261 lines
4.3 KiB
Lua
261 lines
4.3 KiB
Lua
--[[---------------
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LuaBit v0.4
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-------------------
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a bitwise operation lib for lua.
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http://luaforge.net/projects/bit/
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How to use:
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-------------------
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bit.bnot(n) -- bitwise not (~n)
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bit.band(m, n) -- bitwise and (m & n)
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bit.bor(m, n) -- bitwise or (m | n)
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bit.bxor(m, n) -- bitwise xor (m ^ n)
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bit.brshift(n, bits) -- right shift (n >> bits)
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bit.blshift(n, bits) -- left shift (n << bits)
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bit.blogic_rshift(n, bits) -- logic right shift(zero fill >>>)
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Please note that bit.brshift and bit.blshift only support number within
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32 bits.
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2 utility functions are provided too:
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bit.tobits(n) -- convert n into a bit table(which is a 1/0 sequence)
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-- high bits first
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bit.tonumb(bit_tbl) -- convert a bit table into a number
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-------------------
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Under the MIT license.
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copyright(c) 2006~2007 hanzhao (abrash_han@hotmail.com)
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--]]---------------
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do
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------------------------
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-- bit lib implementions
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local function check_int(n)
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-- checking not float
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if(n - math.floor(n) > 0) then
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error("trying to use bitwise operation on non-integer!")
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end
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end
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local function to_bits(n)
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check_int(n)
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if(n < 0) then
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-- negative
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return to_bits(bit.bnot(math.abs(n)) + 1)
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end
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-- to bits table
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local tbl = {}
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local cnt = 1
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while (n > 0) do
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local last = math.mod(n,2)
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if(last == 1) then
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tbl[cnt] = 1
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else
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tbl[cnt] = 0
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end
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n = (n-last)/2
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cnt = cnt + 1
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end
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return tbl
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end
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local function tbl_to_number(tbl)
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local n = table.getn(tbl)
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local rslt = 0
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local power = 1
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for i = 1, n do
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rslt = rslt + tbl[i]*power
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power = power*2
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end
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return rslt
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end
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local function expand(tbl_m, tbl_n)
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local big = {}
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local small = {}
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if(table.getn(tbl_m) > table.getn(tbl_n)) then
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big = tbl_m
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small = tbl_n
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else
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big = tbl_n
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small = tbl_m
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end
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-- expand small
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for i = table.getn(small) + 1, table.getn(big) do
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small[i] = 0
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end
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end
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local function bit_or(m, n)
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local tbl_m = to_bits(m)
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local tbl_n = to_bits(n)
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expand(tbl_m, tbl_n)
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local tbl = {}
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local rslt = math.max(table.getn(tbl_m), table.getn(tbl_n))
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for i = 1, rslt do
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if(tbl_m[i]== 0 and tbl_n[i] == 0) then
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tbl[i] = 0
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else
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tbl[i] = 1
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end
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end
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return tbl_to_number(tbl)
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end
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local function bit_and(m, n)
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local tbl_m = to_bits(m)
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local tbl_n = to_bits(n)
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expand(tbl_m, tbl_n)
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local tbl = {}
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local rslt = math.max(table.getn(tbl_m), table.getn(tbl_n))
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for i = 1, rslt do
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if(tbl_m[i]== 0 or tbl_n[i] == 0) then
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tbl[i] = 0
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else
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tbl[i] = 1
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end
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end
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return tbl_to_number(tbl)
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end
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local function bit_not(n)
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local tbl = to_bits(n)
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local size = math.max(table.getn(tbl), 32)
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for i = 1, size do
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if(tbl[i] == 1) then
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tbl[i] = 0
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else
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tbl[i] = 1
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end
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end
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return tbl_to_number(tbl)
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end
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local function bit_xor(m, n)
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local tbl_m = to_bits(m)
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local tbl_n = to_bits(n)
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expand(tbl_m, tbl_n)
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local tbl = {}
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local rslt = math.max(table.getn(tbl_m), table.getn(tbl_n))
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for i = 1, rslt do
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if(tbl_m[i] ~= tbl_n[i]) then
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tbl[i] = 1
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else
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tbl[i] = 0
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end
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end
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--table.foreach(tbl, print)
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return tbl_to_number(tbl)
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end
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local function bit_rshift(n, bits)
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check_int(n)
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local high_bit = 0
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if(n < 0) then
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-- negative
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n = bit_not(math.abs(n)) + 1
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high_bit = 2147483648 -- 0x80000000
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end
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for i=1, bits do
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n = n/2
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n = bit_or(math.floor(n), high_bit)
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end
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return math.floor(n)
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end
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-- logic rightshift assures zero filling shift
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local function bit_logic_rshift(n, bits)
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check_int(n)
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if(n < 0) then
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-- negative
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n = bit_not(math.abs(n)) + 1
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end
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for i=1, bits do
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n = n/2
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end
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return math.floor(n)
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end
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local function bit_lshift(n, bits)
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check_int(n)
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if(n < 0) then
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-- negative
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n = bit_not(math.abs(n)) + 1
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end
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for i=1, bits do
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n = n*2
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end
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return bit_and(n, 4294967295) -- 0xFFFFFFFF
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end
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local function bit_xor2(m, n)
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local rhs = bit_or(bit_not(m), bit_not(n))
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local lhs = bit_or(m, n)
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local rslt = bit_and(lhs, rhs)
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return rslt
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end
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--------------------
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-- bit lib interface
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bit = {
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-- bit operations
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bnot = bit_not,
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band = bit_and,
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bor = bit_or,
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bxor = bit_xor,
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brshift = bit_rshift,
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blshift = bit_lshift,
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bxor2 = bit_xor2,
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blogic_rshift = bit_logic_rshift,
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-- utility func
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tobits = to_bits,
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tonumb = tbl_to_number,
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}
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end
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--[[
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for i = 1, 100 do
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for j = 1, 100 do
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if(bit.bxor(i, j) ~= bit.bxor2(i, j)) then
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error("bit.xor failed.")
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end
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end
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end
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--]]
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