atomic operations

From: Vadim Egorov (egorovv_at_[hidden])
Date: 2002-03-01 20:58:53

Here is my attempt to fix boost atomicity support using gcc
inline asm for i386 platform.

Comments?

Index: boost/config/compiler/gcc.hpp
===================================================================
RCS file: /cvsroot/boost/boost/boost/config/compiler/gcc.hpp,v
retrieving revision 1.11
diff -c -r1.11 gcc.hpp
*** boost/config/compiler/gcc.hpp	2 Feb 2002 18:36:11 -0000	1.11
--- boost/config/compiler/gcc.hpp	28 Feb 2002 21:27:04 -0000
***************
*** 35,40 ****
--- 35,44 ----
  //
  #define BOOST_HAS_THREADS
  
+ #ifdef __i386__
+ #  define BOOST_HAS_ATOMICOPS
+ #endif
+ 
  //
  // gcc has "long long"
  //
Index: boost/detail/atomic_count.hpp
===================================================================
RCS file: /cvsroot/boost/boost/boost/detail/atomic_count.hpp,v
retrieving revision 1.3
diff -c -r1.3 atomic_count.hpp
*** boost/detail/atomic_count.hpp	4 Feb 2002 08:00:16 -0000	1.3
--- boost/detail/atomic_count.hpp	28 Feb 2002 21:27:05 -0000
***************
*** 93,101 ****
  
  #include <boost/detail/atomic_count_win32.hpp>
  
! #elif defined(linux) || defined(__linux) || defined(__linux__)
  
! #include <boost/detail/atomic_count_linux.hpp>
  
  #elif defined(BOOST_HAS_PTHREADS)
  
--- 93,101 ----
  
  #include <boost/detail/atomic_count_win32.hpp>
  
! #elif defined(BOOST_HAS_ATOMICOPS)
  
! #include <boost/detail/atomic_count_atomic.hpp>
  
  #elif defined(BOOST_HAS_PTHREADS)
  
