include/vlc_atomic.h

   1 /*****************************************************************************
   2  * vlc_atomic.h:
   3  *****************************************************************************
   4  * Copyright (C) 2010 Rémi Denis-Courmont
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU Lesser General Public License as published by
   8  * the Free Software Foundation; either version 2.1 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  14  * GNU Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public License
  17  * along with this program; if not, write to the Free Software Foundation,
  18  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  19  *****************************************************************************/
  20
  21 #ifndef VLC_ATOMIC_H
  22 # define VLC_ATOMIC_H
  23
  24 /**
  25  * \file
  26  * Atomic operations do not require locking, but they are not very powerful.
  27  */
  28
  29 /* Clang older versions support atomics but lacks the stdatomic.h header */
  30 #if defined(__clang__)
  31 # if !defined(__has_include) || !__has_include(<stdatomic.h>)
  32 #  define __STDC_NO_ATOMICS__ 1
  33 # endif
  34 #endif
  35
  36 # ifndef __cplusplus
  37 #  if !defined (__STDC_NO_ATOMICS__)
  38 /*** Native C11 atomics ***/
  39 #   include <stdatomic.h>
  40
  41 #  else
  42 /*** Intel/GCC atomics ***/
  43
  44 #  define ATOMIC_FLAG_INIT false
  45
  46 #  define ATOMIC_VAR_INIT(value) (value)
  47
  48 #  define atomic_init(obj, value) \
  49     do { *(obj) = (value); } while(0)
  50
  51 #  define kill_dependency(y) \
  52     ((void)0)
  53
  54 #  define atomic_thread_fence(order) \
  55     __sync_synchronize()
  56
  57 #  define atomic_signal_fence(order) \
  58     ((void)0)
  59
  60 #  define atomic_is_lock_free(obj) \
  61     false
  62
  63 typedef          bool      atomic_flag;
  64 typedef          bool      atomic_bool;
  65 typedef          char      atomic_char;
  66 typedef   signed char      atomic_schar;
  67 typedef unsigned char      atomic_uchar;
  68 typedef          short     atomic_short;
  69 typedef unsigned short     atomic_ushort;
  70 typedef          int       atomic_int;
  71 typedef unsigned int       atomic_uint;
  72 typedef          long      atomic_long;
  73 typedef unsigned long      atomic_ulong;
  74 typedef          long long atomic_llong;
  75 typedef unsigned long long atomic_ullong;
  76 //typedef          char16_t  atomic_char16_t;
  77 //typedef          char32_t  atomic_char32_t;
  78 typedef          wchar_t   atomic_wchar_t;
  79 typedef       int_least8_t atomic_int_least8_t;
  80 typedef      uint_least8_t atomic_uint_least8_t;
  81 typedef      int_least16_t atomic_int_least16_t;
  82 typedef     uint_least16_t atomic_uint_least16_t;
  83 typedef      int_least32_t atomic_int_least32_t;
  84 typedef     uint_least32_t atomic_uint_least32_t;
  85 typedef      int_least64_t atomic_int_least64_t;
  86 typedef     uint_least64_t atomic_uint_least64_t;
  87 typedef       int_fast8_t atomic_int_fast8_t;
  88 typedef      uint_fast8_t atomic_uint_fast8_t;
  89 typedef      int_fast16_t atomic_int_fast16_t;
  90 typedef     uint_fast16_t atomic_uint_fast16_t;
  91 typedef      int_fast32_t atomic_int_fast32_t;
  92 typedef     uint_fast32_t atomic_uint_fast32_t;
  93 typedef      int_fast64_t atomic_int_fast64_t;
  94 typedef     uint_fast64_t atomic_uint_fast64_t;
  95 typedef          intptr_t atomic_intptr_t;
  96 typedef         uintptr_t atomic_uintptr_t;
  97 typedef            size_t atomic_size_t;
  98 typedef         ptrdiff_t atomic_ptrdiff_t;
  99 typedef          intmax_t atomic_intmax_t;
 100 typedef         uintmax_t atomic_uintmax_t;
 101
 102 #  define atomic_store(object,desired) \
 103     do { \
 104         *(object) = (desired); \
 105         __sync_synchronize(); \
 106     } while (0)
 107
