OC-PsychOS2/lib/liblz16.lua

72 lines
1.3 KiB
Lua

local lz = require "lzss"
local buffer = require "buffer"
lz16 = {}
local function cint(n,l)
local t={}
for i = 0, 7 do
t[i+1] = (n >> (i * 8)) & 0xFF
end
return string.reverse(string.char(table.unpack(t)):sub(1,l))
end
local function toint(s)
local n = 0
local i = 1
for p in s:gmatch(".") do
n = n << 8
n = n | string.byte(p)
i=i+1
end
return n
end
local function readBuffer(fi)
local stream = {}
if fi:read(4) ~= "lz16" then
return false, "not an lz16 archive"
end
function stream.read()
local len = toint(fi:read(2) or "\0\0")
if len < 1 then
return nil
end
coroutine.yield()
return lz.decompress(fi:read(len))
end
function stream.close()
fi:close()
end
return buffer.new("rb",stream)
end
local function writeBuffer(fo)
local stream = {}
function stream:write(data)
local cblock = lz.compress(data)
fo:write(cint(cblock:len(),2)..cblock)
return cblock:len()+2
end
function stream.close()
fo:close()
end
fo:write("lz16") -- write header
return buffer.new("wb",stream)
end
function lz16.buffer(stream)
if stream.mode.w then
return writeBuffer(stream)
end
return readBuffer(stream)
end
function lz16.open(fname, mode)
local f = io.open(fname, mode)
if not f then return false end
f.mode.b = true
return lz16.buffer(f)
end
return lz16