1 files changed, 50 insertions, 0 deletions
diff --git a/libstdc++/src/one_time_construction.cpp b/libstdc++/src/one_time_construction.cpp
new file mode 100644
index 0000000..304afb8
--- /dev/null
+++ b/libstdc++/src/one_time_construction.cpp
@@ -0,0 +1,50 @@
+/*
+ * one_time_construction.cpp
+ *
+ * Copyright 2006 The Android Open Source Project
+ *
+ * This file contains C++ ABI support functions for one time
+ * constructors as defined in the "Run-time ABI for the ARM Architecture"
+ * section 4.4.2
+ */
+
+#include <stddef.h>
+#include <sys/atomics.h>
+
+extern "C" int __futex_wait(volatile void *ftx, int val, const struct timespec *timeout);
+extern "C" int __futex_wake(volatile void *ftx, int count);
+
+
+extern "C" int __cxa_guard_acquire(int volatile * gv)
+{
+    // 0 -> 2, return 1
+    // 2 -> 6, wait and return 0
+    // 6 untouched, wait and return 0
+    // 1 untouched, return 0
+retry:
+    if (__atomic_cmpxchg(0, 0x2, gv) == 0)
+        return 1;
+
+    __atomic_cmpxchg(0x2, 0x6, gv); // Indicate there is a waiter
+    __futex_wait(gv, 0x6, NULL);
+    if(*gv != 1) // __cxa_guard_abort was called, let every thread try since there is no return code for this condition
+        goto retry;
+    return 0;
+}
+
+extern "C" void __cxa_guard_release(int volatile * gv)
+{
+    // 2 -> 1
+    // 6 -> 1, and wake
+    if (__atomic_cmpxchg(0x2, 0x1, gv) == 0)
+        return;
+
+    *gv = 0x1;
+    __futex_wake(gv, 0x7fffffff);
+}
+
+extern "C" void __cxa_guard_abort(int volatile * gv)
+{
+    *gv = 0;
+    __futex_wake(gv, 0x7fffffff);
+}