mirror of https://github.com/20kdc/OC-KittenOS.git
65 lines
1.8 KiB
Lua
65 lines
1.8 KiB
Lua
-- This is released into the public domain.
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-- No warranty is provided, implied or otherwise.
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-- BDIVIDE (r5 edition) and PREPROC (r9 edition)
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-- decompression engine for installer
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$bdPPBuffer = ""
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$bdBDBuffer = ""
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$bdBDWindow = ("\x00"):rep(2^16)
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-- High-level breakdown:
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-- q is unescaper.
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-- It'll only begin to input if at least 3 bytes are available,
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-- so you'll want to throw in 2 extra zeroes at the end of stream as done here.
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-- It uses t (input buffer) and p (output buffer).
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-- Ignore its second argument, as that's a lie, it's just there for a local.
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-- L is the actual decompressor. It has the same quirk as q, wanting two more bytes.
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-- It stores to c (compressed), and w (window).
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-- It outputs that which goes to the window to q also.
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-- And it also uses a fake local.
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-- SEE compress.lua FOR THIS FUNCTION
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function $bdPP(x, y)
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if x == 126 then
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return string.char(y), 3
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elseif x == 127 then
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return string.char(128 + y), 3
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elseif x >= 32 then
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return string.char(x), 2
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elseif x == 31 then
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return "\n", 2
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elseif x == 30 then
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return "\x00", 2
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end
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return string.char(("enart"):byte(x % 5 + 1), ("ndtelh"):byte((x - x % 5) / 5 + 1)), 2
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end
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${
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function $engineInput($L|lData)
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$bdBDBuffer = $bdBDBuffer .. $lData
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while #$bdBDBuffer > 2 do
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$lData = $bdBDBuffer:byte()
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if $lData < 128 then
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$lData = $bdBDBuffer:sub(1, 1)
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$bdBDBuffer = $bdBDBuffer:sub(2)
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else
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${
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$L|bdBDPtr = $bdBDBuffer:byte(2) * 256 + $bdBDBuffer:byte(3) + 1
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$lData = $bdBDWindow:sub($bdBDPtr, $bdBDPtr + $lData - 125)
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$bdBDBuffer = $bdBDBuffer:sub(4)
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$}
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end
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$bdPPBuffer = $bdPPBuffer .. $lData
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$bdBDWindow = ($bdBDWindow .. $lData):sub(-2^16)
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while #$bdPPBuffer > 1 do
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${
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$lData, $L|bdPPAdv = $bdPP($bdPPBuffer:byte(), $bdPPBuffer:byte(2))
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$bdPPBuffer = $bdPPBuffer:sub($bdPPAdv)
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$}
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$engineOutput($lData)
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end
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end
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end
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$}
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