It wouldn't be necessary to use substr to extract a value in a buffer full of packed shorts or longs. The '@' code can be used to move to a specific offset in the buffer before extracting.

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print map { my ($m)=1<<hex($_)&11?' ':'';
$m.=substr('AHJPacehklnorstu',hex($_),1) }
split //,'2fde0abe76c36c914586c';
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