Converting decimal number to flag values

Question

I have some constraints like so:

interesting = 0x1
choked = 0x2
remote_interested = 0x4
remote_choked = 0x8
supports_extensions = 0x10
local_connection = 0x20
handshake = 0x40
connecting = 0x80
queued = 0x100
on_parole = 0x200
seed = 0x400
optimistic_unchoke = 0x800
rc4_encrypted = 0x100000
plaintext_encrypted = 0x200000

and the documentation tells me 'The flags attribute tells you in which state the peer is in. It is set to any combination of the enums above' so basically I call the dll and it fills in the structure with a decimal number representing the flag values, a few examples:

2086227
170
2098227
106

How do I from the decimal determine the flags?

Answer 1

In order to determine which flags were set, you need to use the bitwise AND operation (bit32.band() in Lua 5.2). For example:

function hasFlags(int, ...)
    local all = bit32.bor(...)
    return bit32.band(int, all) == all
end

if hasFlags(2086227, interesting, local_connection) then
    -- do something that has interesting and local_connection
end