85 lines
2.1 KiB
Lua
Executable File
85 lines
2.1 KiB
Lua
Executable File
#!/usr/bin/env luajit
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require("utils")
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local hex = io.open(arg[3]):read("*a")
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--local hex = "8A004A801A8002F478"
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local hexmap = {
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["0"] = "0000", ["1"] = "0001", ["2"] = "0010", ["3"] = "0011",
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["4"] = "0100", ["5"] = "0101", ["6"] = "0110", ["7"] = "0111",
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["8"] = "1000", ["9"] = "1001", ["A"] = "1010", ["B"] = "1011",
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["C"] = "1100", ["D"] = "1101", ["E"] = "1110", ["F"] = "1111",
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}
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local bytes = {}
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for char in chars(hex) do
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if hexmap[char] then table.insert(bytes, hexmap[char]) end
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end
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local bitstring = table.concat(bytes)
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local function literal(bitstring)
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local v = 0
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while char(bitstring, 1) == "1" do
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v = v * 16 + bin2dec(bitstring:sub(2, 5))
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bitstring = bitstring:sub(6)
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end
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v = v * 16 + bin2dec(bitstring:sub(2, 5))
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return v, bitstring:sub(6)
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end
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local function countoperator(bitstring)
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local count = bin2dec(bitstring:sub(1, 11))
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bitstring = bitstring:sub(12)
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local p, packets = nil, {}
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for i = 1, count do
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p, bitstring = packet(bitstring)
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table.insert(packets, p)
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end
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return packets, bitstring
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end
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local function lengthoperator(bitstring)
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local length = bin2dec(bitstring:sub(1, 15))
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bitstring = bitstring:sub(16)
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local target = #bitstring - length
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local p, packets = nil, {}
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while #bitstring > target do
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p, bitstring = packet(bitstring)
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table.insert(packets, p)
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end
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return packets, bitstring
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end
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local function operator(bitstring)
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if char(bitstring, 1) == "1" then
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return countoperator(bitstring:sub(2))
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else
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return lengthoperator(bitstring:sub(2))
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end
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end
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function packet(bitstring)
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local version = bin2dec(bitstring:sub(1, 3))
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local pactype = bin2dec(bitstring:sub(4, 6))
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local content
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if pactype == 4
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then content, bitstring = literal(bitstring:sub(7))
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else content, bitstring = operator(bitstring:sub(7))
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end
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return { version = version, pactype = pactype, content = content }, bitstring
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end
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function sumversions(packet)
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if packet.pactype == 4 then
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return packet.version
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else
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local sum = packet.version
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for i, p in pairs(packet.content) do
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sum = sum + sumversions(p)
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end
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return sum
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end
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end
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print(sumversions(packet(bitstring)))
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