src/util/u_atomic.h

   1 /**
   2  * Many similar implementations exist. See for example libwsbm
   3  * or the linux kernel include/atomic.h
   4  *
   5  * No copyright claimed on this file.
   6  *
   7  */
   8
   9 #ifndef U_ATOMIC_H
  10 #define U_ATOMIC_H
  11
  12 #include <stdbool.h>
  13
  14 /* Favor OS-provided implementations.
  15  *
  16  * Where no OS-provided implementation is available, fall back to
  17  * locally coded assembly, compiler intrinsic or ultimately a
  18  * mutex-based implementation.
  19  */
  20 #if defined(__sun)
  21 #define PIPE_ATOMIC_OS_SOLARIS
  22 #elif defined(_MSC_VER)
  23 #define PIPE_ATOMIC_MSVC_INTRINSIC
  24 #elif defined(__GNUC__)
  25 #define PIPE_ATOMIC_GCC_INTRINSIC
  26 #else
  27 #error "Unsupported platform"
  28 #endif
  29
  30
  31 /* Implementation using GCC-provided synchronization intrinsics
  32  */
  33 #if defined(PIPE_ATOMIC_GCC_INTRINSIC)
  34
  35 #define PIPE_ATOMIC "GCC Sync Intrinsics"
  36
  37 #define p_atomic_set(_v, _i) (*(_v) = (_i))
  38 #define p_atomic_read(_v) (*(_v))
  39 #define p_atomic_dec_zero(v) (__sync_sub_and_fetch((v), 1) == 0)
  40 #define p_atomic_inc(v) (void) __sync_add_and_fetch((v), 1)
  41 #define p_atomic_dec(v) (void) __sync_sub_and_fetch((v), 1)
  42 #define p_atomic_add(v, i) (void) __sync_add_and_fetch((v), (i))
  43 #define p_atomic_inc_return(v) __sync_add_and_fetch((v), 1)
  44 #define p_atomic_dec_return(v) __sync_sub_and_fetch((v), 1)
  45 #define p_atomic_cmpxchg(v, old, _new) \
  46    __sync_val_compare_and_swap((v), (old), (_new))
  47
  48 #endif
  49
  50
  51
  52 /* Unlocked version for single threaded environments, such as some
  53  * windows kernel modules.
  54  */
  55 #if defined(PIPE_ATOMIC_OS_UNLOCKED)
  56
  57 #define PIPE_ATOMIC "Unlocked"
  58
  59 #define p_atomic_set(_v, _i) (*(_v) = (_i))
  60 #define p_atomic_read(_v) (*(_v))
  61 #define p_atomic_dec_zero(_v) (p_atomic_dec_return(_v) == 0)
  62 #define p_atomic_inc(_v) ((void) p_atomic_inc_return(_v))
  63 #define p_atomic_dec(_v) ((void) p_atomic_dec_return(_v))
  64 #define p_atomic_add(_v, _i) (*(_v) = *(_v) + (_i))
  65 #define p_atomic_inc_return(_v) (++(*(_v)))
  66 #define p_atomic_dec_return(_v) (--(*(_v)))
  67 #define p_atomic_cmpxchg(_v, _old, _new) (*(_v) == (_old) ? (*(_v) = (_new), (_old)) : *(_v))
  68
  69 #endif
  70
  71
  72 #if defined(PIPE_ATOMIC_MSVC_INTRINSIC)
  73
  74 #define PIPE_ATOMIC "MSVC Intrinsics"
  75
  76 /* We use the Windows header's Interlocked*64 functions instead of the
  77  * _Interlocked*64 intrinsics wherever we can, as support for the latter varies
  78  * with target CPU, whereas Windows headers take care of all portability
  79  * issues: using intrinsics where available, falling back to library
  80  * implementations where not.
