89 lines
3.8 KiB
C++
89 lines
3.8 KiB
C++
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/*
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* Copyright (c) 1995 John Birrell <jb@cimlogic.com.au>.
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* All rights reserved.
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*
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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
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* are met:
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* 1. 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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* 2. 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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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by John Birrell.
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* 4. Neither the name of the author nor the names of any co-contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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*/
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/*
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* This module uses the magic of C++ static constructors to initialize the
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* threads package at program start-up time.
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*
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* Note: Because of a bug in certain versions of "/usr/lib/c++rt0.o", you
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* should _not_ enclose the body of this module in an "#ifdef _THREAD_SAFE"
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* conditional.
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*/
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extern "C" void _thread_init(void);
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/*
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* First, we declare a class with a constructor.
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*/
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class _thread_init_invoker {
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public:
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_thread_init_invoker(); /* Constructor declaration. */
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};
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/*
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* Here is the definition of the constructor. All it does is call the
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* threads initialization function, "_thread_init".
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*/
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_thread_init_invoker::_thread_init_invoker()
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{
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_thread_init();
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}
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/*
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* Here is a single, static instance of our "_thread_init_invoker" class.
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* The mere existance of this instance will result in its constructor
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* being called, automatically, at program start-up time.
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*/
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static _thread_init_invoker the_thread_init_invoker;
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/*
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* For the shared version of the threads library, the above is sufficient.
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* But for the archive version of the library, we need a little bit more.
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* Namely, we must arrange for this particular module to be pulled in from
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* the archive library at link time. To accomplish that, we define and
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* initialize a variable, "_thread_autoinit_dummy_decl". This variable is
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* referenced (as an extern) from the module "uthread_init.c". So, if
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* that module is used, then it will create a need for this module as well,
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* ensuring that this module will be present in the executable.
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*
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* We know that, if the user does _anything_ at all with threads, then the
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* "uthread_init.c" module will be linked in. That is the case because
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* "uthread_init.c" is the module that defines all of the global variables
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* used by the threads library. The presence of "uthread_init.c" will, in
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* turn, force this module to be linked in. And the presence of this module
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* in the executable will result in the constructor being invoked, and
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* "_thread_init" being called.
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*/
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extern "C" int _thread_autoinit_dummy_decl; /* Declare with "C" linkage */
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int _thread_autoinit_dummy_decl = 0;
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