Rework am_hsm_dispatch() by factoring out hsm_transition()

Author: adel-mamin

libs/hsm/hsm.c

@@ -165,40 +165,16 @@ static void hsm_enter_and_init(struct am_hsm *hsm, struct am_hsm_path *path) {
     hsm_set_state(hsm, &path->state[0]);
 }
 
-static enum am_hsm_rc hsm_dispatch(
-    struct am_hsm *hsm, const struct am_event *event
+/**
+ * Transition from source to destination state.
+ *
+ * @param hsm  transition the state of this HSM
+ * @param src  the source state
+ * @param dst  the destination state
+ */
+static void hsm_transition(
+    struct am_hsm *hsm, struct am_hsm_state src, struct am_hsm_state dst
 ) {
-    struct am_hsm_state src = {.fn = NULL, .ifn = 0};
-    struct am_hsm_state state = hsm->state;
-    enum am_hsm_rc rc = AM_HSM_RC_HANDLED;
-    /*
-     * propagate event up the ancestor chain till it is either
-     * handled or ignored or triggers transition
-     */
-    int cnt = HSM_HIERARCHY_DEPTH_MAX;
-    do {
-        src = hsm->state;
-        hsm->state = state;
-        /* preserve hsm->ifn as the instance of src.fn */
-        rc = src.fn(hsm, event);
-        --cnt;
-        AM_ASSERT(cnt); /* HSM hierarchy depth exceeds HSM_HIERARCHY_DEPTH_MAX*/
-    } while (AM_HSM_RC_SUPER == rc);
-
-    {
-        bool tran = (AM_HSM_RC_TRAN == rc) || (AM_HSM_RC_TRAN_REDISPATCH == rc);
-        if (!tran) { /* event was handled or ignored */
-            hsm_set_state(hsm, &state);
-            return rc;
-        }
-    }
-
-    /* the event triggered state transition */
-
-    struct am_hsm_state dst = hsm->state;
-    AM_ASSERT(dst.fn != am_hsm_top); /* transition to am_hsm_top() is invalid */
-    hsm_set_state(hsm, &state);
-
     if (!am_hsm_state_is_eq(hsm, &src)) {
         hsm_exit(hsm, /*until=*/&src);
         hsm_set_state(hsm, &src);
@@ -212,7 +188,7 @@ static enum am_hsm_rc hsm_dispatch(
         path.len = 1;
         hsm_exit_state(hsm);
         hsm_enter_and_init(hsm, &path);
-        return rc;
+        return;
     }
 
     struct am_hsm_state until = AM_HSM_STATE_CTOR(am_hsm_top);
@@ -222,7 +198,7 @@ static enum am_hsm_rc hsm_dispatch(
         /* src is LCA */
         --path.len;
         hsm_enter_and_init(hsm, &path);
-        return rc;
+        return;
     }
 
     /*
@@ -241,13 +217,48 @@ static enum am_hsm_rc hsm_dispatch(
                 /* LCA is found and it is not am_hsm_top() */
                 path.len = i;
                 hsm_enter_and_init(hsm, &path);
-                return rc;
+                return;
             }
         }
         hsm_exit_state(hsm);
     }
     /* LCA is am_hsm_top() */
     hsm_enter_and_init(hsm, &path);
+}
+
+static enum am_hsm_rc hsm_dispatch(
+    struct am_hsm *hsm, const struct am_event *event
+) {
+    struct am_hsm_state src = {.fn = NULL, .ifn = 0};
+    struct am_hsm_state state = hsm->state;
+    enum am_hsm_rc rc = AM_HSM_RC_HANDLED;
+    /*
+     * propagate event up the ancestor chain till it is either
+     * handled or ignored or triggers transition
+     */
+    int cnt = HSM_HIERARCHY_DEPTH_MAX;
+    do {
+        src = hsm->state;
+        hsm->state = state;
+        /* preserve hsm->ifn as the instance of src.fn */
+        rc = src.fn(hsm, event);
+        --cnt;
+        AM_ASSERT(cnt); /* HSM hierarchy depth exceeds HSM_HIERARCHY_DEPTH_MAX*/
+    } while (AM_HSM_RC_SUPER == rc);
+
+    bool tran = (AM_HSM_RC_TRAN == rc) || (AM_HSM_RC_TRAN_REDISPATCH == rc);
+    if (!tran) { /* event was handled or ignored */
+        hsm_set_state(hsm, &state);
+        return rc;
+    }
+
+    /* the event triggered state transition */
+
+    struct am_hsm_state dst = hsm->state;
+    AM_ASSERT(dst.fn != am_hsm_top); /* transition to am_hsm_top() is invalid */
+    hsm_set_state(hsm, &state);
+
+    hsm_transition(hsm, src, dst);
 
     return rc;
 }