127 lines
2.7 KiB
C++
127 lines
2.7 KiB
C++
// This file is part of the "Irrlicht Engine".
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// For conditions of distribution and use, see copyright notice in irrlicht.h
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#ifndef __IRR_FAST_MATH_COMPAT_H_INCLUDED__
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#define __IRR_FAST_MATH_COMPAT_H_INCLUDED__
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#include "irrMath.h"
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namespace irr
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{
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namespace core
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{
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// IRRLICHT_FAST_MATH functions which I wanted to kick out because they return
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// wrong results. But last time I proposed that I've been asked to keep them for
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// Burnings software renderer. So to avoid changing that accidentally or messing up
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// it's speed I'll keep them around, but only as internal header.
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// They should not be used otherwise any longer.
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// Some examples for unexpected results when using this with IRRLICHT_FAST_MATH:
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// Input 1, expected 1, got 0
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// Input 3, expected 3, got 2
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// Input -1.40129846e-45, expected -1, got 0
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REALINLINE s32 floor32_fast(f32 x)
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{
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#ifdef IRRLICHT_FAST_MATH
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const f32 h = 0.5f;
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s32 t;
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#if defined(_MSC_VER) && !defined(_WIN64)
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__asm
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{
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fld x
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fsub h
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fistp t
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}
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#elif defined(__GNUC__)
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__asm__ __volatile__ (
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"fsub %2 \n\t"
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"fistpl %0"
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: "=m" (t)
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: "t" (x), "f" (h)
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: "st"
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);
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#else
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return (s32) floorf ( x );
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#endif
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return t;
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#else // no fast math
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return (s32) floorf ( x );
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#endif
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}
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// Some examples for unexpected results when using this with IRRLICHT_FAST_MATH:
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// Input 1.40129846e-45, expected 1, got 0
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// Input -1, expected -1, got 0
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// Input -3, expected -3, got -2
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REALINLINE s32 ceil32_fast ( f32 x )
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{
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#ifdef IRRLICHT_FAST_MATH
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const f32 h = 0.5f;
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s32 t;
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#if defined(_MSC_VER) && !defined(_WIN64)
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__asm
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{
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fld x
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fadd h
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fistp t
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}
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#elif defined(__GNUC__)
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__asm__ __volatile__ (
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"fadd %2 \n\t"
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"fistpl %0 \n\t"
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: "=m"(t)
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: "t"(x), "f"(h)
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: "st"
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);
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#else
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return (s32) ceilf ( x );
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#endif
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return t;
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#else // not fast math
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return (s32) ceilf ( x );
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#endif
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}
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// Some examples for unexpected results when using this with IRRLICHT_FAST_MATH:
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// Input 0.5, expected 1, got 0
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// Input 2.5, expected 3, got 2
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// Input -1.40129846e-45, expected -nan(ind), got -inf
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// Input -2.80259693e-45, expected -nan(ind), got -inf
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REALINLINE s32 round32_fast(f32 x)
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{
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#if defined(IRRLICHT_FAST_MATH)
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s32 t;
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#if defined(_MSC_VER) && !defined(_WIN64)
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__asm
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{
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fld x
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fistp t
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}
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#elif defined(__GNUC__)
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__asm__ __volatile__ (
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"fistpl %0 \n\t"
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: "=m"(t)
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: "t"(x)
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: "st"
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);
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#else
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return (s32) round_(x);
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#endif
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return t;
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#else // no fast math
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return (s32) round_(x);
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#endif
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}
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} // end namespace core
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} // end namespace irr
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#endif // __IRR_FAST_MATH_COMPAT_H_INCLUDED__
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