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c89atomic.h
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/*
C89 compatible atomics. Choice of public domain or MIT-0. See license statements at the end of this file.
David Reid - [email protected]
*/
/*
Introduction
============
This library aims to implement an equivalent to the C11 atomics library. It's intended to be used as a way to
enable the use of atomics in a mostly consistent manner to modern C, while still enabling compatibility with
older compilers. This is *not* a drop-in replacement for C11 atomics, but is very similar. Only limited testing
has been done so use at your own risk. I'm happy to accept feedback and pull requests with bug fixes.
When compiling with GCC and Clang, this library will translate to a one-to-one wrapper around the __atomic_*
intrinsics provided by the compiler.
When compiling with Visual C++ things are a bit more complicated because it does not have support for C11 style
atomic intrinsics. This library will try to use the _Interlocked* intrinsics instead, and if unavailable will
use inlined assembly (x86 only).
Supported compilers are Visual Studio back to VC6, GCC and Clang. If you need support for a different compiler
I'm happy to add support (pull requests appreciated). This library currently assumes the `int` data type is
32 bits.
Differences With C11
--------------------
For practicality, this is not a drop-in replacement for C11's `stdatomic.h`. Below are the main differences
between c89atomic and stdatomic.
* All operations require an explicit size which is specified by the name of the function, and only 8-,
16-, 32- and 64-bit operations are supported. Objects of an arbitrary sizes are not supported.
* Some extra APIs are included:
- `c89atomic_compare_and_swap_*()`
- `c89atomic_test_and_set_*()`
- `c89atomic_clear_*()`
* All APIs are namespaced with `c89`.
* `c89atomic_*` data types are undecorated.
Compare Exchange
----------------
This library implements a simple compare-and-swap function called `c89atomic_compare_and_swap_*()` which is
slightly different to C11's `atomic_compare_exchange_*()`. This is named differently to distinguish between
the two. `c89atomic_compare_and_swap_*()` returns the old value as the return value, whereas
`atomic_compare_exchange_*()` will return it through a parameter and supports explicit memory orders for
success and failure cases.
With Visual Studio and versions of GCC earlier than 4.7, an implementation of `atomic_compare_exchange_*()`
is included which is implemented in terms of `c89atomic_compare_and_swap_*()`, but there's subtle details to be
aware of with this implementation. Note that the following only applies for Visual Studio and versions of GCC
earlier than 4.7. Later versions of GCC and Clang use the `__atomic_compare_exchange_n()` intrinsic directly
and are not subject to the following.
Below is the 32-bit implementation of `c89atomic_compare_exchange_strong_explicit_32()` which is implemented
the same for the weak versions and other sizes, and only for Visual Studio and old versions of GCC (prior to
4.7):
```c
c89atomic_bool c89atomic_compare_exchange_strong_explicit_32(volatile c89atomic_uint32* dst,
volatile c89atomic_uint32* expected,
c89atomic_uint32 desired,
c89atomic_memory_order successOrder,
c89atomic_memory_order failureOrder)
{
c89atomic_uint32 expectedValue;
c89atomic_uint32 result;
expectedValue = c89atomic_load_explicit_32(expected, c89atomic_memory_order_seq_cst);
result = c89atomic_compare_and_swap_32(dst, expectedValue, desired);
if (result == expectedValue) {
return 1;
} else {
c89atomic_store_explicit_32(expected, result, failureOrder);
return 0;
}
}
```
The call to `c89atomic_store_explicit_32()` is not atomic with respect to the main compare-and-swap operation
which may cause problems when `expected` points to memory that is shared between threads. This only becomes an
issue if `expected` can be accessed from multiple threads at the same time which for the most part will never
happen because a compare-and-swap will almost always be used in a loop with a local variable being used for the
expected value.
If the above is a concern, you should consider reworking your code to use `c89atomic_compare_and_swap_*()`
directly, which is atomic and more efficient. Alternatively you'll need to use a lock to synchronize access
to `expected`, upgrade your compiler, or use a different library.
