convert between microsoft and oracle guids, reversing first-half endian-ness (2010)

guidconvert.py

# 10/25/2010
import sys, struct
  
def change(l):
  return ''.join( ['{0}{1}'.format(a,b) for a,b in zip(l,l[1:])[::2][::-1]] )

def convert(guidstring):
  ms = guidstring.replace('-','').replace('{','').replace('}','').upper()
  return change(ms[0:8]) + change(ms[8:12]) + change(ms[12:16]) + ms[16:]    
    
def convert2(guidstring):
  guidstring = guidstring.replace('-','').replace('{','').replace('}','')
  assert(len(guidstring)==32)
  a,b,c,d = guidstring[0:8], guidstring[8:12], guidstring[12:16], guidstring[16:]
  a = int(a,16)
  b = int(b,16)
  c = int(c,16)
  x = struct.pack('<LHH',a,b,c).encode('hex')
  
  return (x+d).upper()

if __name__=='__main__':
  ms = '81248ffb-0528-4bc9-8bc2-e559139110e7'
  oracle = 'FB8F24812805C94B8BC2E559139110E7' 
  x = convert(ms)
  assert x == oracle
  x2 = convert2(ms)
  assert x2 == oracle
  
  if len(sys.argv)!=2:
    print 'specify a guid as the one and only argument'
    
  # todo: put it in the clipboard...
  print convert(sys.argv[1])