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)

{

__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 };