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--[[ 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 5.1 didn't have `load` or bitwise operators, just let it fall through.
if _VERSION ~= "Lua 5.1" then
-- Lua 5.3+ has built-in bit operators, wrap them in a function.
-- Use debug.getinfo to get correct file+line numbers for loaded snippet
local info = debug.getinfo(1, "Sl")
local has_bitwise, bitwise = pcall(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))
if has_bitwise then
return bitwise
end
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")
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