//----------------------------------------------------------------------------
// Copyright (C) 2013-2015 Fabrice HARROUET (ENIB)
//
// Permission to use, copy, modify, distribute and sell this software
// and its documentation for any purpose is hereby granted without fee,
// provided that the above copyright notice appear in all copies and
// that both that copyright notice and this permission notice appear
// in supporting documentation.
// The author makes no representations about the suitability of this
// software for any purpose.
// It is provided "as is" without express or implied warranty.
//----------------------------------------------------------------------------

using System;

public class Point
{
public int x,y;

public
Point(int x,
      int y)
  {
  this.x=x;
  this.y=y;
  }
}

public unsafe struct TinyFifo
{
fixed int d[16];
int r,w;
public void put(int v) { fixed(int *p=d) { p[w]=v; } w=(w+1)&15; }
public int get() { int v; fixed(int *p=d) { v=p[r]; } r=(r+1)&15; return v; }
public bool full() { return r==((w+1)&15); }
public bool empty() { return r==w; }
}

public class Test
{
public static
void
Main(string[] args)
  {
  int value=1000;
  unsafe
    {
    int *p1=&value; // value is local so won't move
    int *p2=p1;
    Console.WriteLine("value={0}, p1={1}, p2={2}",
                      value,(IntPtr)p1,(IntPtr)p2);
    *p2=20;
    }
  Console.WriteLine("value={0}",value);
  unsafe
    {
    Point p=new Point(10,20);
    fixed(int *ptr1 = &p.x) // prevent object from moving
    fixed(int *ptr2 = &p.y)
      {
      long delta=ptr2-ptr1;
      Console.WriteLine("&p.x={0} p.x={1}",(IntPtr)ptr1,*ptr1);
      Console.WriteLine("&p.y={0} p.y={1}",(IntPtr)ptr2,*ptr2);
      Console.WriteLine("delta={0}",delta);
      ptr1[0]+=100;
      ptr1[delta]+=200;
      Console.WriteLine("&p.x={0} p.x={1}",(IntPtr)ptr1,*ptr1);
      Console.WriteLine("&p.y={0} p.y={1}",(IntPtr)ptr2,*ptr2);
      }
    }
  TinyFifo[] t=new TinyFifo[5];
  unsafe
    {
    fixed(TinyFifo *p=t)
      {
      for(int i=0;i<100;++i)
        {
        TinyFifo *f=p+(i%5);
        if(!f->full()) f->put(i);
        }
      for(int i=0;i<5;++i)
        {
        TinyFifo *f=p+i;
        while(!f->empty()) Console.Write("{0} ",f->get());
        Console.WriteLine("");
        }
      }
    }
  unsafe
    {
    int sz=20;
    int* prime=stackalloc int[sz];
    prime[0]=1;
    for(int count=1,candidate=2;count<sz;++candidate)
      {
      for(int i=1;i<count;++i) if((candidate%prime[i])==0) goto skip;
      prime[count++]=candidate;
      skip: ;
      }
    for(int i=0;i<sz;++i) Console.Write("{0} ",prime[i]);
    Console.WriteLine("");
    }
  }
}

//----------------------------------------------------------------------------