Types and Functions
-------------------
The following types and functions are implemented:
+-----------------------------------------+-----------------------------------------------+
| C11 Atomics | C89 Atomics |
+-----------------------------------------+-----------------------------------------------+
| #include <stdatomic.h> | #include "c89atomic.h" |
+-----------------------------------------+-----------------------------------------------+
| memory_order | c89atomic_memory_order |
| memory_order_relaxed | c89atomic_memory_order_relaxed |
| memory_order_consume | c89atomic_memory_order_consume |
| memory_order_acquire | c89atomic_memory_order_acquire |
| memory_order_release | c89atomic_memory_order_release |
| memory_order_acq_rel | c89atomic_memory_order_acq_rel |
| memory_order_seq_cst | c89atomic_memory_order_seq_cst |
+-----------------------------------------+-----------------------------------------------+
| atomic_flag | c89atomic_flag |
| atomic_bool | c89atomic_bool |
| atomic_int8 | c89atomic_int8 |
| atomic_uint8 | c89atomic_uint8 |
| atomic_int16 | c89atomic_int16 |
| atomic_uint16 | c89atomic_uint16 |
| atomic_int32 | c89atomic_int32 |
| atomic_uint32 | c89atomic_uint32 |
| atomic_int64 | c89atomic_int64 |
| atomic_uint64 | c89atomic_uint64 |
+-----------------------------------------+-----------------------------------------------+
| atomic_flag_test_and_set | c89atomic_flag_test_and_set |
| atomic_flag_test_and_set_explicit | c89atomic_flag_test_and_set_explicit |
| | c89atomic_test_and_set_8 |
| | c89atomic_test_and_set_16 |
| | c89atomic_test_and_set_32 |
| | c89atomic_test_and_set_64 |
| | c89atomic_test_and_set_explicit_8 |
| | c89atomic_test_and_set_explicit_16 |
| | c89atomic_test_and_set_explicit_32 |
| | c89atomic_test_and_set_explicit_64 |
+-----------------------------------------+-----------------------------------------------+
| atomic_flag_clear | c89atomic_flag_clear |
| atomic_flag_clear_explicit | c89atomic_flag_clear_explicit |
| | c89atomic_clear_8 |
| | c89atomic_clear_16 |
| | c89atomic_clear_32 |
| | c89atomic_clear_64 |
| | c89atomic_clear_explicit_8 |
| | c89atomic_clear_explicit_16 |
| | c89atomic_clear_explicit_32 |
| | c89atomic_clear_explicit_64 |
+-----------------------------------------+-----------------------------------------------+
| atomic_store | c89atomic_store_8 |
| atomic_store_explicit | c89atomic_store_16 |
| | c89atomic_store_32 |
| | c89atomic_store_64 |
| | c89atomic_store_explicit_8 |
| | c89atomic_store_explicit_16 |
| | c89atomic_store_explicit_32 |
| | c89atomic_store_explicit_64 |
+-----------------------------------------+-----------------------------------------------+
| atomic_load | c89atomic_load_8 |
| atomic_load_explicit | c89atomic_load_16 |
| | c89atomic_load_32 |
| | c89atomic_load_64 |
| | c89atomic_load_explicit_8 |
| | c89atomic_load_explicit_16 |
| | c89atomic_load_explicit_32 |
| | c89atomic_load_explicit_64 |
+-----------------------------------------+-----------------------------------------------+
| atomic_exchange | c89atomic_exchange_8 |
| atomic_exchange_explicit | c89atomic_exchange_16 |
| | c89atomic_exchange_32 |
| | c89atomic_exchange_64 |
| | c89atomic_exchange_explicit_8 |
| | c89atomic_exchange_explicit_16 |
| | c89atomic_exchange_explicit_32 |
| | c89atomic_exchange_explicit_64 |
+-----------------------------------------+-----------------------------------------------+
| atomic_compare_exchange_weak | c89atomic_compare_exchange_weak_8 |
| atomic_compare_exchange_weak_explicit | c89atomic_compare_exchange_weak_16 |
| atomic_compare_exchange_strong | c89atomic_compare_exchange_weak_32 |
| atomic_compare_exchange_strong_explicit | c89atomic_compare_exchange_weak_64 |
| | c89atomic_compare_exchange_weak_explicit_8 |
| | c89atomic_compare_exchange_weak_explicit_16 |
| | c89atomic_compare_exchange_weak_explicit_32 |
| | c89atomic_compare_exchange_weak_explicit_64 |
| | c89atomic_compare_exchange_strong_8 |
| | c89atomic_compare_exchange_strong_16 |
| | c89atomic_compare_exchange_strong_32 |
| | c89atomic_compare_exchange_strong_64 |
| | c89atomic_compare_exchange_strong_explicit_8 |
| | c89atomic_compare_exchange_strong_explicit_16 |
| | c89atomic_compare_exchange_strong_explicit_32 |
| | c89atomic_compare_exchange_strong_explicit_64 |
+-----------------------------------------+-----------------------------------------------+
| atomic_fetch_add | c89atomic_fetch_add_8 |
| atomic_fetch_add_explicit | c89atomic_fetch_add_16 |
| | c89atomic_fetch_add_32 |
| | c89atomic_fetch_add_64 |
| | c89atomic_fetch_add_explicit_8 |
| | c89atomic_fetch_add_explicit_16 |
| | c89atomic_fetch_add_explicit_32 |
| | c89atomic_fetch_add_explicit_64 |
+-----------------------------------------+-----------------------------------------------+
| atomic_fetch_sub | c89atomic_fetch_sub_8 |
| atomic_fetch_sub_explicit | c89atomic_fetch_sub_16 |
