comment on

You should be using binmode on your input handle.
($check_value & 0x7fffffff) << 1
might be safer (more portable) than
($check_value << 1) & 0xffffffff

The following is faster (but nowhere near as fast as C would be):

$check_value ^= unpack('L', $_);
$check_value = ( ($check_value & 0x7fffffff) << 1 )
             | ( $check_value >> 31 );
[download]

Using C doesn't require shelling out. perlxstut or Inline::C will allow you to access C code from perl.

In reply to Re: Improving performance of checksum calculation by ikegami
in thread Improving performance of checksum calculation by Crackers2

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