/*  sxfxxadd.cpp  by K.Tsuru  */ 
// function ID = 507    BRADIX
/*****************************************************
SDecimal class
Provides result = m + n where m and n have the same sign.
******************************************************/
#ifndef SN_H
#include "sn.h"
#endif
static const char* func = "XXAdd";
void XXAdd(const SDecimal& m, const SDecimal& n, SDecimal& result)
{
    int msign = m.Sign(), nsign = n.Sign(), sgn = msign*nsign;
    if(sgn == 0){   result = m.Sign() ? m : n;      return; }
    if(sgn < 0) m.SetError(m.SIGN_ERR, func, 507);
//Three objects must have the same size.
    if( (m.figure.size() != n.figure.size()) || (result.figure.size() != n.figure.size()) )
        m.SetError(m.SYNTAX_ERR, func, 507);
    fType t;
    uint rh = result.Size()-1;
    uint rt = min(m.Tail(), n.Tail());
    fType* rv = result.figure.Elements();
    const fType* mv = m.ReadFigures();
    const fType* nv = n.ReadFigures();

#ifndef NDEBUG
result.figure(rh);  m.figure(rh);
#endif
    t = 0;
    int i;
    for(i = rh; i >= (int)rt; i--) {
        t += mv[i] + nv[i];
        rv[i] = t & BRADIX1;
        t >>= BRADIX_BITS;
    }
//Here i = rt -1.
//When rt == 0 result use up to rv[0].
    if(t){      //It proceeds the carry. 
        if(i >= 0){     // rt >= 1
            rv[i] = (fType)t;   rt--;
        } else m.SetError(m.OVERFLOW_ERR, func, 507);
    }
//Clear the outside of the above roop.
    if(result.aHead > rh) result.figure.clear(rh+1, result.aHead);
    if(result.aTail < rt) result.figure.clear(result.aTail, rt-1);
    result.aTail = rt;
//It decides the figure position.
    while(!rv[rh]) rh--;
    result.aHead = rh;
    result.SetSign(msign);  //It must be m+n != 0.
#ifndef NDEBUG
result.figure(rt);  result.figure(rh);
#endif
}