262 lines
11 KiB
C++
262 lines
11 KiB
C++
/*
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* M*LIB - Thin stdatomic wrapper for C++ compatibility
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*
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* Copyright (c) 2017-2018, Patrick Pelissier
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* All rights reserved.
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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* + Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* + Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE REGENTS AND CONTRIBUTORS BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef __M_ATOMIC_H
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#define __M_ATOMIC_H
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/* NOTE: Due to the C++ not having recognized stdatomic.h officialy,
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it is hard to use this header directly with a C++ compiler like
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g++ or MSVC.
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(See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60932 ).
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clang has no issue with this header.
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GCC 4.9 doesn't have a working implementation of 'atomic'
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*/
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#if defined(__cplusplus) && __cplusplus >= 201103L \
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&& !defined(__clang__) && !(defined(__GNUC__) && __GNUC__ < 5)
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/* NOTE: This is what the stdatomic.h header shall do in C++ mode. */
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#include <atomic>
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using std::memory_order;
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using std::atomic_bool;
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using std::atomic_char;
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using std::atomic_short;
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using std::atomic_int;
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using std::atomic_long;
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using std::atomic_llong;
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using std::atomic_uchar;
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using std::atomic_schar;
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using std::atomic_ushort;
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using std::atomic_uint;
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using std::atomic_ulong;
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using std::atomic_ullong;
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using std::atomic_intptr_t;
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using std::atomic_uintptr_t;
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using std::atomic_size_t;
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using std::atomic_ptrdiff_t;
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using std::atomic_intmax_t;
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using std::atomic_uintmax_t;
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using std::atomic_flag;
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using std::kill_dependency;
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using std::atomic_thread_fence;
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using std::atomic_signal_fence;
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using std::atomic_is_lock_free;
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using std::atomic_store_explicit;
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using std::atomic_store;
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using std::atomic_load_explicit;
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using std::atomic_load;
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using std::atomic_exchange_explicit;
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using std::atomic_exchange;
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using std::atomic_compare_exchange_strong_explicit;
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using std::atomic_compare_exchange_strong;
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using std::atomic_compare_exchange_weak_explicit;
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using std::atomic_compare_exchange_weak;
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using std::atomic_fetch_add;
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using std::atomic_fetch_add_explicit;
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using std::atomic_fetch_sub;
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using std::atomic_fetch_sub_explicit;
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using std::atomic_fetch_or;
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using std::atomic_fetch_or_explicit;
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using std::atomic_fetch_xor;
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using std::atomic_fetch_xor_explicit;
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using std::atomic_fetch_and;
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using std::atomic_fetch_and_explicit;
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using std::atomic_flag_test_and_set;
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using std::atomic_flag_test_and_set_explicit;
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using std::atomic_flag_clear;
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using std::atomic_flag_clear_explicit;
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#define _Atomic(T) std::atomic< T >
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#elif (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L) \
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|| ( defined(__GNUC__) && !defined(__clang__) && !defined(__cplusplus) && (__GNUC__*100 + __GNUC_MINOR__) >= 409) \
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|| (defined(__clang__) && __clang_major__ >= 4)
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/* CLANG 3.5 has issues with GCC's stdatomic.h
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and doesn't provide its own stdatomic.h */
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#include <stdatomic.h>
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#else
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/* Non working atomic.h, nor working stdatomic.h found.
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Write a compatible layer using mutex as slin as possible.
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Supports only up to 64-bits atomic (sizeof long long to be more precise).
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The locks are never properly cleared and remain active until
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the end of the program.
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We also assume that the call to the atomic_* interface is "clean".
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*/
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#include "m-mutex.h"
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/* The structure is quite large:
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__val : value of the atomic type,
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__zero : zero value of the atomic type (constant),
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__previous: temporary value used within the mutex lock,
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__lock : the mutex lock.
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*/
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#define _Atomic(T) \
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struct { \
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volatile T __val; \
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T __zero; \
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T __previous; \
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m_mutex_t __lock; \
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}
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/* Even memory order is defined, only the strongest constraint is used */
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typedef enum {
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memory_order_relaxed,
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memory_order_consume,
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memory_order_acquire,
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memory_order_release,
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memory_order_acq_rel,
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memory_order_seq_cst
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} memory_order;
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typedef _Atomic(bool) atomic_bool;
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typedef _Atomic(char) atomic_char;
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typedef _Atomic(short) atomic_short;
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typedef _Atomic(int) atomic_int;
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typedef _Atomic(long) atomic_long;
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typedef _Atomic(long long) atomic_llong;
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typedef _Atomic(unsigned char) atomic_uchar;
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typedef _Atomic(signed char) atomic_schar;
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typedef _Atomic(unsigned short) atomic_ushort;
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typedef _Atomic(unsigned int) atomic_uint;
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typedef _Atomic(unsigned long) atomic_ulong;
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typedef _Atomic(unsigned long long) atomic_ullong;
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typedef _Atomic(intptr_t) atomic_intptr_t;
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typedef _Atomic(uintptr_t) atomic_uintptr_t;
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typedef _Atomic(size_t) atomic_size_t;
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typedef _Atomic(ptrdiff_t) atomic_ptrdiff_t;
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/* Define the minimum size supported by the architecture
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for atomic read or write.
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This can help a lot since it avoids locking for atomic_load and
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atomic_store.
