/*  slflladd.cpp  by K.Tsuru  */
// function ID = 207   DRADIX, BRADIX
/************************************************************************
SLong and SInteger classes
It provides the sum m+n (m and n have same sign).
*************************************************************************/
#ifndef SN_H
#include "sn.h"
#endif
static const char* const func = "\'+\' or LLAdd";
SLong LLAdd(const SLong& m, const SLong& n){
    if(m.Sign() == 0) return n;
    if(n.Sign() == 0) return m;
    if(m.Sign() != n.Sign()) m.SetError(m.SYNTAX_ERR, func, 207);
//It lets m >= n. See DDMult().
    if( m.aHead < n.aHead ) return LLAdd(n, m);
    if(m.Radix() != n.Radix()) m.SetError(m.RADIX_ERR, func, 207);

    SLong result(m);    // result = m
    const fType* nv = n.ReadFigures();
    fType* rv = result.figure.Elements();
    fType rdx = m.Radix();
    fType w = 0;    //work variable 2*(radix-1) + 1 <= fTypeMax = 65535
//addition upto top figure of n
    uint i;
    for(i = n.aTail; i <= n.aHead  ; i++){
        w += rv[i] + nv[i];
        rv[i] = w % rdx;
        w = (w >= rdx) ? 1 : 0;     //  w /= rdx;   w <= 1
    }

    uint hm = m.aHead;
#ifndef NDEBUG
result.figure(hm);
#endif
//When w=0 it is not executed.
//result=m; Then the upper part of "result" is the same as that of m.
//Except the special case such as 9999 9999 ... 9999+1 it ends by a few times.
    for( ; w && (i <= hm) ; i++){
        w += rv[i];     // nv[i] = 0
        rv[i] = w % rdx;
        w = (w >= rdx) ? 1 : 0;     //  w /= rdx;   w <= 1
    }
    if(w){  //carry w <= 1
        hm++;
#ifndef NDEBUG
assert(w <= 1);
#endif
        result.Reserve(hm);
        rv = result.figure.Elements();
        result.figure[hm] = w;      //carry to the top figure
    }

//It detects the figure position.
    result.aHead = hm;
    uint rt = min(m.Tail(), n.Tail());  // aTail --> Tail() since ver 2.191

    while(!rv[rt]) rt++;
    result.aTail = rt;
    result.SetSign(m.Sign());
    return result;
}