C:\test>p1
use Devel::Peek;;

sub toPascal{ return chr( length $_[0] ) . $_[0] };;

Dump toPascal( 'x' x $_ ) for 255, 256;;
SV = PV(0x28d280) at 0x3c599e0
  REFCNT = 1
  FLAGS = (TEMP,POK,pPOK)
  PV = 0x3cb28f8 "\377xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
  CUR = 256
  LEN = 264

SV = PV(0x3c3aa30) at 0x3c599c8
  REFCNT = 1
  FLAGS = (TEMP,POK,pPOK,UTF8)
  PV = 0x3cb2a28 "\304\200xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"]
  CUR = 258
  LEN = 264