Adler32.py

mcandre (Andrew Pennebaker) — Wed, 25 Oct 2006 07:06:08 GMT



__author__="Andrew Pennebaker (andrew.pennebaker@gmail.com)"

__date__="21 Dec 2005 - 17 Jul 2006"

__copyright__="Copyright 2006 Andrew Pennebaker"

__license__="GPL"

__version__="0.3"

__URL__="http://snippets.dzone.com/posts/show/2889"



import HashFunction



class Adler32(HashFunction.HashFunction):

	BLOCK_SIZE=1

	DIGEST_SIZE=2



	INIT=0x0001

	SUM_REQ="Sum >= 0"



	BASE=65521



	TEST_DATA="abc"

	TEST_HASH=0x24d0127



	def __init__(self, sum=0x0001):

		self.sum=sum



	def sumValid(self, sum):

		return sum>=0



	def _update(self, b):

		s1=self.sum&0xffff

		s2=(self.sum>>16)&0xffff



		s1=(s1+(b&0xff))%self.BASE

		s2=(s1+s2)%self.BASE



		self.sum=(s2<<16)|s1



	def digest(self):

		return self.sum



	def formatDigest(self):

		return "%02x" % (self.digest())



	def unformatDigest(self, hash):

		return int(hash, 16)



if __name__=="__main__":

	HashFunction.main(Adler32, "Adler32.py")

DZone Snippets: Adler32 code

Adler32.py