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/*
* Copyright (C) 2011 Apple Inc. All rights reserved.
* Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public License
* along with this library; see the file COPYING.LIB. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*
*/
#ifndef ASCIIFastPath_h
#define ASCIIFastPath_h
#include <stdint.h>
#include <wtf/unicode/Unicode.h>
namespace WTF {
// Assuming that a pointer is the size of a "machine word", then
// uintptr_t is an integer type that is also a machine word.
typedef uintptr_t MachineWord;
const uintptr_t machineWordAlignmentMask = sizeof(MachineWord) - 1;
inline bool isAlignedToMachineWord(const void* pointer)
{
return !(reinterpret_cast<uintptr_t>(pointer) & machineWordAlignmentMask);
}
template<typename T> inline T* alignToMachineWord(T* pointer)
{
return reinterpret_cast<T*>(reinterpret_cast<uintptr_t>(pointer) & ~machineWordAlignmentMask);
}
template<size_t size, typename CharacterType> struct NonASCIIMask;
template<> struct NonASCIIMask<4, UChar> {
static inline uint32_t value() { return 0xFF80FF80U; }
};
template<> struct NonASCIIMask<4, LChar> {
static inline uint32_t value() { return 0x80808080U; }
};
template<> struct NonASCIIMask<8, UChar> {
static inline uint64_t value() { return 0xFF80FF80FF80FF80ULL; }
};
template<> struct NonASCIIMask<8, LChar> {
static inline uint64_t value() { return 0x8080808080808080ULL; }
};
template<typename CharacterType>
inline bool isAllASCII(MachineWord word)
{
return !(word & NonASCIIMask<sizeof(MachineWord), CharacterType>::value());
}
// Note: This function assume the input is likely all ASCII, and
// does not leave early if it is not the case.
template<typename CharacterType>
inline bool charactersAreAllASCII(const CharacterType* characters, size_t length)
{
MachineWord allCharBits = 0;
const CharacterType* end = characters + length;
// Prologue: align the input.
while (!isAlignedToMachineWord(characters) && characters != end) {
allCharBits |= *characters;
++characters;
}
// Compare the values of CPU word size.
const CharacterType* wordEnd = alignToMachineWord(end);
const size_t loopIncrement = sizeof(MachineWord) / sizeof(CharacterType);
while (characters < wordEnd) {
allCharBits |= *(reinterpret_cast<const MachineWord*>(characters));
characters += loopIncrement;
}
// Process the remaining bytes.
while (characters != end) {
allCharBits |= *characters;
++characters;
}
MachineWord nonASCIIBitMask = NonASCIIMask<sizeof(MachineWord), CharacterType>::value();
return !(allCharBits & nonASCIIBitMask);
}
} // namespace WTF
#endif // ASCIIFastPath_h
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