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godotengine
GitHub Repository: godotengine/godot
 Path: blob/master/thirdparty/sdl/libm/s_floor.c
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#include "SDL_internal.h"

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/*

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 * ====================================================

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 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.

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 *

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 * Developed at SunPro, a Sun Microsystems, Inc. business.

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 * Permission to use, copy, modify, and distribute this

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 * software is freely granted, provided that this notice

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 * is preserved.

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 * ====================================================

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 */

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/*

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 * floor(x)

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 * Return x rounded toward -inf to integral value

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 * Method:

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 *	Bit twiddling.

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 * Exception:

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 *	Inexact flag raised if x not equal to floor(x).

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 */

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/*#include <features.h>*/

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/* Prevent math.h from defining a colliding inline */

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#undef __USE_EXTERN_INLINES

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#include "math_libm.h"

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#include "math_private.h"

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#ifdef __WATCOMC__ /* Watcom defines huge=__huge */

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#undef huge

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#endif

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static const double huge = 1.0e300;

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double floor(double x)

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{

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	int32_t i0,i1,j0;

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	u_int32_t i,j;

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	EXTRACT_WORDS(i0,i1,x);

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	j0 = ((i0>>20)&0x7ff)-0x3ff;

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	if(j0<20) {

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	    if(j0<0) { 	/* raise inexact if x != 0 */

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		if(huge+x>0.0) {/* return 0*sign(x) if |x|<1 */

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		    if(i0>=0) {i0=i1=0;}

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		    else if(((i0&0x7fffffff)|i1)!=0)

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			{ i0=0xbff00000;i1=0;}

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		}

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	    } else {

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		i = (0x000fffff)>>j0;

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		if(((i0&i)|i1)==0) return x; /* x is integral */

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		if(huge+x>0.0) {	/* raise inexact flag */

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		    if(i0<0) i0 += (0x00100000)>>j0;

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		    i0 &= (~i); i1=0;

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		}

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	    }

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	} else if (j0>51) {

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	    if(j0==0x400) return x+x;	/* inf or NaN */

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	    else return x;		/* x is integral */

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	} else {

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	    i = ((u_int32_t)(0xffffffff))>>(j0-20);

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	    if((i1&i)==0) return x;	/* x is integral */

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	    if(huge+x>0.0) { 		/* raise inexact flag */

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		if(i0<0) {

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		    if(j0==20) i0+=1;

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		    else {

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			j = i1+(1<<(52-j0));

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			if(j<(u_int32_t)i1) i0 +=1 ; 	/* got a carry */

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			i1=j;

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		    }

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		}

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		i1 &= (~i);

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	    }

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	}

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	INSERT_WORDS(x,i0,i1);

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	return x;

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}

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libm_hidden_def(floor)

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