Some reading which may help:

• http://perldoc.perl.org/perlop.html#Shift-Operators Note that both << and >> in Perl are implemented directly using << and >> in C. If use integer (see Integer Arithmetic) is in force then signed C integers are used, else unsigned C integers are used. Either way, the implementation isn't going to generate results larger than the size of the integer type Perl was built with (32 bits or 64 bits).
• http://shop.oreilly.com/product/9780596004927.do See Chapter 3.9.
• http://stackoverflow.com/questions/4339259/perl-shift-bit-problem A related question at Stack Overflow.
• http://www.perlmonks.org/bare/?node_id=402228 ...and, of course, right here in the Monastery.

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