Datasets:

meddyrat
/

dis-bench

-- $Id: testes/tpack.lua $
-- See Copyright Notice in file lua.h

local pack = string.pack
local packsize = string.packsize
local unpack = string.unpack

print "testing pack/unpack"

-- maximum size for integers
local NB = 16

local sizeshort = packsize("h")
local sizeint = packsize("i")
local sizelong = packsize("l")
local sizesize_t = packsize("T")
local sizeLI = packsize("j")
local sizefloat = packsize("f")
local sizedouble = packsize("d")
local sizenumber = packsize("n")
local little = (pack("i2", 1) == "\1\0")
local align = packsize("!xXi16")

assert(1 <= sizeshort and sizeshort <= sizeint and sizeint <= sizelong and
       sizefloat <= sizedouble)

print("platform:")
print(string.format(
  "\tshort %d, int %d, long %d, size_t %d, float %d, double %d,\n\z
   \tlua Integer %d, lua Number %d",
   sizeshort, sizeint, sizelong, sizesize_t, sizefloat, sizedouble,
   sizeLI, sizenumber))
print("\t" .. (little and "little" or "big") .. " endian")
print("\talignment: " .. align)


-- check errors in arguments
local function checkerror (msg, f, ...)
  local status, err = pcall(f, ...)
  -- print(status, err, msg)
  assert(not status and string.find(err, msg))
end

-- minimum behavior for integer formats
assert(unpack("B", pack("B", 0xff)) == 0xff)
assert(unpack("b", pack("b", 0x7f)) == 0x7f)
assert(unpack("b", pack("b", -0x80)) == -0x80)

assert(unpack("H", pack("H", 0xffff)) == 0xffff)
assert(unpack("h", pack("h", 0x7fff)) == 0x7fff)
assert(unpack("h", pack("h", -0x8000)) == -0x8000)

assert(unpack("L", pack("L", 0xffffffff)) == 0xffffffff)
assert(unpack("l", pack("l", 0x7fffffff)) == 0x7fffffff)
assert(unpack("l", pack("l", -0x80000000)) == -0x80000000)


for i = 1, NB do
  -- small numbers with signal extension ("\xFF...")
  local s = string.rep("\xff", i)
  assert(pack("i" .. i, -1) == s)
  assert(packsize("i" .. i) == #s)
  assert(unpack("i" .. i, s) == -1)

  -- small unsigned number ("\0...\xAA")
  s = "\xAA" .. string.rep("\0", i - 1)
  assert(pack("<I" .. i, 0xAA) == s)
  assert(unpack("<I" .. i, s) == 0xAA)
  assert(pack(">I" .. i, 0xAA) == s:reverse())
  assert(unpack(">I" .. i, s:reverse()) == 0xAA)
end

do
  local lnum = 0x13121110090807060504030201
  local s = pack("<j", lnum)
  assert(unpack("<j", s) == lnum)
  assert(unpack("<i" .. sizeLI + 1, s .. "\0") == lnum)
  assert(unpack("<i" .. sizeLI + 1, s .. "\0") == lnum)

  for i = sizeLI + 1, NB do
    local s = pack("<j", -lnum)
    assert(unpack("<j", s) == -lnum)
    -- strings with (correct) extra bytes
    assert(unpack("<i" .. i, s .. ("\xFF"):rep(i - sizeLI)) == -lnum)
    assert(unpack(">i" .. i, ("\xFF"):rep(i - sizeLI) .. s:reverse()) == -lnum)
    assert(unpack("<I" .. i, s .. ("\0"):rep(i - sizeLI)) == -lnum)

    -- overflows
    checkerror("does not fit", unpack, "<I" .. i, ("\x00"):rep(i - 1) .. "\1")
    checkerror("does not fit", unpack, ">i" .. i, "\1" .. ("\x00"):rep(i - 1))
  end
end

for i = 1, sizeLI do
  local lstr = "\1\2\3\4\5\6\7\8\9\10\11\12\13"
  local lnum = 0x13121110090807060504030201
  local n = lnum & (~(-1 << (i * 8)))
  local s = string.sub(lstr, 1, i)
  assert(pack("<i" .. i, n) == s)
  assert(pack(">i" .. i, n) == s:reverse())
  assert(unpack(">i" .. i, s:reverse()) == n)
end

