nevrax.org : docs

00001 
+00007 /* Copyright, 2000, 2001 Nevrax Ltd.
+00008  *
+00009  * This file is part of NEVRAX NEL.
+00010  * NEVRAX NEL is free software; you can redistribute it and/or modify
+00011  * it under the terms of the GNU General Public License as published by
+00012  * the Free Software Foundation; either version 2, or (at your option)
+00013  * any later version.
+00014 
+00015  * NEVRAX NEL is distributed in the hope that it will be useful, but
+00016  * WITHOUT ANY WARRANTY; without even the implied warranty of
+00017  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+00018  * General Public License for more details.
+00019 
+00020  * You should have received a copy of the GNU General Public License
+00021  * along with NEVRAX NEL; see the file COPYING. If not, write to the
+00022  * Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+00023  * MA 02111-1307, USA.
+00024  */
+00025 
+00026 #ifndef NL_FAST_FLOOR_H
+00027 #define NL_FAST_FLOOR_H
+00028 
+00029 #include "nel/misc/types_nl.h"
+00030 #include <math.h>
+00031 
+00032 namespace NL3D
+00033 {                                         
+00034 
+00035 // fastFloor function. 
+00036 #ifdef NL_OS_WINDOWS
+00037 
+00038 #include <float.h>
+00039 
+00040 // The magic constant value. support both positive and negative numbers.
+00041 extern double   OptFastFloorMagicConst ; 
+00042 extern int OptFastFloorBkupCW ;
+00043 // init float CW.
+00044 inline void  OptFastFloorBegin()
+00045 {
+00046         OptFastFloorBkupCW= _controlfp(0, 0);
+00047         _controlfp( _RC_DOWN|_PC_53, _MCW_RC|_MCW_PC );
+00048 }
+00049 
+00050 // reset float CW.
+00051 inline void  OptFastFloorEnd()
+00052 {
+00053         _controlfp(OptFastFloorBkupCW, _MCW_RC|_MCW_PC);
+00054 }
+00055 
+00056 // Force __stdcall to not pass parameters in registers.
+00057 inline sint32 __stdcall OptFastFloor(float x)
+00058 {       
+00059         static __int64  res;
+00060         __asm
+00061         {
+00062                 fld             x
+00063                 fadd    qword ptr OptFastFloorMagicConst                
+00064                 fstp    qword ptr res           
+00065         }
+00066 
+00067         return (sint32) res;
+00068 }
+00069 
+00070 
+00071 // Force __stdcall to not pass parameters in registers.
+00072 inline float __stdcall OptFastFractionnalPart(float x)
+00073 {
+00074         static double res;
+00075         __asm
+00076         {
+00077                 fld             x
+00078                 fld     st(0)
+00079                 fadd    qword ptr OptFastFloorMagicConst
+00080                 fstp    qword ptr res
+00081                 fisub   dword ptr res           
+00082                 fstp    dword ptr res
+00083         }
+00084 
+00085         return * (float *) &res;
+00086 }
+00087 
+00088 
+00089 
+00090 
+00091 #else
+00092 inline void  OptFastFloorBegin() {}
+00093 inline void  OptFastFloorEnd() {}
+00094 inline sint  OptFastFloor(float x)
+00095 {
+00096         return (sint)floor(x);
+00097 }
+00098 
+00099 inline float  OptFastFractionnalPart(float x)
+00100 {
+00101         return x - (sint) x ;
+00102 }
+00103 
+00104 
+00105 #endif
+00106 
+00107 
+00108 
+00109 } // NL3D
+00110 
+00111 
+00112 #endif // NL_FAST_FLOOR_H
+00113 
+00114 /* End of fast_floor.h */
+