-- (c) William Welch 2004
--
-- This software is provided 'as-is', without any express or implied 
-- warranty. In no event will the authors be held liable for any damages 
-- arising from the use of this software.
--
-- Permission is granted to anyone to use this software for any purpose, 
-- including commercial applications, and to alter it and redistribute it 
-- freely, subject to the following restrictions:
--
-- 1. The origin of this software must not be misrepresented; 
--    you must not claim that you wrote the original software. 
--    If you use this software in a product, an acknowledgment in 
--    the product documentation would be appreciated but is not required.
--
-- 2. Altered source versions must be plainly marked as such, and must 
--    not be misrepresented as being the original software.
--
-- 3. This notice may not be removed or altered from any source distribution.
--
-- This license is commonly known as the zlib/libpng License.
--
-- 
-- ip.jal bvwelch 19 may 2004
-- revised 18 march 2005
-- see RFC 791 for details

function ip_is_for_me return bit is

  -- check for simple/common IPv4 format, no options
  if ( MemRd (ip_off) != 0x45 ) then
    return false
  end if

  -- does it match our IP address?
  if MemCompEx ( IP_OFF , 16 , MYIP , 0 , 4 ) == false then
    return false
  end if

  return true
end function

-- swap source and destination IP addresses.
procedure ip_swap_addr is
  MemSwpEx (  ip_off , 12 , ip_off , 16 , 4 )
end procedure

-- check for 802.3 ethertype
function etype_802_3 return bit is
  return MemComp16Ex ( PKT , 12 , 0 , 8 )
end function

-- swap ethernet source and destination
procedure net_swap_addr is
  MemCpyEx ( PKT , 0 , PKT ,   6 , 6 )
  MemCpyEx ( PKT , 6 , MYMAC , 6 , 6 )
end procedure