[1092] | 1 | /*
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| 2 | -----------------------------------------------------------------------------
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| 3 | This source file is part of OGRE
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| 4 | (Object-oriented Graphics Rendering Engine)
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| 5 | For the latest info, see http://www.ogre3d.org/
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| 6 |
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| 7 | Copyright (c) 2000-2005 The OGRE Team
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| 8 | Also see acknowledgements in Readme.html
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| 9 |
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| 10 | This program is free software; you can redistribute it and/or modify it under
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| 11 | the terms of the GNU Lesser General Public License as published by the Free Software
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| 12 | Foundation; either version 2 of the License, or (at your option) any later
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| 13 | version.
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| 14 |
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| 15 | This program is distributed in the hope that it will be useful, but WITHOUT
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| 16 | ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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| 17 | FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
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| 18 |
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| 19 | You should have received a copy of the GNU Lesser General Public License along with
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| 20 | this program; if not, write to the Free Software Foundation, Inc., 59 Temple
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| 21 | Place - Suite 330, Boston, MA 02111-1307, USA, or go to
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| 22 | http://www.gnu.org/copyleft/lesser.txt.
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| 23 | -----------------------------------------------------------------------------
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| 24 | */
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| 25 | #ifndef _Bitwise_H__
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| 26 | #define _Bitwise_H__
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| 27 |
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| 28 | #include "OgrePrerequisites.h"
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| 29 |
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| 30 | namespace Ogre {
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| 31 |
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| 32 | /** Class for manipulating bit patterns.
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| 33 | */
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| 34 | class Bitwise {
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| 35 | public:
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| 36 | /** Returns the number of bits a pattern must be shifted right by to
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| 37 | remove right-hand zeroes.
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| 38 | */
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| 39 | template<typename T>
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| 40 | static FORCEINLINE unsigned int getBitShift(T mask)
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| 41 | {
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| 42 | if (mask == 0)
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| 43 | return 0;
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| 44 |
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| 45 | unsigned int result = 0;
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| 46 | while ((mask & 1) == 0) {
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| 47 | ++result;
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| 48 | mask >>= 1;
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| 49 | }
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| 50 | return result;
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| 51 | }
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| 52 |
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| 53 | /** Takes a value with a given src bit mask, and produces another
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| 54 | value with a desired bit mask.
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| 55 | @remarks
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| 56 | This routine is useful for colour conversion.
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| 57 | */
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| 58 | template<typename SrcT, typename DestT>
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| 59 | static inline DestT convertBitPattern(SrcT srcValue, SrcT srcBitMask, DestT destBitMask)
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| 60 | {
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| 61 | // Mask off irrelevant source value bits (if any)
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| 62 | srcValue = srcValue & srcBitMask;
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| 63 |
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| 64 | // Shift source down to bottom of DWORD
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| 65 | const unsigned int srcBitShift = getBitShift(srcBitMask);
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| 66 | srcValue >>= srcBitShift;
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| 67 |
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| 68 | // Get max value possible in source from srcMask
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| 69 | const SrcT srcMax = srcBitMask >> srcBitShift;
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| 70 |
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| 71 | // Get max avaiable in dest
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| 72 | const unsigned int destBitShift = getBitShift(destBitMask);
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| 73 | const DestT destMax = destBitMask >> destBitShift;
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| 74 |
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| 75 | // Scale source value into destination, and shift back
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| 76 | DestT destValue = (srcValue * destMax) / srcMax;
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| 77 | return (destValue << destBitShift);
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| 78 | }
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| 79 |
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| 80 | /**
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| 81 | * Convert N bit colour channel value to P bits. It fills P bits with the
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| 82 | * bit pattern repeated. (this is /((1<<n)-1) in fixed point)
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| 83 | */
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| 84 | static inline unsigned int fixedToFixed(uint32 value, unsigned int n, unsigned int p)
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| 85 | {
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| 86 | if(n > p)
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| 87 | {
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| 88 | // Less bits required than available; this is easy
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| 89 | value >>= n-p;
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| 90 | }
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| 91 | else if(n < p)
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| 92 | {
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| 93 | // More bits required than are there, do the fill
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| 94 | // Use old fashioned division, probably better than a loop
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| 95 | if(value == 0)
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| 96 | value = 0;
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| 97 | else if(value == (static_cast<unsigned int>(1)<<n)-1)
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| 98 | value = (1<<p)-1;
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| 99 | else value = value*(1<<p)/((1<<n)-1);
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| 100 | }
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| 101 | return value;
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| 102 | }
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| 103 |
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| 104 | /**
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| 105 | * Convert floating point colour channel value between 0.0 and 1.0 (otherwise clamped)
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| 106 | * to integer of a certain number of bits. Works for any value of bits between 0 and 31.