| | c89atomic_fetch_sub_32 |
| | c89atomic_fetch_sub_64 |
| | c89atomic_fetch_sub_explicit_8 |
| | c89atomic_fetch_sub_explicit_16 |
| | c89atomic_fetch_sub_explicit_32 |
| | c89atomic_fetch_sub_explicit_64 |
+-----------------------------------------+-----------------------------------------------+
| atomic_fetch_or | c89atomic_fetch_or_8 |
| atomic_fetch_or_explicit | c89atomic_fetch_or_16 |
| | c89atomic_fetch_or_32 |
| | c89atomic_fetch_or_64 |
| | c89atomic_fetch_or_explicit_8 |
| | c89atomic_fetch_or_explicit_16 |
| | c89atomic_fetch_or_explicit_32 |
| | c89atomic_fetch_or_explicit_64 |
+-----------------------------------------+-----------------------------------------------+
| atomic_fetch_xor | c89atomic_fetch_xor_8 |
| atomic_fetch_xor_explicit | c89atomic_fetch_xor_16 |
| | c89atomic_fetch_xor_32 |
| | c89atomic_fetch_xor_64 |
| | c89atomic_fetch_xor_explicit_8 |
| | c89atomic_fetch_xor_explicit_16 |
| | c89atomic_fetch_xor_explicit_32 |
| | c89atomic_fetch_xor_explicit_64 |
+-----------------------------------------+-----------------------------------------------+
| atomic_fetch_and | c89atomic_fetch_and_8 |
| atomic_fetch_and_explicit | c89atomic_fetch_and_16 |
| | c89atomic_fetch_and_32 |
| | c89atomic_fetch_and_64 |
| | c89atomic_fetch_and_explicit_8 |
| | c89atomic_fetch_and_explicit_16 |
| | c89atomic_fetch_and_explicit_32 |
| | c89atomic_fetch_and_explicit_64 |
+-----------------------------------------+-----------------------------------------------+
| atomic_thread_fence() | c89atomic_thread_fence |
| atomic_signal_fence() | c89atomic_signal_fence |
+-----------------------------------------+-----------------------------------------------+
| atomic_is_lock_free | c89atomic_is_lock_free_8 |
| | c89atomic_is_lock_free_16 |
| | c89atomic_is_lock_free_32 |
| | c89atomic_is_lock_free_64 |
+-----------------------------------------+-----------------------------------------------+
| (Not Defined) | c89atomic_compare_and_swap_8 |
| | c89atomic_compare_and_swap_16 |
| | c89atomic_compare_and_swap_32 |
| | c89atomic_compare_and_swap_64 |
| | c89atomic_compare_and_swap_ptr |
| | c89atomic_compiler_fence |
+-----------------------------------------+-----------------------------------------------+
*/
#ifndef c89atomic_h
#define c89atomic_h
#if defined(__cplusplus)
extern "C" {
#endif
#if defined(__clang__) || (defined(__GNUC__) && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6)))
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wlong-long"
#if defined(__clang__)
#pragma GCC diagnostic ignored "-Wc++11-long-long"
#endif
#endif
typedef int c89atomic_memory_order;
/* Sized Types */
typedef signed char c89atomic_int8;
typedef unsigned char c89atomic_uint8;
typedef signed short c89atomic_int16;
typedef unsigned short c89atomic_uint16;
typedef signed int c89atomic_int32;
typedef unsigned int c89atomic_uint32;
#if defined(_MSC_VER) && !defined(__clang__)
typedef signed __int64 c89atomic_int64;
typedef unsigned __int64 c89atomic_uint64;
#else
typedef signed long long c89atomic_int64;
typedef unsigned long long c89atomic_uint64;
#endif
typedef unsigned char c89atomic_bool;
/* End Sized Types */
/* Architecture Detection */
#if !defined(C89ATOMIC_64BIT) && !defined(C89ATOMIC_32BIT)
#ifdef _WIN32
#ifdef _WIN64
#define C89ATOMIC_64BIT
#else
#define C89ATOMIC_32BIT
#endif
#endif
#endif
#if !defined(C89ATOMIC_64BIT) && !defined(C89ATOMIC_32BIT)
#ifdef __GNUC__
#ifdef __LP64__
#define C89ATOMIC_64BIT
#else
#define C89ATOMIC_32BIT
#endif
#endif
#endif
#if !defined(C89ATOMIC_64BIT) && !defined(C89ATOMIC_32BIT)
#include <stdint.h>
#if INTPTR_MAX == INT64_MAX
#define C89ATOMIC_64BIT
#else
#define C89ATOMIC_32BIT
#endif
#endif
#if defined(__arm__) || defined(_M_ARM)
#define C89ATOMIC_ARM32
#endif
#if defined(__arm64) || defined(__arm64__) || defined(__aarch64__) || defined(_M_ARM64)
#define C89ATOMIC_ARM64
#endif
#if defined(__x86_64__) || defined(_M_X64)
#define C89ATOMIC_X64
#elif defined(__i386) || defined(_M_IX86)
#define C89ATOMIC_X86
#elif defined(C89ATOMIC_ARM32) || defined(C89ATOMIC_ARM64)
#define C89ATOMIC_ARM
#endif
/* End Architecture Detection */
/* Inline */
/* We want to encourage the compiler to inline. When adding support for a new compiler, make sure it's handled here. */
#if defined(_MSC_VER)
#define C89ATOMIC_INLINE __forceinline
#elif defined(__GNUC__)
/*
I've had a bug report where GCC is emitting warnings about functions possibly not being inlineable. This warning happens when
the __attribute__((always_inline)) attribute is defined without an "inline" statement. I think therefore there must be some
case where "__inline__" is not always defined, thus the compiler emitting these warnings. When using -std=c89 or -ansi on the
command line, we cannot use the "inline" keyword and instead need to use "__inline__". In an attempt to work around this issue
I am using "__inline__" only when we're compiling in strict ANSI mode.
