/* S_FLOOR.C

 * 

 * Portions Copyright (c) 1993-2005 Nokia Corporation and/or its subsidiary(-ies).

 * All rights reserved.

 */

/* @(#)s_floor.c 5.1 93/09/24 */

/*

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

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

 *

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

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

 * software is freely granted, provided that this notice 

 * is preserved.

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

 */

/*

FUNCTION

<<floor>>, <<floorf>>, <<ceil>>, <<ceilf>>---floor and ceiling

INDEX

	floor

INDEX

	floorf

INDEX

	ceil

INDEX

	ceilf

ANSI_SYNOPSIS

	#include <math.h>

	double floor(double <[x]>);

        float floorf(float <[x]>);

        double ceil(double <[x]>);

        float ceilf(float <[x]>);

TRAD_SYNOPSIS

	#include <math.h>

        double floor(<[x]>)

	double <[x]>;

        float floorf(<[x]>) 

	float <[x]>;

        double ceil(<[x]>) 

	double <[x]>;

        float ceilf(<[x]>) 

	float <[x]>;

DESCRIPTION

<<floor>> and <<floorf>> find 

@tex

$\lfloor x \rfloor$, 

@end tex

the nearest integer less than or equal to <[x]>.

<<ceil>> and <<ceilf>> find 

@tex

$\lceil x\rceil$,

@end tex

the nearest integer greater than or equal to <[x]>.

RETURNS

<<floor>> and <<ceil>> return the integer result as a double.

<<floorf>> and <<ceilf>> return the integer result as a float.

PORTABILITY

<<floor>> and <<ceil>> are ANSI.

<<floorf>> and <<ceilf>> are extensions.

*/

/*

 * floor(x)

 * Return x rounded toward -inf to integral value

 * Method:

 *	Bit twiddling.

 * Exception:

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

 */

#include "FDLIBM.H"

static const double huge = 1.0e300;

/**

Round down value.

Returns the largest integer that is less than or equal to x 

@return   Floor of x.

@param x Floating point value

*/	

EXPORT_C double floor(double x) __SOFTFP

{

	__int32_t i0,i1,j0;

	__uint32_t i,j;

	EXTRACT_WORDS(i0,i1,x);

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

	if(j0<20) {

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

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

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

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

			{ i0=0xbff00000;i1=0;}

		}

	    } else {

		i = (0x000fffff)>>j0;

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

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

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

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

		}

	    }

	} else if (j0>51) {

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

	    else return x;		/* x is integral */

	} else {

	    i = ((__uint32_t)(0xffffffff))>>(j0-20);

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

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

		if(i0<0) {

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

		    else {

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

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

			i1=j;

		    }

		}

		i1 &= (~i);

	    }

	}

	INSERT_WORDS(x,i0,i1);

	return x;

}