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

/*
 * modfl(long double x, long double *iptr)
 * return fraction part of x, and return x's integral part in *iptr.
 * Method:
 *      Bit twiddling.
 *
 * Exception:
 *      No exception.
 */

#include <math.h>

#include "math_private.h"

static const long double one = 1.0;

long double
modfl(long double x, long double *iptr)
{
        int64_t i0,i1,jj0;
        u_int64_t i;
        GET_LDOUBLE_WORDS64(i0,i1,x);
        jj0 = ((i0>>48)&0x7fff)-0x3fff; /* exponent of x */
        if(jj0<48) {                    /* integer part in high x */
            if(jj0<0) {                 /* |x|<1 */
                /* *iptr = +-0 */
                SET_LDOUBLE_WORDS64(*iptr,i0&0x8000000000000000ULL,0);
                return x;
            } else {
                i = (0x0000ffffffffffffLL)>>jj0;
                if(((i0&i)|i1)==0) {            /* x is integral */
                    *iptr = x;
                    /* return +-0 */
                    SET_LDOUBLE_WORDS64(x,i0&0x8000000000000000ULL,0);
                    return x;
                } else {
                    SET_LDOUBLE_WORDS64(*iptr,i0&(~i),0);
                    return x - *iptr;
                }
            }
        } else if (jj0>111) {           /* no fraction part */
            *iptr = x*one;
            /* We must handle NaNs separately.  */
            if (jj0 == 0x4000 && ((i0 & 0x0000ffffffffffffLL) | i1))
              return x*one;
            /* return +-0 */
            SET_LDOUBLE_WORDS64(x,i0&0x8000000000000000ULL,0);
            return x;
        } else {                        /* fraction part in low x */
            i = -1ULL>>(jj0-48);
            if((i1&i)==0) {             /* x is integral */
                *iptr = x;
                /* return +-0 */
                SET_LDOUBLE_WORDS64(x,i0&0x8000000000000000ULL,0);
                return x;
            } else {
                SET_LDOUBLE_WORDS64(*iptr,i0,i1&(~i));
                return x - *iptr;
            }
        }
}