--
-- lua-MessagePack : <https://fperrad.frama.io/lua-MessagePack/>
--

local r, jit = pcall(require, 'jit')
if not r then
    jit = nil
end

local SIZEOF_NUMBER = string.pack and #string.pack('n', 0.0) or 8
local maxinteger
local mininteger
if not jit and _VERSION < 'Lua 5.3' then
    -- Lua 5.1 & 5.2
    local loadstring = loadstring or load
    local luac = string.dump(loadstring "a = 1")
    local header = { luac:byte(1, 12) }
    SIZEOF_NUMBER = header[11]
end

local assert = assert
local error = error
local pairs = pairs
local pcall = pcall
local setmetatable = setmetatable
local tostring = tostring
local type = type
local char = require'string'.char
local format = require'string'.format
local floor = require'math'.floor
local tointeger = require'math'.tointeger or floor
local frexp = require'math'.frexp or require'mathx'.frexp
local ldexp = require'math'.ldexp or require'mathx'.ldexp
local huge = require'math'.huge
local tconcat = require'table'.concat

local _ENV = nil
local m = {}

--[[ debug only
local function hexadump (s)
    return (s:gsub('.', function (c) return format('%02X ', c:byte()) end))
end
m.hexadump = hexadump
--]]

local function argerror (caller, narg, extramsg)
    error("bad argument #" .. tostring(narg) .. " to "
          .. caller .. " (" .. extramsg .. ")")
end

local function typeerror (caller, narg, arg, tname)
    argerror(caller, narg, tname .. " expected, got " .. type(arg))
end

local function checktype (caller, narg, arg, tname)
    if type(arg) ~= tname then
        typeerror(caller, narg, arg, tname)
    end
end

local packers = setmetatable({}, {
    __index = function (t, k)
        if k == 1 then return end   -- allows ipairs
        error("pack '" .. k .. "' is unimplemented")
    end
})
m.packers = packers

packers['nil'] = function (buffer)
    buffer[#buffer+1] = char(0xC0)              -- nil
end

packers['boolean'] = function (buffer, bool)
    if bool then
        buffer[#buffer+1] = char(0xC3)          -- true
    else
        buffer[#buffer+1] = char(0xC2)          -- false
    end
end

packers['string_compat'] = function (buffer, str)
    local n = #str
    if n <= 0x1F then
        buffer[#buffer+1] = char(0xA0 + n)      -- fixstr
    elseif n <= 0xFFFF then
        buffer[#buffer+1] = char(0xDA,          -- str16
                                 floor(n / 0x100),
                                 n % 0x100)
    elseif n <= 4294967295.0 then
        buffer[#buffer+1] = char(0xDB,          -- str32
                                 floor(n / 0x1000000),
                                 floor(n / 0x10000) % 0x100,
                                 floor(n / 0x100) % 0x100,
                                 n % 0x100)
    else
        error"overflow in pack 'string_compat'"
    end
    buffer[#buffer+1] = str
end

packers['_string'] = function (buffer, str)
    local n = #str
    if n <= 0x1F then
        buffer[#buffer+1] = char(0xA0 + n)      -- fixstr
    elseif n <= 0xFF then
        buffer[#buffer+1] = char(0xD9,          -- str8
                                 n)
    elseif n <= 0xFFFF then
        buffer[#buffer+1] = char(0xDA,          -- str16
                                 floor(n / 0x100),
                                 n % 0x100)
    elseif n <= 4294967295.0 then
        buffer[#buffer+1] = char(0xDB,          -- str32
                                 floor(n / 0x1000000),
                                 floor(n / 0x10000) % 0x100,
                                 floor(n / 0x100) % 0x100,
                                 n % 0x100)
    else
        error"overflow in pack 'string'"
    end
    buffer[#buffer+1] = str
end

packers['binary'] = function (buffer, str)
    local n = #str
    if n <= 0xFF then
        buffer[#buffer+1] = char(0xC4,          -- bin8
                                 n)
    elseif n <= 0xFFFF then
        buffer[#buffer+1] = char(0xC5,          -- bin16
                                 floor(n / 0x100),
                                 n % 0x100)
    elseif n <= 4294967295.0 then
        buffer[#buffer+1] = char(0xC6,          -- bin32
                                 floor(n / 0x1000000),
                                 floor(n / 0x10000) % 0x100,
                                 floor(n / 0x100) % 0x100,
                                 n % 0x100)
    else
        error"overflow in pack 'binary'"
    end
    buffer[#buffer+1] = str
end

