use POSIX qw( ceil );

my $to_return = $bytes_out-$bytes_in;
my $to_read   = ceil($to_return/$bytes)*$bytes;

seek($fh, $bytes_in, SEEK_SET);
read($fh, my $buffer, $to_return);
seek($fh, $bytes_in+$to_read, SEEK_SET);
return $buffer;
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