OC-KittenOS/inst/bdivide/compress.lua

86 lines
1.9 KiB
Lua

-- This is released into the public domain.
-- No warranty is provided, implied or otherwise.
-- 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