/*  sxfxsmul.cpp  by K.Tsuru  */
// function ID = 509    BRADIX
/*******************************************************************
SDecimal class
Provides the multiplication of SDecimal and a short integer together.
result = m*x, x <= ULONG_MAX/BRADIX
********************************************************************/
#ifndef SN_H
#include "sn.h"
#endif
static const char* const func = "XsMult";
void XsMult(const SDecimal& m, ulong x, SDecimal& result){
    if( !m.Sign() || (x == 0) ){
        result.SetZero();   return;
    }
    if(x == 1){ result = m;     return;     }
    if(x > m.SlOpMaxValue()) m.SetError(m.OUT_OF_RANGE, func, 509);
    if( result.figure.size() != m.figure.size() ) m.SetError(m.SYNTAX_ERR, func, 509);

    uint rh = m.aHead, rt = m.aTail;
    fType* rv = result.figure.Elements();
    const fType* mv = m.ReadFigures();
#ifndef NDEBUG
result.figure[rh];
#endif
    ulong w = 0;
//"rt" must be casted as int considering the case of rt==0.
    int i;
    for(i = (int)rh; i >= (int)rt; i--) {
        w += (ulong)mv[i] * x;
        rv[i] = fType(w & BRADIX1); // = w%BRADIX
        w >>= BRADIX_BITS;          // w /= BRADIX;
    }
    if(w){  //It proceeds the carry. It can be possible that w >= BRADIX.
        for( ; w && (i >= 0) ; i--){
            rv[i] = fType(w & BRADIX1);
            w >>= BRADIX_BITS;
        }
        if(w) m.SetError(m.OVERFLOW_ERR, func, 509);
        rt = i+1;
    }
//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);  // rt > 0
//It decides the figure position.
    result.aTail = rt;
    while(!rv[rh]) rh--;
    result.aHead = rh;
    result.SetSign( m.Sign() );     // result != 0
#ifndef NDEBUG
result.figure(rt);  result.figure(rh);
#endif
}