*/
#if defined(__STRICT_ANSI__) || !defined(__STDC_VERSION__) || (__STDC_VERSION__ < 199901L)
#define C89ATOMIC_INLINE __inline__ __attribute__((always_inline))
#else
#define C89ATOMIC_INLINE inline __attribute__((always_inline))
#endif
#elif defined(__WATCOMC__) || defined(__DMC__)
#define C89ATOMIC_INLINE __inline
#else
#define C89ATOMIC_INLINE
#endif
/* End Inline */
/* Assume everything supports all standard sized atomics by default. We'll #undef these when not supported. */
#define C89ATOMIC_HAS_8
#define C89ATOMIC_HAS_16
#define C89ATOMIC_HAS_32
#define C89ATOMIC_HAS_64
#if (defined(_MSC_VER) /*&& !defined(__clang__)*/) || defined(__WATCOMC__) || defined(__DMC__)
/* Visual C++. */
#define C89ATOMIC_MSVC_ARM_INTRINSIC(dst, src, order, intrin, c89atomicType, msvcType) \
c89atomicType result; \
switch (order) \
{ \
case c89atomic_memory_order_relaxed: \
{ \
result = (c89atomicType)intrin##_nf((volatile msvcType*)dst, (msvcType)src); \
} break; \
case c89atomic_memory_order_consume: \
case c89atomic_memory_order_acquire: \
{ \
result = (c89atomicType)intrin##_acq((volatile msvcType*)dst, (msvcType)src); \
} break; \
case c89atomic_memory_order_release: \
{ \
result = (c89atomicType)intrin##_rel((volatile msvcType*)dst, (msvcType)src); \
} break; \
case c89atomic_memory_order_acq_rel: \
case c89atomic_memory_order_seq_cst: \
default: \
{ \
result = (c89atomicType)intrin((volatile msvcType*)dst, (msvcType)src); \
} break; \
} \
return result;
#define C89ATOMIC_MSVC_ARM_INTRINSIC_COMPARE_EXCHANGE(ptr, expected, desired, order, intrin, c89atomicType, msvcType) \
c89atomicType result; \
switch (order) \
{ \
case c89atomic_memory_order_relaxed: \
{ \
result = (c89atomicType)intrin##_nf((volatile msvcType*)ptr, (msvcType)expected, (msvcType)desired); \
} break; \
case c89atomic_memory_order_consume: \
case c89atomic_memory_order_acquire: \
{ \
result = (c89atomicType)intrin##_acq((volatile msvcType*)ptr, (msvcType)expected, (msvcType)desired); \
} break; \
case c89atomic_memory_order_release: \
{ \
result = (c89atomicType)intrin##_rel((volatile msvcType*)ptr, (msvcType)expected, (msvcType)desired); \
} break; \
case c89atomic_memory_order_acq_rel: \
case c89atomic_memory_order_seq_cst: \
default: \
{ \
result = (c89atomicType)intrin((volatile msvcType*)ptr, (msvcType)expected, (msvcType)desired); \
} break; \
} \
return result;
#define c89atomic_memory_order_relaxed 0
#define c89atomic_memory_order_consume 1
#define c89atomic_memory_order_acquire 2
#define c89atomic_memory_order_release 3
#define c89atomic_memory_order_acq_rel 4
#define c89atomic_memory_order_seq_cst 5
/*
Visual Studio 2003 (_MSC_VER 1300) and earlier have no support for sized atomic operations.
We'll need to use inlined assembly for these compilers.
I've also had a report that 8-bit and 16-bit interlocked intrinsics were only added in Visual
Studio 2010 (_MSC_VER 1600). We'll need to disable these on the 64-bit build because there's
no way to implement them with inlined assembly since Microsoft has decided to drop support for
it from their 64-bit compilers.
To simplify the implementation, any older MSVC compilers targeting 32-bit will use inlined
assembly for everything. I'm not going to use inlined assembly wholesale for all 32-bit builds
regardless of the age of the compiler because I don't trust the compiler will optimize the
inlined assembly properly.
The inlined assembly path supports both MSVC, Digital Mars and OpenWatcom. OpenWatcom is a little
bit too pedantic with it's warnings. A few notes:
- The return value of these functions are defined by the AL/AX/EAX/EAX:EDX registers which
means an explicit return statement is not actually necessary. This is helpful for performance
reasons because it means we can avoid the cost of a declaring a local variable and moving the
value in EAX into that variable, only to then return it. However, unfortunately OpenWatcom
thinks this is a mistake and tries to be helpful by throwing a warning. To work around we're
going to declare a "result" variable and incur this theoretical cost. Most likely the
compiler will optimize this away and make it a non-issue.
- Variables that are assigned within the inline assembly will not be detected as such, and
OpenWatcom will throw a warning about the variable being used without being assigned. To work
around this we just initialize our local variables to 0.
*/
#if _MSC_VER < 1600 && defined(C89ATOMIC_X86) /* 1600 = Visual Studio 2010 */
#define C89ATOMIC_MSVC_USE_INLINED_ASSEMBLY
#endif
#if _MSC_VER < 1600
#undef C89ATOMIC_HAS_8
#undef C89ATOMIC_HAS_16
