JavaScriptCore-1097.3.tar.gz

[apple/javascriptcore.git] / heap / CardSet.h

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+/*
+ * Copyright (C) 2011 Apple Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
+ * THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef CardSet_h
+#define CardSet_h
+
+#include <stdint.h>
+#include <wtf/Assertions.h>
+#include <wtf/Noncopyable.h>
+
+namespace JSC {
+
+template <size_t cardSize, size_t blockSize> class CardSet {
+    WTF_MAKE_NONCOPYABLE(CardSet);
+
+public:
+    static const size_t cardCount = (blockSize + cardSize - 1) / cardSize;
+
+    CardSet()
+    {
+        memset(m_cards, 0, cardCount);
+    }
+
+    bool isCardMarkedForAtom(const void*);
+    void markCardForAtom(const void*);
+    uint8_t& cardForAtom(const void*);
+    bool isCardMarked(size_t);
+    bool testAndClear(size_t);
+
+private:
+    uint8_t m_cards[cardCount];
+    COMPILE_ASSERT(!(cardSize & (cardSize - 1)), cardSet_cardSize_is_power_of_two);
+    COMPILE_ASSERT(!(cardCount & (cardCount - 1)), cardSet_cardCount_is_power_of_two);
+};
+
+template <size_t cardSize, size_t blockSize> uint8_t& CardSet<cardSize, blockSize>::cardForAtom(const void* ptr)
+{
+    ASSERT(ptr > this && ptr < (reinterpret_cast<char*>(this) + cardCount * cardSize));
+    uintptr_t card = (reinterpret_cast<uintptr_t>(ptr) / cardSize) % cardCount;
+    return m_cards[card];
+}
+
+template <size_t cardSize, size_t blockSize> bool CardSet<cardSize, blockSize>::isCardMarkedForAtom(const void* ptr)
+{
+    return cardForAtom(ptr);
+}
+
+template <size_t cardSize, size_t blockSize> void CardSet<cardSize, blockSize>::markCardForAtom(const void* ptr)
+{
+    cardForAtom(ptr) = 1;
+}
+
+template <size_t cardSize, size_t blockSize> bool CardSet<cardSize, blockSize>::isCardMarked(size_t i)
+{
+    ASSERT(i < cardCount);
+    return m_cards[i];
+}
+
+template <size_t cardSize, size_t blockSize> bool CardSet<cardSize, blockSize>::testAndClear(size_t i)
+{
+    ASSERT(i < cardCount);
+    bool result = m_cards[i];
+    m_cards[i] = 0;
+    return result;
+}
+
+}
+
+#endif