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RE: Adding 2 + 2

by and (Pilgrim)
on Sep 12, 2000 at 01:11 UTC ( #31989=note: print w/replies, xml ) Need Help??


in reply to Adding 2 + 2

One lunch I was complaining about how or and die get all of the good work and some of my bit-twiddling coworkers said that they hardly ever have anything to do. We went out for drinks later and they tried to teach me what they know about integers. I find it very hard to understand but I think I figured out how to do 2+2.

sub add { my( $a, $b, $bit, $cary, $sum ) = ( @{$_[0]}, 1, 0, 0 ); $sum |= $bit if 1 & ( $a ^ $b ^ $cary ); $cary = 1 & ( $a & $b | ( $cary & ($a|$b) ) ); return $a | $b ? [$a>>1,$b>>1,$bit<<1,$cary,$sum] : $sum; } my @args = map {0+$_} (@ARGV,2,2)[0,1]; my $acc = add( [@args] ); $acc = add($acc) while ref $acc; print "add[@args] = $acc\n";