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