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https://github.com/mpv-player/mpv
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d27a2bc546
Not all compilers on all platforms have atomics available (even if they could, technically speaking). We don't use atomics that much, only the following things rely on it: 1. the audio pull code, and all audio outputs using it 2. updating global msg levels 3. reading log messages through the client API Just disable 1. and 3. if atomics are not available. For 2., using fake- atomics isn't too bad; at worst, message levels won't properly update under certain situations (but most likely, it will work just fine). This means if atomics are not available, the client API function mpv_request_log_messages() will do nothing. CC: @mpv-player/stable
78 lines
2.3 KiB
C
78 lines
2.3 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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#define HAVE_ATOMICS 1
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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_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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#else
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// This is extremely wrong. The build system actually disables code that has
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// a serious dependency on working atomics, so this is barely ok.
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#define atomic_load(p) ((p)->v)
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#define atomic_store(p, val) ((p)->v = (val))
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#define atomic_fetch_add(a, b) (((a)->v += (b)) - (b))
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#undef HAVE_ATOMICS
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#define HAVE_ATOMICS 0
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#endif /* no atomics */
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#endif /* else HAVE_STDATOMIC */
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#endif
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