1 /* 2 * 3 * (C) Copyright IBM Corp. 1998-2011 - All Rights Reserved 4 * 5 */ 6 7 #ifndef __LESWAPS_H 8 #define __LESWAPS_H 9 10 #include "LETypes.h" 11 12 /** 13 * \file 14 * \brief C++ API: Endian independent access to data for LayoutEngine 15 */ 16 17 U_NAMESPACE_BEGIN 18 19 /** 20 * A convenience macro which invokes the swapWord member function 21 * from a concise call. 22 * 23 * @stable ICU 2.8 24 */ 25 #define SWAPW(value) LESwaps::swapWord((le_uint16)(value)) 26 27 /** 28 * A convenience macro which invokes the swapLong member function 29 * from a concise call. 30 * 31 * @stable ICU 2.8 32 */ 33 #define SWAPL(value) LESwaps::swapLong((le_uint32)(value)) 34 35 /** 36 * This class is used to access data which stored in big endian order 37 * regardless of the conventions of the platform. 38 * 39 * All methods are static and inline in an attempt to induce the compiler 40 * to do most of the calculations at compile time. 41 * 42 * @stable ICU 2.8 43 */ 44 class U_LAYOUT_API LESwaps /* not : public UObject because all methods are static */ { 45 public: 46 47 /** 48 * Reads a big-endian 16-bit word and returns a native-endian value. 49 * No-op on a big-endian platform, byte-swaps on a little-endian platform. 50 * 51 * @param value - the word to be byte swapped 52 * 53 * @return the byte swapped word 54 * 55 * @stable ICU 2.8 56 */ 57 static le_uint16 swapWord(le_uint16 value) 58 { 59 #if (defined(U_IS_BIG_ENDIAN) && U_IS_BIG_ENDIAN) || \ 60 (defined(BYTE_ORDER) && defined(BIG_ENDIAN) && (BYTE_ORDER == BIG_ENDIAN)) || \ 61 defined(__BIG_ENDIAN__) 62 // Fastpath when we know that the platform is big-endian. 63 return value; 64 #else 65 // Reads a big-endian value on any platform. 66 const le_uint8 *p = reinterpret_cast<const le_uint8 *>(&value); 67 return (le_uint16)((p[0] << 8) | p[1]); 68 #endif 69 }; 70 71 /** 72 * Reads a big-endian 32-bit word and returns a native-endian value. 73 * No-op on a big-endian platform, byte-swaps on a little-endian platform. 74 * 75 * @param value - the long to be byte swapped 76 * 77 * @return the byte swapped long 78 * 79 * @stable ICU 2.8 80 */ 81 static le_uint32 swapLong(le_uint32 value) 82 { 83 #if (defined(U_IS_BIG_ENDIAN) && U_IS_BIG_ENDIAN) || \ 84 (defined(BYTE_ORDER) && defined(BIG_ENDIAN) && (BYTE_ORDER == BIG_ENDIAN)) || \ 85 defined(__BIG_ENDIAN__) 86 // Fastpath when we know that the platform is big-endian. 87 return value; 88 #else 89 // Reads a big-endian value on any platform. 90 const le_uint8 *p = reinterpret_cast<const le_uint8 *>(&value); 91 return (le_uint32)((p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3]); 92 #endif 93 }; 94 95 private: 96 LESwaps() {} // private - forbid instantiation 97 }; 98 99 U_NAMESPACE_END 100 #endif 101
