mirror of
https://github.com/mpv-player/mpv
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d4ee5e5a8a
Always require them, instead of just for some components which have hard requirements on correct atomic semantics. They should be widely available, and are supported by all recent gcc and clang compiler versions. We even have the fallbacks builtins, which should keep this working on very old gcc releases. In particular, w32_common.c recently added a hard requirement on atomics, but checking this properly in the build system would have been messy. This commit makes sure it always works. The fallback where weak atomic semantics are always fine is in theory rather questionable as well.
90 lines
3.0 KiB
C
90 lines
3.0 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
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (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 Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along 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 unsigned int v; } atomic_uint;
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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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#define memory_order_relaxed 1
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#define memory_order_seq_cst 2
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#define atomic_load_explicit(p, e) atomic_load(p)
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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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#define atomic_fetch_and(a, b) \
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__atomic_fetch_and(&(a)->v, b, __ATOMIC_SEQ_CST)
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#define atomic_fetch_or(a, b) \
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__atomic_fetch_or(&(a)->v, b, __ATOMIC_SEQ_CST)
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#define atomic_compare_exchange_strong(a, b, c) \
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__atomic_compare_exchange_n(&(a)->v, b, c, 0, __ATOMIC_SEQ_CST, \
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__ATOMIC_SEQ_CST)
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#elif HAVE_SYNC_BUILTINS
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#define atomic_load(p) \
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__sync_fetch_and_add(&(p)->v, 0)
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#define atomic_store(p, val) \
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(__sync_synchronize(), (p)->v = (val), __sync_synchronize())
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#define atomic_fetch_add(a, b) \
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__sync_fetch_and_add(&(a)->v, b)
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#define atomic_fetch_and(a, b) \
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__sync_fetch_and_and(&(a)->v, b)
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#define atomic_fetch_or(a, b) \
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__sync_fetch_and_or(&(a)->v, b)
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// Assumes __sync_val_compare_and_swap is "strong" (using the C11 meaning).
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#define atomic_compare_exchange_strong(p, old, new) \
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({ __typeof__((p)->v) val_ = __sync_val_compare_and_swap(&(p)->v, *(old), new); \
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bool ok_ = val_ == *(old); \
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if (!ok_) *(old) = val_; \
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ok_; })
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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 /* no atomics */
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#endif /* else HAVE_STDATOMIC */
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#endif
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