code.grnet.gr Git - archipelago/blob - xseg/xtypes/xatomic.h

   1 #ifndef _XATOMIC_H
   2 #define _XATOMIC_H
   3
   4 #include <stdint.h>
   5
   6 typedef struct xatomic {
   7         __uint128_t value;
   8 } xatomic;
   9
  10 #define MAX64   (0xffffffffffffffffUL)
  11 #define MAX128  (~(__uint128_t)0)
  12 #define Z128    ((__uint128_t)0)
  13 #define U128    ((__uint128_t)1)
  14
  15 #define declare_cas(at, var)                                            \
  16         uint64_t var, __xatomic_val_##var;                              \
  17         __uint128_t __xatomic_serial_##var;                             \
  18         xatomic *__xatomic_##var = (at)
  19
  20 #define cas_read(var)                                                   \
  21         __xatomic_##var##_restart:                                      \
  22         __xatomic_serial_##var = ((__xatomic_##var)->value >> 64);      \
  23         var = __xatomic_val_##var =                                     \
  24                 ((__xatomic_##var)->value & (0xffffffffffffffffUL)
  25
  26 #define cas_begin(at, var)                              \
  27         uint64_t var, __xatomic_val_##var;              \
  28         xatomic *__xatomic_##var = (at);                \
  29         __xatomic_##var##_restart:                      \
  30         var = __xatomic_val_##var = (__xatomic_##var)->value
  31
  32 #define cas_update(var)                         \
  33         __sync_bool_compare_and_swap    (       \
  34                 &(__xatomic_##var)->value,      \
  35                 __xatomic_val_##var,            \
  36                 var                             \
  37         )
  38
  39 #define cas_restart(var)        \
  40         goto __xatomic_##var##_restart
  41
  42
  43 static inline uint64_t xatomic_read(xatomic *atomic)
  44 {
  45         return (uint64_t)atomic->value;
  46 }
  47
  48 static inline void xatomic_write(xatomic *atomic, uint64_t newval)
  49 {
  50         cas_begin(atomic, val);
  51         val = newval;
  52         if (!cas_update(val))
  53                 cas_restart(val);
  54 }
  55
  56 static inline uint64_t xatomic_inc(xatomic *atomic, uint64_t inc)
  57 {
  58         uint64_t retval;
  59
  60         cas_begin(atomic, val);
  61         retval = val;
  62         val += inc;
  63         if (!cas_update(val))
  64                 cas_restart(val);
  65
  66         return retval;
  67 }
  68
  69 static inline uint64_t xatomic_dec(xatomic *atomic, uint64_t dec)
  70 {
  71         uint64_t retval;
  72
  73         cas_begin(atomic, val);
  74         retval = val;
  75         val -= dec;
  76         if (!cas_update(val))
  77                 cas_restart(val);
  78
  79         return retval;
  80 }
  81
  82 #endif