/** * Many similar implementations exist. See for example libwsbm * or the linux kernel include/atomic.h * * No copyright claimed on this file. * */ #ifndef U_ATOMIC_H #define U_ATOMIC_H #include /* 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(__sun) #define PIPE_ATOMIC_OS_SOLARIS #elif defined(_MSC_VER) #define PIPE_ATOMIC_MSVC_INTRINSIC #elif defined(__GNUC__) #define PIPE_ATOMIC_GCC_INTRINSIC #else #error "Unsupported platform" #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)) #define p_atomic_dec_zero(v) (__sync_sub_and_fetch((v), 1) == 0) #define p_atomic_inc(v) (void) __sync_add_and_fetch((v), 1) #define p_atomic_dec(v) (void) __sync_sub_and_fetch((v), 1) #define p_atomic_inc_return(v) __sync_add_and_fetch((v), 1) #define p_atomic_dec_return(v) __sync_sub_and_fetch((v), 1) #define p_atomic_cmpxchg(v, old, _new) \ __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) (p_atomic_dec_return(_v) == 0) #define p_atomic_inc(_v) ((void) p_atomic_inc_return(_v)) #define p_atomic_dec(_v) ((void) p_atomic_dec_return(_v)) #define p_atomic_inc_return(_v) (++(*(_v))) #define p_atomic_dec_return(_v) (--(*(_v))) #define p_atomic_cmpxchg(_v, _old, _new) (*(_v) == (_old) ? (*(_v) = (_new), (_old)) : *(_v)) #endif #if defined(PIPE_ATOMIC_MSVC_INTRINSIC) #define PIPE_ATOMIC "MSVC Intrinsics" /* We use the Windows header's Interlocked*64 functions instead of the * _Interlocked*64 intrinsics wherever we can, as support for the latter varies * with target CPU, whereas Windows headers take care of all portability * issues: using intrinsics where available, falling back to library * implementations where not. */ #ifndef WIN32_LEAN_AND_MEAN #define WIN32_LEAN_AND_MEAN 1 #endif #include #include #include #if _MSC_VER < 1600 /* Implement _InterlockedCompareExchange8 in terms of InterlockedCompareExchange16 */ static __inline char _InterlockedCompareExchange8(char volatile *Destination8, char Exchange8, char Comparand8) { INT_PTR DestinationAddr = (INT_PTR)Destination8; short volatile *Destination16 = (short volatile *)(DestinationAddr & ~1); const short Shift8 = (DestinationAddr & 1) * 8; const short Mask8 = 0xff << Shift8; short Initial16 = *Destination16; char Initial8 = Initial16 >> Shift8; while (Initial8 == Comparand8) { /* initial *Destination8 matches, so try exchange it while keeping the * neighboring byte untouched */ short Exchange16 = (Initial16 & ~Mask8) | ((short)Exchange8 << Shift8); short Comparand16 = Initial16; short Initial16 = InterlockedCompareExchange16(Destination16, Exchange16, Comparand16); if (Initial16 == Comparand16) { /* succeeded */ return Comparand8; } /* something changed, retry with the new initial value */ Initial8 = Initial16 >> Shift8; } return Initial8; } #endif /* _MSC_VER < 1600 */ /* MSVC supports decltype keyword, but it's only supported on C++ and doesn't * quite work here; and if a C++-only solution is worthwhile, then it would be * better to use templates / function overloading, instead of decltype magic. * Therefore, we rely on implicit casting to LONGLONG for the functions that return */ #define p_atomic_set(_v, _i) (*(_v) = (_i)) #define p_atomic_read(_v) (*(_v)) #define p_atomic_dec_zero(_v) \ (p_atomic_dec_return(_v) == 0) #define p_atomic_inc(_v) \ ((void) p_atomic_inc_return(_v)) #define p_atomic_inc_return(_v) (\ sizeof *(_v) == sizeof(short) ? _InterlockedIncrement16((short *) (_v)) : \ sizeof *(_v) == sizeof(long) ? _InterlockedIncrement ((long *) (_v)) : \ sizeof *(_v) == sizeof(__int64) ? InterlockedIncrement64 ((__int64 *)(_v)) : \ (assert(!"should not get here"), 0)) #define p_atomic_dec(_v) \ ((void) p_atomic_dec_return(_v)) #define p_atomic_dec_return(_v) (\ sizeof *(_v) == sizeof(short) ? _InterlockedDecrement16((short *) (_v)) : \ sizeof *(_v) == sizeof(long) ? _InterlockedDecrement ((long *) (_v)) : \ sizeof *(_v) == sizeof(__int64) ? InterlockedDecrement64 ((__int64 *)(_v)) : \ (assert(!"should not get here"), 0)) #define p_atomic_cmpxchg(_v, _old, _new) (\ sizeof *(_v) == sizeof(char) ? _InterlockedCompareExchange8 ((char *) (_v), (char) (_new), (char) (_old)) : \ sizeof *(_v) == sizeof(short) ? _InterlockedCompareExchange16((short *) (_v), (short) (_new), (short) (_old)) : \ sizeof *(_v) == sizeof(long) ? _InterlockedCompareExchange ((long *) (_v), (long) (_new), (long) (_old)) : \ sizeof *(_v) == sizeof(__int64) ? InterlockedCompareExchange64 ((__int64 *)(_v), (__int64)(_new), (__int64)(_old)) : \ (assert(!"should not get here"), 0)) #endif #if defined(PIPE_ATOMIC_OS_SOLARIS) #define PIPE_ATOMIC "Solaris OS atomic functions" #include #include #define p_atomic_set(_v, _i) (*(_v) = (_i)) #define p_atomic_read(_v) (*(_v)) #define p_atomic_dec_zero(v) (\ sizeof(*v) == sizeof(uint8_t) ? atomic_dec_8_nv ((uint8_t *)(v)) == 0 : \ sizeof(*v) == sizeof(uint16_t) ? atomic_dec_16_nv((uint16_t *)(v)) == 0 : \ sizeof(*v) == sizeof(uint32_t) ? atomic_dec_32_nv((uint32_t *)(v)) == 0 : \ sizeof(*v) == sizeof(uint64_t) ? atomic_dec_64_nv((uint64_t *)(v)) == 0 : \ (assert(!"should not get here"), 0)) #define p_atomic_inc(v) (void) (\ sizeof(*v) == sizeof(uint8_t) ? atomic_inc_8 ((uint8_t *)(v)) : \ sizeof(*v) == sizeof(uint16_t) ? atomic_inc_16((uint16_t *)(v)) : \ sizeof(*v) == sizeof(uint32_t) ? atomic_inc_32((uint32_t *)(v)) : \ sizeof(*v) == sizeof(uint64_t) ? atomic_inc_64((uint64_t *)(v)) : \ (assert(!"should not get here"), 0)) #define p_atomic_inc_return(v) ((typeof(*v)) \ sizeof(*v) == sizeof(uint8_t) ? atomic_inc_8_nv ((uint8_t *)(v)) : \ sizeof(*v) == sizeof(uint16_t) ? atomic_inc_16_nv((uint16_t *)(v)) : \ sizeof(*v) == sizeof(uint32_t) ? atomic_inc_32_nv((uint32_t *)(v)) : \ sizeof(*v) == sizeof(uint64_t) ? atomic_inc_64_nv((uint64_t *)(v)) : \ (assert(!"should not get here"), 0)) #define p_atomic_dec(v) ((void) \ sizeof(*v) == sizeof(uint8_t) ? atomic_dec_8 ((uint8_t *)(v)) : \ sizeof(*v) == sizeof(uint16_t) ? atomic_dec_16((uint16_t *)(v)) : \ sizeof(*v) == sizeof(uint32_t) ? atomic_dec_32((uint32_t *)(v)) : \ sizeof(*v) == sizeof(uint64_t) ? atomic_dec_64((uint64_t *)(v)) : \ (assert(!"should not get here"), 0)) #define p_atomic_dec_return(v) ((typeof(*v)) \ sizeof(*v) == sizeof(uint8_t) ? atomic_dec_8_nv ((uint8_t *)(v)) : \ sizeof(*v) == sizeof(uint16_t) ? atomic_dec_16_nv((uint16_t *)(v)) : \ sizeof(*v) == sizeof(uint32_t) ? atomic_dec_32_nv((uint32_t *)(v)) : \ sizeof(*v) == sizeof(uint64_t) ? atomic_dec_64_nv((uint64_t *)(v)) : \ (assert(!"should not get here"), 0)) #define p_atomic_cmpxchg(v, old, _new) ((typeof(*v)) \ sizeof(*v) == sizeof(uint8_t) ? atomic_cas_8 ((uint8_t *)(v), (uint8_t )(old), (uint8_t )(_new)) : \ sizeof(*v) == sizeof(uint16_t) ? atomic_cas_16((uint16_t *)(v), (uint16_t)(old), (uint16_t)(_new)) : \ sizeof(*v) == sizeof(uint32_t) ? atomic_cas_32((uint32_t *)(v), (uint32_t)(old), (uint32_t)(_new)) : \ sizeof(*v) == sizeof(uint64_t) ? atomic_cas_64((uint64_t *)(v), (uint64_t)(old), (uint64_t)(_new)) : \ (assert(!"should not get here"), 0)) #endif #ifndef PIPE_ATOMIC #error "No pipe_atomic implementation selected" #endif #endif /* U_ATOMIC_H */