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1 | #ifndef BOOST_SMART_PTR_DETAIL_ATOMIC_COUNT_GCC_X86_HPP_INCLUDED |
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2 | #define BOOST_SMART_PTR_DETAIL_ATOMIC_COUNT_GCC_X86_HPP_INCLUDED |
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3 | |
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4 | // |
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5 | // boost/detail/atomic_count_gcc_x86.hpp |
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6 | // |
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7 | // atomic_count for g++ on 486+/AMD64 |
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8 | // |
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9 | // Copyright 2007 Peter Dimov |
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10 | // |
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11 | // Distributed under the Boost Software License, Version 1.0. (See |
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12 | // accompanying file LICENSE_1_0.txt or copy at |
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13 | // http://www.boost.org/LICENSE_1_0.txt) |
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14 | // |
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15 | |
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16 | namespace boost |
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17 | { |
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18 | |
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19 | namespace detail |
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20 | { |
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21 | |
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22 | class atomic_count |
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23 | { |
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24 | public: |
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25 | |
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26 | explicit atomic_count( long v ) : value_( static_cast< int >( v ) ) {} |
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27 | |
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28 | long operator++() |
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29 | { |
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30 | return atomic_exchange_and_add( &value_, +1 ) + 1; |
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31 | } |
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32 | |
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33 | long operator--() |
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34 | { |
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35 | return atomic_exchange_and_add( &value_, -1 ) - 1; |
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36 | } |
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37 | |
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38 | operator long() const |
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39 | { |
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40 | return atomic_exchange_and_add( &value_, 0 ); |
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41 | } |
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42 | |
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43 | private: |
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44 | |
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45 | atomic_count(atomic_count const &); |
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46 | atomic_count & operator=(atomic_count const &); |
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47 | |
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48 | mutable int value_; |
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49 | |
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50 | private: |
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51 | |
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52 | static int atomic_exchange_and_add( int * pw, int dv ) |
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53 | { |
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54 | // int r = *pw; |
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55 | // *pw += dv; |
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56 | // return r; |
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57 | |
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58 | int r; |
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59 | |
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60 | __asm__ __volatile__ |
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61 | ( |
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62 | "lock\n\t" |
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63 | "xadd %1, %0": |
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64 | "+m"( *pw ), "=r"( r ): // outputs (%0, %1) |
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65 | "1"( dv ): // inputs (%2 == %1) |
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66 | "memory", "cc" // clobbers |
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67 | ); |
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68 | |
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69 | return r; |
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70 | } |
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71 | }; |
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72 | |
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73 | } // namespace detail |
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74 | |
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75 | } // namespace boost |
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76 | |
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77 | #endif // #ifndef BOOST_SMART_PTR_DETAIL_ATOMIC_COUNT_GCC_X86_HPP_INCLUDED |
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