local set_string = function (str)
    if str == 'string_compat' then
        packers['string'] = packers['string_compat']
    elseif str == 'string' then
        packers['string'] = packers['_string']
    elseif str == 'binary' then
        packers['string'] = packers['binary']
    else
        argerror('set_string', 1, "invalid option '" .. str .."'")
    end
end
m.set_string = set_string

packers['map'] = function (buffer, tbl, n)
    if n <= 0x0F then
        buffer[#buffer+1] = char(0x80 + n)      -- fixmap
    elseif n <= 0xFFFF then
        buffer[#buffer+1] = char(0xDE,          -- map16
                                 floor(n / 0x100),
                                 n % 0x100)
    elseif n <= 4294967295.0 then
        buffer[#buffer+1] = char(0xDF,          -- map32
                                 floor(n / 0x1000000),
                                 floor(n / 0x10000) % 0x100,
                                 floor(n / 0x100) % 0x100,
                                 n % 0x100)
    else
        error"overflow in pack 'map'"
    end
    for k, v in pairs(tbl) do
        packers[type(k)](buffer, k)
        packers[type(v)](buffer, v)
    end
end

packers['array'] = function (buffer, tbl, n)
    if n <= 0x0F then
        buffer[#buffer+1] = char(0x90 + n)      -- fixarray
    elseif n <= 0xFFFF then
        buffer[#buffer+1] = char(0xDC,          -- array16
                                 floor(n / 0x100),
                                 n % 0x100)
    elseif n <= 4294967295.0 then
        buffer[#buffer+1] = char(0xDD,          -- array32
                                 floor(n / 0x1000000),
                                 floor(n / 0x10000) % 0x100,
                                 floor(n / 0x100) % 0x100,
                                 n % 0x100)
    else
        error"overflow in pack 'array'"
    end
    for i = 1, n do
        local v = tbl[i]
        packers[type(v)](buffer, v)
    end
end

local set_array = function (array)
    if array == 'without_hole' then
        packers['_table'] = function (buffer, tbl)
            local is_map, n, max = false, 0, 0
            for k in pairs(tbl) do
                if type(k) == 'number' and k > 0 then
                    if k > max then
                        max = k
                    end
                else
                    is_map = true
                end
                n = n + 1
            end
            if max ~= n then    -- there are holes
                is_map = true
            end
            if is_map then
                packers['map'](buffer, tbl, n)
            else
                packers['array'](buffer, tbl, n)
            end
        end
    elseif array == 'with_hole' then
        packers['_table'] = function (buffer, tbl)
            local is_map, n, max = false, 0, 0
            for k in pairs(tbl) do
                if type(k) == 'number' and k > 0 then
                    if k > max then
                        max = k
                    end
                else
                    is_map = true
                end
                n = n + 1
            end
            if is_map then
                packers['map'](buffer, tbl, n)
            else
                packers['array'](buffer, tbl, max)
            end
        end
    elseif array == 'always_as_map' then
        packers['_table'] = function(buffer, tbl)
            local n = 0
            for k in pairs(tbl) do
                n = n + 1
            end
            packers['map'](buffer, tbl, n)
        end
    else
        argerror('set_array', 1, "invalid option '" .. array .."'")
    end
end
m.set_array = set_array

