Does any one recognize this binary data storage format

[Bengt Richter]

On Tue, 09 Aug 2005 21:50:06 -0000, Grant Edwards <grante at visi.com> wrote:

>On 2005-08-09, Scott David Daniels <Scott.Daniels at Acm.Org> wrote:
>> Grant Edwards wrote:
>>>>Ex #1)   333-3333
>>>>Hex On disk: 00 00 00 80 6a 6e 49 41
>>>>
>>>>Ex #2) 666-6666
>>>>Hex On disk: 00 00 00 80 6a 6e 59 41
>>> 
>>> So there's only a 1-bit different between the on-disk
>>> representation of 333-3333 and 666-6666.
>>> 
>>> That sounds pretty unlikely.  Are you 100% sure you're looking
>>> at the correct bytes?
>>
>> Perhaps the one bit is an exponent -- some kind of floating point
>> based format?  That matches the doubling of all digits.
>
>That would just be sick.  I can't imagine anybody on an 8-bit
>CPU using FP for a phone number.
>
>-- 
>Grant
>
 >>> def double_binary_lehex_to_double(dhex):
 ...     "convert little-endian hex of ieee double binary to double"
 ...     assert len(dhex)==16, (
 ...         "hex of double in binary must be 8 bytes (hex pairs in little-endian order")
 ...     dhex = ''.join(reversed([dhex[i:i+2] for i in xrange(0,16,2)]))
 ...     m = int(dhex, 16)
 ...     x = ((m>>52)&0x7ff) - 0x3ff - 52
 ...     s = (m>>63)&0x1
 ...     f = (m & ((1<<52)-1))|((m and 1 or 0)<<52)
 ...     return (1.0,-1.0)[s]*f*2.0**x
 ...
 >>> double_binary_lehex_to_double('000000806a6e4941')
 3333333.0
 >>> double_binary_lehex_to_double('000000806a6e5941')
 6666666.0
 >>> double_binary_lehex_to_double('0000108777F9Fc41')
 7777777777.0

;-)

Regards,
Bengt Richter