src/libstrongswan/utils/utils/atomics.c

   1 /*
   2  * Copyright (C) 2008-2014 Tobias Brunner
   3  * Copyright (C) 2005-2008 Martin Willi
   4  * Hochschule fuer Technik Rapperswil
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License as published by the
   8  * Free Software Foundation; either version 2 of the License, or (at your
   9  * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
  10  *
  11  * This program is distributed in the hope that it will be useful, but
  12  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  13  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * for more details.
  15  */
  16
  17 #include <utils/utils.h>
  18
  19 #if !defined(HAVE_GCC_ATOMIC_OPERATIONS) && !defined(HAVE_GCC_SYNC_OPERATIONS)
  20
  21 #include <threading/spinlock.h>
  22
  23 /**
  24  * Spinlock for ref_get/put
  25  */
  26 static spinlock_t *ref_lock;
  27
  28 /**
  29  * Increase refcount
  30  */
  31 refcount_t ref_get(refcount_t *ref)
  32 {
  33         refcount_t current;
  34
  35         ref_lock->lock(ref_lock);
  36         current = ++(*ref);
  37         ref_lock->unlock(ref_lock);
  38
  39         return current;
  40 }
  41
  42 /**
  43  * Decrease refcount
  44  */
  45 bool ref_put(refcount_t *ref)
  46 {
  47         bool more_refs;
  48
  49         ref_lock->lock(ref_lock);
  50         more_refs = --(*ref) > 0;
  51         ref_lock->unlock(ref_lock);
  52         return !more_refs;
  53 }
  54
  55 /**
  56  * Current refcount
  57  */
  58 refcount_t ref_cur(refcount_t *ref)
  59 {
  60         refcount_t current;
  61
  62         ref_lock->lock(ref_lock);
  63         current = *ref;
  64         ref_lock->unlock(ref_lock);
  65
  66         return current;
  67 }
  68
  69 /**
  70  * Spinlock for all compare and swap operations.
  71  */
  72 static spinlock_t *cas_lock;
  73
  74 /**
  75  * Compare and swap if equal to old value
  76  */
  77 #define _cas_impl(name, type) \
  78 bool cas_##name(type *ptr, type oldval, type newval) \
  79 { \
  80         bool swapped; \
  81         cas_lock->lock(cas_lock); \
  82         if ((swapped = (*ptr == oldval))) { *ptr = newval; } \
  83         cas_lock->unlock(cas_lock); \
  84         return swapped; \
  85 }
  86
  87 _cas_impl(bool, bool)
  88 _cas_impl(ptr, void*)
  89
  90 #endif /* !HAVE_GCC_ATOMIC_OPERATIONS && !HAVE_GCC_SYNC_OPERATIONS */
  91
  92 /**
  93  * See header
  94  */
  95 void atomics_init()
  96 {
  97 #if !defined(HAVE_GCC_ATOMIC_OPERATIONS) && !defined(HAVE_GCC_SYNC_OPERATIONS)
  98         ref_lock = spinlock_create();
  99         cas_lock = spinlock_create();
 100 #endif
 101 }
 102
 103 /**
 104  * See header
 105  */
 106 void atomics_deinit()
 107 {
 108 #if !defined(HAVE_GCC_ATOMIC_OPERATIONS) && !defined(HAVE_GCC_SYNC_OPERATIONS)
 109         ref_lock->destroy(ref_lock);
 110         cas_lock->destroy(cas_lock);
 111 #endif
 112 }