#endif
/* We need <intrin.h>, but only if we're not using inlined assembly. */
#if !defined(C89ATOMIC_MSVC_USE_INLINED_ASSEMBLY)
#include <intrin.h>
#endif
/* atomic_compare_and_swap */
#if defined(C89ATOMIC_MSVC_USE_INLINED_ASSEMBLY)
#if defined(C89ATOMIC_HAS_8)
static C89ATOMIC_INLINE c89atomic_uint8 __stdcall c89atomic_compare_and_swap_8(volatile c89atomic_uint8* dst, c89atomic_uint8 expected, c89atomic_uint8 desired)
{
c89atomic_uint8 result = 0;
__asm {
mov ecx, dst
mov al, expected
mov dl, desired
lock cmpxchg [ecx], dl /* Writes to EAX which MSVC will treat as the return value. */
mov result, al
}
return result;
}
#endif
#if defined(C89ATOMIC_HAS_16)
static C89ATOMIC_INLINE c89atomic_uint16 __stdcall c89atomic_compare_and_swap_16(volatile c89atomic_uint16* dst, c89atomic_uint16 expected, c89atomic_uint16 desired)
{
c89atomic_uint16 result = 0;
__asm {
mov ecx, dst
mov ax, expected
mov dx, desired
lock cmpxchg [ecx], dx /* Writes to EAX which MSVC will treat as the return value. */
mov result, ax
}
return result;
}
#endif
#if defined(C89ATOMIC_HAS_32)
static C89ATOMIC_INLINE c89atomic_uint32 __stdcall c89atomic_compare_and_swap_32(volatile c89atomic_uint32* dst, c89atomic_uint32 expected, c89atomic_uint32 desired)
{
c89atomic_uint32 result = 0;
__asm {
mov ecx, dst
mov eax, expected
mov edx, desired
lock cmpxchg [ecx], edx /* Writes to EAX which MSVC will treat as the return value. */
mov result, eax
}
return result;
}
#endif
#if defined(C89ATOMIC_HAS_64)
static C89ATOMIC_INLINE c89atomic_uint64 __stdcall c89atomic_compare_and_swap_64(volatile c89atomic_uint64* dst, c89atomic_uint64 expected, c89atomic_uint64 desired)
{
c89atomic_uint32 resultEAX = 0;
c89atomic_uint32 resultEDX = 0;
__asm {
mov esi, dst /* From Microsoft documentation: "... you don't need to preserve the EAX, EBX, ECX, EDX, ESI, or EDI registers." Choosing ESI since it's the next available one in their list. */
mov eax, dword ptr expected
mov edx, dword ptr expected + 4
mov ebx, dword ptr desired
mov ecx, dword ptr desired + 4
lock cmpxchg8b qword ptr [esi] /* Writes to EAX:EDX which MSVC will treat as the return value. */
mov resultEAX, eax
mov resultEDX, edx
}
return ((c89atomic_uint64)resultEDX << 32) | resultEAX;
}
#endif
#else
#if defined(C89ATOMIC_HAS_8)
#define c89atomic_compare_and_swap_8( dst, expected, desired) (c89atomic_uint8 )_InterlockedCompareExchange8((volatile char*)dst, (char)desired, (char)expected)
#endif
#if defined(C89ATOMIC_HAS_16)
#define c89atomic_compare_and_swap_16(dst, expected, desired) (c89atomic_uint16)_InterlockedCompareExchange16((volatile short*)dst, (short)desired, (short)expected)
#endif
#if defined(C89ATOMIC_HAS_32)
#define c89atomic_compare_and_swap_32(dst, expected, desired) (c89atomic_uint32)_InterlockedCompareExchange((volatile long*)dst, (long)desired, (long)expected)
#endif
#if defined(C89ATOMIC_HAS_64)
#define c89atomic_compare_and_swap_64(dst, expected, desired) (c89atomic_uint64)_InterlockedCompareExchange64((volatile c89atomic_int64*)dst, (c89atomic_int64)desired, (c89atomic_int64)expected)
#endif
#endif
/* atomic_exchange_explicit */
#if defined(C89ATOMIC_MSVC_USE_INLINED_ASSEMBLY)
#if defined(C89ATOMIC_HAS_8)
static C89ATOMIC_INLINE c89atomic_uint8 __stdcall c89atomic_exchange_explicit_8(volatile c89atomic_uint8* dst, c89atomic_uint8 src, c89atomic_memory_order order)
{
c89atomic_uint8 result = 0;
(void)order;
__asm {
mov ecx, dst
mov al, src
lock xchg [ecx], al
mov result, al
}
return result;
}
#endif
#if defined(C89ATOMIC_HAS_16)
static C89ATOMIC_INLINE c89atomic_uint16 __stdcall c89atomic_exchange_explicit_16(volatile c89atomic_uint16* dst, c89atomic_uint16 src, c89atomic_memory_order order)
{
c89atomic_uint16 result = 0;
(void)order;
__asm {
mov ecx, dst
mov ax, src
lock xchg [ecx], ax
mov result, ax
}
return result;
}
#endif
#if defined(C89ATOMIC_HAS_32)
static C89ATOMIC_INLINE c89atomic_uint32 __stdcall c89atomic_exchange_explicit_32(volatile c89atomic_uint32* dst, c89atomic_uint32 src, c89atomic_memory_order order)
{
c89atomic_uint32 result = 0;
(void)order;
__asm {
mov ecx, dst
mov eax, src
lock xchg [ecx], eax
mov result, eax
}
return result;
}
#endif
#else
#if defined(C89ATOMIC_HAS_8)
static C89ATOMIC_INLINE c89atomic_uint8 __stdcall c89atomic_exchange_explicit_8(volatile c89atomic_uint8* dst, c89atomic_uint8 src, c89atomic_memory_order order)
{
#if defined(C89ATOMIC_ARM)
C89ATOMIC_MSVC_ARM_INTRINSIC(dst, src, order, _InterlockedExchange8, c89atomic_uint8, char);
#else
(void)order; /* Always using the strongest memory order. */
