/*  slfctout.cpp  by K.Tsuru  */
// function ID = 222    DRADIX, BRADIX
/******************************************************************************
SLong and SInteger classes
It cuts out a "size" part from "src[pos]" and puts into dest[0]...dest[size-1].
The sign is the same as that of "src".
src[pos]....src[pos+size-1]
If pos+size-1 < src.aTail it sets zero.
*******************************************************************************/
#ifndef SN_H
#include "sn.h"
#endif
void SLong::SLCutOut(SLong& dest, const SLong& src, uint pos, uint size){
    dest.SetType(src.Type());
    if( (src.Sign(222) == 0) || (pos > src.Head() ) || (pos+size < src.Tail()+1u) ){
        dest.SetZero();     return;
    }
    uint n_copy = min(size, src.figure.size() - pos);

    dest.valloc(n_copy, -1);
    fType* df = dest.figure.Elements();

    memcpy(df, src.ReadFigures()+pos, n_copy*sizeof(fType) );
    dest.figure.clear(n_copy);
/*
It gets the figure positions. It must be noticed that there are many zeros
in the middle region such as
                          p+s-1           p
src = 0000 0000 5000 0000 0000 0000 .... 0000 0000 1234 5678 ....
*/
    int j = 0;
    while( (df[j] == 0) && (j < (int)n_copy)) j++;
    if(j == (int)n_copy){
        dest.SetSign(0);        return;
    }
    dest.aTail = (uint)j;

#ifndef NDEBUG
assert( (uint)j < n_copy);
#endif
    j = (int)n_copy-1;
    while(df[j] == 0) j--;
    dest.aHead = (uint)j;
#ifndef NDEBUG
assert(j >= 0);
#endif
    dest.SetSign(src.Sign());   // dest != 0
}