/*  sloplus.cpp  by K.Tsuru  */
// function ID = 201  DARDIX, BRADIX
/**********************
SLong class
operator+() return m+n
***********************/
#ifndef SN_H
#include "sn.h"
#endif

static const char* func = "SL +";
SLong operator+(const SLong& m, const SLong& n) {
    if( m.Type() != n.Type() ) m.SetError(m.RADIX_ERR, func, 201);
    int s = m.Sign(201) * n.Sign(201);

    if( !s ){  //One of m and n is zero.
        if( m.Sign() == 0 ) return n;
        else                return m;
    } else if ( s > 0 ){    //same sign
        SLong t;
        //It lets m >= n. See DDMult().
        if( m.aHead < n.aHead ) return LLAdd(n, m);
        return LLAdd(m, n); //sign is same as that of m(setted in LLAdd())
    } else {                //diffrent sign
        SLong r(m.Type(), 0);
        int c = LLCompare(m, n);
       // m + n = m -(-n) = n-(-m)
        if(c > 0){
            r = n;  r.ChangeSign(201);  // r = -n
            return  LLSub(m, r); // m > n
        }
        if(c){
            r = m;  r.ChangeSign(201);  // r = -m
            return  LLSub(n, r); // m < n
        }
        r.SetZero();
        return r;   // c = 0 : m = n
    }
}