 108 #  define atomic_store_explicit(object,desired,order) \
 109     atomic_store(object,desired)
 110
 111 #  define atomic_load(object) \
 112     (__sync_synchronize(), *(object))
 113
 114 #  define atomic_load_explicit(object,order) \
 115     atomic_load(object)
 116
 117 #  define atomic_exchange(object,desired) \
 118 ({  \
 119     typeof (object) _obj = (object); \
 120     typeof (*object) _old; \
 121     do \
 122         _old = atomic_load(_obj); \
 123     while (!__sync_bool_compare_and_swap(_obj, _old, (desired))); \
 124     _old; \
 125 })
 126
 127 #  define atomic_exchange_explicit(object,desired,order) \
 128     atomic_exchange(object,desired)
 129
 130 #  define atomic_compare_exchange(object,expected,desired) \
 131 ({  \
 132     typeof (object) _exp = (expected); \
 133     typeof (*object) _old = *_exp; \
 134     *_exp = __sync_val_compare_and_swap((object), _old, (desired)); \
 135     *_exp == _old; \
 136 })
 137
 138 #  define atomic_compare_exchange_strong(object,expected,desired) \
 139     atomic_compare_exchange(object, expected, desired)
 140
 141 #  define atomic_compare_exchange_strong_explicit(object,expected,desired,order,order_different) \
 142     atomic_compare_exchange_strong(object, expected, desired)
 143
 144 #  define atomic_compare_exchange_weak(object,expected,desired) \
 145     atomic_compare_exchange(object, expected, desired)
 146
 147 #  define atomic_compare_exchange_weak_explicit(object,expected,desired,order_equal,order_different) \
 148     atomic_compare_exchange_weak(object, expected, desired)
 149
 150 #  define atomic_fetch_add(object,operand) \
 151     __sync_fetch_and_add(object, operand)
 152
 153 #  define atomic_fetch_add_explicit(object,operand,order) \
 154     atomic_fetch_add(object,operand)
 155
 156 #  define atomic_fetch_sub(object,operand) \
 157     __sync_fetch_and_sub(object, operand)
 158
 159 #  define atomic_fetch_sub_explicit(object,operand,order) \
 160     atomic_fetch_sub(object,operand)
 161
 162 #  define atomic_fetch_or(object,operand) \
 163     __sync_fetch_and_or(object, operand)
 164
 165 #  define atomic_fetch_or_explicit(object,operand,order) \
 166     atomic_fetch_or(object,operand)
 167
 168 #  define atomic_fetch_xor(object,operand) \
 169     __sync_fetch_and_sub(object, operand)
 170
 171 #  define atomic_fetch_xor_explicit(object,operand,order) \
 172     atomic_fetch_sub(object,operand)
 173
 174 #  define atomic_fetch_and(object,operand) \
 175     __sync_fetch_and_and(object, operand)
 176
 177 #  define atomic_fetch_and_explicit(object,operand,order) \
 178     atomic_fetch_and(object,operand)
 179
 180 #  define atomic_flag_test_and_set(object) \
 181     atomic_exchange(object, true)
 182
 183 #  define atomic_flag_test_and_set_explicit(object,order) \
 184     atomic_flag_test_and_set(object)
 185
 186 #  define atomic_flag_clear(object) \
 187     atomic_store(object, false)
 188
 189 #  define atomic_flag_clear_explicit(object,order) \
 190     atomic_flag_clear(object)
 191
 192 # endif /* !C11 */
 193
 194 typedef atomic_uint_least32_t vlc_atomic_float;
 195
 196 static inline void vlc_atomic_init_float(vlc_atomic_float *var, float f)
 197 {
 198     union { float f; uint32_t i; } u;
 199     u.f = f;
 200     atomic_init(var, u.i);
 201 }
 202
 203 /** Helper to retrieve a single precision from an atom. */
 204 static inline float vlc_atomic_load_float(vlc_atomic_float *atom)
 205 {
 206     union { float f; uint32_t i; } u;
 207     u.i = atomic_load(atom);
 208     return u.f;
 209 }
 210
 211 /** Helper to store a single precision into an atom. */
 212 static inline void vlc_atomic_store_float(vlc_atomic_float *atom, float f)
 213 {
 214     union { float f; uint32_t i; } u;
 215     u.f = f;
 216     atomic_store(atom, u.i);
 217 }
 218
 219 # else /* C++ */
 220 /*** Native C++11 atomics ***/
 221 #   include <atomic>
 222 # endif /* C++ */
 223
 224 #endif