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*/
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#if defined(_M_X64) || defined(_M_AMD64) || defined(__x86_64__)
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# define ATOMICI_MIN_RW_SIZE 8
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#elif defined(_M_86) || defined (__i386__)
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# define ATOMICI_MIN_RW_SIZE 4
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#else
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# define ATOMICI_MIN_RW_SIZE 0
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#endif
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/* Detect if stdint.h was included */
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#if (defined (INTMAX_C) && defined (UINTMAX_C) && !defined(__cplusplus)) || \
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defined (_STDINT_H) || defined (_STDINT_H_) || defined (_STDINT) || \
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defined (_SYS_STDINT_H_)
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typedef _Atomic(intmax_t) atomic_intmax_t;
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typedef _Atomic(uintmax_t) atomic_uintmax_t;
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#endif
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/* Unlock the mutex and return the given value */
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static inline long long atomic_fetch_unlock (m_mutex_t *lock, long long val)
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{
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m_mutex_unlock (*lock);
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return val;
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}
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/* This is the heart of the wrapper:
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lock the atomic value, read it and returns the value.
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In order to avoid any compiler extension, we need to transform the
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atomic type into 'long long' then convert it back to its value.
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This is because __previous can't be read after the lock, and we can't
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generate temporary variable within a macro.
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The trick is computing _val - _zero within the lock, then
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returns retvalue + _zero after the lock.
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*/
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#define atomic_fetch_op(ptr, val, op) \
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(m_mutex_lock((ptr)->__lock), \
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(ptr)->__previous = (ptr)->__val, \
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(ptr)->__val op (val), \
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atomic_fetch_unlock(&(ptr)->__lock, (ptr)->__previous-(ptr)->__zero)+(ptr)->__zero)
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#define atomic_fetch_add(ptr, val) atomic_fetch_op(ptr, val, +=)
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#define atomic_fetch_sub(ptr, val) atomic_fetch_op(ptr, val, -=)
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#define atomic_fetch_or(ptr, val) atomic_fetch_op(ptr, val, |=)
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#define atomic_fetch_xor(ptr, val) atomic_fetch_op(ptr, val, ^=)
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#define atomic_fetch_and(ptr, val) atomic_fetch_op(ptr, val, &=)
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#define atomic_exchange(ptr, val) atomic_fetch_op(ptr, val, =)
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#define ATOMIC_VAR_INIT(val) { val, 0, 0, M_MUTEXI_INIT_VALUE }
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#define atomic_init(ptr, val) \
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(m_mutex_init((ptr)->__lock), (ptr)->__val = val, (ptr)->__zero = 0)
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#define atomic_load_lock(ptr) \
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(m_mutex_lock((ptr)->__lock), \
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(ptr)->__previous = (ptr)->__val, \
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atomic_fetch_unlock(&(ptr)->__lock, (ptr)->__previous-(ptr)->__zero)+(ptr)->__zero)
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#define atomic_store_lock(ptr, val) \
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(m_mutex_lock((ptr)->__lock), \
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(ptr)->__val = (val), \
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m_mutex_unlock((ptr)->__lock))
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#define atomic_load(ptr) \
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( sizeof ((ptr)->__val) <= ATOMICI_MIN_RW_SIZE \
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? (ptr)->__val \
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: atomic_load_lock(ptr))
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#define atomic_store(ptr, val) do { \
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if ( sizeof ((ptr)->__val) <= ATOMICI_MIN_RW_SIZE) { \
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(ptr)->__val = (val); \
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} else { \
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long long _offset = (val) - (ptr)->__zero; \
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atomic_store_lock(ptr, (ptr)->__zero + _offset); \
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} \
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} while (0)
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#define atomic_compare_exchange_strong(ptr, exp, val) \
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(m_mutex_lock((ptr)->__lock), \
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atomic_fetch_unlock(&(ptr)->__lock, \
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(ptr)->__val == *(exp) \
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? ((ptr)->__val = (val), true) \
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: (*(exp) = (ptr)->__val, false)))
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#define atomic_fetch_add_explicit(ptr, val, mem) atomic_fetch_op(ptr, val, +=)
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#define atomic_fetch_sub_explicit(ptr, val, mem) atomic_fetch_op(ptr, val, -=)
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#define atomic_fetch_or_explicit(ptr, val, mem) atomic_fetch_op(ptr, val, |=)
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#define atomic_fetch_xor_explicit(ptr, val, mem) atomic_fetch_op(ptr, val, ^=)
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#define atomic_fetch_and_explicit(ptr, val, mem) atomic_fetch_op(ptr, val, &=)
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#define atomic_exchange_explicit(ptr, val, mem) atomic_fetch_op(ptr, val, =)
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#define atomic_load_explicit(ptr, mem) atomic_load(ptr)
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#define atomic_store_explicit(ptr, val, mem) atomic_store(ptr, val)
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#define kill_dependency(ptr) atomic_load(ptr)
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#define atomic_thread_fence(mem) (void) 0
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#define atomic_signal_fence(mem) (void) 0
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#define atomic_is_lock_free(ptr) false
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#define atomic_compare_exchange_strong_explicit(ptr, exp, val, mem) atomic_compare_exchange_strong(ptr, exp, val)
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#define atomic_compare_exchange_weak_explicit(ptr, exp, val, mem) atomic_compare_exchange_strong(ptr, exp, val)
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#define atomic_compare_exchange_weak(ptr, exp, val) atomic_compare_exchange_strong(ptr, exp, val)
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/* TODO: Missing atomic_flag. Problem: it needs to be lock free! */
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#endif
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#endif
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