return (c89atomic_uint8)_InterlockedExchange8((volatile char*)dst, (char)src);
#endif
}
#endif
#if defined(C89ATOMIC_HAS_16)
static C89ATOMIC_INLINE c89atomic_uint16 __stdcall c89atomic_exchange_explicit_16(volatile c89atomic_uint16* dst, c89atomic_uint16 src, c89atomic_memory_order order)
{
#if defined(C89ATOMIC_ARM)
C89ATOMIC_MSVC_ARM_INTRINSIC(dst, src, order, _InterlockedExchange16, c89atomic_uint16, short);
#else
(void)order; /* Always using the strongest memory order. */
return (c89atomic_uint16)_InterlockedExchange16((volatile short*)dst, (short)src);
#endif
}
#endif
#if defined(C89ATOMIC_HAS_32)
static C89ATOMIC_INLINE c89atomic_uint32 __stdcall c89atomic_exchange_explicit_32(volatile c89atomic_uint32* dst, c89atomic_uint32 src, c89atomic_memory_order order)
{
#if defined(C89ATOMIC_ARM)
C89ATOMIC_MSVC_ARM_INTRINSIC(dst, src, order, _InterlockedExchange, c89atomic_uint32, long);
#else
(void)order; /* Always using the strongest memory order. */
return (c89atomic_uint32)_InterlockedExchange((volatile long*)dst, (long)src);
#endif
}
#endif
#if defined(C89ATOMIC_HAS_64) && defined(C89ATOMIC_64BIT)
static C89ATOMIC_INLINE c89atomic_uint64 __stdcall c89atomic_exchange_explicit_64(volatile c89atomic_uint64* dst, c89atomic_uint64 src, c89atomic_memory_order order)
{
#if defined(C89ATOMIC_ARM)
C89ATOMIC_MSVC_ARM_INTRINSIC(dst, src, order, _InterlockedExchange64, c89atomic_uint64, long long);
#else
(void)order; /* Always using the strongest memory order. */
return (c89atomic_uint64)_InterlockedExchange64((volatile long long*)dst, (long long)src);
#endif
}
#else
/* Implemented below. */
#endif
#endif
#if defined(C89ATOMIC_HAS_64) && !defined(C89ATOMIC_64BIT) /* atomic_exchange_explicit_64() must be implemented in terms of atomic_compare_and_swap() on 32-bit builds, no matter the version of Visual Studio. */
static C89ATOMIC_INLINE c89atomic_uint64 __stdcall c89atomic_exchange_explicit_64(volatile c89atomic_uint64* dst, c89atomic_uint64 src, c89atomic_memory_order order)
{
c89atomic_uint64 oldValue;
do {
oldValue = *dst;
} while (c89atomic_compare_and_swap_64(dst, oldValue, src) != oldValue);
(void)order; /* Always using the strongest memory order. */
return oldValue;
}
#endif
/* atomic_fetch_add */
#if defined(C89ATOMIC_MSVC_USE_INLINED_ASSEMBLY)
#if defined(C89ATOMIC_HAS_8)
static C89ATOMIC_INLINE c89atomic_uint8 __stdcall c89atomic_fetch_add_explicit_8(volatile c89atomic_uint8* dst, c89atomic_uint8 src, c89atomic_memory_order order)
{
c89atomic_uint8 result = 0;
(void)order;
__asm {
mov ecx, dst
mov al, src
lock xadd [ecx], al
mov result, al
}
return result;
}
#endif
#if defined(C89ATOMIC_HAS_16)
static C89ATOMIC_INLINE c89atomic_uint16 __stdcall c89atomic_fetch_add_explicit_16(volatile c89atomic_uint16* dst, c89atomic_uint16 src, c89atomic_memory_order order)
{
c89atomic_uint16 result = 0;
(void)order;
__asm {
mov ecx, dst
mov ax, src
lock xadd [ecx], ax
mov result, ax
}
return result;
}
#endif
#if defined(C89ATOMIC_HAS_32)
static C89ATOMIC_INLINE c89atomic_uint32 __stdcall c89atomic_fetch_add_explicit_32(volatile c89atomic_uint32* dst, c89atomic_uint32 src, c89atomic_memory_order order)
{
c89atomic_uint32 result = 0;
(void)order;
__asm {
mov ecx, dst
mov eax, src
lock xadd [ecx], eax
mov result, eax
}
return result;
}
#endif
#else
#if defined(C89ATOMIC_HAS_8)
static C89ATOMIC_INLINE c89atomic_uint8 __stdcall c89atomic_fetch_add_explicit_8(volatile c89atomic_uint8* dst, c89atomic_uint8 src, c89atomic_memory_order order)
{
#if defined(C89ATOMIC_ARM)
C89ATOMIC_MSVC_ARM_INTRINSIC(dst, src, order, _InterlockedExchangeAdd8, c89atomic_uint8, char);
#else
(void)order; /* Always using the strongest memory order. */
return (c89atomic_uint8)_InterlockedExchangeAdd8((volatile char*)dst, (char)src);
#endif
}
#endif
#if defined(C89ATOMIC_HAS_16)
static C89ATOMIC_INLINE c89atomic_uint16 __stdcall c89atomic_fetch_add_explicit_16(volatile c89atomic_uint16* dst, c89atomic_uint16 src, c89atomic_memory_order order)
{
#if defined(C89ATOMIC_ARM)
C89ATOMIC_MSVC_ARM_INTRINSIC(dst, src, order, _InterlockedExchangeAdd16, c89atomic_uint16, short);
#else
(void)order; /* Always using the strongest memory order. */
return (c89atomic_uint16)_InterlockedExchangeAdd16((volatile short*)dst, (short)src);
#endif
}
#endif
#if defined(C89ATOMIC_HAS_32)
static C89ATOMIC_INLINE c89atomic_uint32 __stdcall c89atomic_fetch_add_explicit_32(volatile c89atomic_uint32* dst, c89atomic_uint32 src, c89atomic_memory_order order)
{
#if defined(C89ATOMIC_ARM)
C89ATOMIC_MSVC_ARM_INTRINSIC(dst, src, order, _InterlockedExchangeAdd, c89atomic_uint32, long);
#else
