Does any one recognize this binary data storage format

[geskerrett]

Thanks so much for this. It is exactly what I was looking for.

If I am simply reading the bytes from disk, would I still need to
convert the these values HEX characters first with Hexlify, or is there
a more direct route ?
ie. convert them to the double float directly from the byte values ?

 

[Bengt Richter]

Thanks so much for this. It is exactly what I was looking for.

If I am simply reading the bytes from disk, would I still need to
convert the these values HEX characters first with Hexlify, or is there
a more direct route ?
ie. convert them to the double float directly from the byte values ?

Yes. Use struct.unpack ;-)

BTW, my second post was doing ''.join(chr(int(h[i:i+2],16)) for i in xrange(0,16,2))
to undo the hexlify you had done (I'd forgotten that there's a binascii.unhexlify ;-)

Regards,
Bengt Richter

 

[Grant Edwards]

That would just be sick. I can't imagine anybody on an 8-bit
CPU using FP for a phone number.

... "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)*f*2.0**x
...7777777777.0

;-)

Damn.

I still say that's just plain sick.

 

[Grant Edwards]

Well done, Scott & Bengt!!
I've just verified that this works with all 12 corrected examples posted
by the OP.

Grant, MS-DOS implies 16 bits at least;

You're right. For some reason I was thinking you had said CP/M.

and yes there was an FPU (the 8087).

I never met an MS-DOS box that had an 8087 (though I did write
firmware for an 8086+8087 fire-control computer once upon a
time).

And yes there are a lot of sick people who store things as
numbers (whether integer or FP) when the only arithmetic
operations that can be applied to them stuff them up mightily
(like losing leading zeroes off post-codes, having NEGATIVE
tax file numbers, etc) and it's still happening on the best
OSes and 64-bit CPUS. Welcome to the real world

I've been in the real world for a long time, and the dumb
things people (including myself) do still surprise me.

 

[geskerrett]

Thanks again.
Sort of thru me off, but is working perfectly now.

 

[Calvin Spealman]

You're right. For some reason I was thinking you had said CP/M.


I never met an MS-DOS box that had an 8087 (though I did write
firmware for an 8086+8087 fire-control computer once upon a
time).


I've been in the real world for a long time, and the dumb
things people (including myself) do still surprise me.

Original Poster should send this off to thedailywtf.com

 

[Christopher Subich]

Original Poster should send this off to thedailywtf.com

I absolutely agree. This is a terrible programming practice.

 

[Christos Georgiou]

BTW, my second post was doing ''.join(chr(int(h[i:i+2],16)) for i in xrange(0,16,2))
to undo the hexlify you had done (I'd forgotten that there's a binascii.unhexlify ;-)

And there's also str.decode('hex'), at least after 2.3 .