Thanks folks!

I had forgotten about vec :-(.

I need the least significant bit in the rightmost position.

So what I use now is: 

$binary = chr(0) x 8;
vec($binary, $_, 1) = 1 for (SOME, CONSTANTS);
$binary = reverse $binary;

[download]

In reply to Re: how to set bits in an arbitrary length string by busunsl
in thread how to set bits in an arbitrary length string by busunsl

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