Untitled

use strict;

my %PREFIX = (
  kilo => 1000,
  mega => 1000**2,
  giga => 1000**3,
  tera => 1000**4,

  kibi => 1024,
  mebi => 1024**2,
  gibi => 1024**3,
  tebi => 1024**4,
);

sub convert_hash_bytes {
  my ($prefix, $bits_or_bytes, $hashref) = @_;

  my $div = 1;
  if (defined $prefix) {
    die "unknown prefix $prefix" unless $div = $PREFIX{ $prefix };
  }

  die "second arg to convert_hash_bytes must be bits or bytes"
    unless $bits_or_bytes =~ /\A(?:bits|bytes)\z/;

  my $mul = $bits_or_bytes eq 'bits' ? 8 : 1;

  return if $mul == 1 and $div == 1;

  for my $key (grep { /_bytes$/ } keys %$hashref) {
    my $value = delete $hashref->{ $key };
    $hashref->{ $key } = int($value * $mul / $div);
  }

  return;
}


my $hashref = {
  foo => 10,
  bar => 20,
  ugga_bytes => 3810123192,
  ooga_bytes => 38291,
};

use Data::Dumper;
convert_hash_bytes(mebi => bytes => $hashref);
print Dumper($hashref);