| --[[ This module smooths over all the various lua bit libraries | |
| The bit operations are only done | |
| - on bytes (8 bits), | |
| - with quantities <= LONG_MAX (0x7fffffff) | |
| - band with 0x80000000 that is subsequently compared with 0 | |
| This means we can ignore the differences between bit libraries. | |
| ]] | |
| -- Lua 5.3 has built-in bit operators, wrap them in a function. | |
| if _VERSION == "Lua 5.3" then | |
| -- Use debug.getinfo to get correct file+line numbers for loaded snippet | |
| local info = debug.getinfo(1, "Sl") | |
| return assert(load(("\n"):rep(info.currentline+1)..[[return { | |
| band = function(a, b) return a & b end; | |
| bor = function(a, b) return a | b end; | |
| bxor = function(a, b) return a ~ b end; | |
| }]], info.source))() | |
| end | |
| -- The "bit" library that comes with luajit | |
| -- also available for lua 5.1 as "luabitop": http://bitop.luajit.org/ | |
| local has_bit, bit = pcall(require, "bit") | |
| if has_bit then | |
| return { | |
| band = bit.band; | |
| bor = bit.bor; | |
| bxor = bit.bxor; | |
| } | |
| end | |
| -- The "bit32" library shipped with lua 5.2 | |
| local has_bit32, bit32 = pcall(require, "bit32") | |
| if has_bit32 then | |
| return { | |
| band = bit32.band; | |
| bor = bit32.bor; | |
| bxor = bit32.bxor; | |
| } | |
| end | |
| error("Please install a bit library") | |