/*  sxfcvbin.cpp  by K.Tsuru  */
// function ID = 502    BRADIX
/********************************************
SDecimal class
Provides radix conversion DRADIX --> BRADIX.
********************************************/
#ifndef SN_H
#include "sn.h"
#endif

SDecimal SDecimal::ConvToBin(const SDouble& m){
    SDecimal result;    // result = 0;
    if(m.Type() == m.BIN_DEC){  //already converted
        result = m;
        return result;
    }
    if(m.Sign(502) == 0) return result;
    int e = m.NetRdxExp();      // m = 0.M*DRADIX^e
//        1                                   1-e
// m = 0.aaaa|bbbb|...*DRADIX^e = 0.0000|...|aaaa|bbbb|....
// out of effective figures ?
    if( ( e < 0 ) && ( uint(1-e) > m.MaxSize() +1u) ) return result;

//Check the integral part.
    double ipD;
    fType ip = 0;
    SDouble x(Dabs(m)); //It makes a copy.
    if(e >= 1){
        SDouble ipSD;   //integral part
        x = Modf(x, ipSD);  //It divides x into integer and decimal.
        ipD = doubleD(ipSD, 0); //convert into double
        if(ipD >= BRADIX) m.SetError(m.OVERFLOW_ERR,"SX ConvertToBin", 502);
        ip = (fType)ipD;    // ip < BRADIX
    }
//Here x has the decimal part only.
    if(x.Sign(502) == 0){   //integlal part only
        result.figure[0] = ip;
        result.SetSign((int)ip*m.Sign());
        return result;
    }
//Conversion of decimal part
    int f = (int)x.First();
    const fType* xv = x.ReadFigures();
    fType* rv = result.figure.Elements();
    register int i = (int)x.Last();
//value of exponent
    e = x.NetRdxExp();  // e is not positive.
#ifndef NDEBUG
assert(e <= 0);
#endif
    result.SetSign(1);
    rv[0] = xv[i--];

    while(i >= f){
        //The function XsDiv() does not change the address "rv".
        XsDiv(result, DRADIX, result);
        if(xv[i]){
            result.aTail = 0;
            rv[0] += xv[i]; //rv[0] < BRADIX, xv[i]<DRADIX
        }
        i--;
    }
/*
The contribution from exponent.
It divides by DRADIX (1-e) times for two reasons
1.converting finite decimal such as 2^(-10) exactly.
2.avoiding the multiplication by an infinite decimal 1/DRADIX in binary
  which costs time.
*/
    for(i = 0; i < 1-e; i++) XsDiv(result, DRADIX, result);

    int sgn=result.Sign(502);   //maybe result == 0 by above division
//It adds the integral part.
    if(ip){
        result.aTail = 0;
        result.figure[0] += ip;
        sgn=1;
    }
    if(sgn) result.SetSign( m.Sign() );
    return result;
}