95 lines
2.9 KiB
C
95 lines
2.9 KiB
C
/**
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* @file llendianswizzle.h
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* @brief Functions for in-place bit swizzling
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*
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* $LicenseInfo:firstyear=2002&license=viewerlgpl$
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* Second Life Viewer Source Code
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* Copyright (C) 2010, Linden Research, Inc.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation;
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* version 2.1 of the License only.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*
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* Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA
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* $/LicenseInfo$
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*/
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#ifndef LL_LLENDIANSWIZZLE_H
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#define LL_LLENDIANSWIZZLE_H
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/* This function is intended to be used for in-place swizzling, particularly after fread() of
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binary values from a file. Such as:
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numRead = fread(scale.mV, sizeof(float), 3, fp);
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llendianswizzle(scale.mV, sizeof(float), 3);
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It assumes that the values in the file are LITTLE endian, so it's a no-op on a little endian machine.
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It keys off of typesize to do the correct swizzle, so make sure that typesize is the size of the native type.
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64-bit types are not yet handled.
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*/
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#ifdef LL_LITTLE_ENDIAN
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// little endian is native for most things.
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inline void llendianswizzle(void *,int,int)
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{
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// Nothing to do
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}
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#endif
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#ifdef LL_BIG_ENDIAN
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// big endian requires a bit of work.
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inline void llendianswizzle(void *p,int typesize, int count)
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{
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int i;
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switch(typesize)
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{
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case 2:
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{
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U16 temp;
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for(i=count ;i!=0 ;i--)
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{
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temp = ((U16*)p)[0];
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((U16*)p)[0] = ((temp >> 8) & 0x000000FF) | ((temp << 8) & 0x0000FF00);
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p = (void*)(((U16*)p) + 1);
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}
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}
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break;
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case 4:
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{
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U32 temp;
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for(i=count; i!=0; i--)
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{
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temp = ((U32*)p)[0];
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((U32*)p)[0] =
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((temp >> 24) & 0x000000FF) |
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((temp >> 8) & 0x0000FF00) |
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((temp << 8) & 0x00FF0000) |
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((temp << 24) & 0xFF000000);
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p = (void*)(((U32*)p) + 1);
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}
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}
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break;
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}
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}
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#endif
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// Use this when working with a single integral value you want swizzled
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#define llendianswizzleone(x) llendianswizzle(&(x), sizeof(x), 1)
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#endif // LL_LLENDIANSWIZZLE_H
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