os: implement waitable management.

This implements waitable management for Events (and
implements Events). It also refactors PM to use new
Event/Waitable semantics, and also adds STS_ASSERT
as a macro for asserting a boolean expression. The
rest of stratosphere has been refactored to use
STS_ASSERT whenever possible.

stratosphere/libstratosphere/source/os/impl/os_waitable_holder_base.hpp

@@ -0,0 +1,77 @@
+/*
+ * Copyright (c) 2018-2019 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#pragma once
+#include <stratosphere.hpp>
+
+namespace sts::os::impl {
+
+    class WaitableObjectList;
+    class WaitableManagerImpl;
+
+    class WaitableHolderBase {
+        public:
+            util::IntrusiveListNode manager_node;
+            util::IntrusiveListNode object_list_node;
+        private:
+            WaitableManagerImpl *manager = nullptr;
+        public:
+            /* Gets whether the held waitable is currently signaled. */
+            virtual TriBool IsSignaled() const = 0;
+            /* Adds to manager's object list, returns is signaled. */
+            virtual TriBool LinkToObjectList() = 0;
+            /* Removes from the manager's object list. */
+            virtual void UnlinkFromObjectList() = 0;
+            /* Gets handle to output, returns INVALID_HANDLE on failure. */
+            virtual Handle GetHandle() const = 0;
+            /* Gets the amount of time remaining until this wakes up. */
+            virtual u64 GetWakeupTime() const {
+                return U64_MAX;
+            }
+
+            /* Interface with manager. */
+            void SetManager(WaitableManagerImpl *m) {
+                this->manager = m;
+            }
+
+            WaitableManagerImpl *GetManager() const {
+                return this->manager;
+            }
+
+            bool IsLinkedToManager() const {
+                return this->manager != nullptr;
+            }
+    };
+
+    class WaitableHolderOfUserObject : public WaitableHolderBase {
+        public:
+            /* All user objects have no handle to wait on. */
+            virtual Handle GetHandle() const override {
+                return INVALID_HANDLE;
+            }
+    };
+
+    class WaitableHolderOfKernelObject : public WaitableHolderBase {
+        public:
+            /* All kernel objects have native handles, and thus don't have object list semantics. */
+            virtual TriBool LinkToObjectList() override {
+                return TriBool::Undefined;
+            }
+            virtual void UnlinkFromObjectList() override {
+                /* ... */
+            }
+    };
+
+}