1 /* 2 * Copyright (c) 2015, 2016, Oracle and/or its affiliates. All rights reserved. 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 * 8 * - Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 11 * - Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * - Neither the name of Oracle nor the names of its 16 * contributors may be used to endorse or promote products derived 17 * from this software without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS 20 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, 21 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR 23 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 24 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 25 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 26 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF 27 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING 28 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 29 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 #ifndef LIBJIMAGE_ENDIAN_HPP 33 #define LIBJIMAGE_ENDIAN_HPP 34 35 #include "inttypes.hpp" 36 37 // Selectable endian handling. Endian handlers are used when accessing values 38 // that are of unknown (until runtime) endian. The only requirement of the values 39 // accessed are that they are aligned to proper size boundaries (no misalignment.) 40 // To select an endian handler, one should call Endian::get_handler(big_endian); 41 // Where big_endian is true if big endian is required and false otherwise. The 42 // native endian handler can be fetched with Endian::get_native_handler(); 43 // To retrieve a value using the approprate endian, use one of the overloaded 44 // calls to get. To set a value, then use one of the overloaded set calls. 45 // Ex. 46 // s4 value; // Imported value; 47 // ... 48 // Endian* endian = Endian::get_handler(true); // Use big endian 49 // s4 corrected = endian->get(value); 50 // endian->set(value, 1); 51 // 52 class Endian { 53 public: 54 virtual u2 get(u2 x) = 0; 55 virtual u4 get(u4 x) = 0; 56 virtual u8 get(u8 x) = 0; 57 virtual s2 get(s2 x) = 0; 58 virtual s4 get(s4 x) = 0; 59 virtual s8 get(s8 x) = 0; 60 61 virtual void set(u2& x, u2 y) = 0; 62 virtual void set(u4& x, u4 y) = 0; 63 virtual void set(u8& x, u8 y) = 0; 64 virtual void set(s2& x, s2 y) = 0; 65 virtual void set(s4& x, s4 y) = 0; 66 virtual void set(s8& x, s8 y) = 0; 67 68 // Quick little endian test. is_little_endian()69 static bool is_little_endian() { u4 x = 1; return *(u1 *)&x != 0; } 70 71 // Quick big endian test. is_big_endian()72 static bool is_big_endian() { return !is_little_endian(); } 73 74 // Select an appropriate endian handler. 75 static Endian* get_handler(bool big_endian); 76 77 // Return the native endian handler. 78 static Endian* get_native_handler(); 79 80 // get platform u2 from Java Big endian 81 static u2 get_java(u1* x); 82 // set platform u2 to Java Big endian 83 static void set_java(u1* p, u2 x); 84 }; 85 86 // Normal endian handling. 87 class NativeEndian : public Endian { 88 private: 89 static NativeEndian _native; 90 91 public: 92 u2 get(u2 x); 93 u4 get(u4 x); 94 u8 get(u8 x); 95 s2 get(s2 x); 96 s4 get(s4 x); 97 s8 get(s8 x); 98 99 void set(u2& x, u2 y); 100 void set(u4& x, u4 y); 101 void set(u8& x, u8 y); 102 void set(s2& x, s2 y); 103 void set(s4& x, s4 y); 104 void set(s8& x, s8 y); 105 get_native()106 static Endian* get_native() { return &_native; } 107 }; 108 109 // Swapping endian handling. 110 class SwappingEndian : public Endian { 111 private: 112 static SwappingEndian _swapping; 113 114 public: 115 u2 get(u2 x); 116 u4 get(u4 x); 117 u8 get(u8 x); 118 s2 get(s2 x); 119 s4 get(s4 x); 120 s8 get(s8 x); 121 122 void set(u2& x, u2 y); 123 void set(u4& x, u4 y); 124 void set(u8& x, u8 y); 125 void set(s2& x, s2 y); 126 void set(s4& x, s4 y); 127 void set(s8& x, s8 y); 128 get_swapping()129 static Endian* get_swapping() { return &_swapping; } 130 }; 131 #endif // LIBJIMAGE_ENDIAN_HPP 132