packers['table'] = function (buffer, tbl)
    packers['_table'](buffer, tbl)
end

packers['unsigned'] = function (buffer, n)
    if n >= 0 then
        if n <= 0x7F then
            buffer[#buffer+1] = char(n)         -- fixnum_pos
        elseif n <= 0xFF then
            buffer[#buffer+1] = char(0xCC,      -- uint8
                                     n)
        elseif n <= 0xFFFF then
            buffer[#buffer+1] = char(0xCD,      -- uint16
                                     floor(n / 0x100),
                                     n % 0x100)
        elseif n <= 4294967295.0 then
            buffer[#buffer+1] = char(0xCE,      -- uint32
                                     floor(n / 0x1000000),
                                     floor(n / 0x10000) % 0x100,
                                     floor(n / 0x100) % 0x100,
                                     n % 0x100)
        else
            buffer[#buffer+1] = char(0xCF,      -- uint64
                                     0,         -- only 53 bits from double
                                     floor(n / 0x1000000000000) % 0x100,
                                     floor(n / 0x10000000000) % 0x100,
                                     floor(n / 0x100000000) % 0x100,
                                     floor(n / 0x1000000) % 0x100,
                                     floor(n / 0x10000) % 0x100,
                                     floor(n / 0x100) % 0x100,
                                     n % 0x100)
        end
    else
        if n >= -0x20 then
            buffer[#buffer+1] = char(0x100 + n) -- fixnum_neg
        elseif n >= -0x80 then
            buffer[#buffer+1] = char(0xD0,      -- int8
                                     0x100 + n)
        elseif n >= -0x8000 then
            n = 0x10000 + n
            buffer[#buffer+1] = char(0xD1,      -- int16
                                     floor(n / 0x100),
                                     n % 0x100)
        elseif n >= -0x80000000 then
            n = 4294967296.0 + n
            buffer[#buffer+1] = char(0xD2,      -- int32
                                     floor(n / 0x1000000),
                                     floor(n / 0x10000) % 0x100,
                                     floor(n / 0x100) % 0x100,
                                     n % 0x100)
        else
            buffer[#buffer+1] = char(0xD3,      -- int64
                                     0xFF,      -- only 53 bits from double
                                     floor(n / 0x1000000000000) % 0x100,
                                     floor(n / 0x10000000000) % 0x100,
                                     floor(n / 0x100000000) % 0x100,
                                     floor(n / 0x1000000) % 0x100,
                                     floor(n / 0x10000) % 0x100,
                                     floor(n / 0x100) % 0x100,
                                     n % 0x100)
        end
    end
end

packers['signed'] = function (buffer, n)
    if n >= 0 then
        if n <= 0x7F then
            buffer[#buffer+1] = char(n)         -- fixnum_pos
        elseif n <= 0x7FFF then
            buffer[#buffer+1] = char(0xD1,      -- int16
                                     floor(n / 0x100),
                                     n % 0x100)
        elseif n <= 0x7FFFFFFF then
            buffer[#buffer+1] = char(0xD2,      -- int32
                                     floor(n / 0x1000000),
                                     floor(n / 0x10000) % 0x100,
                                     floor(n / 0x100) % 0x100,
                                     n % 0x100)
        else
            buffer[#buffer+1] = char(0xD3,      -- int64
                                     0,         -- only 53 bits from double
                                     floor(n / 0x1000000000000) % 0x100,
                                     floor(n / 0x10000000000) % 0x100,
                                     floor(n / 0x100000000) % 0x100,
                                     floor(n / 0x1000000) % 0x100,
                                     floor(n / 0x10000) % 0x100,
                                     floor(n / 0x100) % 0x100,
                                     n % 0x100)
        end
    else
        if n >= -0x20 then
            buffer[#buffer+1] = char(0xE0 + 0x20 + n)   -- fixnum_neg
        elseif n >= -0x80 then
            buffer[#buffer+1] = char(0xD0,      -- int8
                                     0x100 + n)
        elseif n >= -0x8000 then
            n = 0x10000 + n
            buffer[#buffer+1] = char(0xD1,      -- int16
                                     floor(n / 0x100),
                                     n % 0x100)
        elseif n >= -0x80000000 then
            n = 4294967296.0 + n
            buffer[#buffer+1] = char(0xD2,      -- int32
                                     floor(n / 0x1000000),
                                     floor(n / 0x10000) % 0x100,
                                     floor(n / 0x100) % 0x100,
                                     n % 0x100)
        else
            buffer[#buffer+1] = char(0xD3,      -- int64
                                     0xFF,      -- only 53 bits from double
                                     floor(n / 0x1000000000000) % 0x100,
                                     floor(n / 0x10000000000) % 0x100,
                                     floor(n / 0x100000000) % 0x100,
                                     floor(n / 0x1000000) % 0x100,
                                     floor(n / 0x10000) % 0x100,
                                     floor(n / 0x100) % 0x100,
                                     n % 0x100)
        end
    end
end

local set_integer = function (integer)
    if integer == 'unsigned' then
        packers['integer'] = packers['unsigned']
    elseif integer == 'signed' then
        packers['integer'] = packers['signed']
    else
        argerror('set_integer', 1, "invalid option '" .. integer .."'")
    end
end
m.set_integer = set_integer

