1 files changed, 19 insertions, 9 deletions
diff --git a/include/ntapi/bits/i386/nt_atomic_i386_asm__gcc.h b/include/ntapi/bits/i386/nt_atomic_i386_asm__gcc.h
index 23260e9..1e9ed71 100644
--- a/include/ntapi/bits/i386/nt_atomic_i386_asm__gcc.h
+++ b/include/ntapi/bits/i386/nt_atomic_i386_asm__gcc.h
@@ -251,15 +251,25 @@ static __inline__ int64_t at_locked_cas_64(
 	int64_t			cmp,
 	int64_t			xchg)
 {
-	__atomic_compare_exchange_n(
-		dst,
-		&cmp,
-		xchg,
-		0,
-		__ATOMIC_SEQ_CST,
-		__ATOMIC_SEQ_CST);
-
-	return cmp;
+	unsigned edx, eax;
+	unsigned ecx, ebx;
+
+	eax  = (unsigned)cmp;
+	edx  = (uint64_t)cmp >> 32;
+
+	ebx  = (unsigned)xchg;
+	ecx  = (uint64_t)xchg >> 32;
+
+	__asm__ volatile (
+		"lock;"
+		"cmpxchg8b %6"
+
+		: "=a" (eax), "=d" (edx)
+		: "a"  (eax), "d" (edx), "b" (ebx), "c" (ecx), "m" (*dst)
+		: "memory");
+
+
+	return ((int64_t)edx << 32) + eax;
 }