Cancellable timers: sorted_list::remove, timer cancel, replace done flag with timer cancellation

firmware/include/sorted_list.h

@@ -28,8 +28,8 @@ struct sorted_list {
     T& front() { return head->value(); }
     const T& front() const { return head->value(); }
 
-    void insert(T value) {
-        if (full()) return;
+    node* insert(T value) {
+        if (full()) return nullptr;
         node* n = free_head;
         free_head = n->next;
         new (n->storage) T(std::move(value));
@@ -37,7 +37,7 @@ struct sorted_list {
         if (!head || n->value() < head->value()) {
             n->next = head;
             head = n;
-            return;
+            return n;
         }
 
         node* cur = head;
@@ -45,6 +45,7 @@ struct sorted_list {
             cur = cur->next;
         n->next = cur->next;
         cur->next = n;
+        return n;
     }
 
     void pop_front() {
@@ -55,4 +56,21 @@ struct sorted_list {
         n->next = free_head;
         free_head = n;
     }
+
+    bool remove(node* target) {
+        if (!target || empty()) return false;
+        if (head == target) {
+            pop_front();
+            return true;
+        }
+        node* cur = head;
+        while (cur->next && cur->next != target)
+            cur = cur->next;
+        if (cur->next != target) return false;
+        cur->next = target->next;
+        target->value().~T();
+        target->next = free_head;
+        free_head = target;
+        return true;
+    }
 };