标准C++库的原子操作函数
以下代码来自GUN的libstdc++-v3.0.97
原子操作所在的文件,我们可以看到在配置文件夹cpu下有各种平台的实现文件
atomicity.h
#ifndef _BITS_ATOMICITY_H
#define _BITS_ATOMICITY_H 1
typedef int _Atomic_word;
static inline _Atomic_word
__attribute__ ((__unused__))
__exchange_and_add (volatile _Atomic_word *__mem, int __val)
{
register _Atomic_word __result;
__asm__ __volatile__ ("lock; xaddl %0,%2"
: "=r" (__result)
: "0" (__val), "m" (*__mem)
: "memory");
return __result;
}
static inline void
__attribute__ ((__unused__))
__atomic_add (volatile _Atomic_word* __mem, int __val)
{
__asm__ __volatile__ ("lock; addl %0,%1"
: : "ir" (__val), "m" (*__mem) : "memory");
}
#endif /* atomicity.h */
ios_base中的异常类定义
00166 class failure : public exception
00167 {
00168 public:
00169 #ifdef _GLIBCPP_RESOLVE_LIB_DEFECTS
00170 //48. Use of non-existent exception constructor
00171 explicit
00172 failure(const string& __str) throw();
00173
00174 // This declaration is not useless:
00175 // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118
00176 virtual
00177 ~failure() throw();
00178
00179 virtual const char*
00180 what() const throw();
00181
00182 private:
00183 enum { _M_bufsize = 256 };
00184 char _M_name[_M_bufsize];
00185 #endif
00186 };
ios_base中的回调结构定义,其中涉及原子操作,在前面介绍过
00381 struct _Callback_list
00382 {
00383 // Data Members
00384 _Callback_list* _M_next;
00385 ios_base::event_callback _M_fn;
00386 int _M_index;
00387 _Atomic_word _M_refcount; // 0 means one reference.
00388
00389 _Callback_list(ios_base::event_callback __fn, int __index,
00390 _Callback_list* __cb)
00391 : _M_next(__cb), _M_fn(__fn), _M_index(__index), _M_refcount(0) { }
00392
00393 void
00394 _M_add_reference() { __atomic_add(&_M_refcount, 1); }
00395
00396 // 0 => OK to delete.
00397 int
00398 _M_remove_reference() { return __exchange_and_add(&_M_refcount, -1); }
00399 };
00400
00401 _Callback_list* _M_callbacks;
00402
00403 void
00404 _M_call_callbacks(event __ev) throw();
00405
00406 void
00407 _M_dispose_callbacks(void);
ios_base初始化类定义
00448 class Init
00449 {
00450 friend class ios_base;
00451 public:
00452 Init();
00453 ~Init();
00454
00455 static void
00456 _S_ios_create(bool __sync);
00457
00458 static void
00459 _S_ios_destroy();
00460
00461 private:
00462 static int _S_ios_base_init;
00463 static bool _S_synced_with_stdio;
00464 };