-- sign extension
do
  local u = 0xf0
  for i = 1, sizeLI - 1 do
    assert(unpack("<i"..i, "\xf0"..("\xff"):rep(i - 1)) == -16)
    assert(unpack(">I"..i, "\xf0"..("\xff"):rep(i - 1)) == u)
    u = u * 256 + 0xff
  end
end

-- mixed endianness
do
  assert(pack(">i2 <i2", 10, 20) == "\0\10\20\0")
  local a, b = unpack("<i2 >i2", "\10\0\0\20")
  assert(a == 10 and b == 20)
  assert(pack("=i4", 2001) == pack("i4", 2001))
end

print("testing invalid formats")

checkerror("out of limits", pack, "i0", 0)
checkerror("out of limits", pack, "i" .. NB + 1, 0)
checkerror("out of limits", pack, "!" .. NB + 1, 0)
checkerror("%(17%) out of limits %[1,16%]", pack, "Xi" .. NB + 1)
checkerror("invalid format option 'r'", pack, "i3r", 0)
checkerror("16%-byte integer", unpack, "i16", string.rep('\3', 16))
checkerror("not power of 2", pack, "!4i3", 0);
checkerror("missing size", pack, "c", "")
checkerror("variable%-length format", packsize, "s")
checkerror("variable%-length format", packsize, "z")

-- overflow in option size  (error will be in digit after limit)
checkerror("invalid format", packsize, "c1" .. string.rep("0", 40))

do
  local maxsize = (packsize("j") <= packsize("T")) and
                      math.maxinteger or (1 << (packsize("T") * 8))
  assert (packsize(string.format("c%d", maxsize - 9)) == maxsize - 9)
  checkerror("too large", packsize, string.format("c%dc10", maxsize - 9))
  checkerror("too long", pack, string.format("xxxxxxxxxx c%d", maxsize - 9))
end


-- overflow in packing
for i = 1, sizeLI - 1 do
  local umax = (1 << (i * 8)) - 1
  local max = umax >> 1
  local min = ~max
  checkerror("overflow", pack, "<I" .. i, -1)
  checkerror("overflow", pack, "<I" .. i, min)
  checkerror("overflow", pack, ">I" .. i, umax + 1)

  checkerror("overflow", pack, ">i" .. i, umax)
  checkerror("overflow", pack, ">i" .. i, max + 1)
  checkerror("overflow", pack, "<i" .. i, min - 1)

  assert(unpack(">i" .. i, pack(">i" .. i, max)) == max)
  assert(unpack("<i" .. i, pack("<i" .. i, min)) == min)
  assert(unpack(">I" .. i, pack(">I" .. i, umax)) == umax)
end

-- Lua integer size
assert(unpack(">j", pack(">j", math.maxinteger)) == math.maxinteger)
assert(unpack("<j", pack("<j", math.mininteger)) == math.mininteger)
assert(unpack("<J", pack("<j", -1)) == -1)   -- maximum unsigned integer

if little then
  assert(pack("f", 24) == pack("<f", 24))
else
  assert(pack("f", 24) == pack(">f", 24))
end

print "testing pack/unpack of floating-point numbers" 

for _, n in ipairs{0, -1.1, 1.9, 1/0, -1/0, 1e20, -1e20, 0.1, 2000.7} do
    assert(unpack("n", pack("n", n)) == n)
    assert(unpack("<n", pack("<n", n)) == n)
    assert(unpack(">n", pack(">n", n)) == n)
    assert(pack("<f", n) == pack(">f", n):reverse())
    assert(pack(">d", n) == pack("<d", n):reverse())
end

