text: /*-
   * Copyright (c) 1997,98 The NetBSD Foundation, Inc.
   * All rights reserved.
   *
   * This code is derived from software contributed to The NetBSD Foundation
   * by J.T. Conklin.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   *
   * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
   * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
   * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
   * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   * POSSIBILITY OF SUCH DAMAGE.
   *
   * $FreeBSD: soc2013/dpl/head/lib/libc/include/reentrant.h 204631 2010-03-02 17:20:04Z joel $
   */
  
  /*
   * Requirements:
   * 
   * 1. The thread safe mechanism should be lightweight so the library can
   *    be used by non-threaded applications without unreasonable overhead.
   * 
   * 2. There should be no dependency on a thread engine for non-threaded
   *    applications.
   * 
   * 3. There should be no dependency on any particular thread engine.
   * 
   * 4. The library should be able to be compiled without support for thread
   *    safety.
   * 
   * 
   * Rationale:
   * 
   * One approach for thread safety is to provide discrete versions of the
   * library: one thread safe, the other not.  The disadvantage of this is
   * that libc is rather large, and two copies of a library which are 99%+
   * identical is not an efficent use of resources.
   * 
   * Another approach is to provide a single thread safe library.  However,
   * it should not add significant run time or code size overhead to non-
   * threaded applications.
   * 
   * Since the NetBSD C library is used in other projects, it should be
   * easy to replace the mutual exclusion primitives with ones provided by
   * another system.  Similarly, it should also be easy to remove all
   * support for thread safety completely if the target environment does
   * not support threads.
   * 
   * 
   * Implementation Details:
   * 
   * The mutex primitives used by the library (mutex_t, mutex_lock, etc.)
   * are macros which expand to the cooresponding primitives provided by
   * the thread engine or to nothing.  The latter is used so that code is
   * not unreasonably cluttered with #ifdefs when all thread safe support
   * is removed.
   * 
   * The mutex macros can be directly mapped to the mutex primitives from
   * pthreads, however it should be reasonably easy to wrap another mutex
   * implementation so it presents a similar interface.
   * 
   * Stub implementations of the mutex functions are provided with *weak*
   * linkage.  These functions simply return success.  When linked with a
   * thread library (i.e. -lpthread), the functions will override the
   * stubs.
   */
  
  #include <pthread.h>
  #include <pthread_np.h>
  #include "libc_private.h"
  
  #define mutex_t			pthread_mutex_t
  #define cond_t			pthread_cond_t
  #define rwlock_t		pthread_rwlock_t
  #define once_t			pthread_once_t
  
  #define thread_key_t		pthread_key_t
  #define MUTEX_INITIALIZER	PTHREAD_MUTEX_INITIALIZER
  #define RWLOCK_INITIALIZER	PTHREAD_RWLOCK_INITIALIZER
  #define ONCE_INITIALIZER	PTHREAD_ONCE_INIT
  
  #define mutex_init(m, a)	_pthread_mutex_init(m, a)
  #define mutex_lock(m)		if (__isthreaded) \
  				_pthread_mutex_lock(m)
  #define mutex_unlock(m)		if (__isthreaded) \
  				_pthread_mutex_unlock(m)
  #define mutex_trylock(m)	(__isthreaded ? 0 : _pthread_mutex_trylock(m))
  
  #define cond_init(c, a, p)	_pthread_cond_init(c, a)
  #define cond_signal(m)		if (__isthreaded) \
  				_pthread_cond_signal(m)
  #define cond_broadcast(m)	if (__isthreaded) \
  				_pthread_cond_broadcast(m)
  #define cond_wait(c, m)		if (__isthreaded) \
  				_pthread_cond_wait(c, m)
  
  #define rwlock_init(l, a)	_pthread_rwlock_init(l, a)
  #define rwlock_rdlock(l)	if (__isthreaded) \
  				_pthread_rwlock_rdlock(l)
  #define rwlock_wrlock(l)	if (__isthreaded) \
  				_pthread_rwlock_wrlock(l)
  #define rwlock_unlock(l)	if (__isthreaded) \
  				_pthread_rwlock_unlock(l)
  
  #define thr_keycreate(k, d)	_pthread_key_create(k, d)
  #define thr_setspecific(k, p)	_pthread_setspecific(k, p)
  #define thr_getspecific(k)	_pthread_getspecific(k)
  #define thr_sigsetmask(f, n, o)	_pthread_sigmask(f, n, o)
  
  #define thr_once(o, i)		_pthread_once(o, i)
  #define thr_self()		_pthread_self()
  #define thr_exit(x)		_pthread_exit(x)
  #define thr_main()		_pthread_main_np()
  