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https://github.com/mpv-player/mpv
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885b744767
This should be more correct. The builtins were made to directly map to C11, and the way we use them is now relatively close to how gcc implements atomics in 4.9. In particular, we make use of the load and store builtins. I'm not entirely sure why gcc didn't support stdatomic.h in 4.8 already. Maybe support for the builtins was incomplete or broken - so there's a lot of room for doubt about the correctness of this.
67 lines
2.0 KiB
C
67 lines
2.0 KiB
C
/*
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* This file is part of mpv.
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* Copyright (c) 2013 Stefano Pigozzi <stefano.pigozzi@gmail.com>
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*
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* mpv is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* mpv is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with mpv. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef MP_ATOMICS_H
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#define MP_ATOMICS_H
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#include <inttypes.h>
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#include "config.h"
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#if HAVE_STDATOMIC
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#include <stdatomic.h>
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#else
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// Emulate the parts of C11 stdatomic.h needed by mpv.
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// Still relies on gcc/clang atomic builtins.
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typedef struct { volatile unsigned long v; } atomic_ulong;
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typedef struct { volatile int v; } atomic_int;
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typedef struct { volatile _Bool v; } atomic_bool;
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typedef struct { volatile long long v; } atomic_llong;
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typedef struct { volatile uint_least32_t v; } atomic_uint_least32_t;
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typedef struct { volatile unsigned long long v; } atomic_ullong;
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#define ATOMIC_VAR_INIT(x) \
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{.v = (x)}
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#if HAVE_ATOMIC_BUILTINS
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#define atomic_load(p) \
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__atomic_load_n(&(p)->v, __ATOMIC_SEQ_CST)
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#define atomic_store(p, val) \
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__atomic_store_n(&(p)->v, val, __ATOMIC_SEQ_CST)
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#define atomic_fetch_add(a, b) \
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__atomic_fetch_add(&(a)->v, b, __ATOMIC_SEQ_CST)
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#elif HAVE_SYNC_BUILTINS
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#define atomic_load(p) \
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(__sync_synchronize(), (p)->v)
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#define atomic_store(p, val) \
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((p)->v = (val), __sync_synchronize())
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#define atomic_fetch_add(a, b) \
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(__sync_add_and_fetch(&(a)->v, b), __sync_synchronize())
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#else
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# error "this should have been a configuration error, report a bug please"
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#endif
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#endif /* else HAVE_STDATOMIC */
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#endif
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