source: trunk/minix/lib/gnu/ieee_float/frexp.c@ 20

/*
libc/ieee_float/frexp.c

Created:        Oct 14, 1993 by Philip Homburg <philip@cs.vu.nl>

Implementation of frexp that directly manipulates the exponent bits in an
ieee float
*/

#include <sys/types.h>
#include <math.h>

#include "ieee_float.h"

double frexp(value, eptr)
double value;
int *eptr;
{
        struct f64 *f64p;
        int exp, exp_bias;
        double factor;

        f64p= (struct f64 *)&value;
        exp_bias= 0;

        exp= F64_GET_EXP(f64p);
        if (exp == F64_EXP_MAX)
        {       /* Either infinity or Nan */
                *eptr= 0;
                return value;
        }
        if (exp == 0)
        {
                /* Either 0 or denormal */
                if (F64_GET_MANT_LOW(f64p) == 0 &&
                        F64_GET_MANT_HIGH(f64p) == 0)
                {
                        *eptr= 0;
                        return value;
                }

                /* Multiply by 2^64 */
                factor= 65536.0;        /* 2^16 */
                factor *= factor;       /* 2^32 */
                factor *= factor;       /* 2^64 */
                value *= factor;
                exp_bias= 64;
                exp= F64_GET_EXP(f64p);
        }

        exp= exp - F64_EXP_BIAS - exp_bias + 1;
        *eptr= exp;
        F64_SET_EXP(f64p, F64_EXP_BIAS-1);

        return value;
}

/*
 * $PchId: frexp.c,v 1.3 1996/02/22 21:01:39 philip Exp $
 */