OgreBitwise.h
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/*
-----------------------------------------------------------------------------
This source file is part of OGRE
(Object-oriented Graphics Rendering Engine)
For the latest info, see http://www.ogre3d.org/
Copyright (c) 2000-2013 Torus Knot Software Ltd
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
-----------------------------------------------------------------------------
*/
#ifndef _Bitwise_H__
#define _Bitwise_H__
#include "OgrePrerequisites.h"
namespace Ogre {
class Bitwise {
public:
static FORCEINLINE unsigned int mostSignificantBitSet(unsigned int value)
{
unsigned int result = 0;
while (value != 0) {
++result;
value >>= 1;
}
return result-1;
}
static FORCEINLINE uint32 firstPO2From(uint32 n)
{
--n;
n |= n >> 16;
n |= n >> 8;
n |= n >> 4;
n |= n >> 2;
n |= n >> 1;
++n;
return n;
}
template<typename T>
static FORCEINLINE bool isPO2(T n)
{
return (n & (n-1)) == 0;
}
template<typename T>
static FORCEINLINE unsigned int getBitShift(T mask)
{
if (mask == 0)
return 0;
unsigned int result = 0;
while ((mask & 1) == 0) {
++result;
mask >>= 1;
}
return result;
}
template<typename SrcT, typename DestT>
static inline DestT convertBitPattern(SrcT srcValue, SrcT srcBitMask, DestT destBitMask)
{
// Mask off irrelevant source value bits (if any)
srcValue = srcValue & srcBitMask;
// Shift source down to bottom of DWORD
const unsigned int srcBitShift = getBitShift(srcBitMask);
srcValue >>= srcBitShift;
// Get max value possible in source from srcMask
const SrcT srcMax = srcBitMask >> srcBitShift;
// Get max available in dest
const unsigned int destBitShift = getBitShift(destBitMask);
const DestT destMax = destBitMask >> destBitShift;
// Scale source value into destination, and shift back
DestT destValue = (srcValue * destMax) / srcMax;
return (destValue << destBitShift);
}
static inline unsigned int fixedToFixed(uint32 value, unsigned int n, unsigned int p)
{
if(n > p)
{
// Less bits required than available; this is easy
value >>= n-p;
}
else if(n < p)
{
// More bits required than are there, do the fill
// Use old fashioned division, probably better than a loop
if(value == 0)
value = 0;
else if(value == (static_cast<unsigned int>(1)<<n)-1)
value = (1<<p)-1;
else value = value*(1<<p)/((1<<n)-1);
}
return value;
}
static inline unsigned int floatToFixed(const float value, const unsigned int bits)
{
if(value <= 0.0f) return 0;
else if (value >= 1.0f) return (1<<bits)-1;
else return (unsigned int)(value * (1<<bits));
}
static inline float fixedToFloat(unsigned value, unsigned int bits)
{
return (float)value/(float)((1<<bits)-1);
}
static inline void intWrite(void *dest, const int n, const unsigned int value)
{
switch(n) {
case 1:
((uint8*)dest)[0] = (uint8)value;
break;
case 2:
((uint16*)dest)[0] = (uint16)value;
break;
case 3:
#if OGRE_ENDIAN == OGRE_ENDIAN_BIG
((uint8*)dest)[0] = (uint8)((value >> 16) & 0xFF);
((uint8*)dest)[1] = (uint8)((value >> 8) & 0xFF);
((uint8*)dest)[2] = (uint8)(value & 0xFF);
#else
((uint8*)dest)[2] = (uint8)((value >> 16) & 0xFF);
((uint8*)dest)[1] = (uint8)((value >> 8) & 0xFF);
((uint8*)dest)[0] = (uint8)(value & 0xFF);
#endif
break;
case 4:
((uint32*)dest)[0] = (uint32)value;
break;
}
}
static inline unsigned int intRead(const void *src, int n) {
switch(n) {
case 1:
return ((const uint8*)src)[0];
case 2:
return ((const uint16*)src)[0];
case 3:
#if OGRE_ENDIAN == OGRE_ENDIAN_BIG
return ((uint32)((const uint8*)src)[0]<<16)|
((uint32)((const uint8*)src)[1]<<8)|
((uint32)((const uint8*)src)[2]);
#else
return ((uint32)((const uint8*)src)[0])|
((uint32)((const uint8*)src)[1]<<8)|
((uint32)((const uint8*)src)[2]<<16);
#endif
case 4:
return ((const uint32*)src)[0];
}
return 0; // ?
