/* @(#)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.
 * ====================================================
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

/*
 * 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 <float.h>

#include "math.h"
#include "math_private.h"

static const double huge = 1.0e300;

double
floor(double x)
{
    int32_t i0,i1,j0;
    u_int32_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 = ((u_int32_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<(u_int32_t)i1) i0 +=1 ;   /* got a carry */
                    i1=j;
                }
            }
            i1 &= (~i);
        }
    }
    INSERT_WORDS(x,i0,i1);
    return x;
}

#if SUPPORT_LONG_DOUBLE

#if LDBL_MANT_DIG == 53
__weak_reference(floor, floorl);
#endif

#endif