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OC-KittenOS/inst/bdivide/compress.lua
20kdc dcd7154ec2 License 'change' (Please see #5)
This license change should only increase the amount of stuff people can do in countries where the public domain is not a valid concept.
If this license somehow restricts you as opposed to the previous one, please file an issue.
2021-01-12 12:16:50 +00:00

90 lines
2.5 KiB
Lua

-- Copyright (C) 2018-2021 by KittenOS NEO contributors
--
-- Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby granted.
--
-- THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
-- THIS SOFTWARE.
-- PREPROC (r9 edition): preprocess input to be 7-bit
local frw = require("libs.frw")
local
-- SHARED WITH DECOMPRESSION ENGINE
function p(x, y)
if x == 126 then
return string.char(y), 3
elseif x == 127 then
return string.char(128 + y), 3
elseif x >= 32 then
return string.char(x), 2
elseif x == 31 then
return "\n", 2
elseif x == 30 then
return "\x00", 2
end
return string.char(("enart"):byte(x % 5 + 1), ("ndtelh"):byte((x - x % 5) / 5 + 1)), 2
end
local preprocParts = {}
local preprocMaxLen = 0
for i = 0, 127 do
for j = 0, 127 do
local d, l = p(i, j)
if d then
preprocMaxLen = math.max(preprocMaxLen, #d)
l = l - 1
if (not preprocParts[d]) or (#preprocParts[d] > l) then
if l == 2 then
preprocParts[d] = string.char(i, j)
else
preprocParts[d] = string.char(i)
end
end
end
end
end
local function preprocWithPadding(blk, p)
local out = ""
local needsPadding = false
while blk ~= "" do
p(blk)
local len = math.min(preprocMaxLen, #blk)
while len > 0 do
local seg = blk:sub(1, len)
if preprocParts[seg] then
out = out .. preprocParts[seg]
needsPadding = #preprocParts[seg] < 2
blk = blk:sub(#seg + 1)
break
end
len = len - 1
end
assert(len ~= 0)
end
-- This needsPadding bit is just sort of quickly added in
-- to keep this part properly maintained
-- even though it might never get used
if needsPadding then
return out .. "\x00"
end
return out
end
local bdCore = require("bdivide.core")
return function (data, lexCrunch)
io.stderr:write("preproc: ")
local pi = frw.progress()
local function p(b)
pi(1 - (#b / #data))
end
data = preprocWithPadding(data, p)
io.stderr:write("\nbdivide: ")
pi = frw.progress()
data = bdCore.bdividePad(bdCore.bdivide(data, p))
io.stderr:write("\n")
return lexCrunch.process(frw.read("bdivide/instdeco.lua"), {}), data
end