/*  dbl2lne.cpp  by K.Tsuru  */
/****************************
SN class's auxiliary function
*****************************/
#ifndef SN_H
#include "sn.h"
#endif
/*-----------------------------------------------------------------------------
Try to convert double "d" using long "L" into a form
  d = L * 10^e    ( 0 =< |L| <= mt).
When it is successed, return true. The operation between SDouble and double can
be reduced into one between SDouble and short integer.
e.g. x/1.3 ---> (x/13000)*DRADIX.
Usually take mt = (double)d.SlOpMaxValue() (= ULONG_MAX/radix);
-------------------------------------------------------------------------------*/
bool doubleTolongExp(double d, long* L, int* e, double mt){
//  if(fabs(d) > mt) return false;
    if(d == 0.0){
        *L = 0;     *e = 0;     return true;
    }
    FigBlock res;
    uint sz;
    int exp, j;
    exp = doubleToArray(d, res, &sz);
    if(sz > 4) return false;    // 0.0001 2345 6789 1000 (ten figures sz = 5) > SlOpMaxValue()
    double rdx = DRADIX, r = res(sz-1);

    for(j = (int)sz-2; j >= 1; j--){
        r += res(j)*rdx;
        rdx *= DRADIX;
    }
    exp = (exp - (int)sz +1)*DFIGURES;
    if(r > mt){ //It is desirable that "exp" is a multiple of "DFIGURES" if possible.
        while( fmod(r, 10.0) < DBL_EPSILON){    //remove lower zeros
            exp++;      r /= 10.0;
//          if( !( abs(exp) % DFIGURES ) && (r < mt) ) break;
        }
    }
    *e = exp;
    r += ROUND_DBL_INT;
    if(r > mt) return false;    //fail to convert
// convert to long
    *L =  (long)r;
    if(d < 0.0)  *L = -*L;
    return true;
}