#  Convert Linux (little-endian) 32-bit Storable format to 64-bit.
#  Doesn't yet handle a few Storable types.
#  Tweak xxx lines for your architectures.
#
#  Greg Ubben, 18 June 2012
#
sub fix_frozen {
    local $data = shift;
    local $pos  = 15;            # xxx length of new header below
    local $lev  = 0;

    # version, byte order, sizes (int, long, ptr, double)
    $data =~ s{^\x04\x07\x041234\x04\x04\x04\x08}               # xxx
              {\x04\x08\x0812345678\x04\x08\x08\x08}            # xxx
                        or die "not a 32-bit x86 Storable";
    object();
    die "length error"  if $pos != length( $data );
    return $data;
}

sub object {
    local $_ = chr( 64 + byte() );
    local $lev = $lev + 1;
    #printf "%8d %*s\n", $pos, $lev * 2, $_;     # DEBUG

    return                          if /E|N|O|P/;
    return $pos += 1                if /H/;
    return $pos += 4                if /@|I/;
    return $pos += byte()           if /J|W/;
    return $pos += len()            if /A|X/;
    return object()                 if /D|T|K|L|M/;
    return object( $pos += vnum())  if /Q/;
    return object( vnum() )         if /R/;
    return fix_integer()            if /F/;
    return fix_double()             if /G/;

    if (/B|C|Y/) {            # array or hash
        my $n = len();
        $pos++  if /Y/;
        while ($n--) {
            object();
            $pos++         if /Y/;
            $pos += len()  if not /B/;
        }
        return;
    }
    die sprintf "Type %d unknown at pos %d\n", ord()-64, $pos-1;
}

sub byte {
    return ord( substr( $data, $pos++, 1 ));
}

sub len {
    my $len = unpack 'L', substr( $data, $pos, 4 );   # xxx 'V' or 'N' ?
    $pos += 4;
    return $len;
}

sub vnum {
    my $n = byte();
    return ($n < 128 ? $n : len());
}

sub fix_integer {       # xxx
    my $n = unpack 'l', substr( $data, $pos, 4 );   # was 32-bit
    substr( $data, $pos, 4 ) = pack 'q', $n;        # now 64-bit
    $pos += 8;
}

sub fix_double {        # xxx
    $pos += 8;          # assume same floating-point format
}