J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 3 | * |
| 4 | * This code is free software; you can redistribute it and/or modify it |
| 5 | * under the terms of the GNU General Public License version 2 only, as |
| 6 | * published by the Free Software Foundation. Sun designates this |
| 7 | * particular file as subject to the "Classpath" exception as provided |
| 8 | * by Sun in the LICENSE file that accompanied this code. |
| 9 | * |
| 10 | * This code is distributed in the hope that it will be useful, but WITHOUT |
| 11 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 12 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| 13 | * version 2 for more details (a copy is included in the LICENSE file that |
| 14 | * accompanied this code). |
| 15 | * |
| 16 | * You should have received a copy of the GNU General Public License version |
| 17 | * 2 along with this work; if not, write to the Free Software Foundation, |
| 18 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| 19 | * |
| 20 | * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 21 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 22 | * have any questions. |
| 23 | * |
| 24 | */ |
| 25 | |
| 26 | |
| 27 | /* |
| 28 | * |
| 29 | * (C) Copyright IBM Corp. 1998-2004 - All Rights Reserved |
| 30 | * |
| 31 | */ |
| 32 | |
| 33 | #ifndef __LESWAPS_H |
| 34 | #define __LESWAPS_H |
| 35 | |
| 36 | #include "LETypes.h" |
| 37 | |
| 38 | #if !defined(U_IS_BIG_ENDIAN) |
| 39 | #ifdef _LITTLE_ENDIAN |
| 40 | #define U_IS_BIG_ENDIAN 0 |
| 41 | #endif |
| 42 | #endif |
| 43 | |
| 44 | /** |
| 45 | * A convenience macro which invokes the swapWord member function |
| 46 | * from a concise call. |
| 47 | * |
| 48 | * @stable ICU 2.8 |
| 49 | */ |
| 50 | |
| 51 | #if defined(U_IS_BIG_ENDIAN) |
| 52 | #if U_IS_BIG_ENDIAN |
| 53 | #define SWAPW(value) (value) |
| 54 | #else |
| 55 | #define SWAPW(value) LESwaps::swapWord(value) |
| 56 | #endif |
| 57 | #else |
| 58 | #define SWAPW(value) (LESwaps::isBigEndian() ? (value) : LESwaps::swapWord(value)) |
| 59 | #endif |
| 60 | |
| 61 | /** |
| 62 | * A convenience macro which invokes the swapLong member function |
| 63 | * from a concise call. |
| 64 | * |
| 65 | * @stable ICU 2.8 |
| 66 | */ |
| 67 | |
| 68 | #if defined(U_IS_BIG_ENDIAN) |
| 69 | #if U_IS_BIG_ENDIAN |
| 70 | #define SWAPL(value) (value) |
| 71 | #else |
| 72 | #define SWAPL(value) LESwaps::swapLong(value) |
| 73 | #endif |
| 74 | #else |
| 75 | #define SWAPL(value) (LESwaps::isBigEndian() ? (value) : LESwaps::swapLong(value)) |
| 76 | #endif |
| 77 | |
| 78 | /** |
| 79 | * This class is used to access data which stored in big endian order |
| 80 | * regardless of the conventions of the platform. It has been designed |
| 81 | * to automatically detect the endian-ness of the platform, so that a |
| 82 | * compilation flag is not needed. |
| 83 | * |
| 84 | * All methods are static and inline in an attempt to induce the compiler |
| 85 | * to do most of the calculations at compile time. |
| 86 | * |
| 87 | * @stable ICU 2.8 |
| 88 | */ |
| 89 | class LESwaps |
| 90 | { |
| 91 | public: |
| 92 | |
| 93 | #if !defined(U_IS_BIG_ENDIAN) |
| 94 | /** |
| 95 | * This method detects the endian-ness of the platform by |
| 96 | * casting a pointer to a word to a pointer to a byte. On |
| 97 | * big endian platforms the FF will be in the byte with the |
| 98 | * lowest address. On little endian platforms, the FF will |
| 99 | * be in the byte with the highest address. |
| 100 | * |
| 101 | * @return TRUE if the platform is big endian |
| 102 | * |
| 103 | * @stable ICU 2.8 |
| 104 | */ |
| 105 | static le_uint8 isBigEndian() |
| 106 | { |
| 107 | const le_uint16 word = 0xFF00; |
| 108 | |
| 109 | return *((le_uint8 *) &word); |
| 110 | }; |
| 111 | #endif |
| 112 | |
| 113 | /** |
| 114 | * This method does the byte swap required on little endian platforms |
| 115 | * to correctly access a (16-bit) word. |
| 116 | * |
| 117 | * @param value - the word to be byte swapped |
| 118 | * |
| 119 | * @return the byte swapped word |
| 120 | * |
| 121 | * @stable ICU 2.8 |
| 122 | */ |
| 123 | static le_uint16 swapWord(le_uint16 value) |
| 124 | { |
| 125 | return (((le_uint8) (value >> 8)) | (value << 8)); |
| 126 | }; |
| 127 | |
| 128 | /** |
| 129 | * This method does the byte swapping required on little endian platforms |
| 130 | * to correctly access a (32-bit) long. |
| 131 | * |
| 132 | * @param value - the long to be byte swapped |
| 133 | * |
| 134 | * @return the byte swapped long |
| 135 | * |
| 136 | * @stable ICU 2.8 |
| 137 | */ |
| 138 | static le_uint32 swapLong(le_uint32 value) |
| 139 | { |
| 140 | return swapWord((le_uint16) (value >> 16)) | (swapWord((le_uint16) value) << 16); |
| 141 | }; |
| 142 | |
| 143 | private: |
| 144 | LESwaps() {} // private - forbid instantiation |
| 145 | }; |
| 146 | |
| 147 | #endif |