-- for non-native precisions, test only with "round" numbers
for _, n in ipairs{0, -1.5, 1/0, -1/0, 1e10, -1e9, 0.5, 2000.25} do
  assert(unpack("<f", pack("<f", n)) == n)
  assert(unpack(">f", pack(">f", n)) == n)
  assert(unpack("<d", pack("<d", n)) == n)
  assert(unpack(">d", pack(">d", n)) == n)
end

print "testing pack/unpack of strings"
do
  local s = string.rep("abc", 1000)
  assert(pack("zB", s, 247) == s .. "\0\xF7")
  local s1, b = unpack("zB", s .. "\0\xF9")
  assert(b == 249 and s1 == s)
  s1 = pack("s", s)
  assert(unpack("s", s1) == s)

  checkerror("does not fit", pack, "s1", s)

  checkerror("contains zeros", pack, "z", "alo\0");

  checkerror("unfinished string", unpack, "zc10000000", "alo")

  for i = 2, NB do
    local s1 = pack("s" .. i, s)
    assert(unpack("s" .. i, s1) == s and #s1 == #s + i)
  end
end

do
  local x = pack("s", "alo")
  checkerror("too short", unpack, "s", x:sub(1, -2))
  checkerror("too short", unpack, "c5", "abcd")
  checkerror("out of limits", pack, "s100", "alo")
end

do
  assert(pack("c0", "") == "")
  assert(packsize("c0") == 0)
  assert(unpack("c0", "") == "")
  assert(pack("<! c3", "abc") == "abc")
  assert(packsize("<! c3") == 3)
  assert(pack(">!4 c6", "abcdef") == "abcdef")
  assert(pack("c3", "123") == "123")
  assert(pack("c0", "") == "")
  assert(pack("c8", "123456") == "123456\0\0")
  assert(pack("c88 c1", "", "X") == string.rep("\0", 88) .. "X")
  assert(pack("c188 c2", "ab", "X\1") ==
         "ab" .. string.rep("\0", 188 - 2) .. "X\1")
  local a, b, c = unpack("!4 z c3", "abcdefghi\0xyz")
  assert(a == "abcdefghi" and b == "xyz" and c == 14)
  checkerror("longer than", pack, "c3", "1234")
end


-- testing multiple types and sequence
do
  local x = pack("<b h b f d f n i", 1, 2, 3, 4, 5, 6, 7, 8)
  assert(#x == packsize("<b h b f d f n i"))
  local a, b, c, d, e, f, g, h = unpack("<b h b f d f n i", x)
  assert(a == 1 and b == 2 and c == 3 and d == 4 and e == 5 and f == 6 and
         g == 7 and h == 8) 
end

print "testing alignment"
do
  assert(pack(" < i1 i2 ", 2, 3) == "\2\3\0")   -- no alignment by default
  local x = pack(">!8 b Xh i4 i8 c1 Xi8", -12, 100, 200, "\xEC")
  assert(#x == packsize(">!8 b Xh i4 i8 c1 Xi8"))
  assert(x == "\xf4" .. "\0\0\0" ..
              "\0\0\0\100" ..
              "\0\0\0\0\0\0\0\xC8" .. 
              "\xEC" .. "\0\0\0\0\0\0\0")
  local a, b, c, d, pos = unpack(">!8 c1 Xh i4 i8 b Xi8 XI XH", x)
  assert(a == "\xF4" and b == 100 and c == 200 and d == -20 and (pos - 1) == #x)

  x = pack(">!4 c3 c4 c2 z i4 c5 c2 Xi4",
                  "abc", "abcd", "xz", "hello", 5, "world", "xy")
  assert(x == "abcabcdxzhello\0\0\0\0\0\5worldxy\0")
  local a, b, c, d, e, f, g, pos = unpack(">!4 c3 c4 c2 z i4 c5 c2 Xh Xi4", x)
  assert(a == "abc" and b == "abcd" and c == "xz" and d == "hello" and
         e == 5 and f == "world" and g == "xy" and (pos - 1) % 4 == 0)

  x = pack(" b b Xd b Xb x", 1, 2, 3)
  assert(packsize(" b b Xd b Xb x") == 4)
  assert(x == "\1\2\3\0")
  a, b, c, pos = unpack("bbXdb", x)
  assert(a == 1 and b == 2 and c == 3 and pos == #x)

