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:
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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,
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25 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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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//
52class Endian {
53public:
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.
69 static bool is_little_endian() { u4 x = 1; return *(u1 *)&x != 0; }
70
71 // Quick big endian test.
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.
87class NativeEndian : public Endian {
88private:
89 static NativeEndian _native;
90
91public:
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
106 static Endian* get_native() { return &_native; }
107};
108
109// Swapping endian handling.
110class SwappingEndian : public Endian {
111private:
112 static SwappingEndian _swapping;
113
114public:
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
129 static Endian* get_swapping() { return &_swapping; }
130};
131#endif // LIBJIMAGE_ENDIAN_HPP
132