mirror of
https://github.com/bryanthaboi/gen1recomp.git
synced 2026-08-21 05:00:43 +02:00
bryanthaboi
93 lines
2.5 KiB
Lua
93 lines
2.5 KiB
Lua
local SkinZip = {}
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local bxor
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do
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local ok, bit = pcall(require, "bit")
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if ok and bit and bit.bxor then
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bxor = function(a, b) return bit.bxor(a, b) % 0x100000000 end
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else
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local byteXor = {}
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local function xor8(a, b)
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local key = a * 256 + b
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local memo = byteXor[key]
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if memo then return memo end
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local r, bitv = 0, 1
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local x, y = a, b
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for _ = 1, 8 do
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if (x % 2) ~= (y % 2) then r = r + bitv end
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x, y, bitv = math.floor(x / 2), math.floor(y / 2), bitv * 2
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end
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byteXor[key] = r
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return r
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end
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bxor = function(a, b)
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local r, mul = 0, 1
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for _ = 1, 4 do
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r = r + xor8(a % 256, b % 256) * mul
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a, b, mul = math.floor(a / 256), math.floor(b / 256), mul * 256
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end
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return r
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end
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end
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end
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local crcTable
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local function crc32(s)
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if not crcTable then
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crcTable = {}
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for i = 0, 255 do
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local c = i
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for _ = 1, 8 do
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if c % 2 == 1 then
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c = bxor(math.floor(c / 2), 0xEDB88320)
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else
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c = math.floor(c / 2)
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end
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end
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crcTable[i] = c
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end
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end
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local crc = 0xFFFFFFFF
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for i = 1, #s do
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crc = bxor(crcTable[bxor(crc, s:byte(i)) % 256], math.floor(crc / 256))
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end
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return bxor(crc, 0xFFFFFFFF) % 0x100000000
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end
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local function le16(n)
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n = math.floor(n) % 0x10000
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return string.char(n % 256, math.floor(n / 256) % 256)
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end
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local function le32(n)
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n = math.floor(n) % 0x100000000
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return string.char(n % 256, math.floor(n / 256) % 256,
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math.floor(n / 65536) % 256, math.floor(n / 16777216) % 256)
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end
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function SkinZip.encode(entries)
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local out, central, offset = {}, {}, 0
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for _, entry in ipairs(entries) do
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local name, data = entry.name, entry.data or ""
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local crc, size = crc32(data), #data
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local local_ = "PK\3\4" .. le16(20) .. le16(0) .. le16(0)
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.. le16(0) .. le16(0)
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.. le32(crc) .. le32(size) .. le32(size)
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.. le16(#name) .. le16(0) .. name
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out[#out + 1] = local_
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out[#out + 1] = data
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central[#central + 1] = "PK\1\2" .. le16(20) .. le16(20) .. le16(0) .. le16(0)
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.. le16(0) .. le16(0)
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.. le32(crc) .. le32(size) .. le32(size)
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.. le16(#name) .. le16(0) .. le16(0) .. le16(0) .. le16(0)
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.. le32(0) .. le32(offset) .. name
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offset = offset + #local_ + #data
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end
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local dir = table.concat(central)
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return table.concat(out) .. dir
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.. "PK\5\6" .. le16(0) .. le16(0) .. le16(#entries) .. le16(#entries)
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.. le32(#dir) .. le32(offset) .. le16(0)
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end
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return SkinZip
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