Initial import

libc/bits/atomic.h

@@ -0,0 +1,52 @@
+#ifndef COSMOPOLITAN_LIBC_BITS_ATOMIC_H_
+#define COSMOPOLITAN_LIBC_BITS_ATOMIC_H_
+#include "libc/bits/bits.h"
+#if !(__ASSEMBLER__ + __LINKER__ + 0)
+COSMOPOLITAN_C_START_
+
+/**
+ * @fileoverview C11 version of The Cosmopolitan Atomics Library.
+ *
+ *   - Forty-two different ways to say MOV.
+ *   - Fourteen different ways to say XCHG.
+ *   - Twenty different ways to say LOCK CMPXCHG.
+ *
+ * Living proof high-level languages can be lower-level than assembly.
+ */
+
+#define memory_order         int
+#define memory_order_relaxed 0
+#define memory_order_consume 1
+#define memory_order_acquire 2
+#define memory_order_release 3
+#define memory_order_acq_rel 4
+#define memory_order_seq_cst 5
+
+#define atomic_flag            struct AtomicFlag
+#define atomic_flag_clear(PTR) atomic_store((PTR)->__cacheline, 0)
+#define atomic_flag_test_and_set(PTR)        \
+  ({                                         \
+    uint32_t ax = 0;                         \
+    lockcmpxchg((PTR)->__cacheline, &ax, 1); \
+  })
+#define atomic_init(PTR, VAL)                         atomic_store(PTR, VAL)
+#define atomic_exchange(PTR, VAL)                     lockxchg(PTR, &(VAL))
+#define atomic_compare_exchange_strong(X, Y, Z)       lockcmpxchg(X, Y, Z)
+#define atomic_compare_exchange_weak(X, Y, Z)         lockcmpxchg(X, Y, Z)
+#define atomic_load_explicit(PTR, ORDER)              atomic_load(PTR)
+#define atomic_store_explicit(PTR, VAL, ORDER)        atomic_store(PTR, VAL)
+#define atomic_flag_clear_explicit(PTR, ORDER)        atomic_store(PTR, 0)
+#define atomic_exchange_explicit(PTR, VAL, ORDER)     lockxchg(PTR, &(VAL))
+#define atomic_flag_test_and_set_explicit(PTR, ORDER) lockcmpxchg(PTR, 0, 1)
+#define atomic_compare_exchange_strong_explicit(X, Y, Z, S, F) \
+  lockcmpxchg(X, Y, Z)
+#define atomic_compare_exchange_weak_explicit(X, Y, Z, S, F) \
+  lockcmpxchg(X, Y, Z)
+
+struct AtomicFlag {
+  uint32_t __cacheline[16]; /* Intel V.O §9.4.6 */
+} aligned(64);
+
+COSMOPOLITAN_C_END_
+#endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */
+#endif /* COSMOPOLITAN_LIBC_BITS_ATOMIC_H_ */