src/libm/s_floor.c
author Ryan C. Gordon <icculus@icculus.org>
Fri, 12 Aug 2016 19:59:00 -0400
changeset 10266 c09f06c4e8c8
parent 6044 35448a5ea044
permissions -rw-r--r--
emscripten: send fake mouse events for touches, like other targets do. (This really should be handled at the higher level and not in the individual targets, but this fixes the immediate bug.)

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

#if defined(LIBM_SCCS) && !defined(lint)
static const char rcsid[] =
    "$NetBSD: s_floor.c,v 1.8 1995/05/10 20:47:20 jtc Exp $";
#endif

/*
 * 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 "math_libm.h"
#include "math_private.h"

#ifdef __STDC__
static const double huge_val = 1.0e300;
#else
static double huge_val = 1.0e300;
#endif

libm_hidden_proto(floor)
#ifdef __STDC__
     double floor(double x)
#else
     double floor(x)
     double x;
#endif
{
    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_val + 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_val + 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_val + 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;
}

libm_hidden_def(floor)