packers['float'] = function (buffer, n)
    local sign = 0
    if n < 0.0 then
        sign = 0x80
        n = -n
    end
    local mant, expo = frexp(n)
    if mant ~= mant then
        buffer[#buffer+1] = char(0xCA,  -- nan
                                 0xFF, 0x88, 0x00, 0x00)
    elseif mant == huge or expo > 0x80 then
        if sign == 0 then
            buffer[#buffer+1] = char(0xCA,      -- inf
                                     0x7F, 0x80, 0x00, 0x00)
        else
            buffer[#buffer+1] = char(0xCA,      -- -inf
                                     0xFF, 0x80, 0x00, 0x00)
        end
    elseif (mant == 0.0 and expo == 0) or expo < -0x7E then
        buffer[#buffer+1] = char(0xCA,  -- zero
                                 sign, 0x00, 0x00, 0x00)
    else
        expo = expo + 0x7E
        mant = floor((mant * 2.0 - 1.0) * ldexp(0.5, 24))
        buffer[#buffer+1] = char(0xCA,
                                 sign + floor(expo / 0x2),
                                 (expo % 0x2) * 0x80 + floor(mant / 0x10000),
                                 floor(mant / 0x100) % 0x100,
                                 mant % 0x100)
    end
end

packers['double'] = function (buffer, n)
    local sign = 0
    if n < 0.0 then
        sign = 0x80
        n = -n
    end
    local mant, expo = frexp(n)
    if mant ~= mant then
        buffer[#buffer+1] = char(0xCB,  -- nan
                                 0xFF, 0xF8, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00)
    elseif mant == huge or expo > 0x400 then
        if sign == 0 then
            buffer[#buffer+1] = char(0xCB,      -- inf
                                     0x7F, 0xF0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00)
        else
            buffer[#buffer+1] = char(0xCB,      -- -inf
                                     0xFF, 0xF0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00)
        end
    elseif (mant == 0.0 and expo == 0) or expo < -0x3FE then
        buffer[#buffer+1] = char(0xCB,  -- zero
                                 sign, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00)
    else
        expo = expo + 0x3FE
        mant = floor((mant * 2.0 - 1.0) * ldexp(0.5, 53))
        buffer[#buffer+1] = char(0xCB,
                                 sign + floor(expo / 0x10),
                                 (expo % 0x10) * 0x10 + floor(mant / 0x1000000000000),
                                 floor(mant / 0x10000000000) % 0x100,
                                 floor(mant / 0x100000000) % 0x100,
                                 floor(mant / 0x1000000) % 0x100,
                                 floor(mant / 0x10000) % 0x100,
                                 floor(mant / 0x100) % 0x100,
                                 mant % 0x100)
    end
end

local set_number = function (number)
    if number == 'float' then
        packers['number'] = function (buffer, n)
            if floor(n) == n and n < maxinteger and n > mininteger then
                packers['integer'](buffer, n)
            else
                packers['float'](buffer, n)
            end
        end
    elseif number == 'double' then
        packers['number'] = function (buffer, n)
            if floor(n) == n and n < maxinteger and n > mininteger then
                packers['integer'](buffer, n)
            else
                packers['double'](buffer, n)
            end
        end
    else
        argerror('set_number', 1, "invalid option '" .. number .."'")
    end
end
m.set_number = set_number

for k = 0, 4 do
    local n = tointeger(2^k)
    local fixext = 0xD4 + k
    packers['fixext' .. tostring(n)] = function (buffer, tag, data)
        assert(#data == n, "bad length for fixext" .. tostring(n))
        buffer[#buffer+1] = char(fixext,
                                 tag < 0 and tag + 0x100 or tag)
        buffer[#buffer+1] = data
    end
end

packers['ext'] = function (buffer, tag, data)
    local n = #data
    if n <= 0xFF then
        buffer[#buffer+1] = char(0xC7,          -- ext8
                                 n,
                                 tag < 0 and tag + 0x100 or tag)
    elseif n <= 0xFFFF then
        buffer[#buffer+1] = char(0xC8,          -- ext16
                                 floor(n / 0x100),
                                 n % 0x100,
                                 tag < 0 and tag + 0x100 or tag)
    elseif n <= 4294967295.0 then
        buffer[#buffer+1] = char(0xC9,          -- ext&32
                                 floor(n / 0x1000000),
                                 floor(n / 0x10000) % 0x100,
                                 floor(n / 0x100) % 0x100,
                                 n % 0x100,
                                 tag < 0 and tag + 0x100 or tag)
    else
        error"overflow in pack 'ext'"
    end
    buffer[#buffer+1] = data
end

