equeue: add user allocated event support

Allow posting events allocated outside queue memory

Author: maciejbocianski

events/equeue.h

@@ -165,9 +165,9 @@ void equeue_event_dtor(void *event, void (*dtor)(void *));
 // Post an event onto the event queue
 //
 // The equeue_post function takes a callback and a pointer to an event
-// allocated by equeue_alloc. The specified callback will be executed in the
-// context of the event queue's dispatch loop with the allocated event
-// as its argument.
+// allocated by equeue_alloc or allocated by user. The specified callback will
+// be executed in the context of the event queue's dispatch loop with
+// the allocated event as its argument.
 //
 // The equeue_post function is irq safe and can act as a mechanism for
 // moving events out of irq contexts.

events/source/equeue.c

@@ -21,6 +21,12 @@
 #include <stdint.h>
 #include <string.h>
 
+// check if the event is allocaded by user - event address is outside queues internal buffer address range
+#define IS_USER_ALLOCATED_EVENT(e) (((unsigned int)(e) < (unsigned int)q->buffer) || ((unsigned int)(e) > ((unsigned int)q->slab.data)))
+// for user allocated events set id as its address with first bit set
+#define MAKE_USER_ALLOCATED_EVENT_ID(e) ((int)(((unsigned int)e) | 1))
+#define IS_USER_ALLOCATED_EVENT_ID(id) (((id) & 1) == 1)
+
 // calculate the relative-difference between absolute times while
 // correctly handling overflow conditions
 static inline int equeue_tickdiff(unsigned a, unsigned b)
@@ -220,15 +226,16 @@ void equeue_dealloc(equeue_t *q, void *p)
         e->dtor(e + 1);
     }
 
-    equeue_mem_dealloc(q, e);
+    if (!IS_USER_ALLOCATED_EVENT(e)) {
+        equeue_mem_dealloc(q, e);
+    }
 }
 
-
 // equeue scheduling functions
 static int equeue_enqueue(equeue_t *q, struct equeue_event *e, unsigned tick)
 {
     // setup event and hash local id with buffer offset for unique id
-    int id = (e->id << q->npw2) | ((unsigned char *)e - q->buffer);
+    int id = IS_USER_ALLOCATED_EVENT(e) ? MAKE_USER_ALLOCATED_EVENT_ID(e) : ((e->id << q->npw2) | ((unsigned char *)e - q->buffer));
     e->target = tick + equeue_clampdiff(e->target, tick);
     e->generation = q->generation;
 
@@ -275,14 +282,29 @@ static int equeue_enqueue(equeue_t *q, struct equeue_event *e, unsigned tick)
 
 static struct equeue_event *equeue_unqueue(equeue_t *q, int id)
 {
-    // decode event from unique id and check that the local id matches
-    struct equeue_event *e = (struct equeue_event *)
-                             &q->buffer[id & ((1 << q->npw2) - 1)];
-
-    equeue_mutex_lock(&q->queuelock);
-    if (e->id != id >> q->npw2) {
-        equeue_mutex_unlock(&q->queuelock);
-        return 0;
+    struct equeue_event *e = 0;
+    if (IS_USER_ALLOCATED_EVENT_ID(id)) {
+        equeue_mutex_lock(&q->queuelock);
+        struct equeue_event *cur = q->queue;
+        while (cur) {
+            if (MAKE_USER_ALLOCATED_EVENT_ID(cur) == id) {
+                e = cur;
+                break;
+            }
+            cur = cur->next;
+        }
+        if (!e) {
+            equeue_mutex_unlock(&q->queuelock);
+            return 0;
+        }
+    } else {
+        // decode event from unique id and check that the local id matches
+        e = (struct equeue_event *)&q->buffer[id & ((1 << q->npw2) - 1)];
+        equeue_mutex_lock(&q->queuelock);
+        if (e->id != id >> q->npw2) {
+            equeue_mutex_unlock(&q->queuelock);
+            return 0;
+        }
     }
 
     // clear the event and check if already in-flight
@@ -311,7 +333,9 @@ static struct equeue_event *equeue_unqueue(equeue_t *q, int id)
         }
     }
 
-    equeue_incid(q, e);
+    if (!IS_USER_ALLOCATED_EVENT_ID(id)) {
+        equeue_incid(q, e);
+    }
     equeue_mutex_unlock(&q->queuelock);
 
     return e;
@@ -394,11 +418,22 @@ int equeue_timeleft(equeue_t *q, int id)
         return -1;
     }
 
-    // decode event from unique id and check that the local id matches
-    struct equeue_event *e = (struct equeue_event *)
-                             &q->buffer[id & ((1 << q->npw2) - 1)];
-
+    struct equeue_event *e = 0;
     equeue_mutex_lock(&q->queuelock);
+    if (IS_USER_ALLOCATED_EVENT_ID(id)) {
+        struct equeue_event *cur = q->queue;
+        while (cur) {
+            if (MAKE_USER_ALLOCATED_EVENT_ID(cur) == id) {
+                e = cur;
+                break;
+            }
+            cur = cur->next;
+        }
+    } else {
+        // decode event from unique id and check that the local id matches
+        e = (struct equeue_event *)&q->buffer[id & ((1 << q->npw2) - 1)];
+    }
+
     if (e->id == id >> q->npw2) {
         ret = equeue_clampdiff(e->target, equeue_tick());
     }