82 lines
2.0 KiB
C++
82 lines
2.0 KiB
C++
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/*
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* @(#)LESwaps.h 1.3 00/03/15
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*
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* (C) Copyright IBM Corp. 1998, 1999, 2000 - All Rights Reserved
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*
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*/
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#ifndef __LESWAPS_H
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#define __LESWAPS_H
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#include "LETypes.h"
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U_NAMESPACE_BEGIN
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/**
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* These are convenience macros which invoke the swap functions
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* from a concise call.
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*/
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#define SWAPW(value) (LESwaps::isBigEndian() ? (value) : LESwaps::swapWord(value))
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#define SWAPL(value) (LESwaps::isBigEndian() ? (value) : LESwaps::swapLong(value))
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/**
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* This class is used to access data which stored in big endian order
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* regardless of the conventions of the platform. It has been designed
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* to automatically detect the endian-ness of the platform, so that a
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* compilation flag is not needed.
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*
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* All methods are static and inline in an attempt to induce the compiler
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* to do most of the calculations at compile time.
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*/
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class LESwaps
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{
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public:
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/**
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* This method detects the endian-ness of the platform by
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* casting a pointer to a word to a pointer to a byte. On
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* big endian platforms the FF will be in the byte with the
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* lowest address. On little endian platforms, the FF will
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* be in the byte with the highest address.
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*
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* @return true if the platform is big endian
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*/
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static le_bool isBigEndian()
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{
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static le_uint16 word = 0xFF00;
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static le_uint8 *byte = (le_uint8 *) &word;
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return *byte;
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};
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/**
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* This method the byte swap required on little endian platforms
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* to correctly access a word.
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*
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* @param value - the word to be byte swapped
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*
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* @return the byte swapped word
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*/
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static le_uint16 swapWord(le_uint16 value)
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{
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return (((le_uint8) (value >> 8)) | (value << 8));
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};
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/**
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* This method does the byte swapping required on little endian platforms
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* to correctly access a long.
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*
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* @param value - the long to be byte swapped
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*
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* @return the byte swapped long
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*/
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static le_uint32 swapLong(le_uint32 value)
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{
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return swapWord((le_uint16) (value >> 16)) | (swapWord((le_uint16) value) << 16);
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};
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};
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U_NAMESPACE_END
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#endif
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