function m.pack (data)
    local buffer = {}
    packers[type(data)](buffer, data)
    return tconcat(buffer)
end


local unpackers         -- forward declaration

local function unpack_cursor (c)
    local s, i, j = c.s, c.i, c.j
    if i > j then
        c:underflow(i)
        s, i, j = c.s, c.i, c.j
    end
    local val = s:byte(i)
    c.i = i+1
    return unpackers[val](c, val)
end
m.unpack_cursor = unpack_cursor

local function unpack_str (c, n)
    local s, i, j = c.s, c.i, c.j
    local e = i+n-1
    if e > j or n < 0 then
        c:underflow(e)
        s, i, j = c.s, c.i, c.j
        e = i+n-1
    end
    c.i = i+n
    return s:sub(i, e)
end

local function unpack_array (c, n)
    local t = {}
    for i = 1, n do
        t[i] = unpack_cursor(c)
    end
    return t
end

local function unpack_map (c, n)
    local t = {}
    for i = 1, n do
        local k = unpack_cursor(c)
        local val = unpack_cursor(c)
        if k == nil or k ~= k then
            k = m.sentinel
        end
        if k ~= nil then
            t[k] = val
        end
    end
    return t
end

local function unpack_float (c)
    local s, i, j = c.s, c.i, c.j
    if i+3 > j then
        c:underflow(i+3)
        s, i, j = c.s, c.i, c.j
    end
    local b1, b2, b3, b4 = s:byte(i, i+3)
    local sign = b1 > 0x7F
    local expo = (b1 % 0x80) * 0x2 + floor(b2 / 0x80)
    local mant = ((b2 % 0x80) * 0x100 + b3) * 0x100 + b4
    if sign then
        sign = -1
    else
        sign = 1
    end
    local n
    if mant == 0 and expo == 0 then
        n = sign * 0.0
    elseif expo == 0xFF then
        if mant == 0 then
            n = sign * huge
        else
            n = 0.0/0.0
        end
    else
        n = sign * ldexp(1.0 + mant / 0x800000, expo - 0x7F)
    end
    c.i = i+4
    return n
end

local function unpack_double (c)
    local s, i, j = c.s, c.i, c.j
    if i+7 > j then
        c:underflow(i+7)
        s, i, j = c.s, c.i, c.j
    end
    local b1, b2, b3, b4, b5, b6, b7, b8 = s:byte(i, i+7)
    local sign = b1 > 0x7F
    local expo = (b1 % 0x80) * 0x10 + floor(b2 / 0x10)
    local mant = ((((((b2 % 0x10) * 0x100 + b3) * 0x100 + b4) * 0x100 + b5) * 0x100 + b6) * 0x100 + b7) * 0x100 + b8
    if sign then
        sign = -1
    else
        sign = 1
    end
    local n
    if mant == 0 and expo == 0 then
        n = sign * 0.0
    elseif expo == 0x7FF then
        if mant == 0 then
            n = sign * huge
        else
            n = 0.0/0.0
        end
    else
        n = sign * ldexp(1.0 + mant / 4503599627370496.0, expo - 0x3FF)
    end
    c.i = i+8
    return n
end

local function unpack_uint8 (c)
    local s, i, j = c.s, c.i, c.j
    if i > j then
        c:underflow(i)
        s, i, j = c.s, c.i, c.j
    end
    local b1 = s:byte(i)
    c.i = i+1
    return b1
end

local function unpack_uint16 (c)
    local s, i, j = c.s, c.i, c.j
    if i+1 > j then
        c:underflow(i+1)
        s, i, j = c.s, c.i, c.j
    end
    local b1, b2 = s:byte(i, i+1)
    c.i = i+2
    return b1 * 0x100 + b2
end

local function unpack_uint32 (c)
    local s, i, j = c.s, c.i, c.j
    if i+3 > j then
        c:underflow(i+3)
        s, i, j = c.s, c.i, c.j
    end
    local b1, b2, b3, b4 = s:byte(i, i+3)
    c.i = i+4
    return ((b1 * 0x100 + b2) * 0x100 + b3) * 0x100 + b4
end

