1/*
2 * Copyright 2006 The Android Open Source Project
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#ifndef SkBuffer_DEFINED
9#define SkBuffer_DEFINED
10
11#include "include/core/SkScalar.h"
12#include "include/core/SkTypes.h"
13#include "include/private/SkNoncopyable.h"
14#include "src/core/SkSafeMath.h"
15
16#include <limits>
17
18/** \class SkRBuffer
19
20 Light weight class for reading data from a memory block.
21 The RBuffer is given the buffer to read from, with either a specified size
22 or no size (in which case no range checking is performed). It is iillegal
23 to attempt to read a value from an empty RBuffer (data == null).
24*/
25class SkRBuffer : SkNoncopyable {
26public:
27 SkRBuffer() : fData(nullptr), fPos(nullptr), fStop(nullptr) {}
28
29 /** Initialize RBuffer with a data point and length.
30 */
31 SkRBuffer(const void* data, size_t size) {
32 SkASSERT(data != nullptr || size == 0);
33 fData = (const char*)data;
34 fPos = (const char*)data;
35 fStop = (const char*)data + size;
36 }
37
38 /** Return the number of bytes that have been read from the beginning
39 of the data pointer.
40 */
41 size_t pos() const { return fPos - fData; }
42 /** Return the total size of the data pointer. Only defined if the length was
43 specified in the constructor or in a call to reset().
44 */
45 size_t size() const { return fStop - fData; }
46 /** Return true if the buffer has read to the end of the data pointer.
47 Only defined if the length was specified in the constructor or in a call
48 to reset(). Always returns true if the length was not specified.
49 */
50 bool eof() const { return fPos >= fStop; }
51
52 size_t available() const { return fStop - fPos; }
53
54 bool isValid() const { return fValid; }
55
56 /** Read the specified number of bytes from the data pointer. If buffer is not
57 null, copy those bytes into buffer.
58 */
59 bool read(void* buffer, size_t size);
60 bool skipToAlign4();
61
62 bool readU8(uint8_t* x) { return this->read(x, 1); }
63 bool readS32(int32_t* x) { return this->read(x, 4); }
64 bool readU32(uint32_t* x) { return this->read(x, 4); }
65
66 // returns nullptr on failure
67 const void* skip(size_t bytes);
68 template <typename T> const T* skipCount(size_t count) {
69 return static_cast<const T*>(this->skip(SkSafeMath::Mul(count, sizeof(T))));
70 }
71
72private:
73 const char* fData;
74 const char* fPos;
75 const char* fStop;
76 bool fValid = true;
77};
78
79/** \class SkWBuffer
80
81 Light weight class for writing data to a memory block.
82 The WBuffer is given the buffer to write into, with either a specified size
83 or no size, in which case no range checking is performed. An empty WBuffer
84 is legal, in which case no data is ever written, but the relative pos()
85 is updated.
86*/
87class SkWBuffer : SkNoncopyable {
88public:
89 SkWBuffer() : fData(nullptr), fPos(nullptr), fStop(nullptr) {}
90 SkWBuffer(void* data) { reset(data); }
91 SkWBuffer(void* data, size_t size) { reset(data, size); }
92
93 void reset(void* data) {
94 fData = (char*)data;
95 fPos = (char*)data;
96 fStop = nullptr; // no bounds checking
97 }
98
99 void reset(void* data, size_t size) {
100 SkASSERT(data != nullptr || size == 0);
101 fData = (char*)data;
102 fPos = (char*)data;
103 fStop = (char*)data + size;
104 }
105
106 size_t pos() const { return fPos - fData; }
107 void* skip(size_t size); // return start of skipped data
108
109 void write(const void* buffer, size_t size) {
110 if (size) {
111 this->writeNoSizeCheck(buffer, size);
112 }
113 }
114
115 size_t padToAlign4();
116
117 void writePtr(const void* x) { this->writeNoSizeCheck(&x, sizeof(x)); }
118 void writeScalar(SkScalar x) { this->writeNoSizeCheck(&x, 4); }
119 void write32(int32_t x) { this->writeNoSizeCheck(&x, 4); }
120 void write16(int16_t x) { this->writeNoSizeCheck(&x, 2); }
121 void write8(int8_t x) { this->writeNoSizeCheck(&x, 1); }
122 void writeBool(bool x) { this->write8(x); }
123
124private:
125 void writeNoSizeCheck(const void* buffer, size_t size);
126
127 char* fData;
128 char* fPos;
129 char* fStop;
130};
131
132#endif
133