Subversion Repositories planix.SVN

/*
 * The authors of this software are Rob Pike and Ken Thompson.
 *              Copyright (c) 2002 by Lucent Technologies.
 * Permission to use, copy, modify, and distribute this software for any
 * purpose without fee is hereby granted, provided that this entire notice
 * is included in all copies of any software which is or includes a copy
 * or modification of this software and in all copies of the supporting
 * documentation for such software.
 * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED
 * WARRANTY.  IN PARTICULAR, NEITHER THE AUTHORS NOR LUCENT TECHNOLOGIES MAKE ANY
 * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY
 * OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.
 */
#include <stdarg.h>
#include <string.h>
#include "utf.h"
#include "fmt.h"
#include "fmtdef.h"

/*
 * Reads a floating-point number by interpreting successive characters
 * returned by (*f)(vp).  The last call it makes to f terminates the
 * scan, so is not a character in the number.  It may therefore be
 * necessary to back up the input stream up one byte after calling charstod.
 */

double
fmtcharstod(int(*f)(void*), void *vp)
{
        double num, dem;
        int neg, eneg, dig, exp, c;

        num = 0;
        neg = 0;
        dig = 0;
        exp = 0;
        eneg = 0;

        c = (*f)(vp);
        while(c == ' ' || c == '\t')
                c = (*f)(vp);
        if(c == '-' || c == '+'){
                if(c == '-')
                        neg = 1;
                c = (*f)(vp);
        }
        while(c >= '0' && c <= '9'){
                num = num*10 + c-'0';
                c = (*f)(vp);
        }
        if(c == '.')
                c = (*f)(vp);
        while(c >= '0' && c <= '9'){
                num = num*10 + c-'0';
                dig++;
                c = (*f)(vp);
        }
        if(c == 'e' || c == 'E'){
                c = (*f)(vp);
                if(c == '-' || c == '+'){
                        if(c == '-'){
                                dig = -dig;
                                eneg = 1;
                        }
                        c = (*f)(vp);
                }
                while(c >= '0' && c <= '9'){
                        exp = exp*10 + c-'0';
                        c = (*f)(vp);
                }
        }
        exp -= dig;
        if(exp < 0){
                exp = -exp;
                eneg = !eneg;
        }
        dem = __fmtpow10(exp);
        if(eneg)
                num /= dem;
        else
                num *= dem;
        if(neg)
                return -num;
        return num;
}