1/*
2 * Copyright (C) 2012 Koji Ishii <kojiishi@gmail.com>
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1.  Redistributions of source code must retain the above copyright
8 *     notice, this list of conditions and the following disclaimer.
9 * 2.  Redistributions in binary form must reproduce the above copyright
10 *     notice, this list of conditions and the following disclaimer in the
11 *     documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND ANY
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
15 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
16 * DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY
17 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
18 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
19 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
20 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
21 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
22 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
23 */
24
25#ifndef OpenTypeTypes_h
26#define OpenTypeTypes_h
27
28#include "SharedBuffer.h"
29
30namespace WebCore {
31namespace OpenType {
32
33struct BigEndianShort {
34    operator short() const { return (v & 0x00ff) << 8 | v >> 8; }
35    BigEndianShort(short u) : v((u & 0x00ff) << 8 | u >> 8) { }
36    unsigned short v;
37};
38
39struct BigEndianUShort {
40    operator unsigned short() const { return (v & 0x00ff) << 8 | v >> 8; }
41    BigEndianUShort(unsigned short u) : v((u & 0x00ff) << 8 | u >> 8) { }
42    unsigned short v;
43};
44
45struct BigEndianLong {
46    operator int() const { return (v & 0xff) << 24 | (v & 0xff00) << 8 | (v & 0xff0000) >> 8 | v >> 24; }
47    BigEndianLong(int u) : v((u & 0xff) << 24 | (u & 0xff00) << 8 | (u & 0xff0000) >> 8 | u >> 24) { }
48    unsigned v;
49};
50
51struct BigEndianULong {
52    operator unsigned() const { return (v & 0xff) << 24 | (v & 0xff00) << 8 | (v & 0xff0000) >> 8 | v >> 24; }
53    BigEndianULong(unsigned u) : v((u & 0xff) << 24 | (u & 0xff00) << 8 | (u & 0xff0000) >> 8 | u >> 24) { }
54    unsigned v;
55};
56
57typedef BigEndianShort Int16;
58typedef BigEndianUShort UInt16;
59typedef BigEndianLong Int32;
60typedef BigEndianULong UInt32;
61
62typedef UInt32 Fixed;
63typedef UInt16 Offset;
64typedef UInt16 GlyphID;
65
66// OTTag is native because it's only compared against constants, so we don't
67// do endian conversion here but make sure constants are in big-endian order.
68// Note that multi-character literal is implementation-defined in C++0x.
69typedef uint32_t Tag;
70#define OT_MAKE_TAG(ch1, ch2, ch3, ch4) ((((uint32_t)(ch4)) << 24) | (((uint32_t)(ch3)) << 16) | (((uint32_t)(ch2)) << 8) | ((uint32_t)(ch1)))
71
72template <typename T> static const T* validateTable(const RefPtr<SharedBuffer>& buffer, size_t count = 1)
73{
74    if (!buffer || buffer->size() < sizeof(T) * count)
75        return 0;
76    return reinterpret_cast<const T*>(buffer->data());
77}
78
79struct TableBase {
80protected:
81    static bool isValidEnd(const SharedBuffer& buffer, const void* position)
82    {
83        if (position < buffer.data())
84            return false;
85        size_t offset = reinterpret_cast<const char*>(position) - buffer.data();
86        return offset <= buffer.size(); // "<=" because end is included as valid
87    }
88
89    template <typename T> static const T* validatePtr(const SharedBuffer& buffer, const void* position)
90    {
91        const T* casted = reinterpret_cast<const T*>(position);
92        if (!isValidEnd(buffer, &casted[1]))
93            return 0;
94        return casted;
95    }
96
97    template <typename T> const T* validateOffset(const SharedBuffer& buffer, uint16_t offset) const
98    {
99        return validatePtr<T>(buffer, reinterpret_cast<const int8_t*>(this) + offset);
100    }
101};
102
103#if ENABLE(OPENTYPE_VERTICAL) || ENABLE(OPENTYPE_MATH)
104struct CoverageTable : TableBase {
105    OpenType::UInt16 coverageFormat;
106};
107
108struct Coverage1Table : CoverageTable {
109    OpenType::UInt16 glyphCount;
110    OpenType::GlyphID glyphArray[1];
111};
112
113struct Coverage2Table : CoverageTable {
114    OpenType::UInt16 rangeCount;
115    struct RangeRecord {
116        OpenType::GlyphID start;
117        OpenType::GlyphID end;
118        OpenType::UInt16 startCoverageIndex;
119    } ranges[1];
120};
121#endif // ENABLE(OPENTYPE_VERTICAL) || ENABLE(OPENTYPE_MATH)
122
123#if ENABLE(OPENTYPE_MATH)
124struct TableWithCoverage : TableBase {
125protected:
126    bool getCoverageIndex(const SharedBuffer& buffer, const CoverageTable* coverage, Glyph glyph, uint32_t& coverageIndex) const
127    {
128        switch (coverage->coverageFormat) {
129        case 1: { // Coverage Format 1
130            const Coverage1Table* coverage1 = validatePtr<Coverage1Table>(buffer, coverage);
131            if (!coverage1)
132                return false;
133            uint16_t glyphCount = coverage1->glyphCount;
134            if (!isValidEnd(buffer, &coverage1->glyphArray[glyphCount]))
135                return false;
136
137            // We do a binary search on the glyph indexes.
138            uint32_t imin = 0, imax = glyphCount;
139            while (imin < imax) {
140                uint32_t imid = (imin + imax) >> 1;
141                uint16_t glyphMid = coverage1->glyphArray[imid];
142                if (glyphMid == glyph) {
143                    coverageIndex = imid;
144                    return true;
145                }
146                if (glyphMid < glyph)
147                    imin = imid + 1;
148                else
149                    imax = imid;
150            }
151            break;
152        }
153        case 2: { // Coverage Format 2
154            const Coverage2Table* coverage2 = validatePtr<Coverage2Table>(buffer, coverage);
155            if (!coverage2)
156                return false;
157            uint16_t rangeCount = coverage2->rangeCount;
158            if (!isValidEnd(buffer, &coverage2->ranges[rangeCount]))
159                return false;
160
161            // We do a binary search on the ranges.
162            uint32_t imin = 0, imax = rangeCount;
163            while (imin < imax) {
164                uint32_t imid = (imin + imax) >> 1;
165                uint16_t rStart = coverage2->ranges[imid].start;
166                uint16_t rEnd = coverage2->ranges[imid].end;
167                if (rEnd < glyph)
168                    imin = imid + 1;
169                else if (glyph < rStart)
170                    imax = imid;
171                else {
172                    coverageIndex = coverage2->ranges[imid].startCoverageIndex + glyph - rStart;
173                    return true;
174                }
175            }
176            break;
177        }
178        }
179        return false;
180    }
181};
182#endif
183
184} // namespace OpenType
185} // namespace WebCore
186#endif // OpenTypeTypes_h
187