os: implement SdkRecursiveMutex

libraries/libstratosphere/source/os/os_sdk_recursive_mutex.cpp

@@ -0,0 +1,69 @@
+/*
+ * Copyright (c) 2018-2020 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/>.
+ */
+#include <stratosphere.hpp>
+
+namespace ams::os {
+
+    void InitializeSdkRecursiveMutex(SdkRecursiveMutexType *rmutex) {
+        /* Initialize the critical section. */
+        GetReference(rmutex->_storage).Initialize();
+
+        /* Set recursive count. */
+        rmutex->recursive_count = 0;
+    }
+
+    bool IsSdkRecursiveMutexLockedByCurrentThread(const SdkRecursiveMutexType *rmutex) {
+        /* Check whether the critical section is held. */
+        return GetReference(rmutex->_storage).IsLockedByCurrentThread();
+    }
+
+    void LockSdkRecursiveMutex(SdkRecursiveMutexType *rmutex) {
+        /* If we don't hold the mutex, enter the critical section. */
+        if (!IsSdkRecursiveMutexLockedByCurrentThread(rmutex)) {
+            GetReference(rmutex->_storage).Enter();
+        }
+
+        /* Increment (and check) recursive count. */
+        ++rmutex->recursive_count;
+        AMS_ABORT_UNLESS(rmutex->recursive_count != 0);
+    }
+
+    bool TryLockSdkRecursiveMutex(SdkRecursiveMutexType *rmutex) {
+        /* If we don't hold the mutex, try to enter the critical section. */
+        if (!IsSdkRecursiveMutexLockedByCurrentThread(rmutex)) {
+            if (!GetReference(rmutex->_storage).TryEnter()) {
+                return false;
+            }
+        }
+
+        /* Increment (and check) recursive count. */
+        ++rmutex->recursive_count;
+        AMS_ABORT_UNLESS(rmutex->recursive_count != 0);
+
+        return true;
+    }
+
+    void UnlockSdkRecursiveMutex(SdkRecursiveMutexType *rmutex) {
+        /* Check pre-conditions. */
+        AMS_ABORT_UNLESS(IsSdkRecursiveMutexLockedByCurrentThread(rmutex));
+
+        /* Decrement recursive count, and leave critical section if we no longer hold the mutex. */
+        if ((--rmutex->recursive_count) == 0) {
+            GetReference(rmutex->_storage).Leave();
+        }
+    }
+
+}