1 files changed, 104 insertions, 0 deletions
diff --git a/libc/arch-x86/bionic/atomics_x86.c b/libc/arch-x86/bionic/atomics_x86.c
new file mode 100644
index 0000000..b7b20e6
--- /dev/null
+++ b/libc/arch-x86/bionic/atomics_x86.c
@@ -0,0 +1,104 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+#include <sys/atomics.h>
+
+#define FUTEX_SYSCALL 240
+#define FUTEX_WAIT 0
+#define FUTEX_WAKE 1
+
+int __futex_wait(volatile void *ftx, int val)
+{
+    int ret;
+    asm volatile (
+        "int $0x80;"
+        : "=a" (ret)
+        : "0" (FUTEX_SYSCALL),
+          "b" (ftx),
+          "c" (FUTEX_WAIT),
+          "d" (val),
+          "S" (0)
+    );
+    return ret;
+}
+
+int __futex_wake(volatile void *ftx, int count)
+{
+    int ret;
+    asm volatile (
+        "int $0x80;"
+        : "=a" (ret)
+        : "0" (FUTEX_SYSCALL),
+          "b" (ftx),
+          "c" (FUTEX_WAKE),
+          "d" (count)
+    );
+    return ret;
+}
+
+int __atomic_cmpxchg(int old, int new, volatile int* addr) {
+    int xchg;
+    asm volatile (
+        "lock;"
+        "cmpxchg %%ecx, (%%edx);"
+        "setne %%al;"
+        : "=a" (xchg)
+        : "a" (old),
+          "c" (new),
+          "d" (addr)
+    );
+    return xchg;
+}
+
+int __atomic_swap(int new, volatile int* addr) {
+    int old;
+    asm volatile (
+        "lock;"
+        "xchg %%ecx, (%%edx);"
+        : "=c" (old)
+        : "c" (new),
+          "d" (addr)
+    );
+    return old;
+}
+
+int __atomic_dec(volatile int* addr) {
+    int old;
+    do {
+        old = *addr;
+    } while (atomic_cmpxchg(old, old-1, addr));
+    return old;
+}
+
+int __atomic_inc(volatile int* addr) {
+    int old;
+    do {
+        old = *addr;
+    } while (atomic_cmpxchg(old, old+1, addr));
+    return old;
+}
+