Lua, dealing with non-ascii byte streams, byteorder change

Question

Need to encode & decode byte-stream (containing non-ascii characters possibly), from/into uint16, uint32, uint64 (their typical C/C++ meaning), taking care of endianness

Answer 1

my suggestion for an "Int16ToByte"-function without checking of parameters:

function Int16ToBytes(num, endian)
  if num < 0 then 
      num = num & 0xFFFF
  end

  highByte = (num & 0xFF00) >> 8
  lowByte  = num & 0xFF

  if endian == "little" then
      lowByte, highByte = highByte, lowByte
  end

  return string.char(highByte,lowByte)
end