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73 lines
2.1 KiB
Lua
73 lines
2.1 KiB
Lua
-- This is released into the public domain. XX
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-- No warranty is provided, implied or otherwise. XX
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local sector = io.write -- XX
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-- XX
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-- BUNDIVIDE (r5 edition) reference implementation for integration XX
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-- Lines ending with XX are not included in the output. XX
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-- Lines that both start and end with -- are only for use in the output, XX
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-- and are thus not executed during any sanity-check procedure. XX
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-- XX
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Cp,Ct,Cc,Cw="","","",("\x00"):rep(65536)
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-- High-level breakdown: XX
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-- CP is unescaper & TAR-sector-breakup. XX
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-- It'll only begin to input if at least 3 bytes are available, XX
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-- so you'll want to throw in 2 extra zeroes at the end of stream as done here. XX
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-- It uses Ct (input buffer) and Cp (output buffer). XX
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-- Ignore its second argument, as that's a lie, it's just there for a local. XX
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-- CD is the actual decompressor. It has the same quirk as CP, wanting two more bytes. XX
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-- It stores to Cc (compressed), and Cw (window). XX
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-- It uses Ca as the "first null" activation flag. XX
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-- It outputs that which goes to the window to CP also. XX
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-- And it also uses a fake local. XX
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CP = function (d, b)
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Ct = Ct .. d
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while #Ct > 2 do
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b = Ct:byte()
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Ct = Ct:sub(2)
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if b == 127 then
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b = Ct:byte()
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Ct = Ct:sub(2)
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if b == 127 then
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b = Ct:byte() + 254
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if b > 255 then
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b = b - 256
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end
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Ct = Ct:sub(2)
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else
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b = b + 127
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end
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end
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Cp = Cp .. string.char(b)
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if #Cp == 512 then
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sector(Cp)
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Cp = ""
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end
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end
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end
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-- XX
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CD = function (d, b, p)
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Cc = Cc .. d
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while #Cc > 2 do
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b = Cc:byte()
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if not Ca then
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Ca, b, Cc = b < 1, "", Cc:sub(2)
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elseif b < 128 then
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b, Cc = Cc:sub(1, 1), Cc:sub(2)
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else
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p = Cc:byte(2) * 256 + Cc:byte(3) + 1
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b, Cc = Cw:sub(p, p + b - 125), Cc:sub(4)
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end
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CP(b)
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Cw = (Cw .. b):sub(-65536)
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end
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end
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-- XX
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CD(io.read("*a")) -- XX
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--D.remove("init-bdivide.lua")--
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--D.rename("init.lua","init-bdivide.lua")--
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--local Ch=D.open("init-bdivide.lua","rb")--
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--dieCB=function()D.close(Ch)D.remove("init-bdivide.lua")end--
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--while true do local t=D.read(Ch, 64)if not t then break end CD(t)end--
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-- XX
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CD("\x00\x00")CP("\x00\x00")
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