(void)order; /* Always using the strongest memory order. */
return (c89atomic_uint32)_InterlockedExchangeAdd((volatile long*)dst, (long)src);
#endif
}
#endif
#if defined(C89ATOMIC_HAS_64) && defined(C89ATOMIC_64BIT)
static C89ATOMIC_INLINE c89atomic_uint64 __stdcall c89atomic_fetch_add_explicit_64(volatile c89atomic_uint64* dst, c89atomic_uint64 src, c89atomic_memory_order order)
{
#if defined(C89ATOMIC_ARM)
C89ATOMIC_MSVC_ARM_INTRINSIC(dst, src, order, _InterlockedExchangeAdd64, c89atomic_uint64, long long);
#else
(void)order; /* Always using the strongest memory order. */
return (c89atomic_uint64)_InterlockedExchangeAdd64((volatile long long*)dst, (long long)src);
#endif
}
#else
/* Implemented below. */
#endif
#endif
#if defined(C89ATOMIC_HAS_64) && !defined(C89ATOMIC_64BIT) /* 9atomic_fetch_add_explicit_64() must be implemented in terms of atomic_compare_and_swap() on 32-bit builds, no matter the version of Visual Studio. */
static C89ATOMIC_INLINE c89atomic_uint64 __stdcall c89atomic_fetch_add_explicit_64(volatile c89atomic_uint64* dst, c89atomic_uint64 src, c89atomic_memory_order order)
{
c89atomic_uint64 oldValue;
c89atomic_uint64 newValue;
do {
oldValue = *dst;
newValue = oldValue + src;
} while (c89atomic_compare_and_swap_64(dst, oldValue, newValue) != oldValue);
(void)order;
return oldValue;
}
#endif
/* atomic_thread_fence */
#if defined(C89ATOMIC_MSVC_USE_INLINED_ASSEMBLY)
static C89ATOMIC_INLINE void __stdcall c89atomic_thread_fence(c89atomic_memory_order order)
{
(void)order;
__asm {
lock add [esp], 0
}
}
#else
/* Can't use MemoryBarrier() for this as it require Windows headers which we want to avoid in the header section of c89atomic. */
#if defined(C89ATOMIC_X64)
#define c89atomic_thread_fence(order) __faststorefence(), (void)order
#elif defined(C89ATOMIC_ARM64)
#define c89atomic_thread_fence(order) __dmb(_ARM64_BARRIER_ISH), (void)order
#else
static C89ATOMIC_INLINE void c89atomic_thread_fence(c89atomic_memory_order order)
{
volatile c89atomic_uint32 barrier = 0;
c89atomic_fetch_add_explicit_32(&barrier, 0, order);
}
#endif /* C89ATOMIC_X64 */
#endif
/*
I'm not sure how to implement a compiler barrier for old MSVC so I'm just making it a thread_fence() and hopefully the compiler will see the volatile and not do
any reshuffling. If anybody has a better idea on this please let me know! Cannot use _ReadWriteBarrier() as it has been marked as deprecated.
*/
#define c89atomic_compiler_fence() c89atomic_thread_fence(c89atomic_memory_order_seq_cst)
/* I'm not sure how to implement this for MSVC. For now just using thread_fence(). */
#define c89atomic_signal_fence(order) c89atomic_thread_fence(order)
/* Atomic loads can be implemented in terms of a compare-and-swap. Need to implement as functions to silence warnings about `order` being unused. */
#if defined(C89ATOMIC_HAS_8)
static C89ATOMIC_INLINE c89atomic_uint8 c89atomic_load_explicit_8(volatile const c89atomic_uint8* ptr, c89atomic_memory_order order)
{
#if defined(C89ATOMIC_ARM)
C89ATOMIC_MSVC_ARM_INTRINSIC_COMPARE_EXCHANGE(ptr, 0, 0, order, _InterlockedCompareExchange8, c89atomic_uint8, char);
#else
(void)order; /* Always using the strongest memory order. */
return c89atomic_compare_and_swap_8((volatile c89atomic_uint8*)ptr, 0, 0);
#endif
}
#endif
#if defined(C89ATOMIC_HAS_16)
static C89ATOMIC_INLINE c89atomic_uint16 c89atomic_load_explicit_16(volatile const c89atomic_uint16* ptr, c89atomic_memory_order order)
{
#if defined(C89ATOMIC_ARM)
C89ATOMIC_MSVC_ARM_INTRINSIC_COMPARE_EXCHANGE(ptr, 0, 0, order, _InterlockedCompareExchange16, c89atomic_uint16, short);
#else
(void)order; /* Always using the strongest memory order. */
return c89atomic_compare_and_swap_16((volatile c89atomic_uint16*)ptr, 0, 0);
#endif
}
#endif
#if defined(C89ATOMIC_HAS_32)
static C89ATOMIC_INLINE c89atomic_uint32 c89atomic_load_explicit_32(volatile const c89atomic_uint32* ptr, c89atomic_memory_order order)
{
#if defined(C89ATOMIC_ARM)
C89ATOMIC_MSVC_ARM_INTRINSIC_COMPARE_EXCHANGE(ptr, 0, 0, order, _InterlockedCompareExchange, c89atomic_uint32, long);
#else
(void)order; /* Always using the strongest memory order. */
return c89atomic_compare_and_swap_32((volatile c89atomic_uint32*)ptr, 0, 0);
#endif
}
#endif
#if defined(C89ATOMIC_HAS_64)
static C89ATOMIC_INLINE c89atomic_uint64 c89atomic_load_explicit_64(volatile const c89atomic_uint64* ptr, c89atomic_memory_order order)
{
#if defined(C89ATOMIC_ARM)
C89ATOMIC_MSVC_ARM_INTRINSIC_COMPARE_EXCHANGE(ptr, 0, 0, order, _InterlockedCompareExchange64, c89atomic_uint64, long long);
#else
