/*  sdfd2dbl.cpp  by K.Tsuru  */
// function ID 3001
/********************************************************************
SDouble class
Provides a conversion SDouble --> double.
If you let err = 0, an out of range of double does not terminate the
program and return DBL_MAX or 0.0. The error (OVERFLOW_ERR or UNDERFLOW_ERR)
can be detected by SNError().
Default value is declared as err = 1.
*********************************************************************/
#ifndef SN_H
#include "sn.h"
#endif

static const char* func = "doubleD";
double doubleD(const SDouble& sd, int err){
    if(sd.Type() != sd.REAL) SNManager::SetError(sd.RADIX_ERR, func, 3001);
    if(sd.SNSign() == 0) return 0.0;

// detect error
    long de = sd.DExp();
    SNManager::SNErrorFlag error = sd.NO_ERR;
    double d = 0.0;

    if(de > DBL_MAX_10_EXP-1){
        error = sd.OVERFLOW_ERR;
        d = DBL_MAX;
    }else if( de < DBL_MIN_10_EXP+1 ){
        error = sd.UNDERFLOW_ERR;
        d = 0.0;
    }

    if(error != sd.NO_ERR){
        if(err) sd.SetError(error, func, 3001);
        else    sd.SetErrorFlag(error);
        return d;
    }

    RealSize C;
//To get fifteen figures in double it needs
// 0.000x yyyy zzzz aaaa bbbb HHHH(hidden) .... six figures
    uint fig = DOUBLE_FIG/DFIGURES +3u;
    SDouble x;
    x = sd.TakeOutFigures(fig+2u);
    x.StdReform(3001);
    C.SetEffFig(fig);
    x.Round(x.STD_REF | x.CUR_MAX); // round off
    C.SetEffFig(0);

    uint i = x.First(), last = x.Last();
    double qpowFig = dpow10(-DFIGURES), eps = dpow10(-DOUBLE_FIG-DFIGURES);
    double r = qpowFig;
    d = x[i++];     //d have one figure at least.
    for( ; (i <= last) && (r > eps) ; i++){
        d += (double)x[i]*r;
        r *= qpowFig;
    }
//multiply by D^e
    int e = x.NetRdxExp()-1;
    d *= pow((double)DRADIX, (double)e);

    return (x.Sign(3001) > 0) ? d : -d;
}