The (canonical) way to perform sign extension is via xor and subtract: sub sxtb { (shift ^ 0x80) - 0x80 }

For CRC digest, I'd consider using a specific module, but in a pinch, the following should work: 

sub sxt { ((0xffffffff & shift) ^ 0x80000000) - 0x80000000 }
...

       $crc = ($crc >> 8) ^ ...
       $crc = sxt $crc;
...

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In reply to Re: reproducing javascripts >> operator by oiskuu
in thread reproducing javascripts >> operator by mje

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