  -- only alignment
  assert(packsize("!8 xXi8") == 8)
  local pos = unpack("!8 xXi8", "0123456701234567"); assert(pos == 9)
  assert(packsize("!8 xXi2") == 2)
  local pos = unpack("!8 xXi2", "0123456701234567"); assert(pos == 3)
  assert(packsize("!2 xXi2") == 2)
  local pos = unpack("!2 xXi2", "0123456701234567"); assert(pos == 3)
  assert(packsize("!2 xXi8") == 2)
  local pos = unpack("!2 xXi8", "0123456701234567"); assert(pos == 3)
  assert(packsize("!16 xXi16") == 16)
  local pos = unpack("!16 xXi16", "0123456701234567"); assert(pos == 17)

  checkerror("invalid next option", pack, "X")
  checkerror("invalid next option", unpack, "XXi", "")
  checkerror("invalid next option", unpack, "X i", "")
  checkerror("invalid next option", pack, "Xc1")
end

do    -- testing initial position
  local x = pack("i4i4i4i4", 1, 2, 3, 4)
  for pos = 1, 16, 4 do
    local i, p = unpack("i4", x, pos)
    assert(i == pos//4 + 1 and p == pos + 4)
  end

  -- with alignment
  for pos = 0, 12 do    -- will always round position to power of 2
    local i, p = unpack("!4 i4", x, pos + 1)
    assert(i == (pos + 3)//4 + 1 and p == i*4 + 1)
  end

  -- negative indices
  local i, p = unpack("!4 i4", x, -4)
  assert(i == 4 and p == 17)
  local i, p = unpack("!4 i4", x, -7)
  assert(i == 4 and p == 17)
  local i, p = unpack("!4 i4", x, -#x)
  assert(i == 1 and p == 5)

  -- limits
  for i = 1, #x + 1 do
    assert(unpack("c0", x, i) == "")
  end
  checkerror("out of string", unpack, "c0", x, #x + 2)
 
end

print "OK"

	-- $Id: testes/tpack.lua $
	-- See Copyright Notice in file lua.h

	local pack = string.pack
	local packsize = string.packsize
	local unpack = string.unpack

	print "testing pack/unpack"

	-- maximum size for integers
	local NB = 16

	local sizeshort = packsize("h")
	local sizeint = packsize("i")
	local sizelong = packsize("l")
	local sizesize_t = packsize("T")
	local sizeLI = packsize("j")
	local sizefloat = packsize("f")
	local sizedouble = packsize("d")
	local sizenumber = packsize("n")
	local little = (pack("i2", 1) == "\1\0")
	local align = packsize("!xXi16")

	assert(1 <= sizeshort and sizeshort <= sizeint and sizeint <= sizelong and
	sizefloat <= sizedouble)

	print("platform:")
	print(string.format(
	"\tshort %d, int %d, long %d, size_t %d, float %d, double %d,\n\z
	\tlua Integer %d, lua Number %d",
	sizeshort, sizeint, sizelong, sizesize_t, sizefloat, sizedouble,
	sizeLI, sizenumber))
	print("\t" .. (little and "little" or "big") .. " endian")
	print("\talignment: " .. align)


	-- check errors in arguments
	local function checkerror (msg, f, ...)
	local status, err = pcall(f, ...)
	-- print(status, err, msg)
	assert(not status and string.find(err, msg))
	end

	-- minimum behavior for integer formats
	assert(unpack("B", pack("B", 0xff)) == 0xff)
	assert(unpack("b", pack("b", 0x7f)) == 0x7f)
	assert(unpack("b", pack("b", -0x80)) == -0x80)

	assert(unpack("H", pack("H", 0xffff)) == 0xffff)
	assert(unpack("h", pack("h", 0x7fff)) == 0x7fff)
	assert(unpack("h", pack("h", -0x8000)) == -0x8000)

	assert(unpack("L", pack("L", 0xffffffff)) == 0xffffffff)
	assert(unpack("l", pack("l", 0x7fffffff)) == 0x7fffffff)
	assert(unpack("l", pack("l", -0x80000000)) == -0x80000000)


	for i = 1, NB do
	-- small numbers with signal extension ("\xFF...")
	local s = string.rep("\xff", i)
	assert(pack("i" .. i, -1) == s)
	assert(packsize("i" .. i) == #s)
	assert(unpack("i" .. i, s) == -1)

