aboutsummaryrefslogtreecommitdiffhomepage
path: root/src/core/SkWriter32.cpp
blob: dfa18a0c657b5f281e21d9edf6d0680909a5407d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252

/*
 * Copyright 2011 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */
#include "SkWriter32.h"

struct SkWriter32::Block {
    Block*  fNext;
    size_t  fSize;
    size_t  fAllocated;
    
    size_t  available() const { return fSize - fAllocated; }
    char*   base() { return (char*)(this + 1); }
    const char* base() const { return (const char*)(this + 1); }
    
    uint32_t* alloc(size_t size) {
        SkASSERT(SkAlign4(size) == size);
        SkASSERT(this->available() >= size);
        void* ptr = this->base() + fAllocated;
        fAllocated += size;
        SkASSERT(fAllocated <= fSize);
        return (uint32_t*)ptr;
    }
    
    uint32_t* peek32(size_t offset) {
        SkASSERT(offset <= fAllocated + 4);
        void* ptr = this->base() + offset;
        return (uint32_t*)ptr;
    }

    static Block* Create(size_t size) {
        SkASSERT(SkAlign4(size) == size);
        Block* block = (Block*)sk_malloc_throw(sizeof(Block) + size);
        block->fNext = NULL;
        block->fSize = size;
        block->fAllocated = 0;
        return block;
    }
};

///////////////////////////////////////////////////////////////////////////////

SkWriter32::~SkWriter32() {
    this->reset();
}

void SkWriter32::reset() {
    Block* block = fHead;    
    while (block) {
        Block* next = block->fNext;
        sk_free(block);
        block = next;
    }

    fSize = 0;
    fHead = fTail = NULL;
    fSingleBlock = NULL;
}

void SkWriter32::reset(void* block, size_t size) {
    this->reset();
    SkASSERT(0 == ((fSingleBlock - (char*)0) & 3));   // need 4-byte alignment
    fSingleBlock = (char*)block;
    fSingleBlockSize = (size & ~3);
}

uint32_t* SkWriter32::reserve(size_t size) {
    SkASSERT(SkAlign4(size) == size);

    if (fSingleBlock) {
        uint32_t* ptr = (uint32_t*)(fSingleBlock + fSize);
        fSize += size;
        SkASSERT(fSize <= fSingleBlockSize);
        return ptr;
    }

    Block* block = fTail;

    if (NULL == block) {
        SkASSERT(NULL == fHead);
        fHead = fTail = block = Block::Create(SkMax32(size, fMinSize));
    } else if (block->available() < size) {
        fTail = Block::Create(SkMax32(size, fMinSize));
        block->fNext = fTail;
        block = fTail;
    }
    
    fSize += size;

    return block->alloc(size);
}

uint32_t* SkWriter32::peek32(size_t offset) {
    SkASSERT(SkAlign4(offset) == offset);
    SkASSERT(offset <= fSize);

    if (fSingleBlock) {
        return (uint32_t*)(fSingleBlock + offset);
    }

    Block* block = fHead;
    SkASSERT(NULL != block);
    
    while (offset >= block->fAllocated) {
        offset -= block->fAllocated;
        block = block->fNext;
        SkASSERT(NULL != block);
    }
    return block->peek32(offset);
}

void SkWriter32::flatten(void* dst) const {
    if (fSingleBlock) {
        memcpy(dst, fSingleBlock, fSize);
        return;
    }

    const Block* block = fHead;
    SkDEBUGCODE(size_t total = 0;)

    while (block) {
        size_t allocated = block->fAllocated;
        memcpy(dst, block->base(), allocated);
        dst = (char*)dst + allocated;
        block = block->fNext;

        SkDEBUGCODE(total += allocated;)
        SkASSERT(total <= fSize);
    }
    SkASSERT(total == fSize);
}

void SkWriter32::writePad(const void* src, size_t size) {
    size_t alignedSize = SkAlign4(size);
    char* dst = (char*)this->reserve(alignedSize);
    memcpy(dst, src, size);
    dst += size;
    int n = alignedSize - size;
    while (--n >= 0) {
        *dst++ = 0;
    }
}

#include "SkStream.h"

size_t SkWriter32::readFromStream(SkStream* stream, size_t length) {
    if (fSingleBlock) {
        SkASSERT(fSingleBlockSize >= fSize);
        size_t remaining = fSingleBlockSize - fSize;
        if (length > remaining) {
            length = remaining;
        }
        stream->read(fSingleBlock + fSize, length);
        fSize += length;
        return length;
    }

    char scratch[1024];
    const size_t MAX = sizeof(scratch);
    size_t remaining = length;
    
    while (remaining != 0) {
        size_t n = remaining;
        if (n > MAX) {
            n = MAX;
        }
        size_t bytes = stream->read(scratch, n);
        this->writePad(scratch, bytes);
        remaining -= bytes;
        if (bytes != n) {
            break;
        }
    }
    return length - remaining;
}

bool SkWriter32::writeToStream(SkWStream* stream) {
    if (fSingleBlock) {
        return stream->write(fSingleBlock, fSize);
    }

    const Block* block = fHead;    
    while (block) {
        if (!stream->write(block->base(), block->fAllocated)) {
            return false;
        }
        block = block->fNext;
    }
    return true;
}

///////////////////////////////////////////////////////////////////////////////

#include "SkReader32.h"
#include "SkString.h"

/*
 *  Strings are stored as: length[4-bytes] + string_data + '\0' + pad_to_mul_4
 */

const char* SkReader32::readString(size_t* outLen) {
    size_t len = this->readInt();
    const void* ptr = this->peek();

    // skip over teh string + '\0' and then pad to a multiple of 4
    size_t alignedSize = SkAlign4(len + 1);
    this->skip(alignedSize);

    if (outLen) {
        *outLen = len;
    }
    return (const char*)ptr;
}

size_t SkReader32::readIntoString(SkString* copy) {
    size_t len;
    const char* ptr = this->readString(&len);
    if (copy) {
        copy->set(ptr, len);
    }
    return len;
}

void SkWriter32::writeString(const char str[], size_t len) {
    if ((long)len < 0) {
        SkASSERT(str);
        len = strlen(str);
    }
    this->write32(len);
    // add 1 since we also write a terminating 0
    size_t alignedLen = SkAlign4(len + 1);
    char* ptr = (char*)this->reserve(alignedLen);
    memcpy(ptr, str, len);
    ptr[len] = 0;
    // we may have left 0,1,2,3 bytes uninitialized, since we reserved align4
    // number of bytes. That's ok, since the reader will know to skip those
}

size_t SkWriter32::WriteStringSize(const char* str, size_t len) {
    if ((long)len < 0) {
        SkASSERT(str);
        len = strlen(str);
    }
    const size_t lenBytes = 4;    // we use 4 bytes to record the length
    // add 1 since we also write a terminating 0
    return SkAlign4(lenBytes + len + 1);
}