ehofman
0bc49bf244
This patch makesFlightGear at least compile on MSVC. I hope I have removed reference of my other local changes. DSP and DSW files are included for reference. They have been reconstructed with am2dsp.pl. I had to introduce a change to am2dsp because of the need of filenames with embedded spaces. (Yuck) The major direction is to remove clutter like the _USE_MATH_DEFINES and have it on the compiler command line sice there is no central include file. You will have to put it on the command line for your locale Project files, if it not there, already. I added the _CRT_SECURE_NO_DEPRECATE define for 2005, since it does no harm to other VC version. Third Party Libs like plib, OpenALSDK, freeglut, pthreads-win32, zlib are unpacked as is side by side. Only change put the includes of OpenAL into include/AL rather directly into include.
115 lines
2.4 KiB
C++
115 lines
2.4 KiB
C++
/*
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* \file fastmath.hxx
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* fast mathematics routines.
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*
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* Refferences:
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*
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* A Fast, Compact Approximation of the Exponential Function
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* Nicol N. Schraudolph
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* IDSIA, Lugano, Switzerland
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* http://www.inf.ethz.ch/~schraudo/pubs/exp.pdf
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*
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* Fast log() Function, by Laurent de Soras:
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* http://www.flipcode.com/cgi-bin/msg.cgi?showThread=Tip-Fastlogfunction&forum=totd&id=-1
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*
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*/
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/*
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* $Id$
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*/
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#ifndef _SG_FMATH_HXX
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#define _SG_FMATH_HXX 1
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#ifndef __cplusplus
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# error This library requires C++
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#endif
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#include <math.h>
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double fast_exp(double val);
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double fast_exp2(const double val);
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float fast_pow(const float val1, const float val2);
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float fast_log2(const float cal);
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float fast_root(const float f, const int n);
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float _fast_pow2(const float cal);
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float _fast_log2(const float val);
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float fast_sin(const float val);
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float fast_cos(const float val);
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float fast_tan(const float val);
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float fast_asin(const float val);
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float fast_acos(const float val);
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float fast_atan(const float val);
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void fast_BSL(float &x, register unsigned long shiftAmount);
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void fast_BSR(float &x, register unsigned long shiftAmount);
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inline float fast_log2 (float val)
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{
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int * const exp_ptr = reinterpret_cast <int *> (&val);
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int x = *exp_ptr;
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const int log_2 = ((x >> 23) & 255) - 128;
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x &= ~(255 << 23);
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x += 127 << 23;
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*exp_ptr = x;
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val = ((-1.0f/3) * val + 2) * val - 2.0f/3; // (1)
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return (val + log_2);
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}
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/**
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* This function is about 3 times faster than the system log() function
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* and has an error of about 0.01%
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*/
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inline float fast_log (const float &val)
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{
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return (fast_log2 (val) * 0.69314718f);
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}
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inline float fast_log10 (const float &val)
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{
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return (fast_log2(val) / 3.321928095f);
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}
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/**
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* This function is about twice as fast as the system pow(x,y) function
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*/
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inline float fast_pow(const float val1, const float val2)
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{
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return _fast_pow2(val2 * _fast_log2(val1));
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}
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/*
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* Haven't seen this elsewhere, probably because it is too obvious?
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* Anyway, these functions are intended for 32-bit floating point numbers
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* only and should work a bit faster than the regular ones.
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*/
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inline float fast_abs(float f)
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{
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int i=((*(int*)&f)&0x7fffffff);
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return (*(float*)&i);
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}
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inline float fast_neg(float f)
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{
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int i=((*(int*)&f)^0x80000000);
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return (*(float*)&i);
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}
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inline int fast_sgn(float f)
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{
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return 1+(((*(int*)&f)>>31)<<1);
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}
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#endif // !_SG_FMATH_HXX
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