Atomic operating function of standard C libraries
The following code from Gun's libstdc - v3.0.97
The file where the atomic operation is located, we can see the implementation files of various platforms under the configuration folder CPU
Atomicity.h
#ifndef _bits_atomicity_h
#define _bits_atomicity_h 1
TypedEf INT _TOMIC_WORD;
Static inline _tomic_word
__ATTRIBUTE__ (__unused__)))
__exchange_and_add (volatile _tomic_word * __ MEM, INT __VAL)
{
Register _tomic_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 _tomic_word * __mem, int __val)
{
__ASM__ __Volatile__ ("Lock; AddL% 0,% 1"
:: "IR" (__val), "M" (* __MEM): "Memory");
}
#ENDIF / * Atomicity.h * /
Anomaly class definition in iOS_Base
00166 Class Failure: Public Exception: PUBLIC EXCEPTION
00167 {
00168 public:
00169 #ifDef _glibcpp_resolve_lib_defects
00170 // 48. Use of non-evtructor
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 *
0000 () const throw ();
00181
00182 private:
00183 enum {_m_bufsize = 256};
00184 char _m_name [_m_bufsize];
00185 #ENDIF
00186};
The callback structure definition in iOS_BASE, involving atomic operations, introduced earlier
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 _tomic_word _m_refcount; // 0 means one reason.00388
00389 _Callback_List (iOS_BASE :: Event_Callback __fn, int __index,
00390 _Callback_list * __cb)
00391: _m_next (__ cb), _m_fn (__fn), _m_index (_ ingx), _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 initialization class definition
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};