local function unpack_uint64 (c)
    local s, i, j = c.s, c.i, c.j
    if i+7 > j then
        c:underflow(i+7)
        s, i, j = c.s, c.i, c.j
    end
    local b1, b2, b3, b4, b5, b6, b7, b8 = s:byte(i, i+7)
    c.i = i+8
    return ((((((b1 * 0x100 + b2) * 0x100 + b3) * 0x100 + b4) * 0x100 + b5) * 0x100 + b6) * 0x100 + b7) * 0x100 + b8
end

local function unpack_int8 (c)
    local s, i, j = c.s, c.i, c.j
    if i > j then
        c:underflow(i)
        s, i, j = c.s, c.i, c.j
    end
    local b1 = s:byte(i)
    c.i = i+1
    if b1 < 0x80 then
        return b1
    else
        return b1 - 0x100
    end
end

local function unpack_int16 (c)
    local s, i, j = c.s, c.i, c.j
    if i+1 > j then
        c:underflow(i+1)
        s, i, j = c.s, c.i, c.j
    end
    local b1, b2 = s:byte(i, i+1)
    c.i = i+2
    if b1 < 0x80 then
        return b1 * 0x100 + b2
    else
        return ((b1 - 0xFF) * 0x100 + (b2 - 0xFF)) - 1
    end
end

local function unpack_int32 (c)
    local s, i, j = c.s, c.i, c.j
    if i+3 > j then
        c:underflow(i+3)
        s, i, j = c.s, c.i, c.j
    end
    local b1, b2, b3, b4 = s:byte(i, i+3)
    c.i = i+4
    if b1 < 0x80 then
        return ((b1 * 0x100 + b2) * 0x100 + b3) * 0x100 + b4
    else
        return ((((b1 - 0xFF) * 0x100 + (b2 - 0xFF)) * 0x100 + (b3 - 0xFF)) * 0x100 + (b4 - 0xFF)) - 1
    end
end

local function unpack_int64 (c)
    local s, i, j = c.s, c.i, c.j
    if i+7 > j then
        c:underflow(i+7)
        s, i, j = c.s, c.i, c.j
    end
    local b1, b2, b3, b4, b5, b6, b7, b8 = s:byte(i, i+7)
    c.i = i+8
    if b1 < 0x80 then
        return ((((((b1 * 0x100 + b2) * 0x100 + b3) * 0x100 + b4) * 0x100 + b5) * 0x100 + b6) * 0x100 + b7) * 0x100 + b8
    else
        return ((((((((b1 - 0xFF) * 0x100 + (b2 - 0xFF)) * 0x100 + (b3 - 0xFF)) * 0x100 + (b4 - 0xFF)) * 0x100 + (b5 - 0xFF)) * 0x100 + (b6 - 0xFF)) * 0x100 + (b7 - 0xFF)) * 0x100 + (b8 - 0xFF)) - 1
    end
end

function m.build_ext (tag, data)
    return nil
end

local function unpack_ext (c, n, tag)
    local s, i, j = c.s, c.i, c.j
    local e = i+n-1
    if e > j or n < 0 then
        c:underflow(e)
        s, i, j = c.s, c.i, c.j
        e = i+n-1
    end
    c.i = i+n
    return m.build_ext(tag, s:sub(i, e))
end