Index: boost/detail/atomic_count_atomic.hpp
===================================================================
RCS file: boost/detail/atomic_count_atomic.hpp
diff -N boost/detail/atomic_count_atomic.hpp
*** /dev/null	1 Jan 1970 00:00:00 -0000
--- boost/detail/atomic_count_atomic.hpp	28 Feb 2002 21:27:05 -0000
***************
*** 0 ****
--- 1,47 ----
+ #ifndef BOOST_DETAIL_ATOMIC_COUNT_ATOMIC_HPP_INCLUDED
+ #define BOOST_DETAIL_ATOMIC_COUNT_ATOMIC_HPP_INCLUDED
+ 
+ #include <boost/detail/atomic_ops.hpp>
+ 
+ namespace boost
+ {
+ 
+ namespace detail
+ {
+ 
+ class atomic_count
+ {
+ public:
+ 
+   explicit atomic_count(long v) : v_(v)
+     {
+     }
+ 
+     void operator++()
+     {
+         atomic_inc(&value_);
+     }
+ 
+     long operator--()
+     {
+         return !atomic_dec_and_test(&value_);
+     }
+ 
+     operator long() const
+     {
+         return value_;
+     }
+ 
+ private:
+ 
+     atomic_count(atomic_count const &);
+     atomic_count & operator=(atomic_count const &);
+ 
+     atomic_t value_;
+ };
+ 
+ } // namespace detail
+ 
+ } // namespace boost
+ 
+ #endif // #ifndef BOOST_DETAIL_ATOMIC_COUNT_ATOMIC_HPP_INCLUDED
Index: boost/detail/atomic_ops.hpp
===================================================================
RCS file: boost/detail/atomic_ops.hpp
diff -N boost/detail/atomic_ops.hpp
*** /dev/null	1 Jan 1970 00:00:00 -0000
--- boost/detail/atomic_ops.hpp	28 Feb 2002 21:27:05 -0000
***************
*** 0 ****
--- 1,30 ----
+ #ifndef BOOST_DETAIL_ATOMIC_OPS_HPP_INCLUDED
+ #define BOOST_DETAIL_ATOMIC_OPS_HPP_INCLUDED
+ 
+ #include <boost/config.hpp>
+ 
+ #if defined(__GNUC__) && defined(__i386__)
+ 
+ static inline long 
+ atomic_inc(volatile long *mem)
+ {
+   register long result;
+   __asm__ __volatile__ ("lock; incl %0"
+ 			:"=m" (*mem)
+ 			:"m" (*mem));
+   return result;
+ }
+ 
+ static inline bool
+ atomic_dec_and_test(volatile long* mem)
+ {
+   unsigned char c;
+   __asm__ __volatile__ ("lock; decl %0; sete %1"
+ 			:"=m" (*mem), "=qm" (c)
+ 			:"m" (*mem) : "memory");
+   return c != 0;
+ }
+ 
+ #endif // defined(__GNUC__) && defined(__i386__)
+ 
+ #endif // #ifndef BOOST_DETAIL_ATOMIC_OPS_HPP_INCLUDED
Index: boost/detail/lightweight_mutex.hpp
===================================================================
RCS file: /cvsroot/boost/boost/boost/detail/lightweight_mutex.hpp,v
retrieving revision 1.3
diff -c -r1.3 lightweight_mutex.hpp
*** boost/detail/lightweight_mutex.hpp	27 Feb 2002 16:35:15 -0000	1.3
--- boost/detail/lightweight_mutex.hpp	28 Feb 2002 21:27:05 -0000
***************
*** 38,47 ****
  #  include <boost/detail/lwm_nop.hpp>
  #elif defined(WIN32) || defined(_WIN32) || defined(__WIN32__)
  #  include <boost/detail/lwm_win32.hpp>
- #elif defined(linux) || defined(__linux) || defined(__linux__)
- #  include <boost/detail/lwm_linux.hpp>
  #elif defined(__sgi)
  #  include <boost/detail/lwm_irix.hpp>
  #elif defined(BOOST_HAS_PTHREADS)
  #  include <boost/detail/lwm_pthreads.hpp>
  #else
--- 38,47 ----
  #  include <boost/detail/lwm_nop.hpp>
  #elif defined(WIN32) || defined(_WIN32) || defined(__WIN32__)
  #  include <boost/detail/lwm_win32.hpp>
  #elif defined(__sgi)
  #  include <boost/detail/lwm_irix.hpp>
+ #elif defined(BOOST_HAS_ATOMICOPS)
+ #  include <boost/detail/lwm_atomic.hpp>
  #elif defined(BOOST_HAS_PTHREADS)
  #  include <boost/detail/lwm_pthreads.hpp>
  #else
Index: boost/detail/lwm_atomic.hpp
===================================================================
RCS file: boost/detail/lwm_atomic.hpp
diff -N boost/detail/lwm_atomic.hpp
*** /dev/null	1 Jan 1970 00:00:00 -0000
--- boost/detail/lwm_atomic.hpp	28 Feb 2002 21:27:06 -0000
***************
*** 0 ****
--- 1,70 ----
+ #ifndef BOOST_DETAIL_LWM_ATOMIC_HPP_INCLUDED
+ #define BOOST_DETAIL_LWM_ATOMIC_HPP_INCLUDED
+ 
+ #if _MSC_VER >= 1020
+ #pragma once
+ #endif
+ 
+ #if defined(BOOST_HAS_SCHED_YIELD)
+ #include <sched.h>
+ #endif // BOOST_HAS_SCHED_YIELD
+ #include <boost/detail/atomic_ops.hpp>
+ 
+ namespace boost
+ {
+ 
+ namespace detail
+ {
+ 
+ class lightweight_mutex
+ {
+ private:
+ 
+     long a_;
+ 
+     lightweight_mutex(lightweight_mutex const &);
+     lightweight_mutex & operator=(lightweight_mutex const &);
+ 
+ public:
+ 
+   lightweight_mutex() : a_(1)
+     {
+     }
+ 
+     class scoped_lock;
+     friend class scoped_lock;
+ 
+     class scoped_lock
+     {
+     private:
+ 
+         lightweight_mutex & m_;
+ 
+         scoped_lock(scoped_lock const &);
+         scoped_lock & operator=(scoped_lock const &);
+ 
+     public:
+ 
+         explicit scoped_lock(lightweight_mutex & m): m_(m)
+         {
+             while( !atomic_dec_and_test(&m_.a_) )
+             {
+                 atomic_inc(&m_.a_);
+ #if defined(BOOST_HAS_SCHED_YIELD)
+                 sched_yield();
+ #endif
+             }
+         }
+ 
+         ~scoped_lock()
+         {
+             atomic_inc(&m_.a_);
+         }
+     };
+ };
+ 
+ } // namespace detail
+ 
+ } // namespace boost
+ 
+ #endif // #ifndef BOOST_DETAIL_LWM_ATOMIC_HPP_INCLUDED

-- 
Thanks,
Vadim

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