Sha256: c76e2607032d2e1cf0c66e51fce2e6f54b76daaac7a84451d281915753eb87e7
Contents?: true
Size: 1.28 KB
Versions: 14
Compression:
Stored size: 1.28 KB
Contents
# A simple stateful class for keeping track of a CRC32 value through multiple writes
class ZipTricks::StreamCRC32
# Compute a CRC32 value from an IO object. The object should respond to `read` and `eof?`
#
# @param io[IO] the IO to read the data from
# @return [Fixnum] the computed CRC32 value
def self.from_io(io)
crc = new
crc << io.read(1024 * 512) until io.eof?
crc.to_i
end
# Creates a new streaming CRC32 calculator
def initialize
@crc = Zlib.crc32('')
end
# Append data to the CRC32. Updates the contained CRC32 value in place.
#
# @param blob[String] the string to compute the CRC32 from
# @return [self]
def <<(blob)
@crc = Zlib.crc32_combine(@crc, Zlib.crc32(blob), blob.bytesize)
self
end
# Returns the CRC32 value computed so far
#
# @return [Fixnum] the updated CRC32 value for all the blobs so far
def to_i
@crc
end
# Appends a known CRC32 value to the current one, and combines the
# contained CRC32 value in-place.
#
# @param crc32[Fixnum] the CRC32 value to append
# @param blob_size[Fixnum] the size of the daata the `crc32` is computed from
# @return [Fixnum] the updated CRC32 value for all the blobs so far
def append(crc32, blob_size)
@crc = Zlib.crc32_combine(@crc, crc32, blob_size)
end
end
Version data entries
14 entries across 14 versions & 1 rubygems