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#ifndef Py_ATOMIC_H

#define Py_ATOMIC_H

#ifdef Py_BUILD_CORE

#include "dynamic_annotations.h"

#include "pyconfig.h"

#if defined(HAVE_STD_ATOMIC)

#include <stdatomic.h>

#endif

/* This is modeled after the atomics interface from C1x, according to

* the draft at

* http://www.open-std.org/JTC1/SC22/wg14/www/docs/n1425.pdf.

* Operations and types are named the same except with a _Py_ prefix

* and have the same semantics.

* Beware, the implementations here are deep magic.

#if defined(HAVE_STD_ATOMIC)

typedef enum _Py_memory_order {

_Py_memory_order_relaxed = memory_order_relaxed,

_Py_memory_order_acquire = memory_order_acquire,

_Py_memory_order_release = memory_order_release,

_Py_memory_order_acq_rel = memory_order_acq_rel,

_Py_memory_order_seq_cst = memory_order_seq_cst

} _Py_memory_order;

typedef struct _Py_atomic_address {

atomic_uintptr_t _value;

} _Py_atomic_address;

typedef struct _Py_atomic_int {

atomic_int _value;

} _Py_atomic_int;

#define _Py_atomic_signal_fence(/*memory_order*/ ORDER) \

atomic_signal_fence(ORDER)

#define _Py_atomic_thread_fence(/*memory_order*/ ORDER) \

atomic_thread_fence(ORDER)

#define _Py_atomic_store_explicit(ATOMIC_VAL, NEW_VAL, ORDER) \

atomic_store_explicit(&(ATOMIC_VAL)->_value, NEW_VAL, ORDER)

#define _Py_atomic_load_explicit(ATOMIC_VAL, ORDER) \

atomic_load_explicit(&(ATOMIC_VAL)->_value, ORDER)

/* Use builtin atomic operations in GCC >= 4.7 */

#elif defined(HAVE_BUILTIN_ATOMIC)

typedef enum _Py_memory_order {

_Py_memory_order_relaxed = __ATOMIC_RELAXED,

_Py_memory_order_acquire = __ATOMIC_ACQUIRE,

_Py_memory_order_release = __ATOMIC_RELEASE,

_Py_memory_order_acq_rel = __ATOMIC_ACQ_REL,

_Py_memory_order_seq_cst = __ATOMIC_SEQ_CST

} _Py_memory_order;

typedef struct _Py_atomic_address {

Py_uintptr_t _value;

} _Py_atomic_address;

typedef struct _Py_atomic_int {

int _value;

} _Py_atomic_int;

#define _Py_atomic_signal_fence(/*memory_order*/ ORDER) \

__atomic_signal_fence(ORDER)

#define _Py_atomic_thread_fence(/*memory_order*/ ORDER) \

__atomic_thread_fence(ORDER)

#define _Py_atomic_store_explicit(ATOMIC_VAL, NEW_VAL, ORDER) \

(assert((ORDER) == __ATOMIC_RELAXED \

|| (ORDER) == __ATOMIC_SEQ_CST \

|| (ORDER) == __ATOMIC_RELEASE), \

__atomic_store_n(&(ATOMIC_VAL)->_value, NEW_VAL, ORDER))

#define _Py_atomic_load_explicit(ATOMIC_VAL, ORDER) \

(assert((ORDER) == __ATOMIC_RELAXED \

|| (ORDER) == __ATOMIC_SEQ_CST \

|| (ORDER) == __ATOMIC_ACQUIRE \

|| (ORDER) == __ATOMIC_CONSUME), \

__atomic_load_n(&(ATOMIC_VAL)->_value, ORDER))

#else

typedef enum _Py_memory_order {

_Py_memory_order_relaxed,

_Py_memory_order_acquire,

_Py_memory_order_release,

_Py_memory_order_acq_rel,

_Py_memory_order_seq_cst

} _Py_memory_order;

typedef struct _Py_atomic_address {

Py_uintptr_t _value;

} _Py_atomic_address;

typedef struct _Py_atomic_int {

int _value;

} _Py_atomic_int;

/* Only support GCC (for expression statements) and x86 (for simple

* atomic semantics) for now */

#if defined(__GNUC__) && (defined(__i386__) || defined(__amd64))

static __inline__ void

_Py_atomic_signal_fence(_Py_memory_order order)

{

if (order != _Py_memory_order_relaxed)

__asm__ volatile("":::"memory");

}

static __inline__ void

_Py_atomic_thread_fence(_Py_memory_order order)

{

if (order != _Py_memory_order_relaxed)

__asm__ volatile("mfence":::"memory");

}

/* Tell the race checker about this operation's effects. */

static __inline__ void

_Py_ANNOTATE_MEMORY_ORDER(const volatile void *address, _Py_memory_order order)

