
todo: 

- Make a QUICK mode. 
    use the iteration number as a floating point number. Say 4 bits 
    mantissa, rest is exponent. 
          1  2  3 4 5 6 7 8 9 10 11 12 13 14 15 // special case?
      16 17 18 ...                           31 // exp is excess 1 
      32 34 36 ... 
      64 68 72 ... 

(we will hit the end of the disk and determine  its size with 4 bits 
accuracy within a 16 * log2 (sizeofdisk in blocks) )


- Make the data generation quicker. 
  - prepare a buffer of say 1Mb of data, and then xor the current 
    blockno with the data while writing it. 

- ...???  




