init commit

arch/x86_64/atomic_arch.h

@@ -0,0 +1,26 @@
+#ifndef _ELIBC_ATOMIC_ARCH_H
+#define _ELIBC_ATOMIC_ARCH_H
+
+/* x86_64: minimal atomic ops via locked cmpxchg (CPU-local, no syscall) */
+
+static inline int a_cas(volatile int *p, int t, int s)
+{
+    int old;
+    __asm__ volatile ("lock; cmpxchg %3, %1"
+        : "=a"(old), "=m"(*p)
+        : "a"(t), "r"(s), "m"(*p)
+        : "memory");
+    return old;
+}
+
+static inline void a_inc(volatile int *p)
+{
+    __asm__ volatile ("lock; incl %0" : "=m"(*p) : "m"(*p) : "memory");
+}
+
+static inline void a_dec(volatile int *p)
+{
+    __asm__ volatile ("lock; decl %0" : "=m"(*p) : "m"(*p) : "memory");
+}
+
+#endif