{

(void)address; /* shut up -Wunused-parameter */

switch(order) {

case _Py_memory_order_release:

case _Py_memory_order_acq_rel:

case _Py_memory_order_seq_cst:

_Py_ANNOTATE_HAPPENS_BEFORE(address);

break;

case _Py_memory_order_relaxed:

case _Py_memory_order_acquire:

break;

}

switch(order) {

case _Py_memory_order_acquire:

case _Py_memory_order_acq_rel:

case _Py_memory_order_seq_cst:

_Py_ANNOTATE_HAPPENS_AFTER(address);

break;

case _Py_memory_order_relaxed:

case _Py_memory_order_release:

break;

}

#define _Py_atomic_store_explicit(ATOMIC_VAL, NEW_VAL, ORDER) \

__extension__ ({ \

__typeof__(ATOMIC_VAL) atomic_val = ATOMIC_VAL; \

__typeof__(atomic_val->_value) new_val = NEW_VAL;\

volatile __typeof__(new_val) *volatile_data = &atomic_val->_value; \

_Py_memory_order order = ORDER; \

_Py_ANNOTATE_MEMORY_ORDER(atomic_val, order); \

/* Perform the operation. */ \

_Py_ANNOTATE_IGNORE_WRITES_BEGIN(); \

switch(order) { \

case _Py_memory_order_release: \

_Py_atomic_signal_fence(_Py_memory_order_release); \

/* fallthrough */ \

case _Py_memory_order_relaxed: \

*volatile_data = new_val; \

break; \

case _Py_memory_order_acquire: \

case _Py_memory_order_acq_rel: \

case _Py_memory_order_seq_cst: \

__asm__ volatile("xchg %0, %1" \

: "+r"(new_val) \

: "m"(atomic_val->_value) \

: "memory"); \

break; \

} \

_Py_ANNOTATE_IGNORE_WRITES_END(); \

})

#define _Py_atomic_load_explicit(ATOMIC_VAL, ORDER) \

__extension__ ({ \

__typeof__(ATOMIC_VAL) atomic_val = ATOMIC_VAL; \

__typeof__(atomic_val->_value) result; \

volatile __typeof__(result) *volatile_data = &atomic_val->_value; \

_Py_memory_order order = ORDER; \

_Py_ANNOTATE_MEMORY_ORDER(atomic_val, order); \

/* Perform the operation. */ \

_Py_ANNOTATE_IGNORE_READS_BEGIN(); \

switch(order) { \

case _Py_memory_order_release: \

case _Py_memory_order_acq_rel: \

case _Py_memory_order_seq_cst: \

/* Loads on x86 are not releases by default, so need a */ \

/* thread fence. */ \

_Py_atomic_thread_fence(_Py_memory_order_release); \

break; \

default: \

/* No fence */ \

break; \

} \

result = *volatile_data; \

switch(order) { \

case _Py_memory_order_acquire: \

case _Py_memory_order_acq_rel: \

case _Py_memory_order_seq_cst: \

/* Loads on x86 are automatically acquire operations so */ \

/* can get by with just a compiler fence. */ \

_Py_atomic_signal_fence(_Py_memory_order_acquire); \

break; \

default: \

/* No fence */ \

break; \

} \

_Py_ANNOTATE_IGNORE_READS_END(); \

result; \

})

#else /* !gcc x86 */

/* Fall back to other compilers and processors by assuming that simple

volatile accesses are atomic. This is false, so people should port

this. */

#define _Py_atomic_signal_fence(/*memory_order*/ ORDER) ((void)0)

#define _Py_atomic_thread_fence(/*memory_order*/ ORDER) ((void)0)

#define _Py_atomic_store_explicit(ATOMIC_VAL, NEW_VAL, ORDER) \

((ATOMIC_VAL)->_value = NEW_VAL)

#define _Py_atomic_load_explicit(ATOMIC_VAL, ORDER) \

((ATOMIC_VAL)->_value)

#endif /* !gcc x86 */

#endif

/* Standardized shortcuts. */

#define _Py_atomic_store(ATOMIC_VAL, NEW_VAL) \

_Py_atomic_store_explicit(ATOMIC_VAL, NEW_VAL, _Py_memory_order_seq_cst)

#define _Py_atomic_load(ATOMIC_VAL) \

_Py_atomic_load_explicit(ATOMIC_VAL, _Py_memory_order_seq_cst)

/* Python-local extensions */

#define _Py_atomic_store_relaxed(ATOMIC_VAL, NEW_VAL) \

_Py_atomic_store_explicit(ATOMIC_VAL, NEW_VAL, _Py_memory_order_relaxed)

#define _Py_atomic_load_relaxed(ATOMIC_VAL) \

_Py_atomic_load_explicit(ATOMIC_VAL, _Py_memory_order_relaxed)

#endif /* Py_BUILD_CORE */

#endif /* Py_ATOMIC_H */

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