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| 107 | */
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| 108 | static inline unsigned int floatToFixed(const float value, const unsigned int bits)
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| 109 | {
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| 110 | if(value <= 0.0f) return 0;
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| 111 | else if (value >= 1.0f) return (1<<bits)-1;
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| 112 | else return (unsigned int)(value * (1<<bits));
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| 113 | }
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| 114 |
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| 115 | /**
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| 116 | * Fixed point to float
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| 117 | */
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| 118 | static inline float fixedToFloat(unsigned value, unsigned int bits)
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| 119 | {
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| 120 | return (float)value/(float)((1<<bits)-1);
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| 121 | }
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| 122 |
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| 123 | /**
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| 124 | * Write a n*8 bits integer value to memory in native endian.
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| 125 | */
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| 126 | static inline void intWrite(const void *dest, const int n, const unsigned int value)
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| 127 | {
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| 128 | switch(n) {
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| 129 | case 1:
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| 130 | ((uint8*)dest)[0] = (uint8)value;
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| 131 | break;
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| 132 | case 2:
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| 133 | ((uint16*)dest)[0] = (uint16)value;
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| 134 | break;
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| 135 | case 3:
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| 136 | #if OGRE_ENDIAN == OGRE_ENDIAN_BIG
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| 137 | ((uint8*)dest)[0] = (uint8)((value >> 16) & 0xFF);
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| 138 | ((uint8*)dest)[1] = (uint8)((value >> 8) & 0xFF);
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| 139 | ((uint8*)dest)[2] = (uint8)(value & 0xFF);
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| 140 | #else
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| 141 | ((uint8*)dest)[2] = (uint8)((value >> 16) & 0xFF);
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| 142 | ((uint8*)dest)[1] = (uint8)((value >> 8) & 0xFF);
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| 143 | ((uint8*)dest)[0] = (uint8)(value & 0xFF);
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| 144 | #endif
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| 145 | break;
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| 146 | case 4:
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| 147 | ((uint32*)dest)[0] = (uint32)value;
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| 148 | break;
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| 149 | }
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| 150 | }
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| 151 | /**
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| 152 | * Read a n*8 bits integer value to memory in native endian.
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| 153 | */
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| 154 | static inline unsigned int intRead(const void *src, int n) {
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| 155 | switch(n) {
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| 156 | case 1:
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| 157 | return ((uint8*)src)[0];
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| 158 | case 2:
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| 159 | return ((uint16*)src)[0];
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| 160 | case 3:
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| 161 | #if OGRE_ENDIAN == OGRE_ENDIAN_BIG
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| 162 | return ((uint32)((uint8*)src)[0]<<16)|
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| 163 | ((uint32)((uint8*)src)[1]<<8)|
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| 164 | ((uint32)((uint8*)src)[2]);
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| 165 | #else
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| 166 | return ((uint32)((uint8*)src)[0])|
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| 167 | ((uint32)((uint8*)src)[1]<<8)|
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| 168 | ((uint32)((uint8*)src)[2]<<16);
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| 169 | #endif
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| 170 | case 4:
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| 171 | return ((uint32*)src)[0];
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| 172 | }
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| 173 | return 0; // ?
