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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 U_ATOMIC_H
#define U_ATOMIC_H
#include <stdbool.h>
/* 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_add(v, i) (void) __sync_add_and_fetch((v), (i))
#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_add(_v, _i) (*(_v) = *(_v) + (_i))
#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 <windows.h>
#include <intrin.h>
#include <assert.h>
#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;
}
/* Implement _InterlockedExchangeAdd16 in terms of _InterlockedCompareExchange16 */
static __inline short
_InterlockedExchangeAdd16(short volatile *addend, short value)
{
short initial = *addend;
short comparand;
do {
short exchange = initial + value;
comparand = initial;
/* if *addend==comparand then *addend=exchange, return original *addend */
initial = _InterlockedCompareExchange16(addend, exchange, comparand);
} while(initial != comparand);
return comparand;
}
/* Implement _InterlockedExchangeAdd8 in terms of _InterlockedCompareExchange8 */
static __inline char
_InterlockedExchangeAdd8(char volatile *addend, char value)
{
char initial = *addend;
char comparand;
do {
char exchange = initial + value;
comparand = initial;
initial = _InterlockedCompareExchange8(addend, exchange, comparand);
} while(initial != comparand);
return comparand;
}
#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_add(_v, _i) (\
sizeof *(_v) == sizeof(char) ? _InterlockedExchangeAdd8 ((char *) (_v), (_i)) : \
sizeof *(_v) == sizeof(short) ? _InterlockedExchangeAdd16((short *) (_v), (_i)) : \
sizeof *(_v) == sizeof(long) ? _InterlockedExchangeAdd ((long *) (_v), (_i)) : \
sizeof *(_v) == sizeof(__int64) ? InterlockedExchangeAdd64((__int64 *)(_v), (_i)) : \
(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 <atomic.h>
#include <assert.h>
#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_add(v, i) ((void) \
sizeof(*v) == sizeof(uint8_t) ? atomic_add_8 ((uint8_t *)(v), (i)) : \
sizeof(*v) == sizeof(uint16_t) ? atomic_add_16((uint16_t *)(v), (i)) : \
sizeof(*v) == sizeof(uint32_t) ? atomic_add_32((uint32_t *)(v), (i)) : \
sizeof(*v) == sizeof(uint64_t) ? atomic_add_64((uint64_t *)(v), (i)) : \
(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 */
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