Difference between a+b and bit32.band(a+b)

[waspoza <waspoza@...>]

Hi,

I'm a fresh lua user and i stumbled upon a interesting thing in sha256
algorithm from page: http://lua-users.org/wiki/SecureHashAlgorithm

In digestblock function there is a line: H[1] = band(H[1] + a).

Why addition result is being passed to binary and funcion? In same
function there are other additions without 'and', so i dont really
understand whats the point of it.

TIA.