1/*
2 * Copyright 2011 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8#include "SkReader32.h"
9#include "SkString.h"
10#include "SkWriter32.h"
11
12/*
13 *  Strings are stored as: length[4-bytes] + string_data + '\0' + pad_to_mul_4
14 */
15
16const char* SkReader32::readString(size_t* outLen) {
17    size_t len = this->readU32();
18    const void* ptr = this->peek();
19
20    // skip over the string + '\0' and then pad to a multiple of 4
21    size_t alignedSize = SkAlign4(len + 1);
22    this->skip(alignedSize);
23
24    if (outLen) {
25        *outLen = len;
26    }
27    return (const char*)ptr;
28}
29
30size_t SkReader32::readIntoString(SkString* copy) {
31    size_t len;
32    const char* ptr = this->readString(&len);
33    if (copy) {
34        copy->set(ptr, len);
35    }
36    return len;
37}
38
39void SkWriter32::writeString(const char str[], size_t len) {
40    if (NULL == str) {
41        str = "";
42        len = 0;
43    }
44    if ((long)len < 0) {
45        len = strlen(str);
46    }
47
48    // [ 4 byte len ] [ str ... ] [1 - 4 \0s]
49    uint32_t* ptr = this->reservePad(sizeof(uint32_t) + len + 1);
50    *ptr = SkToU32(len);
51    char* chars = (char*)(ptr + 1);
52    memcpy(chars, str, len);
53    chars[len] = '\0';
54}
55
56size_t SkWriter32::WriteStringSize(const char* str, size_t len) {
57    if ((long)len < 0) {
58        SkASSERT(str);
59        len = strlen(str);
60    }
61    const size_t lenBytes = 4;    // we use 4 bytes to record the length
62    // add 1 since we also write a terminating 0
63    return SkAlign4(lenBytes + len + 1);
64}
65
66void SkWriter32::growToAtLeast(size_t size) {
67    const bool wasExternal = (fExternal != NULL) && (fData == fExternal);
68
69    fCapacity = 4096 + SkTMax(size, fCapacity + (fCapacity / 2));
70    fInternal.realloc(fCapacity);
71    fData = fInternal.get();
72
73    if (wasExternal) {
74        // we were external, so copy in the data
75        memcpy(fData, fExternal, fUsed);
76    }
77    // Invalidate the snapshot, we know it is no longer useful.
78    fSnapshot.reset(NULL);
79}
80
81SkData* SkWriter32::snapshotAsData() const {
82    // get a non const version of this, we are only conceptually const
83    SkWriter32& mutable_this = *const_cast<SkWriter32*>(this);
84    // we use size change detection to invalidate the cached data
85    if ((fSnapshot.get() != NULL) && (fSnapshot->size() != fUsed)) {
86        mutable_this.fSnapshot.reset(NULL);
87    }
88    if (fSnapshot.get() == NULL) {
89        uint8_t* buffer = NULL;
90        if ((fExternal != NULL) && (fData == fExternal)) {
91            // We need to copy to an allocated buffer before returning.
92            buffer = (uint8_t*)sk_malloc_throw(fUsed);
93            memcpy(buffer, fData, fUsed);
94        } else {
95            buffer = mutable_this.fInternal.detach();
96            // prepare us to do copy on write, by pretending the data buffer
97            // is external and size limited
98            mutable_this.fData = buffer;
99            mutable_this.fCapacity = fUsed;
100            mutable_this.fExternal = buffer;
101        }
102        mutable_this.fSnapshot.reset(SkData::NewFromMalloc(buffer, fUsed));
103    }
104    return SkRef(fSnapshot.get()); // Take an extra ref for the caller.
105}
106