	-- small unsigned number ("\0...\xAA")
	s = "\xAA" .. string.rep("\0", i - 1)
	assert(pack("<I" .. i, 0xAA) == s)
	assert(unpack("<I" .. i, s) == 0xAA)
	assert(pack(">I" .. i, 0xAA) == s:reverse())
	assert(unpack(">I" .. i, s:reverse()) == 0xAA)
	end

	do
	local lnum = 0x13121110090807060504030201
	local s = pack("<j", lnum)
	assert(unpack("<j", s) == lnum)
	assert(unpack("<i" .. sizeLI + 1, s .. "\0") == lnum)
	assert(unpack("<i" .. sizeLI + 1, s .. "\0") == lnum)

	for i = sizeLI + 1, NB do
	local s = pack("<j", -lnum)
	assert(unpack("<j", s) == -lnum)
	-- strings with (correct) extra bytes
	assert(unpack("<i" .. i, s .. ("\xFF"):rep(i - sizeLI)) == -lnum)
	assert(unpack(">i" .. i, ("\xFF"):rep(i - sizeLI) .. s:reverse()) == -lnum)
	assert(unpack("<I" .. i, s .. ("\0"):rep(i - sizeLI)) == -lnum)

	-- overflows
	checkerror("does not fit", unpack, "<I" .. i, ("\x00"):rep(i - 1) .. "\1")
	checkerror("does not fit", unpack, ">i" .. i, "\1" .. ("\x00"):rep(i - 1))
	end
	end

	for i = 1, sizeLI do
	local lstr = "\1\2\3\4\5\6\7\8\9\10\11\12\13"
	local lnum = 0x13121110090807060504030201
	local n = lnum & (~(-1 << (i * 8)))
	local s = string.sub(lstr, 1, i)
	assert(pack("<i" .. i, n) == s)
	assert(pack(">i" .. i, n) == s:reverse())
	assert(unpack(">i" .. i, s:reverse()) == n)
	end

	-- sign extension
	do
	local u = 0xf0
	for i = 1, sizeLI - 1 do
	assert(unpack("<i"..i, "\xf0"..("\xff"):rep(i - 1)) == -16)
	assert(unpack(">I"..i, "\xf0"..("\xff"):rep(i - 1)) == u)
	u = u * 256 + 0xff
	end
	end

	-- mixed endianness
	do
	assert(pack(">i2 <i2", 10, 20) == "\0\10\20\0")
	local a, b = unpack("<i2 >i2", "\10\0\0\20")
	assert(a == 10 and b == 20)
	assert(pack("=i4", 2001) == pack("i4", 2001))
	end

	print("testing invalid formats")

	checkerror("out of limits", pack, "i0", 0)
	checkerror("out of limits", pack, "i" .. NB + 1, 0)
	checkerror("out of limits", pack, "!" .. NB + 1, 0)
	checkerror("%(17%) out of limits %[1,16%]", pack, "Xi" .. NB + 1)
	checkerror("invalid format option 'r'", pack, "i3r", 0)
	checkerror("16%-byte integer", unpack, "i16", string.rep('\3', 16))
	checkerror("not power of 2", pack, "!4i3", 0);
	checkerror("missing size", pack, "c", "")
	checkerror("variable%-length format", packsize, "s")
	checkerror("variable%-length format", packsize, "z")

	-- overflow in option size (error will be in digit after limit)
	checkerror("invalid format", packsize, "c1" .. string.rep("0", 40))

	do
	local maxsize = (packsize("j") <= packsize("T")) and
	math.maxinteger or (1 << (packsize("T") * 8))
	assert (packsize(string.format("c%d", maxsize - 9)) == maxsize - 9)
	checkerror("too large", packsize, string.format("c%dc10", maxsize - 9))
	checkerror("too long", pack, string.format("xxxxxxxxxx c%d", maxsize - 9))
	end


