Adler-32 (RFC 1950): the zlib-stream trailer checksum. Two 16-bit rolling sums modulo 65521, combined as (b shl 16) or a. Faster but weaker than CRC-32.
(b shl 16) or a
Check value: ADLER32("123456789") == 0x091E01DE.
ADLER32("123456789") == 0x091E01DE
Reset to the initial state so the instance can be reused.
Feed a slice of bytes into the running checksum.
Current checksum value (low bits of the Long).