(void)order; /* Always using the strongest memory order. */
return c89atomic_compare_and_swap_64((volatile c89atomic_uint64*)ptr, 0, 0);
#endif
}
#endif
/* atomic_store() is the same as atomic_exchange() but returns void. */
#if defined(C89ATOMIC_HAS_8)
#define c89atomic_store_explicit_8( dst, src, order) (void)c89atomic_exchange_explicit_8 (dst, src, order)
#endif
#if defined(C89ATOMIC_HAS_16)
#define c89atomic_store_explicit_16(dst, src, order) (void)c89atomic_exchange_explicit_16(dst, src, order)
#endif
#if defined(C89ATOMIC_HAS_32)
#define c89atomic_store_explicit_32(dst, src, order) (void)c89atomic_exchange_explicit_32(dst, src, order)
#endif
#if defined(C89ATOMIC_HAS_64)
#define c89atomic_store_explicit_64(dst, src, order) (void)c89atomic_exchange_explicit_64(dst, src, order)
#endif
/* fetch_sub() */
#if defined(C89ATOMIC_HAS_8)
static C89ATOMIC_INLINE c89atomic_uint8 __stdcall c89atomic_fetch_sub_explicit_8(volatile c89atomic_uint8* dst, c89atomic_uint8 src, c89atomic_memory_order order)
{
c89atomic_uint8 oldValue;
c89atomic_uint8 newValue;
do {
oldValue = *dst;
newValue = (c89atomic_uint8)(oldValue - src);
} while (c89atomic_compare_and_swap_8(dst, oldValue, newValue) != oldValue);
(void)order;
return oldValue;
}
#endif
#if defined(C89ATOMIC_HAS_16)
static C89ATOMIC_INLINE c89atomic_uint16 __stdcall c89atomic_fetch_sub_explicit_16(volatile c89atomic_uint16* dst, c89atomic_uint16 src, c89atomic_memory_order order)
{
c89atomic_uint16 oldValue;
c89atomic_uint16 newValue;
do {
oldValue = *dst;
newValue = (c89atomic_uint16)(oldValue - src);
} while (c89atomic_compare_and_swap_16(dst, oldValue, newValue) != oldValue);
(void)order;
return oldValue;
}
#endif
#if defined(C89ATOMIC_HAS_32)
static C89ATOMIC_INLINE c89atomic_uint32 __stdcall c89atomic_fetch_sub_explicit_32(volatile c89atomic_uint32* dst, c89atomic_uint32 src, c89atomic_memory_order order)
{
c89atomic_uint32 oldValue;
c89atomic_uint32 newValue;
do {
oldValue = *dst;
newValue = oldValue - src;
} while (c89atomic_compare_and_swap_32(dst, oldValue, newValue) != oldValue);
(void)order;
return oldValue;
}
#endif
#if defined(C89ATOMIC_HAS_64)
static C89ATOMIC_INLINE c89atomic_uint64 __stdcall c89atomic_fetch_sub_explicit_64(volatile c89atomic_uint64* dst, c89atomic_uint64 src, c89atomic_memory_order order)
{
c89atomic_uint64 oldValue;
c89atomic_uint64 newValue;
do {
oldValue = *dst;
newValue = oldValue - src;
} while (c89atomic_compare_and_swap_64(dst, oldValue, newValue) != oldValue);
(void)order;
return oldValue;
}
#endif
/* fetch_and() */
#if defined(C89ATOMIC_HAS_8)
static C89ATOMIC_INLINE c89atomic_uint8 __stdcall c89atomic_fetch_and_explicit_8(volatile c89atomic_uint8* dst, c89atomic_uint8 src, c89atomic_memory_order order)
{
#if defined(C89ATOMIC_ARM)
C89ATOMIC_MSVC_ARM_INTRINSIC(dst, src, order, _InterlockedAnd8, c89atomic_uint8, char);
#else
c89atomic_uint8 oldValue;
c89atomic_uint8 newValue;
do {
oldValue = *dst;
newValue = (c89atomic_uint8)(oldValue & src);
} while (c89atomic_compare_and_swap_8(dst, oldValue, newValue) != oldValue);
(void)order;
return oldValue;
#endif
}
#endif
#if defined(C89ATOMIC_HAS_16)
static C89ATOMIC_INLINE c89atomic_uint16 __stdcall c89atomic_fetch_and_explicit_16(volatile c89atomic_uint16* dst, c89atomic_uint16 src, c89atomic_memory_order order)
{
#if defined(C89ATOMIC_ARM)
C89ATOMIC_MSVC_ARM_INTRINSIC(dst, src, order, _InterlockedAnd16, c89atomic_uint16, short);
#else
c89atomic_uint16 oldValue;
c89atomic_uint16 newValue;
do {
oldValue = *dst;
newValue = (c89atomic_uint16)(oldValue & src);
} while (c89atomic_compare_and_swap_16(dst, oldValue, newValue) != oldValue);
(void)order;
return oldValue;
#endif
}
#endif
#if defined(C89ATOMIC_HAS_32)
static C89ATOMIC_INLINE c89atomic_uint32 __stdcall c89atomic_fetch_and_explicit_32(volatile c89atomic_uint32* dst, c89atomic_uint32 src, c89atomic_memory_order order)
{
#if defined(C89ATOMIC_ARM)
C89ATOMIC_MSVC_ARM_INTRINSIC(dst, src, order, _InterlockedAnd, c89atomic_uint32, long);
#else
c89atomic_uint32 oldValue;
c89atomic_uint32 newValue;
do {
oldValue = *dst;
newValue = oldValue & src;
} while (c89atomic_compare_and_swap_32(dst, oldValue, newValue) != oldValue);
(void)order;
return oldValue;
#endif
}
#endif
#if defined(C89ATOMIC_HAS_64)
static C89ATOMIC_INLINE c89atomic_uint64 __stdcall c89atomic_fetch_and_explicit_64(volatile c89atomic_uint64* dst, c89atomic_uint64 src, c89atomic_memory_order order)
{
#if defined(C89ATOMIC_ARM)
C89ATOMIC_MSVC_ARM_INTRINSIC(dst, src, order, _InterlockedAnd64, c89atomic_uint64, long long);
#else
c89atomic_uint64 oldValue;
c89atomic_uint64 newValue;