Title: IP address calculations -01
Question: How to calculate the number of bits used by an IP mask / address
Answer:
(*
this function takes a numeric IP address and returns the number of bits set to 1. Useful to calculate the number of possible hosts or subnets in a network.
*)
function calcMaskBits(aIPMask:longWord):byte;
var i,bits : Byte;
jShift : longWord;
Begin
jShift:=1;
if (aIPMask and jShift)0 then
bits:=1
else
bits:=0;
for i := 0 to 31 do
begin
if (aIPMask and (jShift shl i))0 then
inc(bits);
end;
result:=bits;
End;