  81  */
  82 #ifndef WIN32_LEAN_AND_MEAN
  83 #define WIN32_LEAN_AND_MEAN 1
  84 #endif
  85 #include <windows.h>
  86 #include <intrin.h>
  87 #include <assert.h>
  88
  89 #if _MSC_VER < 1600
  90
  91 /* Implement _InterlockedCompareExchange8 in terms of _InterlockedCompareExchange16 */
  92 static __inline char
  93 _InterlockedCompareExchange8(char volatile *destination8, char exchange8, char comparand8)
  94 {
  95    INT_PTR destinationAddr = (INT_PTR)destination8;
  96    short volatile *destination16 = (short volatile *)(destinationAddr & ~1);
  97    const short shift8 = (destinationAddr & 1) * 8;
  98    const short mask8 = 0xff << shift8;
  99    short initial16 = *destination16;
 100    char initial8 = initial16 >> shift8;
 101    while (initial8 == comparand8) {
 102       /* initial *destination8 matches, so try exchange it while keeping the
 103        * neighboring byte untouched */
 104       short exchange16 = (initial16 & ~mask8) | ((short)exchange8 << shift8);
 105       short comparand16 = initial16;
 106       short initial16 = _InterlockedCompareExchange16(destination16, exchange16, comparand16);
 107       if (initial16 == comparand16) {
 108          /* succeeded */
 109          return comparand8;
 110       }
 111       /* something changed, retry with the new initial value */
 112       initial8 = initial16 >> shift8;
 113    }
 114    return initial8;
 115 }
 116
 117 /* Implement _InterlockedExchangeAdd16 in terms of _InterlockedCompareExchange16 */
 118 static __inline short
 119 _InterlockedExchangeAdd16(short volatile *addend, short value)
 120 {
 121    short initial = *addend;
 122    short comparand;
 123    do {
 124       short exchange = initial + value;
 125       comparand = initial;
 126       /* if *addend==comparand then *addend=exchange, return original *addend */
 127       initial = _InterlockedCompareExchange16(addend, exchange, comparand);
 128    } while(initial != comparand);
 129    return comparand;
 130 }
 131
 132 /* Implement _InterlockedExchangeAdd8 in terms of _InterlockedCompareExchange8 */
 133 static __inline char
 134 _InterlockedExchangeAdd8(char volatile *addend, char value)
 135 {
 136    char initial = *addend;
 137    char comparand;
 138    do {
 139       char exchange = initial + value;
 140       comparand = initial;
 141       initial = _InterlockedCompareExchange8(addend, exchange, comparand);
 142    } while(initial != comparand);
 143    return comparand;
 144 }
 145
 146 #endif /* _MSC_VER < 1600 */
 147
 148 /* MSVC supports decltype keyword, but it's only supported on C++ and doesn't
 149  * quite work here; and if a C++-only solution is worthwhile, then it would be
 150  * better to use templates / function overloading, instead of decltype magic.
 151  * Therefore, we rely on implicit casting to LONGLONG for the functions that return
 152  */
 153
 154 #define p_atomic_set(_v, _i) (*(_v) = (_i))
 155 #define p_atomic_read(_v) (*(_v))
 156
 157 #define p_atomic_dec_zero(_v) \
 158    (p_atomic_dec_return(_v) == 0)
 159
 160 #define p_atomic_inc(_v) \
 161    ((void) p_atomic_inc_return(_v))
 162
 163 #define p_atomic_inc_return(_v) (\
 164    sizeof *(_v) == sizeof(short)   ? _InterlockedIncrement16((short *)  (_v)) : \
 165    sizeof *(_v) == sizeof(long)    ? _InterlockedIncrement  ((long *)   (_v)) : \
 166    sizeof *(_v) == sizeof(__int64) ? InterlockedIncrement64 ((__int64 *)(_v)) : \
 167                                      (assert(!"should not get here"), 0))
 168
 169 #define p_atomic_dec(_v) \
 170    ((void) p_atomic_dec_return(_v))
 171
 172 #define p_atomic_dec_return(_v) (\
 173    sizeof *(_v) == sizeof(short)   ? _InterlockedDecrement16((short *)  (_v)) : \
 174    sizeof *(_v) == sizeof(long)    ? _InterlockedDecrement  ((long *)   (_v)) : \
 175    sizeof *(_v) == sizeof(__int64) ? InterlockedDecrement64 ((__int64 *)(_v)) : \
 176                                      (assert(!"should not get here"), 0))
 177
 178 #define p_atomic_add(_v, _i) (\
 179    sizeof *(_v) == sizeof(char)    ? _InterlockedExchangeAdd8 ((char *)   (_v), (_i)) : \
 180    sizeof *(_v) == sizeof(short)   ? _InterlockedExchangeAdd16((short *)  (_v), (_i)) : \
 181    sizeof *(_v) == sizeof(long)    ? _InterlockedExchangeAdd  ((long *)   (_v), (_i)) : \
 182    sizeof *(_v) == sizeof(__int64) ? InterlockedExchangeAdd64((__int64 *)(_v), (_i)) : \