	-- overflow in packing
	for i = 1, sizeLI - 1 do
	local umax = (1 << (i * 8)) - 1
	local max = umax >> 1
	local min = ~max
	checkerror("overflow", pack, "<I" .. i, -1)
	checkerror("overflow", pack, "<I" .. i, min)
	checkerror("overflow", pack, ">I" .. i, umax + 1)

	checkerror("overflow", pack, ">i" .. i, umax)
	checkerror("overflow", pack, ">i" .. i, max + 1)
	checkerror("overflow", pack, "<i" .. i, min - 1)

	assert(unpack(">i" .. i, pack(">i" .. i, max)) == max)
	assert(unpack("<i" .. i, pack("<i" .. i, min)) == min)
	assert(unpack(">I" .. i, pack(">I" .. i, umax)) == umax)
	end

	-- Lua integer size
	assert(unpack(">j", pack(">j", math.maxinteger)) == math.maxinteger)
	assert(unpack("<j", pack("<j", math.mininteger)) == math.mininteger)
	assert(unpack("<J", pack("<j", -1)) == -1) -- maximum unsigned integer

	if little then
	assert(pack("f", 24) == pack("<f", 24))
	else
	assert(pack("f", 24) == pack(">f", 24))
	end

	print "testing pack/unpack of floating-point numbers"

	for _, n in ipairs{0, -1.1, 1.9, 1/0, -1/0, 1e20, -1e20, 0.1, 2000.7} do
	assert(unpack("n", pack("n", n)) == n)
	assert(unpack("<n", pack("<n", n)) == n)
	assert(unpack(">n", pack(">n", n)) == n)
	assert(pack("<f", n) == pack(">f", n):reverse())
	assert(pack(">d", n) == pack("<d", n):reverse())
	end

	-- for non-native precisions, test only with "round" numbers
	for _, n in ipairs{0, -1.5, 1/0, -1/0, 1e10, -1e9, 0.5, 2000.25} do
	assert(unpack("<f", pack("<f", n)) == n)
	assert(unpack(">f", pack(">f", n)) == n)
	assert(unpack("<d", pack("<d", n)) == n)
	assert(unpack(">d", pack(">d", n)) == n)
	end

	print "testing pack/unpack of strings"
	do
	local s = string.rep("abc", 1000)
	assert(pack("zB", s, 247) == s .. "\0\xF7")
	local s1, b = unpack("zB", s .. "\0\xF9")
	assert(b == 249 and s1 == s)
	s1 = pack("s", s)
	assert(unpack("s", s1) == s)

	checkerror("does not fit", pack, "s1", s)

	checkerror("contains zeros", pack, "z", "alo\0");

	checkerror("unfinished string", unpack, "zc10000000", "alo")

	for i = 2, NB do
	local s1 = pack("s" .. i, s)
	assert(unpack("s" .. i, s1) == s and #s1 == #s + i)
	end
	end

	do
	local x = pack("s", "alo")
	checkerror("too short", unpack, "s", x:sub(1, -2))
	checkerror("too short", unpack, "c5", "abcd")
	checkerror("out of limits", pack, "s100", "alo")
	end

	do
	assert(pack("c0", "") == "")
	assert(packsize("c0") == 0)
	assert(unpack("c0", "") == "")
	assert(pack("<! c3", "abc") == "abc")
	assert(packsize("<! c3") == 3)
	assert(pack(">!4 c6", "abcdef") == "abcdef")
	assert(pack("c3", "123") == "123")
	assert(pack("c0", "") == "")
	assert(pack("c8", "123456") == "123456\0\0")
	assert(pack("c88 c1", "", "X") == string.rep("\0", 88) .. "X")
	assert(pack("c188 c2", "ab", "X\1") ==
	"ab" .. string.rep("\0", 188 - 2) .. "X\1")
	local a, b, c = unpack("!4 z c3", "abcdefghi\0xyz")
	assert(a == "abcdefghi" and b == "xyz" and c == 14)
	checkerror("longer than", pack, "c3", "1234")
	end


