70 lines
1.4 KiB
C++
70 lines
1.4 KiB
C++
/*
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* ShadowGuard.h
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*
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* Created on: 10 ìàÿ 2017 ã.
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* Author: titov
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*/
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#ifndef SOURCES_COMMON_SHADOWGUARD_H_
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#define SOURCES_COMMON_SHADOWGUARD_H_
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//!Êëàññ äëÿ ïåðåäà÷è äàííûõ ìåæäó ïîòîêàìè.
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/*!Êëàññ ãàðàíòèðóåò áåçîïàñíóþ ïåðåäà÷ó äàííûõ â ñëó÷àå åñëè ôóíêöèÿ update íå áóäåò ïðåðâàíà ôóíêöèåé operator =.
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*
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*/
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template<typename V>
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class ShadowGuard : public V {
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private:
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V shadow_value;
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bool upd;
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public:
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ShadowGuard(const V &);
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//!Áåçîïàñíîå ïðèñâàèâàíèå â ïðåðûâàåìîì ïîòîêå.
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void operator=(const V & new_value);
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//!Áåçîïàñíîå îáíîâëåíèå â ïðåðûâàþùåì ïîòîêå.
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void update();
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};
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template<typename V>
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inline void ShadowGuard<V>::operator =(const V & new_value) {
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upd = false; shadow_value = new_value; upd = true;
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}
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template<typename V>
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inline ShadowGuard<V>::ShadowGuard(const V & rv) :
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V(rv), shadow_value(rv), upd(false) {}
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template<typename V>
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inline void ShadowGuard<V>::update() {
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if(upd) {
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volatile V new_value = shadow_value;
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// do {
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// new_value = shadow_value;
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// } while( new_value != shadow_value );
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*static_cast<V *>(this) = shadow_value;
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upd = false;
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}
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}
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template<typename V>
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V read_from_fast( volatile const V * value ) {
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V * fast_value = const_cast<V *>(value);
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V temp(*fast_value);
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do {
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temp = *fast_value;
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} while( temp != *fast_value );
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return temp;
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}
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#endif /* SOURCES_COMMON_SHADOWGUARD_H_ */
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