各位帮忙看一下代码，大致意思明白，但语句的写法、含义没弄懂！

控件为memo
procedure TForm_modi_message.showpos;
begin
 lpos:=sendmessage(memo_message.Handle,em_linefromchar,memo_message.SelStart,0);
 cpos:=sendmessage(memo_message.handle,em_lineindex,lpos,0);
 linelength:=sendmessage(memo_message.handle,em_linelength,cpos,0);
 cpos:=memo_message.SelStart-cpos;
 lpos:=lpos+1;
 cpos:=cpos+1;
 StatusBar1.SimpleText:='行：'+inttostr(lpos)+'    列：'+inttostr(cpos)+'     此行字数'+inttostr(linelength);
end;