/*  sdfddiv2.cpp  by K.Tsuru  */
// function ID = 327  DRADIX, BRADIX
/*********************************************
SDouble and SDecimal classes
n/2
It is faster than DsDiv but without large roop
use DsDiv(n, 2).
**********************************************/
#ifndef SN_H
#include "sn.h"
#endif
SDouble DDiv2(const SDouble& n){
    uint rf = n.First(), rl = n.Last(); // rl < n.CurrentMaxSize()
    if(n.IsPointFixed() && n.IsHidden() && (rf == rl) && (n.figure(rf) < 2) ){
        return SDZero(n);   // |n| == 0.0000 ..... 0001
    }
    SDouble result(n.Type(), 0);
    result.rdxExp = n.rdxExp;
    const fType* np;
    if( rf && (n.figure(rf) == 1) && !n.IsPointFixed()){
    //If first figure is equal to one,it shifts to upper to avoid to lose precision.
        result = n;
        result.ShiftArray(-1);  result.rdxExp--;
        rf--;   rl--;
        np = result.figure.Elements();
    }else {
        np = n.ReadFigures();
//do not use result.figure.size(n.figure.size(), -1);
        result.valloc(n.figure.size(), -1);
        if(rf) result.figure.clear(0, rf-1);
        result.figure.clear(rl+1);
    }
    fType* rp = result.figure.Elements();
    fType rem = 0, u;       // rem : remainder
    fType rdx = n.Radix();
    uint i;
#ifndef NDEBUG
result.figure(rl);  n.figure(rl);
#endif

    for(i = rf; i <= rl; i++) {
        u =  np[i];
        if( rem ) u += rdx;
        rem = u & 1;        // rem = 0 or 1
        rp[i] = u >> 1;
    }
// rem = 0 or 1
    if(rem && result.Reserve(i)){
        rp = result.figure.Elements();
        rl = i;
        result.figure[i] = rdx/2;//It increases by one figure.
    }
/******************************************************
Do not set result.aHead = rl.
Dividing n = 0.1234 0000 0000 ... 0000 0001 by two gives
result = 0.0617 0000 0000 ... 0000.
The last position largely moves to upper.
*******************************************************/
    while(!rp[rl] && (rl > rf) ) rl--;
    if( (rl == rf) && !rp[rl] ){
        result.SetZero();   return result;
    }
    result.aHead = rl;

    while(!rp[rf]) rf++;
    result.aTail = rf;
    result.SetSign(n.Sign(327));
    result.Reform(327);
    return result;
}