unpackers = setmetatable({
    [0xC0] = function () return nil end,
    [0xC2] = function () return false end,
    [0xC3] = function () return true end,
    [0xC4] = function (c) return unpack_str(c, unpack_uint8(c)) end,    -- bin8
    [0xC5] = function (c) return unpack_str(c, unpack_uint16(c)) end,   -- bin16
    [0xC6] = function (c) return unpack_str(c, unpack_uint32(c)) end,   -- bin32
    [0xC7] = function (c) return unpack_ext(c, unpack_uint8(c), unpack_int8(c)) end,
    [0xC8] = function (c) return unpack_ext(c, unpack_uint16(c), unpack_int8(c)) end,
    [0xC9] = function (c) return unpack_ext(c, unpack_uint32(c), unpack_int8(c)) end,
    [0xCA] = unpack_float,
    [0xCB] = unpack_double,
    [0xCC] = unpack_uint8,
    [0xCD] = unpack_uint16,
    [0xCE] = unpack_uint32,
    [0xCF] = unpack_uint64,
    [0xD0] = unpack_int8,
    [0xD1] = unpack_int16,
    [0xD2] = unpack_int32,
    [0xD3] = unpack_int64,
    [0xD4] = function (c) return unpack_ext(c, 1, unpack_int8(c)) end,
    [0xD5] = function (c) return unpack_ext(c, 2, unpack_int8(c)) end,
    [0xD6] = function (c) return unpack_ext(c, 4, unpack_int8(c)) end,
    [0xD7] = function (c) return unpack_ext(c, 8, unpack_int8(c)) end,
    [0xD8] = function (c) return unpack_ext(c, 16, unpack_int8(c)) end,
    [0xD9] = function (c) return unpack_str(c, unpack_uint8(c)) end,
    [0xDA] = function (c) return unpack_str(c, unpack_uint16(c)) end,
    [0xDB] = function (c) return unpack_str(c, unpack_uint32(c)) end,
    [0xDC] = function (c) return unpack_array(c, unpack_uint16(c)) end,
    [0xDD] = function (c) return unpack_array(c, unpack_uint32(c)) end,
    [0xDE] = function (c) return unpack_map(c, unpack_uint16(c)) end,
    [0xDF] = function (c) return unpack_map(c, unpack_uint32(c)) end,
}, {
    __index = function (t, k)
        if k < 0xC0 then
            if k < 0x80 then
                return function (c, val) return val end
            elseif k < 0x90 then
                return function (c, val) return unpack_map(c, val % 0x10) end
            elseif k < 0xA0 then
                return function (c, val) return unpack_array(c, val % 0x10) end
            else
                return function (c, val) return unpack_str(c, val % 0x20) end
            end
        elseif k > 0xDF then
            return function (c, val) return val - 0x100 end
        else
            return function () error("unpack '" .. format('%#x', k) .. "' is unimplemented") end
        end
    end
})

local function cursor_string (str)
    return {
        s = str,
        i = 1,
        j = #str,
        underflow = function ()
                        error "missing bytes"
                    end,
    }
end

local function cursor_loader (ld)
    return {
        s = '',
        i = 1,
        j = 0,
        underflow = function (self, e)
                        self.s = self.s:sub(self.i)
                        e = e - self.i + 1
                        self.i = 1
                        self.j = 0
                        while e > self.j do
                            local chunk = ld()
                            if not chunk then
                                error "missing bytes"
                            end
                            self.s = self.s .. chunk
                            self.j = #self.s
                        end
                    end,
    }
end

function m.unpack (s)
    checktype('unpack', 1, s, 'string')
    local cursor = cursor_string(s)
    local data = unpack_cursor(cursor)
    if cursor.i <= cursor.j then
        error "extra bytes"
    end
    return data
end

function m.unpacker (src)
    if type(src) == 'string' then
        local cursor = cursor_string(src)
        return function ()
            if cursor.i <= cursor.j then
                return cursor.i, unpack_cursor(cursor)
            end
        end
    elseif type(src) == 'function' then
        local cursor = cursor_loader(src)
        return function ()
            if cursor.i > cursor.j then
                pcall(cursor.underflow, cursor, cursor.i)
            end
            if cursor.i <= cursor.j then
                return true, unpack_cursor(cursor)
            end
        end
    else
        argerror('unpacker', 1, "string or function expected, got " .. type(src))
    end
end

set_string'string_compat'
set_integer'unsigned'
if SIZEOF_NUMBER == 4 then
    maxinteger = 16777215
    mininteger = -maxinteger
    m.small_lua = true
    unpackers[0xCB] = nil       -- double
    unpackers[0xCF] = nil       -- uint64
    unpackers[0xD3] = nil       -- int64
    set_number'float'
else
    maxinteger = 9007199254740991
    mininteger = -maxinteger
    set_number'double'
    if SIZEOF_NUMBER > 8 then
        m.long_double = true
    end
end
set_array'without_hole'

m._VERSION = '0.5.2'
m._DESCRIPTION = "lua-MessagePack : a pure Lua implementation"
m._COPYRIGHT = "Copyright (c) 2012-2019 Francois Perrad"
return m
--
-- This library is licensed under the terms of the MIT/X11 license,
-- like Lua itself.
--