Just one mistake: your poly is reflected. Try 

my $ctx = Digest::CRC->new(width=>16, poly=>0x1021, init=>0xffff, refi
+n=>1, refout=>1);

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In reply to Re: Using Digest::CRC to find CRC16 checksum by Anonymous Monk
in thread Using Digest::CRC to find CRC16 checksum by mldvx4

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