1/*
2 * Copyright (C) 2011, 2012 Apple Inc. All rights reserved.
3 * Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
4 *
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Library General Public
7 * License as published by the Free Software Foundation; either
8 * version 2 of the License, or (at your option) any later version.
9 *
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13 * Library General Public License for more details.
14 *
15 * You should have received a copy of the GNU Library General Public License
16 * along with this library; see the file COPYING.LIB.  If not, write to
17 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
18 * Boston, MA 02110-1301, USA.
19 *
20 */
21
22#ifndef ASCIIFastPath_h
23#define ASCIIFastPath_h
24
25#include "wtf/Alignment.h"
26#include "wtf/CPU.h"
27#include "wtf/StdLibExtras.h"
28#include "wtf/unicode/Unicode.h"
29#include <stdint.h>
30
31#if OS(MACOSX) && (CPU(X86) || CPU(X86_64))
32#include <emmintrin.h>
33#endif
34
35namespace WTF {
36
37// Assuming that a pointer is the size of a "machine word", then
38// uintptr_t is an integer type that is also a machine word.
39typedef uintptr_t MachineWord;
40const uintptr_t machineWordAlignmentMask = sizeof(MachineWord) - 1;
41
42inline bool isAlignedToMachineWord(const void* pointer)
43{
44    return !(reinterpret_cast<uintptr_t>(pointer) & machineWordAlignmentMask);
45}
46
47template<typename T> inline T* alignToMachineWord(T* pointer)
48{
49    return reinterpret_cast<T*>(reinterpret_cast<uintptr_t>(pointer) & ~machineWordAlignmentMask);
50}
51
52template<size_t size, typename CharacterType> struct NonASCIIMask;
53template<> struct NonASCIIMask<4, UChar> {
54    static inline uint32_t value() { return 0xFF80FF80U; }
55};
56template<> struct NonASCIIMask<4, LChar> {
57    static inline uint32_t value() { return 0x80808080U; }
58};
59template<> struct NonASCIIMask<8, UChar> {
60    static inline uint64_t value() { return 0xFF80FF80FF80FF80ULL; }
61};
62template<> struct NonASCIIMask<8, LChar> {
63    static inline uint64_t value() { return 0x8080808080808080ULL; }
64};
65
66
67template<typename CharacterType>
68inline bool isAllASCII(MachineWord word)
69{
70    return !(word & NonASCIIMask<sizeof(MachineWord), CharacterType>::value());
71}
72
73// Note: This function assume the input is likely all ASCII, and
74// does not leave early if it is not the case.
75template<typename CharacterType>
76inline bool charactersAreAllASCII(const CharacterType* characters, size_t length)
77{
78    MachineWord allCharBits = 0;
79    const CharacterType* end = characters + length;
80
81    // Prologue: align the input.
82    while (!isAlignedToMachineWord(characters) && characters != end) {
83        allCharBits |= *characters;
84        ++characters;
85    }
86
87    // Compare the values of CPU word size.
88    const CharacterType* wordEnd = alignToMachineWord(end);
89    const size_t loopIncrement = sizeof(MachineWord) / sizeof(CharacterType);
90    while (characters < wordEnd) {
91        allCharBits |= *(reinterpret_cast_ptr<const MachineWord*>(characters));
92        characters += loopIncrement;
93    }
94
95    // Process the remaining bytes.
96    while (characters != end) {
97        allCharBits |= *characters;
98        ++characters;
99    }
100
101    MachineWord nonASCIIBitMask = NonASCIIMask<sizeof(MachineWord), CharacterType>::value();
102    return !(allCharBits & nonASCIIBitMask);
103}
104
105inline void copyLCharsFromUCharSource(LChar* destination, const UChar* source, size_t length)
106{
107#if OS(MACOSX) && (CPU(X86) || CPU(X86_64))
108    const uintptr_t memoryAccessSize = 16; // Memory accesses on 16 byte (128 bit) alignment
109    const uintptr_t memoryAccessMask = memoryAccessSize - 1;
110
111    size_t i = 0;
112    for (;i < length && !isAlignedTo<memoryAccessMask>(&source[i]); ++i) {
113        ASSERT(!(source[i] & 0xff00));
114        destination[i] = static_cast<LChar>(source[i]);
115    }
116
117    const uintptr_t sourceLoadSize = 32; // Process 32 bytes (16 UChars) each iteration
118    const size_t ucharsPerLoop = sourceLoadSize / sizeof(UChar);
119    if (length > ucharsPerLoop) {
120        const size_t endLength = length - ucharsPerLoop + 1;
121        for (; i < endLength; i += ucharsPerLoop) {
122#if ENABLE(ASSERT)
123            for (unsigned checkIndex = 0; checkIndex < ucharsPerLoop; ++checkIndex)
124                ASSERT(!(source[i+checkIndex] & 0xff00));
125#endif
126            __m128i first8UChars = _mm_load_si128(reinterpret_cast<const __m128i*>(&source[i]));
127            __m128i second8UChars = _mm_load_si128(reinterpret_cast<const __m128i*>(&source[i+8]));
128            __m128i packedChars = _mm_packus_epi16(first8UChars, second8UChars);
129            _mm_storeu_si128(reinterpret_cast<__m128i*>(&destination[i]), packedChars);
130        }
131    }
132
133    for (; i < length; ++i) {
134        ASSERT(!(source[i] & 0xff00));
135        destination[i] = static_cast<LChar>(source[i]);
136    }
137#elif COMPILER(GCC) && CPU(ARM_NEON) && !(CPU(BIG_ENDIAN) || CPU(MIDDLE_ENDIAN)) && defined(NDEBUG)
138    const LChar* const end = destination + length;
139    const uintptr_t memoryAccessSize = 8;
140
141    if (length >= (2 * memoryAccessSize) - 1) {
142        // Prefix: align dst on 64 bits.
143        const uintptr_t memoryAccessMask = memoryAccessSize - 1;
144        while (!isAlignedTo<memoryAccessMask>(destination))
145            *destination++ = static_cast<LChar>(*source++);
146
147        // Vector interleaved unpack, we only store the lower 8 bits.
148        const uintptr_t lengthLeft = end - destination;
149        const LChar* const simdEnd = end - (lengthLeft % memoryAccessSize);
150        do {
151            asm("vld2.8   { d0-d1 }, [%[SOURCE]] !\n\t"
152                "vst1.8   { d0 }, [%[DESTINATION],:64] !\n\t"
153                : [SOURCE]"+r" (source), [DESTINATION]"+r" (destination)
154                :
155                : "memory", "d0", "d1");
156        } while (destination != simdEnd);
157    }
158
159    while (destination != end)
160        *destination++ = static_cast<LChar>(*source++);
161#else
162    for (size_t i = 0; i < length; ++i) {
163        ASSERT(!(source[i] & 0xff00));
164        destination[i] = static_cast<LChar>(source[i]);
165    }
166#endif
167}
168
169} // namespace WTF
170
171#endif // ASCIIFastPath_h
172