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Diffstat (limited to 'libguile/atomics-internal.h')
-rw-r--r-- | libguile/atomics-internal.h | 85 |
1 files changed, 85 insertions, 0 deletions
diff --git a/libguile/atomics-internal.h b/libguile/atomics-internal.h new file mode 100644 index 000000000..1859daa92 --- /dev/null +++ b/libguile/atomics-internal.h @@ -0,0 +1,85 @@ +#ifndef SCM_ATOMICS_INTERNAL_H +#define SCM_ATOMICS_INTERNAL_H + +/* Copyright (C) 2016 + * Free Software Foundation, Inc. + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public License + * as published by the Free Software Foundation; either version 3 of + * the License, or (at your option) any later version. + * + * This library is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this library; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA + * 02110-1301 USA + */ + + + + +#include <stdint.h> + + + + +#define HAVE_C11_ATOMICS (__STDC_VERSION__ >= 201112L && !defined(__STDC_NO_ATOMICS__)) + +#if HAVE_C11_ATOMICS + +#include <stdatomic.h> +static inline uint32_t +scm_atomic_subtract_uint32 (uint32_t *obj, uint32_t arg) +{ + return atomic_fetch_sub (obj, arg); +} +static inline _Bool +scm_atomic_compare_and_swap_uint32 (uint32_t *obj, uint32_t *expected, + uint32_t desired) +{ + return atomic_compare_exchange_weak (obj, expected, desired); +} + +#else /* HAVE_C11_ATOMICS */ + +/* Fallback implementation using locks. */ +#include "libguile/threads.h" +static scm_i_pthread_mutex_t atomics_lock = SCM_I_PTHREAD_MUTEX_INITIALIZER; +static inline uint32_t +scm_atomic_subtract_uint32 (uint32_t *obj, uint32_t arg) +{ + uint32_t ret; + scm_i_pthread_mutex_lock (&atomics_lock); + ret = *obj; + *obj -= arg; + scm_i_pthread_mutex_unlock (&atomics_lock); + return ret; +} +static inline int +scm_atomic_compare_and_swap_uint32 (uint32_t *obj, uint32_t *expected, + uint32_t desired) +{ + int ret; + scm_i_pthread_mutex_lock (&atomics_lock); + if (*obj == *expected) + { + *obj = desired; + ret = 1; + } + else + { + *expected = *obj; + ret = 0; + } + scm_i_pthread_mutex_unlock (&atomics_lock); + return ret; +} + +#endif /* HAVE_C11_ATOMICS */ + +#endif /* SCM_ATOMICS_INTERNAL_H */ |