Minetest-WorldEditAdditions/worldeditadditions_core/utils/bit.lua

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