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lua5.1 compatibility #5

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lua5.1 compatibility #5

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78b8676
lua5.1 compatibility
smarek Aug 10, 2020
7609195
Update kaitaistruct.lua
smarek Sep 30, 2020
6f1e309
revert removal of method read_bits_int_le
smarek Oct 2, 2020
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84 changes: 51 additions & 33 deletions kaitaistruct.lua
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Open in desktop
Original file line number Diff line number Diff line change
@@ -1,5 +1,18 @@
local class = require("class")
local stringstream = require("string_stream")
local lunpack = require("struct").unpack

local function try_require(name)
local success, mod = pcall(require, name)
if success then
return mod
else
return nil
end
end

-- bit is required in translated lua files, so provide it in this parent module
bit = try_require('bit') or try_require('bit32') or error[[no bitwise library found]]

KaitaiStruct = class.class()

Expand Down Expand Up @@ -74,79 +87,79 @@ end
-------------------------------------------------------------------------------

function KaitaiStream:read_s1()
return string.unpack('b', self._io:read(1))
return lunpack('b', self._io:read(1))
end

--.............................................................................
-- Big-endian
--.............................................................................

function KaitaiStream:read_s2be()
return string.unpack('>i2', self._io:read(2))
return lunpack('>h', self._io:read(2))
end

function KaitaiStream:read_s4be()
return string.unpack('>i4', self._io:read(4))
return lunpack('>i', self._io:read(4))
end

function KaitaiStream:read_s8be()
return string.unpack('>i8', self._io:read(8))
return lunpack('>l', self._io:read(8))
end

--.............................................................................
-- Little-endian
--.............................................................................

function KaitaiStream:read_s2le()
return string.unpack('<i2', self._io:read(2))
return lunpack('<h', self._io:read(2))
end

function KaitaiStream:read_s4le()
return string.unpack('<i4', self._io:read(4))
return lunpack('<i', self._io:read(4))
end

function KaitaiStream:read_s8le()
return string.unpack('<i8', self._io:read(8))
return lunpack('<l', self._io:read(8))
end

-------------------------------------------------------------------------------
-- Unsigned
-------------------------------------------------------------------------------

function KaitaiStream:read_u1()
return string.unpack('B', self._io:read(1))
return lunpack('B', self._io:read(1))
end

--.............................................................................
-- Big-endian
--.............................................................................

function KaitaiStream:read_u2be()
return string.unpack('>I2', self._io:read(2))
return lunpack('>H', self._io:read(2))
end

function KaitaiStream:read_u4be()
return string.unpack('>I4', self._io:read(4))
return lunpack('>I', self._io:read(4))
end

function KaitaiStream:read_u8be()
return string.unpack('>I8', self._io:read(8))
return lunpack('>L', self._io:read(8))
end

--.............................................................................
-- Little-endian
--.............................................................................

function KaitaiStream:read_u2le()
return string.unpack('<I2', self._io:read(2))
return lunpack('<H', self._io:read(2))
end

function KaitaiStream:read_u4le()
return string.unpack('<I4', self._io:read(4))
return lunpack('<I', self._io:read(4))
end

function KaitaiStream:read_u8le()
return string.unpack('<I8', self._io:read(8))
return lunpack('<L', self._io:read(8))
end

--=============================================================================
Expand All @@ -158,23 +171,23 @@ end
-------------------------------------------------------------------------------

function KaitaiStream:read_f4be()
return string.unpack('>f', self._io:read(4))
return lunpack('>f', self._io:read(4))
end

function KaitaiStream:read_f8be()
return string.unpack('>d', self._io:read(8))
return lunpack('>d', self._io:read(8))
end

-------------------------------------------------------------------------------
-- Little-endian
-------------------------------------------------------------------------------

function KaitaiStream:read_f4le()
return string.unpack('<f', self._io:read(4))
return lunpack('<f', self._io:read(4))
end

function KaitaiStream:read_f8le()
return string.unpack('<d', self._io:read(8))
return lunpack('<d', self._io:read(8))
end

--=============================================================================
Expand All @@ -196,21 +209,21 @@ function KaitaiStream:read_bits_int_be(n)
local buf = self._io:read(bytes_needed)
for i = 1, #buf do
local byte = buf:byte(i)
self.bits = self.bits << 8
self.bits = self.bits | byte
self.bits = bit.lshift(self.bits, 8)
self.bits = bit.bor(self.bits, byte)
self.bits_left = self.bits_left + 8
end
end

