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/**
* Many similar implementations exist. See for example libwsbm
* or the linux kernel include/atomic.h
*
* No copyright claimed on this file.
*
*/
#ifndef P_ATOMIC_H
#define P_ATOMIC_H
#include "p_compiler.h"
#include "p_defines.h"
#ifdef __cplusplus
extern "C" {
#endif
/* Favor OS-provided implementations.
*
* Where no OS-provided implementation is available, fall back to
* locally coded assembly, compiler intrinsic or ultimately a
* mutex-based implementation.
*/
#if (defined(PIPE_SUBSYSTEM_WINDOWS_DISPLAY) || \
defined(PIPE_SUBSYSTEM_WINDOWS_MINIPORT))
#define PIPE_ATOMIC_OS_UNLOCKED
#elif defined(PIPE_CC_MSVC)
#define PIPE_ATOMIC_MSVC_INTRINSIC
#elif (defined(PIPE_CC_MSVC) && defined(PIPE_ARCH_X86))
#define PIPE_ATOMIC_ASM_MSVC_X86
#elif (defined(PIPE_CC_GCC) && defined(PIPE_ARCH_X86))
#define PIPE_ATOMIC_ASM_GCC_X86
#elif defined(PIPE_CC_GCC)
#define PIPE_ATOMIC_GCC_INTRINSIC
#else
#error "Unsupported platform"
#endif
#if defined(PIPE_ATOMIC_ASM_GCC_X86)
#define PIPE_ATOMIC "GCC x86 assembly"
#define p_atomic_set(_v, _i) (*(_v) = (_i))
#define p_atomic_read(_v) (*(_v))
static INLINE boolean
p_atomic_dec_zero(int32_t *v)
{
unsigned char c;
__asm__ __volatile__("lock; decl %0; sete %1":"+m"(*v), "=qm"(c)
::"memory");
return c != 0;
}
static INLINE void
p_atomic_inc(int32_t *v)
{
__asm__ __volatile__("lock; incl %0":"+m"(*v));
}
static INLINE void
p_atomic_dec(int32_t *v)
{
__asm__ __volatile__("lock; decl %0":"+m"(*v));
}
static INLINE int32_t
p_atomic_cmpxchg(int32_t *v, int32_t old, int32_t _new)
{
return __sync_val_compare_and_swap(v, old, _new);
}
#endif
/* Implementation using GCC-provided synchronization intrinsics
*/
#if defined(PIPE_ATOMIC_GCC_INTRINSIC)
#define PIPE_ATOMIC "GCC Sync Intrinsics"
#define p_atomic_set(_v, _i) (*(_v) = (_i))
#define p_atomic_read(_v) (*(_v))
static INLINE boolean
p_atomic_dec_zero(int32_t *v)
{
return (__sync_sub_and_fetch(v, 1) == 0);
}
static INLINE void
p_atomic_inc(int32_t *v)
{
(void) __sync_add_and_fetch(v, 1);
}
static INLINE void
p_atomic_dec(int32_t *v)
{
(void) __sync_sub_and_fetch(v, 1);
}
static INLINE int32_t
p_atomic_cmpxchg(int32_t *v, int32_t old, int32_t _new)
{
return __sync_val_compare_and_swap(v, old, _new);
}
#endif
/* Unlocked version for single threaded environments, such as some
* windows kernel modules.
*/
#if defined(PIPE_ATOMIC_OS_UNLOCKED)
#define PIPE_ATOMIC "Unlocked"
#define p_atomic_set(_v, _i) (*(_v) = (_i))
#define p_atomic_read(_v) (*(_v))
#define p_atomic_dec_zero(_v) ((boolean) --(*(_v)))
#define p_atomic_inc(_v) ((void) (*(_v))++)
#define p_atomic_dec(_v) ((void) (*(_v))--)
#define p_atomic_cmpxchg(_v, old, _new) (*(_v) == old ? *(_v) = (_new) : *(_v))
#endif
/* Locally coded assembly for MSVC on x86:
*/
#if defined(PIPE_ATOMIC_ASM_MSVC_X86)
#define PIPE_ATOMIC "MSVC x86 assembly"
#define p_atomic_set(_v, _i) (*(_v) = (_i))
#define p_atomic_read(_v) (*(_v))
static INLINE boolean
p_atomic_dec_zero(int32_t *v)
{
unsigned char c;
__asm {
mov eax, [v]
lock dec dword ptr [eax]
sete byte ptr [c]
}
return c != 0;
}
static INLINE void
p_atomic_inc(int32_t *v)
{
__asm {
mov eax, [v]
lock inc dword ptr [eax]
}
}
static INLINE void
p_atomic_dec(int32_t *v)
{
__asm {
mov eax, [v]
lock dec dword ptr [eax]
}
}
static INLINE int32_t
p_atomic_cmpxchg(int32_t *v, int32_t old, int32_t _new)
{
int32_t orig;
__asm {
mov ecx, [v]
mov eax, [old]
mov edx, [_new]
lock cmpxchg [ecx], edx
mov [orig], eax
}
return orig;
}
#endif
#if defined(PIPE_ATOMIC_MSVC_INTRINSIC)
#define PIPE_ATOMIC "MSVC Intrinsics"
#include <intrin.h>
#pragma intrinsic(_InterlockedIncrement)
#pragma intrinsic(_InterlockedDecrement)
#pragma intrinsic(_InterlockedCompareExchange)
#define p_atomic_set(_v, _i) (*(_v) = (_i))
#define p_atomic_read(_v) (*(_v))
static INLINE boolean
p_atomic_dec_zero(int32_t *v)
{
return _InterlockedDecrement(v) == 0;
}
static INLINE void
p_atomic_inc(int32_t *v)
{
_InterlockedIncrement(v);
}
static INLINE void
p_atomic_dec(int32_t *v)
{
_InterlockedDecrement(v);
}
static INLINE int32_t
p_atomic_cmpxchg(int32_t *v, int32_t old, int32_t _new)
{
return _InterlockedCompareExchange(v, _new, old);
}
#endif
#ifndef PIPE_ATOMIC
#error "No pipe_atomic implementation selected"
#endif
#ifdef __cplusplus
}
#endif
#endif /* P_ATOMIC_H */
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