/indra/llcommon/llendianswizzle.h

/** 
 * @file llendianswizzle.h
 * @brief Functions for in-place bit swizzling
 *
 * $LicenseInfo:firstyear=2002&license=viewerlgpl$
 * Second Life Viewer Source Code
 * Copyright (C) 2010, Linden Research, Inc.
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation;
 * version 2.1 of the License only.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 * 
 * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
 * $/LicenseInfo$
 */

#ifndef LL_LLENDIANSWIZZLE_H
#define LL_LLENDIANSWIZZLE_H

/* This function is intended to be used for in-place swizzling, particularly after fread() of
	binary values from a file.  Such as:
	
	numRead = fread(scale.mV, sizeof(float), 3, fp);
	llendianswizzle(scale.mV, sizeof(float), 3);
	
	It assumes that the values in the file are LITTLE endian, so it's a no-op on a little endian machine.
	
	It keys off of typesize to do the correct swizzle, so make sure that typesize is the size of the native type.
	
	64-bit types are not yet handled.
*/

#ifdef LL_LITTLE_ENDIAN
	// little endian is native for most things.
	inline void llendianswizzle(void *,int,int)
	{
		// Nothing to do
	}
#endif

#ifdef LL_BIG_ENDIAN
	// big endian requires a bit of work.
	inline void llendianswizzle(void *p,int typesize, int count)
	{
		int i;
		switch(typesize)
		{
			case 2:
			{
				U16 temp;
				for(i=count ;i!=0 ;i--)
				{
					temp = ((U16*)p)[0];
					((U16*)p)[0] = 	((temp >> 8)  & 0x000000FF) | ((temp << 8)  & 0x0000FF00);
					p = (void*)(((U16*)p) + 1);
				}
			}
			break;
			
			case 4:
			{
				U32 temp;
				for(i=count; i!=0; i--)
				{
					temp = ((U32*)p)[0];
					((U32*)p)[0] = 	
							((temp >> 24) & 0x000000FF) | 
							((temp >> 8)  & 0x0000FF00) | 
							((temp << 8)  & 0x00FF0000) |
							((temp << 24) & 0xFF000000);
					p = (void*)(((U32*)p) + 1);
				}
			}
			break;
		}
		
	}
#endif

// Use this when working with a single integral value you want swizzled

#define llendianswizzleone(x) llendianswizzle(&(x), sizeof(x), 1)

#endif // LL_LLENDIANSWIZZLE_H