1 files changed, 68 insertions, 0 deletions

diff --git a/tw_atomic.cpp b/tw_atomic.cpp
new file mode 100644
index 000000000..31cdd859f
--- /dev/null
+++ b/tw_atomic.cpp
@@ -0,0 +1,68 @@
+/*
+ * Copyright (C) 2015 The Team Win Recovery Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <pthread.h>
+#include <stdio.h>
+#include "tw_atomic.hpp"
+
+/*
+ * According to this documentation:
+ * https://developer.android.com/training/articles/smp.html
+ * it is recommended to use mutexes instead of atomics. This class
+ * provides us with a wrapper to make "atomic" variables easy to use.
+ */
+
+TWAtomicInt::TWAtomicInt(int initial_value /* = 0 */) {
+	if (pthread_mutex_init(&mutex_lock, NULL) != 0) {
+		// This should hopefully never happen. If it does, the
+		// operations will not be atomic, but we will allow things to
+		// continue anyway after logging the issue and just hope for
+		// the best.
+		printf("TWAtomic error initializing mutex.\n");
+		use_mutex = false;
+	} else {
+		use_mutex = true;
+	}
+	value = initial_value;
+}
+
+TWAtomicInt::~TWAtomicInt() {
+	if (use_mutex)
+		pthread_mutex_destroy(&mutex_lock);
+}
+
+void TWAtomicInt::set_value(int new_value) {
+	if (use_mutex) {
+		pthread_mutex_lock(&mutex_lock);
+		value = new_value;
+		pthread_mutex_unlock(&mutex_lock);
+	} else {
+		value = new_value;
+	}
+}
+
+int TWAtomicInt::get_value(void) {
+	int ret_val;
+
+	if (use_mutex) {
+		pthread_mutex_lock(&mutex_lock);
+		ret_val = value;
+		pthread_mutex_unlock(&mutex_lock);
+	} else {
+		ret_val = value;
+	}
+	return ret_val;
+}