	-- testing multiple types and sequence
	do
	local x = pack("<b h b f d f n i", 1, 2, 3, 4, 5, 6, 7, 8)
	assert(#x == packsize("<b h b f d f n i"))
	local a, b, c, d, e, f, g, h = unpack("<b h b f d f n i", x)
	assert(a == 1 and b == 2 and c == 3 and d == 4 and e == 5 and f == 6 and
	g == 7 and h == 8)
	end

	print "testing alignment"
	do
	assert(pack(" < i1 i2 ", 2, 3) == "\2\3\0") -- no alignment by default
	local x = pack(">!8 b Xh i4 i8 c1 Xi8", -12, 100, 200, "\xEC")
	assert(#x == packsize(">!8 b Xh i4 i8 c1 Xi8"))
	assert(x == "\xf4" .. "\0\0\0" ..
	"\0\0\0\100" ..
	"\0\0\0\0\0\0\0\xC8" ..
	"\xEC" .. "\0\0\0\0\0\0\0")
	local a, b, c, d, pos = unpack(">!8 c1 Xh i4 i8 b Xi8 XI XH", x)
	assert(a == "\xF4" and b == 100 and c == 200 and d == -20 and (pos - 1) == #x)

	x = pack(">!4 c3 c4 c2 z i4 c5 c2 Xi4",
	"abc", "abcd", "xz", "hello", 5, "world", "xy")
	assert(x == "abcabcdxzhello\0\0\0\0\0\5worldxy\0")
	local a, b, c, d, e, f, g, pos = unpack(">!4 c3 c4 c2 z i4 c5 c2 Xh Xi4", x)
	assert(a == "abc" and b == "abcd" and c == "xz" and d == "hello" and
	e == 5 and f == "world" and g == "xy" and (pos - 1) % 4 == 0)

	x = pack(" b b Xd b Xb x", 1, 2, 3)
	assert(packsize(" b b Xd b Xb x") == 4)
	assert(x == "\1\2\3\0")
	a, b, c, pos = unpack("bbXdb", x)
	assert(a == 1 and b == 2 and c == 3 and pos == #x)

	-- only alignment
	assert(packsize("!8 xXi8") == 8)
	local pos = unpack("!8 xXi8", "0123456701234567"); assert(pos == 9)
	assert(packsize("!8 xXi2") == 2)
	local pos = unpack("!8 xXi2", "0123456701234567"); assert(pos == 3)
	assert(packsize("!2 xXi2") == 2)
	local pos = unpack("!2 xXi2", "0123456701234567"); assert(pos == 3)
	assert(packsize("!2 xXi8") == 2)
	local pos = unpack("!2 xXi8", "0123456701234567"); assert(pos == 3)
	assert(packsize("!16 xXi16") == 16)
	local pos = unpack("!16 xXi16", "0123456701234567"); assert(pos == 17)

	checkerror("invalid next option", pack, "X")
	checkerror("invalid next option", unpack, "XXi", "")
	checkerror("invalid next option", unpack, "X i", "")
	checkerror("invalid next option", pack, "Xc1")
	end

	do -- testing initial position
	local x = pack("i4i4i4i4", 1, 2, 3, 4)
	for pos = 1, 16, 4 do
	local i, p = unpack("i4", x, pos)
	assert(i == pos//4 + 1 and p == pos + 4)
	end

	-- with alignment
	for pos = 0, 12 do -- will always round position to power of 2
	local i, p = unpack("!4 i4", x, pos + 1)
	assert(i == (pos + 3)//4 + 1 and p == i*4 + 1)
	end

	-- negative indices
	local i, p = unpack("!4 i4", x, -4)
	assert(i == 4 and p == 17)
	local i, p = unpack("!4 i4", x, -7)
	assert(i == 4 and p == 17)
	local i, p = unpack("!4 i4", x, -#x)
	assert(i == 1 and p == 5)

	-- limits
	for i = 1, #x + 1 do
	assert(unpack("c0", x, i) == "")
	end
	checkerror("out of string", unpack, "c0", x, #x + 2)

	end

	print "OK"