1 2/* 3 * Copyright 2006 The Android Open Source Project 4 * 5 * Use of this source code is governed by a BSD-style license that can be 6 * found in the LICENSE file. 7 */ 8 9 10#ifndef SkBuffer_DEFINED 11#define SkBuffer_DEFINED 12 13#include "SkScalar.h" 14 15/** \class SkRBuffer 16 17 Light weight class for reading data from a memory block. 18 The RBuffer is given the buffer to read from, with either a specified size 19 or no size (in which case no range checking is performed). It is iillegal 20 to attempt to read a value from an empty RBuffer (data == null). 21*/ 22class SkRBuffer : SkNoncopyable { 23public: 24 SkRBuffer() : fData(0), fPos(0), fStop(0) {} 25 /** Initialize RBuffer with a data pointer, but no specified length. 26 This signals the RBuffer to not perform range checks during reading. 27 */ 28 SkRBuffer(const void* data) { 29 fData = (const char*)data; 30 fPos = (const char*)data; 31 fStop = 0; // no bounds checking 32 } 33 /** Initialize RBuffer with a data point and length. 34 */ 35 SkRBuffer(const void* data, size_t size) { 36 SkASSERT(data != 0 || size == 0); 37 fData = (const char*)data; 38 fPos = (const char*)data; 39 fStop = (const char*)data + size; 40 } 41 42 /** Return the number of bytes that have been read from the beginning 43 of the data pointer. 44 */ 45 size_t pos() const { return fPos - fData; } 46 /** Return the total size of the data pointer. Only defined if the length was 47 specified in the constructor or in a call to reset(). 48 */ 49 size_t size() const { return fStop - fData; } 50 /** Return true if the buffer has read to the end of the data pointer. 51 Only defined if the length was specified in the constructor or in a call 52 to reset(). Always returns true if the length was not specified. 53 */ 54 bool eof() const { return fPos >= fStop; } 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 void read(void* buffer, size_t size) { 60 if (size) { 61 this->readNoSizeCheck(buffer, size); 62 } 63 } 64 65 const void* skip(size_t size); // return start of skipped data 66 size_t skipToAlign4(); 67 68 void* readPtr() { void* ptr; read(&ptr, sizeof(ptr)); return ptr; } 69 SkScalar readScalar() { SkScalar x; read(&x, 4); return x; } 70 uint32_t readU32() { uint32_t x; read(&x, 4); return x; } 71 int32_t readS32() { int32_t x; read(&x, 4); return x; } 72 uint16_t readU16() { uint16_t x; read(&x, 2); return x; } 73 int16_t readS16() { int16_t x; read(&x, 2); return x; } 74 uint8_t readU8() { uint8_t x; read(&x, 1); return x; } 75 bool readBool() { return this->readU8() != 0; } 76 77protected: 78 void readNoSizeCheck(void* buffer, size_t size); 79 80 const char* fData; 81 const char* fPos; 82 const char* fStop; 83}; 84 85/** \class SkWBuffer 86 87 Light weight class for writing data to a memory block. 88 The WBuffer is given the buffer to write into, with either a specified size 89 or no size, in which case no range checking is performed. An empty WBuffer 90 is legal, in which case no data is ever written, but the relative pos() 91 is updated. 92*/ 93class SkWBuffer : SkNoncopyable { 94public: 95 SkWBuffer() : fData(0), fPos(0), fStop(0) {} 96 SkWBuffer(void* data) { reset(data); } 97 SkWBuffer(void* data, size_t size) { reset(data, size); } 98 99 void reset(void* data) { 100 fData = (char*)data; 101 fPos = (char*)data; 102 fStop = 0; // no bounds checking 103 } 104 105 void reset(void* data, size_t size) { 106 SkASSERT(data != 0 || size == 0); 107 fData = (char*)data; 108 fPos = (char*)data; 109 fStop = (char*)data + size; 110 } 111 112 size_t pos() const { return fPos - fData; } 113 void* skip(size_t size); // return start of skipped data 114 115 void write(const void* buffer, size_t size) { 116 if (size) { 117 this->writeNoSizeCheck(buffer, size); 118 } 119 } 120 121 size_t padToAlign4(); 122 123 void writePtr(const void* x) { this->writeNoSizeCheck(&x, sizeof(x)); } 124 void writeScalar(SkScalar x) { this->writeNoSizeCheck(&x, 4); } 125 void write32(int32_t x) { this->writeNoSizeCheck(&x, 4); } 126 void write16(int16_t x) { this->writeNoSizeCheck(&x, 2); } 127 void write8(int8_t x) { this->writeNoSizeCheck(&x, 1); } 128 void writeBool(bool x) { this->write8(x); } 129 130protected: 131 void writeNoSizeCheck(const void* buffer, size_t size); 132 133 char* fData; 134 char* fPos; 135 char* fStop; 136}; 137 138#endif 139 140