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| 174 | }
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| 175 |
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| 176 | /** Convert a float32 to a float16 (NV_half_float)
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| 177 | Courtesy of OpenEXR
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| 178 | */
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| 179 | static inline uint16 floatToHalf(float i)
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| 180 | {
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| 181 | return floatToHalfI(*reinterpret_cast<uint32*>(&i));
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| 182 | }
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| 183 | /** Converts float in uint32 format to a a half in uint16 format
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| 184 | */
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| 185 | static inline uint16 floatToHalfI(uint32 i)
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| 186 | {
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| 187 | register int s = (i >> 16) & 0x00008000;
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| 188 | register int e = ((i >> 23) & 0x000000ff) - (127 - 15);
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| 189 | register int m = i & 0x007fffff;
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| 190 |
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| 191 | if (e <= 0)
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| 192 | {
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| 193 | if (e < -10)
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| 194 | {
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| 195 | return 0;
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| 196 | }
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| 197 | m = (m | 0x00800000) >> (1 - e);
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| 198 |
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| 199 | return s | (m >> 13);
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| 200 | }
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| 201 | else if (e == 0xff - (127 - 15))
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| 202 | {
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| 203 | if (m == 0) // Inf
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| 204 | {
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| 205 | return s | 0x7c00;
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| 206 | }
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| 207 | else // NAN
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| 208 | {
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| 209 | m >>= 13;
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| 210 | return s | 0x7c00 | m | (m == 0);
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| 211 | }
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| 212 | }
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| 213 | else
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| 214 | {
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| 215 | if (e > 30) // Overflow
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| 216 | {
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| 217 | return s | 0x7c00;
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| 218 | }
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| 219 |
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| 220 | return s | (e << 10) | (m >> 13);
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| 221 | }
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| 222 | }
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| 223 |
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| 224 | /**
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| 225 | * Convert a float16 (NV_half_float) to a float32
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| 226 | * Courtesy of OpenEXR
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| 227 | */
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| 228 | static inline float halfToFloat(uint16 y)
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| 229 | {
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| 230 | uint32 r = halfToFloatI(y);
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| 231 | return *reinterpret_cast<float*>(&r);
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| 232 | }
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| 233 | /** Converts a half in uint16 format to a float
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| 234 | in uint32 format
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| 235 | */
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| 236 | static inline uint32 halfToFloatI(uint16 y)
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| 237 | {
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| 238 | register int s = (y >> 15) & 0x00000001;
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| 239 | register int e = (y >> 10) & 0x0000001f;
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| 240 | register int m = y & 0x000003ff;
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| 241 |
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| 242 | if (e == 0)
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| 243 | {
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| 244 | if (m == 0) // Plus or minus zero
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| 245 | {
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| 246 | return s << 31;
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| 247 | }
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| 248 | else // Denormalized number -- renormalize it
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| 249 | {
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| 250 | while (!(m & 0x00000400))
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| 251 | {
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| 252 | m <<= 1;
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| 253 | e -= 1;
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| 254 | }
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| 255 |
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| 256 | e += 1;
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| 257 | m &= ~0x00000400;
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| 258 | }
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| 259 | }
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| 260 | else if (e == 31)
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| 261 | {
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| 262 | if (m == 0) // Inf
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| 263 | {
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| 264 | return (s << 31) | 0x7f800000;
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| 265 | }
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| 266 | else // NaN
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| 267 | {
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| 268 | return (s << 31) | 0x7f800000 | (m << 13);
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| 269 | }
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| 270 | }
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| 271 |
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| 272 | e = e + (127 - 15);
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| 273 | m = m << 13;
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| 274 |
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| 275 | return (s << 31) | (e << 23) | m;
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| 276 | }
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| 277 |
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| 278 |
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| 279 | };
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| 280 | }
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| 281 |
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| 282 | #endif
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