src/boost/boost/smart_ptr/detail/spinlock_gcc_arm.hpp

   1 #ifndef BOOST_SMART_PTR_DETAIL_SPINLOCK_GCC_ARM_HPP_INCLUDED
   2 #define BOOST_SMART_PTR_DETAIL_SPINLOCK_GCC_ARM_HPP_INCLUDED
   3
   4 //
   5 //  Copyright (c) 2008, 2011 Peter Dimov
   6 //
   7 //  Distributed under the Boost Software License, Version 1.0.
   8 //  See accompanying file LICENSE_1_0.txt or copy at
   9 //  http://www.boost.org/LICENSE_1_0.txt)
  10 //
  11
  12 #include <boost/smart_ptr/detail/yield_k.hpp>
  13
  14 #if defined(__ARM_ARCH_7__) || defined(__ARM_ARCH_7A__) || defined(__ARM_ARCH_7R__) || defined(__ARM_ARCH_7M__) || defined(__ARM_ARCH_7EM__)
  15
  16 # define BOOST_SP_ARM_BARRIER "dmb"
  17
  18 #elif defined(__ARM_ARCH_6__) || defined(__ARM_ARCH_6J__) || defined(__ARM_ARCH_6K__) || defined(__ARM_ARCH_6Z__) || defined(__ARM_ARCH_6ZK__) || defined(__ARM_ARCH_6T2__)
  19
  20 # define BOOST_SP_ARM_BARRIER "mcr p15, 0, r0, c7, c10, 5"
  21
  22 #else
  23
  24 # define BOOST_SP_ARM_BARRIER ""
  25
  26 #endif
  27
  28 namespace boost
  29 {
  30
  31 namespace detail
  32 {
  33
  34 class spinlock
  35 {
  36 public:
  37
  38     int v_;
  39
  40 public:
  41
  42     bool try_lock()
  43     {
  44         int r;
  45
  46         __asm__ __volatile__(
  47             "swp %0, %1, [%2]\n\t"
  48                         BOOST_SP_ARM_BARRIER :
  49             "=&r"( r ): // outputs
  50             "r"( 1 ), "r"( &v_ ): // inputs
  51             "memory", "cc" );
  52
  53         return r == 0;
  54     }
  55
  56     void lock()
  57     {
  58         for( unsigned k = 0; !try_lock(); ++k )
  59         {
  60             boost::detail::yield( k );
  61         }
  62     }
  63
  64     void unlock()
  65     {
  66         __asm__ __volatile__( BOOST_SP_ARM_BARRIER ::: "memory" );
  67         *const_cast< int volatile* >( &v_ ) = 0;
  68     }
  69
  70 public:
  71
  72     class scoped_lock
  73     {
  74     private:
  75
  76         spinlock & sp_;
  77
  78         scoped_lock( scoped_lock const & );
  79         scoped_lock & operator=( scoped_lock const & );
  80
  81     public:
  82
  83         explicit scoped_lock( spinlock & sp ): sp_( sp )
  84         {
  85             sp.lock();
  86         }
  87
  88         ~scoped_lock()
  89         {
  90             sp_.unlock();
  91         }
  92     };
  93 };
  94
  95 } // namespace detail
  96 } // namespace boost
  97
  98 #define BOOST_DETAIL_SPINLOCK_INIT {0}
  99
 100 #undef BOOST_SP_ARM_BARRIER
 101
 102 #endif // #ifndef BOOST_SMART_PTR_DETAIL_SPINLOCK_GCC_ARM_HPP_INCLUDED