usr/src/lib/libc/gen/frexp.c

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)frexp.c     5.3 (Berkeley) %G%";
#endif LIBC_SCCS and not lint

#include <math.h>

/*
 *      the call
 *              x = frexp(arg,&exp);
 *      must return a double fp quantity x which is <1.0
 *      and the corresponding binary exponent "exp".
 *      such that
 *              arg = x*2^exp
 *      if the argument is 0.0, return 0.0 mantissa and 0 exponent.
 */

double
frexp(x,i)
double x;
int *i;
{
        int neg;
        int j;
        j = 0;
        neg = 0;
        if(x<0){
                x = -x;
                neg = 1;
                }
        if(x>=1.0)
                while(x>=1.0){
                        j = j+1;
                        x = x/2;
                        }
        else if(x<0.5 && x != 0.0)
                while(x<0.5){
                        j = j-1;
                        x = 2*x;
                        }
        *i = j;
        if(neg) x = -x;
        return(x);
        }