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authorSteve Block <steveblock@google.com>2011-05-13 06:44:40 -0700
committerAndroid (Google) Code Review <android-gerrit@google.com>2011-05-13 06:44:40 -0700
commit08014c20784f3db5df3a89b73cce46037b77eb59 (patch)
tree47749210d31e19e6e2f64036fa8fae2ad693476f /Source/JavaScriptCore/runtime/CachedTranscendentalFunction.h
parent860220379e56aeb66424861ad602b07ee22b4055 (diff)
parent4c3661f7918f8b3f139f824efb7855bedccb4c94 (diff)
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Merge changes Ide388898,Ic49f367c,I1158a808,Iacb6ca5d,I2100dd3a,I5c1abe54,Ib0ef9902,I31dbc523,I570314b3
* changes: Merge WebKit at r75315: Update WebKit version Merge WebKit at r75315: Add FrameLoaderClient PageCache stubs Merge WebKit at r75315: Stub out AXObjectCache::remove() Merge WebKit at r75315: Fix ImageBuffer Merge WebKit at r75315: Fix PluginData::initPlugins() Merge WebKit at r75315: Fix conflicts Merge WebKit at r75315: Fix Makefiles Merge WebKit at r75315: Move Android-specific WebCore files to Source Merge WebKit at r75315: Initial merge by git.
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diff --git a/Source/JavaScriptCore/runtime/CachedTranscendentalFunction.h b/Source/JavaScriptCore/runtime/CachedTranscendentalFunction.h
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+/*
+ * Copyright (C) 2010 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. ``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
+ * 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 CachedTranscendentalFunction_h
+#define CachedTranscendentalFunction_h
+
+#include "JSValue.h"
+
+namespace JSC {
+
+extern const double NaN;
+
+typedef double (*TranscendentalFunctionPtr)(double);
+
+// CachedTranscendentalFunction provides a generic mechanism to cache results
+// for pure functions with the signature "double func(double)", and where NaN
+// maps to NaN.
+template<TranscendentalFunctionPtr orignalFunction>
+class CachedTranscendentalFunction {
+ struct CacheEntry {
+ double operand;
+ double result;
+ };
+
+public:
+ CachedTranscendentalFunction()
+ : m_cache(0)
+ {
+ }
+
+ ~CachedTranscendentalFunction()
+ {
+ if (m_cache)
+ fastFree(m_cache);
+ }
+
+ JSValue operator() (double operand)
+ {
+ if (UNLIKELY(!m_cache))
+ initialize();
+ CacheEntry* entry = &m_cache[hash(operand)];
+
+ if (entry->operand == operand)
+ return jsDoubleNumber(entry->result);
+ double result = orignalFunction(operand);
+ entry->operand = operand;
+ entry->result = result;
+ return jsDoubleNumber(result);
+ }
+
+private:
+ void initialize()
+ {
+ // Lazily allocate the table, populate with NaN->NaN mapping.
+ m_cache = static_cast<CacheEntry*>(fastMalloc(s_cacheSize * sizeof(CacheEntry)));
+ for (unsigned x = 0; x < s_cacheSize; ++x) {
+ m_cache[x].operand = NaN;
+ m_cache[x].result = NaN;
+ }
+ }
+
+ static unsigned hash(double d)
+ {
+ union doubleAndUInt64 {
+ double d;
+ uint32_t is[2];
+ } u;
+ u.d = d;
+
+ unsigned x = u.is[0] ^ u.is[1];
+ x = (x >> 20) ^ (x >> 8);
+ return x & (s_cacheSize - 1);
+ }
+
+ static const unsigned s_cacheSize = 0x1000;
+ CacheEntry* m_cache;
+};
+
+}
+
+#endif // CachedTranscendentalFunction_h