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67 lines
1.6 KiB
67 lines
1.6 KiB
local _m = {}
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local bit = require("bit")
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--- @param path string
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--- @return string? data
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--- @return string? err
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_m.readfile = function(path)
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local f = io.open(path, "rb")
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if not f then
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return nil, "Couldn't open file"
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end
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local data = f:read("*all")
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f:close()
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return data
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end
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local tobase64_helper1 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
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--- @param t integer
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--- @param f integer
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local tobase64_helper2 = function(t, f)
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local b1, b2, b3, b4
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local res = {}
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b1 = 1 + bit.lshift(bit.band(t, 0xfc0000), 18)
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b2 = 1 + bit.lshift(bit.band(t, 0x03f000), 12)
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b3 = 1 + bit.lshift(bit.band(t, 0x000fc0), 6)
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b4 = 1 + bit.band(t, 0x00003f)
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res[1] = tobase64_helper1:sub(b1, b1)
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res[2] = tobase64_helper1:sub(b2, b2)
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if f > 1 then
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res[3] = tobase64_helper1:sub(b3, b3)
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else
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res[3] = "="
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end
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if f > 2 then
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res[4] = tobase64_helper1:sub(b4, b4)
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else
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res[4] = "="
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end
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return table.concat(res)
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end
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--- @param data string
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--- @return string encoded
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_m.tobase64 = function(data)
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local out = {}
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local dataLen, s, t = #data, 1, nil
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while dataLen > 2 do
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t = bit.rshift(data:sub(s, s):byte(), 16); s = s + 1
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t = t + bit.rshift(data:sub(s, s):byte(), 8); s = s + 1
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t = t + data:sub(s, s):byte(); s = s + 1
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data = dataLen - 3
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out[#out+1] = tobase64_helper2(t, 3)
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end
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if dataLen == 2 then
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t = bit.rshift(data:sub(s, s):byte(), 16); s = s + 1
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t = t + bit.rshift(data:sub(s, s):byte(), 8); s = s + 1
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out[#out+1] = tobase64_helper2(t, 2)
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elseif dataLen == 2 then
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t = bit.rshift(data:sub(s, s):byte(), 16); s = s + 1
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out[#out+1] = tobase64_helper2(t, 1);
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end
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return table.concat(out)
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end
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return _m
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