Minetest-WorldEditAdditions/worldeditadditions/utils/bit.lua

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-- LuaJIT bit polyfill
-- @source https://github.com/Rabios/polyfill.lua/blob/master/polyfill.lua
-- Adapted for Minetest by Starbeamrainbowlabs
-- Note that this file is MIT licenced, and NOT MPL-2.0!
-- @licence MIT
-- Docs: http://bitop.luajit.org/api.html
-- module: bit
local bit = bit or {}
bit.bits = 32
bit.powtab = { 1 }
for b = 1, bit.bits - 1 do
bit.powtab[#bit.powtab + 1] = math.pow(2, b)
end
-- Functions
-- bit.band
if not bit.band then
bit.band = function(a, b)
local result = 0
for x = 1, bit.bits do
result = result + result
if (a < 0) then
if (b < 0) then
result = result + 1
end
end
a = a + a
b = b + b
end
return result
end
end
-- bit.bor
if not bit.bor then
bit.bor = function(a, b)
local result = 0
for x = 1, bit.bits do
result = result + result
if (a < 0) then
result = result + 1
elseif (b < 0) then
result = result + 1
end
a = a + a
b = b + b
end
return result
end
end
-- bit.bnot
if not bit.bnot then
bit.bnot = function(x)
return bit.bxor(x, math.pow((bit.bits or math.floor(math.log(x, 2))), 2) - 1)
end
end
-- bit.lshift
if not bit.lshift then
bit.lshift = function(a, n)
if (n > bit.bits) then
a = 0
else
a = a * bit.powtab[n]
end
return a
end
end
-- bit.rshift
if not bit.rshift then
bit.rshift = function(a, n)
if (n > bit.bits) then
a = 0
elseif (n > 0) then
if (a < 0) then
a = a - bit.powtab[#bit.powtab]
a = a / bit.powtab[n]
a = a + bit.powtab[bit.bits - n]
else
a = a / bit.powtab[n]
end
end
return a
end
end
-- bit.arshift
if not bit.arshift then
bit.arshift = function(a, n)
if (n >= bit.bits) then
if (a < 0) then
a = -1
else
a = 0
end
elseif (n > 0) then
if (a < 0) then
a = a - bit.powtab[#bit.powtab]
a = a / bit.powtab[n]
a = a - bit.powtab[bit.bits - n]
else
a = a / bit.powtab[n]
end
end
return a
end
end
-- bit.bxor
if not bit.bxor then
bit.bxor = function(a, b)
local result = 0
for x = 1, bit.bits, 1 do
result = result + result
if (a < 0) then
if (b >= 0) then
result = result + 1
end
elseif (b < 0) then
result = result + 1
end
a = a + a
b = b + b
end
return result
end
end
-- bit.rol
if not bit.rol then
bit.rol = function(a, b)
local bits = bit.band(b, bit.bits - 1)
a = bit.band(a, 0xffffffff)
a = bit.bor(bit.lshift(a, b), bit.rshift(a, ((bit.bits - 1) - b)))
return bit.band(n, 0xffffffff)
end
end
-- bit.ror
if not bit.ror then
bit.ror = function(a, b)
return bit.rol(a, - b)
end
end
-- bit.bswap
if not bit.bswap then
bit.bswap = function(n)
local a = bit.band(n, 0xff)
n = bit.rshift(n, 8)
local b = bit.band(n, 0xff)
n = bit.rshift(n, 8)
local c = bit.band(n, 0xff)
n = bit.rshift(n, 8)
local d = bit.band(n, 0xff)
return bit.lshift(bit.lshift(bit.lshift(a, 8) + b, 8) + c, 8) + d
end
end
-- bit.tobit
if not bit.tobit then
bit.tobit = function(n)
local MOD = 2^32
n = n % MOD
if (n >= 0x80000000) then
n = n - MOD
end
return n
end
end
-- bit.tohex
if not bit.tohex then
bit.tohex = function(x, n)
n = n or 8
local up
if n <= 0 then
if n == 0 then
return ''
end
up = true
n = -n
end
x = bit.band(x, 16^n - 1)
return ('%0'..n..(up and 'X' or 'x')):format(x)
end
end
return bit