littobig.h

linux下的一款播放器

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/*

	CLittleEndianToBigEndian

	This class supports functions for converting data from LittleEndian byte order to 
	BigEndian byte order.

	This is different from using NetByte and HostByte order, becuase using the NetToHost fucntion 
	would not work on LittleEndian machines, as they are considered NetByte in the first place.

*/


#ifndef _CLITTOBIG_H
#define _CLITTOBIG_H

#include "hxtypes.h"

// GR 5/10/02 The old version of this class does a runtime test for endianness,
// and makes function calls to maybe swap the bytes.  None of that should really
// be necessary.  
//
// I'm only checking in a new version for Mac since that's all I can test on right now, 
// though the second inline version below for little-endian ought to work, too, and makes
// sense to use for Windows.

#if defined(_BIG_ENDIAN)

#define CLittleEndianToBigEndian_INLINE 1

class	CLittleEndianToBigEndian
{
  public:
    
    static inline	BOOL	TestBigEndian() { return TRUE; }
    
    static inline	void	ReverseWORD(UINT16& w) 
	{ 	
	    w = (((((UINT16) w)<<8) & 0xFF00) 
		 | ((((UINT16) w)>>8) & 0x00FF)); 
	}
    static inline	void	ReverseDWORD(ULONG32& w)
	{
	    w = (((((UINT32) w)<<24) & 0xFF000000)  | 
		 ((((UINT32) w)<< 8) & 0x00FF0000)  | 
		 ((((UINT32) w)>> 8) & 0x0000FF00)  | 
		 ((((UINT32) w)>>24) & 0x000000FF));
	}


};

#elif defined(_LITTLE_ENDIAN)

#define CLittleEndianToBigEndian_INLINE 1

class	CLittleEndianToBigEndian
{
  public:
    static inline	BOOL	TestBigEndian() { return FALSE; }
    
    static inline	void	ReverseWORD(UINT16& w) {}
    static inline	void	ReverseDWORD(ULONG32& w) {}
};


#else
// This is the old one which compiles to run-time tests of endianness, 
// which probably shouldn't needed for any platform

class	CLittleEndianToBigEndian
{
public:
	
	static	void	ReverseWORD(UINT16& w);
	static	void	ReverseDWORD(ULONG32& w);

	static	BOOL	TestBigEndian();

private:
	static	BOOL	mBigEndian;
	static	BOOL	mInitialized;
	
};

#endif



#endif // _CLITTOBIG_H