zobrazenie krivky-osciloskop

Vedel by mi niekto poradit robim jednoduchý osciloskop v Turbo C++ funguje to ako ma len chcem aby mi po spustení krivka zacinala v nule v Timer1Timer priradujem kazdej vzorke jej velkost ako to spravim tak aby to vykreslovanie krivky zacinalo az od nulovej vzorky??poradte prosiiim

void Draw()
{

int y,x;
bmp->Canvas->Brush->Color=clBlack;
bmp->Canvas->FillRect(TRect(0,0,440,396));

bmp->Canvas->Pen->Color=clBlue;
bmp->Canvas->Pen->Width=10;

/////////////////////////vykreslenie mriezky///////////////////////////////
bmp->Canvas->MoveTo(0,0);
bmp->Canvas->LineTo(0,312);
bmp->Canvas->Pen->Width=1;
bmp->Canvas->MoveTo(40,396);
bmp->Canvas->LineTo(40,0);
bmp->Canvas->MoveTo(80,0);
bmp->Canvas->LineTo(80,396);
bmp->Canvas->MoveTo(120,396);
bmp->Canvas->LineTo(120,0);
bmp->Canvas->MoveTo(160,0);
bmp->Canvas->LineTo(160,396);
bmp->Canvas->MoveTo(200,396);
bmp->Canvas->LineTo(200,0);
bmp->Canvas->MoveTo(240,0);
bmp->Canvas->LineTo(240,396);
bmp->Canvas->MoveTo(280,396);
bmp->Canvas->LineTo(280,0);
bmp->Canvas->MoveTo(320,0);
bmp->Canvas->LineTo(320,396);
bmp->Canvas->MoveTo(360,396);
bmp->Canvas->LineTo(360,0);
bmp->Canvas->MoveTo(400,0);
bmp->Canvas->LineTo(400,396);
bmp->Canvas->Pen->Width=10;
bmp->Canvas->MoveTo(437,396);
bmp->Canvas->LineTo(437,0);
bmp->Canvas->Pen->Width=10;
bmp->Canvas->LineTo(0,0);
bmp->Canvas->Pen->Width=1;
bmp->Canvas->MoveTo(649,40);
bmp->Canvas->LineTo(0,40);
bmp->Canvas->MoveTo(0,80);
bmp->Canvas->LineTo(649,80);
bmp->Canvas->MoveTo(649,120);
bmp->Canvas->LineTo(0,120);
bmp->Canvas->Pen->Color=clLime;
bmp->Canvas->Pen->Width=3;
bmp->Canvas->MoveTo(0,160);
bmp->Canvas->LineTo(649,160);
bmp->Canvas->Pen->Color=clBlue;
bmp->Canvas->Pen->Width=1;
bmp->Canvas->MoveTo(649,200);
bmp->Canvas->Pen->Width=1;
bmp->Canvas->Pen->Color=clBlue;
bmp->Canvas->LineTo(0,200);
bmp->Canvas->MoveTo(0,240);
bmp->Canvas->LineTo(649,240);
bmp->Canvas->MoveTo(649,280);
bmp->Canvas->LineTo(0,280);
bmp->Canvas->Pen->Width=10;
bmp->Canvas->MoveTo(0,312);
bmp->Canvas->LineTo(649,312);


//////////////////////vykreslenie krivky/////////////////////////////

bmp->Canvas->Pen->Width=1;
bmp->Canvas->Pen->Color=clRed;

int i,di;
di=(vzoriek/432)/S;

x=6; for (i=0;i<vzoriek;i+=di)
{


y=vzorky[i];


y=W-y;

if (!i)

bmp->Canvas->MoveTo(x,y);
else bmp->Canvas->LineTo(x,y);
x++;

}


/////////////////////////////////////////////////////
Form1->Canvas->Draw(0,0,bmp);

}


__fastcall TForm1::TForm1(TComponent* Owner): TForm(Owner)
{
dsound_init(Handle);
vzorky=new BYTE[buff_size];
vzoriek=0;
}
//---------------------------------------------------------------------------


void __fastcall TForm1::FormResize(TObject *Sender)
{
bmp->Width=440;
bmp->Height=350;
Draw();
}
//---------------------------------------------------------------------------



void __fastcall TForm1::Button1Click(TObject *Sender)
{
Timer1->Enabled=true;
Shape1->Brush->Color=clRed;
Shape2->Brush->Color=clGreen;
Draw();
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Button2Click(TObject *Sender)
{
Timer1->Enabled=false;
Shape2->Brush->Color=clRed;
Shape1->Brush->Color=clGreen;
Draw();
}
//---------------------------------------------------------------------------
void __fastcall TForm1::FormPaint(TObject *Sender)
{
Draw();
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Timer1Timer(TObject *Sender)
{
static int cnt=0;
dsound_lock();
BYTE *p; int i,j,sz;
sz=dsound_siz0+dsound_siz1;

p=(BYTE*)dsound_adr0; i=0;

for (j=0;j<sz;j++)
{
if (j==dsound_siz0)
{
p=(BYTE*)dsound_adr1;
}
vzorky[j]=p[i];
i++;
}
vzoriek=j;
dsound_unlock();
cnt++;
Caption=cnt;

Draw();
}