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switched to using string.(un)pack in libmtar and liblz16, meaning it works on both big and little endian machines, and should be smaller and faster

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This commit is contained in:
Izaya 2021-05-26 16:15:24 +10:00
parent c5f304380e
commit 8e84eb0c67
2 changed files with 5 additions and 42 deletions
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22
lib/liblz16.lua
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@ -3,31 +3,13 @@ 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")
local len = string.unpack(">I2", fi:read(2) or "\0\0")
if len < 1 then
return nil
end
@ -44,7 +26,7 @@ local function writeBuffer(fo)
local stream = {}
function stream:write(data)
local cblock = lz.compress(data)
fo:write(cint(cblock:len(),2)..cblock)
fo:write(string.pack(">I2", cblock:len()) .. cblock)
return cblock:len()+2
end
function stream.close()

25
lib/libmtar.lua
View File

@ -1,24 +1,5 @@
local mtar = {}
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 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 cleanPath(path)
local pt = {}
for segment in path:gmatch("[^/]+") do
@ -32,7 +13,7 @@ local function cleanPath(path)
end
function mtar.genHeader(fname,len) -- string number -- string -- generate a header for file *fname* when provided with file length *len*
return string.format("%s%s%s",cint(fname:len(),2),fname,cint(len,2))
return string.format("%s%s%s", string.pack(">I2",fname:len()), fname, string.pack(">I2",len))
end
function mtar.iter(stream) -- table -- function -- Given buffer *stream*, returns an iterator suitable for use with *for* that returns, for each iteration, the file name, a function to read from the file, and the length of the file.
@ -46,12 +27,12 @@ function mtar.iter(stream) -- table -- function -- Given buffer *stream*, return
while remain > 0 do
remain=remain-#stream:read(math.min(remain,2048))
end
local nlen = toint(stream:read(2) or "\0\0")
local nlen = string.unpack(">I2", stream:read(2) or "\0\0")
if nlen == 0 then
return
end
local name = cleanPath(stream:read(nlen))
local fsize = toint(stream:read(2))
local fsize = string.unpack(">I2", stream:read(2))
remain = fsize
return name, read, fsize
end