Lua module for CRC-32 calculation implemented in C.

Tested with Lua 5.1, 5.2 and 5.3.

Also included is a pure Lua implementation of the same API, using https://github.com/davidm/lua-digest-crc32lua.

Module API

local crc32 = require 'crc32'

• crc32.crc32 = function (crc_in, data)
  • crc_in is input CRC. It can be either a Lua number, or a string. If string is used, it should be 4 bytes in big endian order. If string shorter than 4 bytes, then CRC is left padded with zeros.
  • data is the input data to apply to CRC, as a Lua string.
  • returns updated CRC. If crc_in is number, then returns number. If crc_in is string, then return as string, 4 bytes in big endian order.
• crc32.newcrc32 = function ()
  • returns a stateful CRC-32 calculator object (userdata). It is useful for streaming CRC calculation, as it keep the current CRC as a native uint32_t between calls, reducing conversion overhead.
• crc32.version = string

crc32.newcrc32 API

local c = crc32.newcrc32()

• c.update = function (self, data)
  • data is the input data to apply to CRC, as a Lua string.
  • returns self
• c.reset = function (self)
  • Resets the current CRC to 0.
  • returns self
• c.tonumber = function (self)
  • returns current CRC as Lua number
• c.tostring = function (self)
  • returns current CRC as string, 4 bytes in big endian order.
• c.tohex = function (self)
  • returns current CRC as 8 character hex encoded string.