-- Raw mask with required number of 1s, starting from lowest bit
local mask = (1 << n) - 1
local mask = bit.lshift(1, n) - 1
-- Shift self.bits to align the highest bits with the mask & derive reading result
local shift_bits = self.bits_left - n
local res = (self.bits >> shift_bits) & mask
local res = bit.band(bit.rshift(self.bits, shift_bits), mask)
-- Clear top bits that we've just read => AND with 1s
self.bits_left = self.bits_left - n
mask = (1 << self.bits_left) - 1
self.bits = self.bits & mask
mask = bit.lshift(1, self.bits_left) - 1
self.bits = bit.band(self.bits, mask)

return res
end
Expand All @@ -234,18 +247,23 @@ function KaitaiStream:read_bits_int_le(n)
local buf = self._io:read(bytes_needed)
for i = 1, #buf do
local byte = buf:byte(i)
self.bits = self.bits | (byte << self.bits_left)
self.bits = bit.lshift(self.bits, 8)
self.bits = bit.bor(self.bits, byte)
self.bits_left = self.bits_left + 8
end
end

-- Raw mask with required number of 1s, starting from lowest bit
local mask = (1 << n) - 1
local mask = bit.lshift(1, n) - 1
-- Shift mask to align with highest bits available in self.bits
local shift_bits = self.bits_left - n
mask = bit.lshift(mask, shift_bits)
-- Derive reading result
local res = self.bits & mask
-- Remove bottom bits that we've just read by shifting
self.bits = self.bits >> n
local res = bit.rshift(bit.band(self.bits, mask), shift_bits)
-- Clear top bits that we've just read => AND with 1s
self.bits_left = self.bits_left - n
mask = bit.lshift(1, self.bits_left) - 1
self.bits = bit.band(self.bits, mask)

return res
end
Expand Down Expand Up @@ -348,7 +366,7 @@ function KaitaiStream.process_xor_one(data, key)
local r = ""

for i = 1, #data do
local c = data:byte(i) ~ key
local c = bit.bxor(data:byte(i), key)
r = r .. string.char(c)
end

Expand All @@ -361,7 +379,7 @@ function KaitaiStream.process_xor_many(data, key)
local ki = 1

for i = 1, #data do
local c = data:byte(i) ~ key:byte(ki)
local c = bit.bxor(data:byte(i), key:byte(ki))
r = r .. string.char(c)
ki = ki + 1
if ki > kl then
Expand All @@ -379,11 +397,11 @@ function KaitaiStream.process_rotate_left(data, amount, group_size)

local result = ""
local mask = group_size * 8 - 1
local anti_amount = -amount & mask
local anti_amount = bit.band(-amount, mask)

for i = 1, #data do
local c = data:byte(i)
c = ((c << amount) & 0xFF) | (c >> anti_amount)
c = bit.bor(bit.band(bit.lshift(c, amount), 0xFF), bit.rshift(c, anti_amount))
result = result .. string.char(c)
end

Expand Down
35 changes: 7 additions & 28 deletions string_decode.lua
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Original file line number Diff line number Diff line change
Expand Up @@ -2,42 +2,21 @@
-- String decoder functions
--

local stringdecode = {}

-- From http://lua-users.org/wiki/LuaUnicode
local function utf8_to_32(utf8str)
assert(type(utf8str) == "string")
local res, seq, val = {}, 0, nil

for i = 1, #utf8str do
local c = string.byte(utf8str, i)
if seq == 0 then
table.insert(res, val)
seq = c < 0x80 and 1 or c < 0xE0 and 2 or c < 0xF0 and 3 or
c < 0xF8 and 4 or --c < 0xFC and 5 or c < 0xFE and 6 or
error("Invalid UTF-8 character sequence")
val = bit32.band(c, 2^(8-seq) - 1)
else
val = bit32.bor(bit32.lshift(val, 6), bit32.band(c, 0x3F))
end

seq = seq - 1
end
local lunicode = require(".unicode")
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Congratulations!
Yet the dot here must be a typo?

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Similar uses utf8.lua for relative require, and the unicode module is relative to string_decode.lua in the same directory currently, so it seemed appropriate
https://github.com/Stepets/utf8.lua/blame/master/README.md#L54

currently works even with tests, so I'm not sure it's wrong, however that might change with implementing #11


table.insert(res, val)

return res
end
local stringdecode = {}

function stringdecode.decode(str, encoding)
local enc = encoding and encoding:lower() or "ascii"

if enc == "ascii" then
return str
elseif enc == "utf-8" then
local code_points = utf8_to_32(str)

return utf8.char(table.unpack(code_points))
return lunicode.transcode(str, lunicode.utf8_dec, lunicode.utf8_enc, false, false)
elseif enc == "sjis" then
return table.concat(lunicode.decode(str, lunicode.sjis_dec, true))
elseif enc == "cp437" then
return lunicode.transcode(str, lunicode.cp437_dec, lunicode.utf8_enc, false, false)
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else
error("Encoding " .. encoding .. " not supported")
end
Expand Down
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