 183                                      (assert(!"should not get here"), 0))
 184
 185 #define p_atomic_cmpxchg(_v, _old, _new) (\
 186    sizeof *(_v) == sizeof(char)    ? _InterlockedCompareExchange8 ((char *)   (_v), (char)   (_new), (char)   (_old)) : \
 187    sizeof *(_v) == sizeof(short)   ? _InterlockedCompareExchange16((short *)  (_v), (short)  (_new), (short)  (_old)) : \
 188    sizeof *(_v) == sizeof(long)    ? _InterlockedCompareExchange  ((long *)   (_v), (long)   (_new), (long)   (_old)) : \
 189    sizeof *(_v) == sizeof(__int64) ? InterlockedCompareExchange64 ((__int64 *)(_v), (__int64)(_new), (__int64)(_old)) : \
 190                                      (assert(!"should not get here"), 0))
 191
 192 #endif
 193
 194 #if defined(PIPE_ATOMIC_OS_SOLARIS)
 195
 196 #define PIPE_ATOMIC "Solaris OS atomic functions"
 197
 198 #include <atomic.h>
 199 #include <assert.h>
 200
 201 #define p_atomic_set(_v, _i) (*(_v) = (_i))
 202 #define p_atomic_read(_v) (*(_v))
 203
 204 #define p_atomic_dec_zero(v) (\
 205    sizeof(*v) == sizeof(uint8_t)  ? atomic_dec_8_nv ((uint8_t  *)(v)) == 0 : \
 206    sizeof(*v) == sizeof(uint16_t) ? atomic_dec_16_nv((uint16_t *)(v)) == 0 : \
 207    sizeof(*v) == sizeof(uint32_t) ? atomic_dec_32_nv((uint32_t *)(v)) == 0 : \
 208    sizeof(*v) == sizeof(uint64_t) ? atomic_dec_64_nv((uint64_t *)(v)) == 0 : \
 209                                     (assert(!"should not get here"), 0))
 210
 211 #define p_atomic_inc(v) (void) (\
 212    sizeof(*v) == sizeof(uint8_t)  ? atomic_inc_8 ((uint8_t  *)(v)) : \
 213    sizeof(*v) == sizeof(uint16_t) ? atomic_inc_16((uint16_t *)(v)) : \
 214    sizeof(*v) == sizeof(uint32_t) ? atomic_inc_32((uint32_t *)(v)) : \
 215    sizeof(*v) == sizeof(uint64_t) ? atomic_inc_64((uint64_t *)(v)) : \
 216                                     (assert(!"should not get here"), 0))
 217
 218 #define p_atomic_inc_return(v) ((typeof(*v)) \
 219    sizeof(*v) == sizeof(uint8_t)  ? atomic_inc_8_nv ((uint8_t  *)(v)) : \
 220    sizeof(*v) == sizeof(uint16_t) ? atomic_inc_16_nv((uint16_t *)(v)) : \
 221    sizeof(*v) == sizeof(uint32_t) ? atomic_inc_32_nv((uint32_t *)(v)) : \
 222    sizeof(*v) == sizeof(uint64_t) ? atomic_inc_64_nv((uint64_t *)(v)) : \
 223                                     (assert(!"should not get here"), 0))
 224
 225 #define p_atomic_dec(v) ((void) \
 226    sizeof(*v) == sizeof(uint8_t)  ? atomic_dec_8 ((uint8_t  *)(v)) : \
 227    sizeof(*v) == sizeof(uint16_t) ? atomic_dec_16((uint16_t *)(v)) : \
 228    sizeof(*v) == sizeof(uint32_t) ? atomic_dec_32((uint32_t *)(v)) : \
 229    sizeof(*v) == sizeof(uint64_t) ? atomic_dec_64((uint64_t *)(v)) : \
 230                                     (assert(!"should not get here"), 0))
 231
 232 #define p_atomic_dec_return(v) ((typeof(*v)) \
 233    sizeof(*v) == sizeof(uint8_t)  ? atomic_dec_8_nv ((uint8_t  *)(v)) : \
 234    sizeof(*v) == sizeof(uint16_t) ? atomic_dec_16_nv((uint16_t *)(v)) : \
 235    sizeof(*v) == sizeof(uint32_t) ? atomic_dec_32_nv((uint32_t *)(v)) : \
 236    sizeof(*v) == sizeof(uint64_t) ? atomic_dec_64_nv((uint64_t *)(v)) : \
 237                                     (assert(!"should not get here"), 0))
 238
 239 #define p_atomic_add(v, i) ((void)                                   \
 240    sizeof(*v) == sizeof(uint8_t)  ? atomic_add_8 ((uint8_t  *)(v), (i)) : \
 241    sizeof(*v) == sizeof(uint16_t) ? atomic_add_16((uint16_t *)(v), (i)) : \
 242    sizeof(*v) == sizeof(uint32_t) ? atomic_add_32((uint32_t *)(v), (i)) : \
 243    sizeof(*v) == sizeof(uint64_t) ? atomic_add_64((uint64_t *)(v), (i)) : \
 244                                     (assert(!"should not get here"), 0))
 245
 246 #define p_atomic_cmpxchg(v, old, _new) ((typeof(*v)) \
 247    sizeof(*v) == sizeof(uint8_t)  ? atomic_cas_8 ((uint8_t  *)(v), (uint8_t )(old), (uint8_t )(_new)) : \
 248    sizeof(*v) == sizeof(uint16_t) ? atomic_cas_16((uint16_t *)(v), (uint16_t)(old), (uint16_t)(_new)) : \
 249    sizeof(*v) == sizeof(uint32_t) ? atomic_cas_32((uint32_t *)(v), (uint32_t)(old), (uint32_t)(_new)) : \
 250    sizeof(*v) == sizeof(uint64_t) ? atomic_cas_64((uint64_t *)(v), (uint64_t)(old), (uint64_t)(_new)) : \
 251                                     (assert(!"should not get here"), 0))
 252
 253 #endif
 254
 255 #ifndef PIPE_ATOMIC
 256 #error "No pipe_atomic implementation selected"
 257 #endif
 258
 259
 260
 261 #endif /* U_ATOMIC_H */