        {
+            timeout_cancel(curr); /* cancel */
+        }
+    }
+}
+
+/* Cancels a timeout callback - can be called from the ISR */
+void timeout_cancel(struct timeout *tmo)
+{
+    int oldlevel = disable_irq_save();
+    int rc = remove_array_ptr((void **)tmo_list, tmo);
+
+    if(rc >= 0 && *tmo_list == NULL)
+    {
+        tick_remove_task(timeout_tick); /* Last one - remove task */
+    }
+
+    restore_irq(oldlevel);
+}
+
+/* Adds a timeout callback - calling with an active timeout resets the
+   interval - can be called from the ISR */
+void timeout_register(struct timeout *tmo, timeout_cb_type callback,
+                      int ticks, intptr_t data)
+{
+    int oldlevel;
+    void **arr, **p;
+
+    if(tmo == NULL)
+        return;
+
+    oldlevel = disable_irq_save();
+
+    /* See if this one is already registered */
+    arr = (void **)tmo_list;
+    p = find_array_ptr(arr, tmo);
+
+    if(p - arr < MAX_NUM_TIMEOUTS)
+    {
+        /* Vacancy */
+        if(*p == NULL)
+        {
+            /* Not present */
+            if(*tmo_list == NULL)
+            {
+                tick_add_task(timeout_tick); /* First one - add task */
+            }
+
+            *p = tmo;
+        }
+
+        tmo->callback = callback;
+        tmo->data = data;
+        tmo->expires = current_tick + ticks;
+    }
+
+    restore_irq(oldlevel);
+}