This response was originally tacked onto the end of another node but I decided to promote it to a new response just so it'd be more visible.

I should note - the whole point of this exercise was to find out whether things like the following code fragment would produce similar results on differing endian machines. I didn't know whether reading from B's FLAGS attribute was like using unpack 'L', unpack 'P4', pack 'L', 12+\$pad_str to read directly from memory. I'd expect the direct memory read to non-portable for a couple of reasons. I just didn't know what would happen if I read the value properly. It appears to come out alright which is just great.

As for why I'm doing something so obscure - just for obfus. It'd be no fun to write more poetry and have it fail or not work because of differing endian-ness. Thanks for playing all!

 require B;
 my $pad_int = 1;
 $o = B::svref_2object( \ $pad_int );
 $flags = $o -> FLAGS;
 $type  = $flags &   0xff;
 $flags = $flags & ~ 0xff;

 $, = " ";
 print "\$pad_int == $pad_int (",type($type),flags($flags),")";
 # Prints "$pad_int == 1 ( IV PADBUSY PADMY IOK pIOK OK )"

 sub type { ('NULL', 'IV'  , 'NV'  , 'RV'  , 'PV'  ,
             'PVIV', 'PVNV', 'PVMG', 'PVBM', 'PVLV',
             'PVAV', 'PVHV', 'PVCV', 'PVGV', 'PVFM',
             'PVIO')[ $_[0] ] }

 # I included these routines just for fun - I already had it written d
+own
 # and just transcribed it. So this is at least a sniff at the fun thi
+ngs
 # you can check if you can actually do this reliably - which it appea
+rs
 # you can.
 sub flags {
     my @flags = ();
     my $flags = shift;
     
     # Mask off the TYPE portion
     $flags &= ~ 0xff;

     push @flags, 'PADBUSY'   if $flags & 0x100;
     # reserved for tmp or my already

     push @flags, 'PADTMP'    if $flags & 0x200;
     # in use as tmp

     push @flags, 'PADMY'     if $flags & 0x400;
     # in use as "my" variable

     push @flags, 'TEMP'      if $flags & 0x800;
     # string is stealable?

     push @flags, 'OBJECT'    if $flags & 0x1000;
     # is "blessed"

     push @flags, 'GMG'       if $flags & 0x2000;
     # has magical get method

     push @flags, 'SMG'       if $flags & 0x4000;
     # has magical set method

     push @flags, 'RMG'       if $flags & 0x8000;
     # has random magical methods

     push @flags, 'IOK'       if $flags & 0x10000;
     # has valid public integer value

     push @flags, 'NOK'       if $flags & 0x20000;
     # has valid public numeric value

     push @flags, 'POK'       if $flags & 0x40000;
     # has valid pointer value

     push @flags, 'ROK'       if $flags & 0x80000;
     # has a valid reference pointer

     push @flags, 'FAKE'      if $flags & 0x100000;
     # glob or lexical is just a copy

     push @flags, 'OOK'       if $flags & 0x200000;
     # has valid offset value

     push @flags, 'BREAK'     if $flags & 0x400000;
     # refcnt is artificially low

     push @flags, 'READONLY'  if $flags & 0x800000;
     # may not be modified

     push @flags, 'pIOK'      if $flags & 0x1000000;
     # has valid non-public integer value

     push @flags, 'pNOK'      if $flags & 0x2000000;
     # has valid non-public numeric value

     push @flags, 'pPOK'      if $flags & 0x4000000;
     # has valid non-public pointer value

     push @flags, 'SCREAM'    if $flags & 0x8000000;
     # has been studied?

     push @flags, 'UTF8'      if $flags & 0x20000000;
     # SvPVX is UTF-8 encoded

     push @flags, 'THINKFIRST' if $flags & (0x00800000 |
                                            0x00080000 |
                                            0x00100000 |
                                            0x20000000);
     # READONLY, ROK, FAKE or UTF-8

     push @flags, 'OK'        if $flags & (0x0010000 |
                                           0x0020000 |
                                           0x0040000 |
                                           0x0080000 |
                                           0x1000000 |
                                           0x2000000 |
                                           0x4000000);
     # IOK, NOK, POK, ROK, pIOK, pNOK or pPOK

     push @flags, 'AMAGIC'    if $flags & 0x10000000;
     # has magical overloaded methods

     # Some private flags

     # SVpad_OUR may be set on SVt_PV{NV,MG,GV} types
     push @flags, 'OUR'       if $flags & 0x80000000;
     # pad name is "our" instead of "my"

     push @flags, 'IVisUV'    if $flags & 0x80000000;
     # use XPVUV instead of XPVIV

     push @flags, 'COMPILED'  if $flags & 0x80000000;
     # FORMLINE is compiled

     push @flags, 'VALID'     if $flags & 0x80000000;
     push @flags, 'TAIL'      if $flags & 0x40000000;

     push @flags, 'EVAL'      if $flags & 0x40000000;
     # Replacemenet part of S///e

     push @flags, 'SHAREKEYS' if $flags & 0x20000000;
     # keys live on shared string table

     push @flags, 'LAZYDEL'   if $flags & 0x40000000;
     # entry in xhv_eiter must be deleted

     push @flags, 'WEAKREF'   if $flags & 0x80000000; # Weak reference

     return @flags
 }
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