C / C++ / MFC

class coroutine {
public:
	void (*action1)(int);
	Stack local_stack;
	coroutine(void (*action)(int ), int id); ///< will create coroutine
	~coroutine();
	static void yield();
	};

coroutine *global_coro;
fcontext_t context_array[2];
coroutine :: coroutine(void (*action)(int), int id)
			{
			global_coro=this;
			action1=action;
			fcontext_t f_ctx = make_fcontext(global_coro->local_stack.local_stack, 1000, global_coro->action1);//Save the current context of coroutine for the sake of making switch context.
// make_fcontext is in .S file taken from boost::context
			context_array[0]=f_ctx; // Global Array to store the coroutine context so that i can switch the context
			}

coroutine::~coroutine(){}

void coroutine::yield(){

transfer_t tr = jump_fcontext(context_of_current_corotine, context_of_next_coroutine ); //Also in .S file 

extern MemoryPool memPoolObj;

class Stack {
public:
	void *local_stack;
	MemoryPool& m_memPool=memPoolObj;
	Stack();
	~Stack();
};

#include "Stack.h"
MemoryPool memPoolObj;
Stack::Stack() {
	auto *local_stack= m_memPool.Allocate();
}
Stack::~Stack() {}

typedef void*   fcontext_t;

struct transfer_t
{
    fcontext_t  fctx;
    void    *   data;
};

extern "C"
transfer_t jump_fcontext( fcontext_t const to, void * vp);
extern "C"
fcontext_t make_fcontext( void * sp, std::size_t size, void (* fn)( int) );

#include "coroutine.h"
void workPackage(int id){
	printf("Coroutine with id %d is called\n", id);
	coroutine::yield();
	printf("Coroutine with id %d is resumed after first yield\n", id);
	coroutine::yield();
	printf("Coroutine with id %d is resumed after second yield\n", id);
}



int main() {
	coroutine Coro1(workPackage, 1);
	coroutine Coro2(workPackage, 2);
	printf("Main is finished \n");
}

Use of uninitialised value of size 8
==24145==    at 0x10922B: make_fcontext (in /home/user1/eclipse-workspace/coroutines/Debug/coroutines)
==24145==    by 0x10912D: main (main.cpp:32)
==24145== 
==24145== (action on error) vgdb me ... 
==24145== Continuing ...
==24145== Invalid write of size 8
==24145==    at 0x10922B: make_fcontext (in /home/user1/eclipse-workspace/coroutines/Debug/coroutines)
==24145==    by 0x10912D: main (main.cpp:32)
==24145==  Address 0xffffffffffffffe8 is not stack'd, malloc'd or (recently) free'd

void OnDraw()
{
    CPen pen;
    pen.CreatePen(PS_SOLID, 1, RGB(0, 0, 0));
    CPen* OldPen = pDC->SelectObject(&pen);

    CRect rcView;
    GetClientRect(rcView);
    int iClientWidth = rcView.right;
    int iClientHeight = rcView.bottom;
    int iMemWidth = 1900;
    int iMemHeight = 950;
    CDC memDC;
    CBitmap memBitmap;
    memDC.CreateCompatibleDC(pDC);
    memBitmap.CreateCompatibleBitmap(pDC, iMemWidth, iMemHeight);
    memDC.SelectObject(&memBitmap);
    memDC.SetMapMode(MM_LOMETRIC);
    CPen pen1;
    pen1.CreatePen(PS_SOLID, 3, RGB(0, 0, 0));
    memDC.SelectObject(&pen1);
    CBrush brBK;
    brBK.CreateSolidBrush(RGB(255, 255, 255));
    memDC.SelectObject(&brBK);
    RECT rc;
    rc.left = 0;
    rc.top = 0;
    rc.right = iMemWidth;
    rc.bottom = iMemHeight;
    memDC.FillRect(&rc, &brBK);
    memDC.Rectangle(rc.left, rc.top, rc.right, -rc.bottom);
    memDC.MoveTo(0, 0);
    memDC.LineTo(1900, -950);

    memDC.MoveTo(0, -950);
    memDC.LineTo(200, -750);

    CFont font;
    font.CreateFont(
        50,                        // nHeight
        0,                         // nWidth
        0,                         // nEscapement
        0,                         // nOrientation
        FW_NORMAL,                 // nWeight
        FALSE,                     // bItalic
        FALSE,                     // bUnderline
        0,                         // cStrikeOut
        ANSI_CHARSET,              // nCharSet
        OUT_DEFAULT_PRECIS,        // nOutPrecision
        CLIP_DEFAULT_PRECIS,       // nClipPrecision
        DEFAULT_QUALITY,           // nQuality
        DEFAULT_PITCH | FF_SWISS,  // nPitchAndFamily
        _T("Arial"));
    memDC.SelectObject(&font);
    memDC.TextOut(100, -100, _T("Hello"));


    pDC->BitBlt(10, -10, iMemWidth, -iMemHeight, &memDC, 0, 0, SRCCOPY);
    font.DeleteObject();
    brBK.DeleteObject();
    memDC.DeleteDC();
    memBitmap.DeleteObject();
    pen.DeleteObject();
    pen1.DeleteObject();
}

void OnInitialUpdate()
{
    CScrollView::OnInitialUpdate();

    CSize sizeTotal;
    sizeTotal.cx = 3830;
    sizeTotal.cy = 1995;
    SetScrollSizes(MM_LOMETRIC, sizeTotal);
}