add liblz16 and lzss for use with pkgfs, and eventually mtar probably

lib/liblz16.lua

@@ -0,0 +1,71 @@
+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

lib/lzss.lua

@@ -0,0 +1,123 @@
+--[[----------------------------------------------------------------------------
+
+	LZSS - encoder / decoder
+
+	This is free and unencumbered software released into the public domain.
+
+	Anyone is free to copy, modify, publish, use, compile, sell, or
+	distribute this software, either in source code form or as a compiled
+	binary, for any purpose, commercial or non-commercial, and by any
+	means.
+
+	In jurisdictions that recognize copyright laws, the author or authors
+	of this software dedicate any and all copyright interest in the
+	software to the public domain. We make this dedication for the benefit
+	of the public at large and to the detriment of our heirs and
+	successors. We intend this dedication to be an overt act of
+	relinquishment in perpetuity of all present and future rights to this
+	software under copyright law.
+
+	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+	EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+	MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+	IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+	OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+	ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+	OTHER DEALINGS IN THE SOFTWARE.
+
+	For more information, please refer to <http://unlicense.org/>
+
+--]]----------------------------------------------------------------------------
+--------------------------------------------------------------------------------
+local M = {}
+local string, table = string, table
+
+--------------------------------------------------------------------------------
+local POS_BITS = 12
+local LEN_BITS = 16 - POS_BITS
+local POS_SIZE = 1 << POS_BITS
+local LEN_SIZE = 1 << LEN_BITS
+local LEN_MIN = 3
+
+--------------------------------------------------------------------------------
+function M.compress(input)
+	local offset, output = 1, {}
+	local window = ''
+
+	local function search()
+		for i = LEN_SIZE + LEN_MIN - 1, LEN_MIN, -1 do
+			local str = string.sub(input, offset, offset + i - 1)
+			local pos = string.find(window, str, 1, true)
+			if pos then
+				return pos, str
+			end
+		end
+	end
+
+	while offset <= #input do
+		local flags, buffer = 0, {}
+
+		for i = 0, 7 do
+			if offset <= #input then
+				local pos, str = search()
+				if pos and #str >= LEN_MIN then
+					local tmp = ((pos - 1) << LEN_BITS) | (#str - LEN_MIN)
+					buffer[#buffer + 1] = string.pack('>I2', tmp)
+				else
+					flags = flags | (1 << i)
+					str = string.sub(input, offset, offset)
+					buffer[#buffer + 1] = str
+				end
+				window = string.sub(window .. str, -POS_SIZE)
+				offset = offset + #str
+			else
+				break
+			end
+		end
+
+		if #buffer > 0 then
+			output[#output + 1] = string.char(flags)
+			output[#output + 1] = table.concat(buffer)
+		end
+	end
+
+	return table.concat(output)
+end
+
+--------------------------------------------------------------------------------
+function M.decompress(input)
+	local offset, output = 1, {}
+	local window = ''
+
+	while offset <= #input do
+		local flags = string.byte(input, offset)
+		offset = offset + 1
+
+		for i = 1, 8 do
+			local str = nil
+			if (flags & 1) ~= 0 then
+				if offset <= #input then
+					str = string.sub(input, offset, offset)
+					offset = offset + 1
+				end
+			else
+				if offset + 1 <= #input then
+					local tmp = string.unpack('>I2', input, offset)
+					offset = offset + 2
+					local pos = (tmp >> LEN_BITS) + 1
+					local len = (tmp & (LEN_SIZE - 1)) + LEN_MIN
+					str = string.sub(window, pos, pos + len - 1)
+				end
+			end
+			flags = flags >> 1
+			if str then
+				output[#output + 1] = str
+				window = string.sub(window .. str, -POS_SIZE)
+			end
+		end
+	end
+
+	return table.concat(output)
+end
+
+return M