}
static inline uint16 floatToHalf(float i)
{
union { float f; uint32 i; } v;
v.f = i;
return floatToHalfI(v.i);
}
static inline uint16 floatToHalfI(uint32 i)
{
register int s = (i >> 16) & 0x00008000;
register int e = ((i >> 23) & 0x000000ff) - (127 - 15);
register int m = i & 0x007fffff;
if (e <= 0)
{
if (e < -10)
{
return 0;
}
m = (m | 0x00800000) >> (1 - e);
return static_cast<uint16>(s | (m >> 13));
}
else if (e == 0xff - (127 - 15))
{
if (m == 0) // Inf
{
return static_cast<uint16>(s | 0x7c00);
}
else // NAN
{
m >>= 13;
return static_cast<uint16>(s | 0x7c00 | m | (m == 0));
}
}
else
{
if (e > 30) // Overflow
{
return static_cast<uint16>(s | 0x7c00);
}
return static_cast<uint16>(s | (e << 10) | (m >> 13));
}
}
static inline float halfToFloat(uint16 y)
{
union { float f; uint32 i; } v;
v.i = halfToFloatI(y);
return v.f;
}
static inline uint32 halfToFloatI(uint16 y)
{
register int s = (y >> 15) & 0x00000001;
register int e = (y >> 10) & 0x0000001f;
register int m = y & 0x000003ff;
if (e == 0)
{
if (m == 0) // Plus or minus zero
{
return s << 31;
}
else // Denormalized number -- renormalize it
{
while (!(m & 0x00000400))
{
m <<= 1;
e -= 1;
}
e += 1;
m &= ~0x00000400;
}
}
else if (e == 31)
{
if (m == 0) // Inf
{
return (s << 31) | 0x7f800000;
}
else // NaN
{
return (s << 31) | 0x7f800000 | (m << 13);
}
}
e = e + (127 - 15);
m = m << 13;
return (s << 31) | (e << 23) | m;
}
};
}
#endif
Ogre::Bitwise::intRead
static unsigned int intRead(const void *src, int n)
Read a n*8 bits integer value to memory in native endian.
Definition: OgreBitwise.h:197
Ogre::Bitwise::halfToFloat
static float halfToFloat(uint16 y)
Convert a float16 (NV_half_float) to a float32 Courtesy of OpenEXR.
Definition: OgreBitwise.h:273
Ogre::Bitwise::mostSignificantBitSet
static FORCEINLINE unsigned int mostSignificantBitSet(unsigned int value)
Returns the most significant bit set in a value.
Definition: OgreBitwise.h:47
Ogre::Bitwise::fixedToFloat
static float fixedToFloat(unsigned value, unsigned int bits)
Fixed point to float.
Definition: OgreBitwise.h:161
OgrePrerequisites.h
Ogre::uint8
unsigned char uint8
Definition: OgrePlatform.h:361
Ogre::Bitwise::floatToHalf
static uint16 floatToHalf(float i)
Convert a float32 to a float16 (NV_half_float) Courtesy of OpenEXR.
Definition: OgreBitwise.h:222
Ogre::Bitwise::intWrite
static void intWrite(void *dest, const int n, const unsigned int value)
Write a n*8 bits integer value to memory in native endian.
Definition: OgreBitwise.h:169
Ogre::Bitwise::isPO2
static FORCEINLINE bool isPO2(T n)
Determines whether the number is power-of-two or not.
Definition: OgreBitwise.h:75
Ogre::uint32
unsigned int uint32
Definition: OgrePlatform.h:359
Ogre::Bitwise
Class for manipulating bit patterns.
Definition: OgreBitwise.h:43
Ogre::Bitwise::floatToHalfI
static uint16 floatToHalfI(uint32 i)
Converts float in uint32 format to a a half in uint16 format.
Definition: OgreBitwise.h:230
Ogre
Definition: OgreAndroidLogListener.h:34
Ogre::Bitwise::floatToFixed
static unsigned int floatToFixed(const float value, const unsigned int bits)
Convert floating point colour channel value between 0.0 and 1.0 (otherwise clamped) to integer of a c...
Definition: OgreBitwise.h:151
Ogre::Bitwise::getBitShift
static FORCEINLINE unsigned int getBitShift(T mask)
Returns the number of bits a pattern must be shifted right by to remove right-hand zeros...
Definition: OgreBitwise.h:83
Ogre::Bitwise::halfToFloatI
static uint32 halfToFloatI(uint16 y)
Converts a half in uint16 format to a float in uint32 format.
Definition: OgreBitwise.h:282
Ogre::Bitwise::convertBitPattern
static DestT convertBitPattern(SrcT srcValue, SrcT srcBitMask, DestT destBitMask)
Takes a value with a given src bit mask, and produces another value with a desired bit mask...
Definition: OgreBitwise.h:102
Ogre::Bitwise::fixedToFixed
static unsigned int fixedToFixed(uint32 value, unsigned int n, unsigned int p)
Convert N bit colour channel value to P bits.
Definition: OgreBitwise.h:127
FORCEINLINE
#define FORCEINLINE
Definition: OgrePlatform.h:102
Ogre::Bitwise::firstPO2From
static FORCEINLINE uint32 firstPO2From(uint32 n)
Returns the closest power-of-two number greater or equal to value.
Definition: OgreBitwise.h:60
Ogre::uint16
unsigned short uint16
Definition: OgrePlatform.h:360

Copyright © 2012 Torus Knot Software Ltd
This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.