How is 252.0 = 406F 8000 ?

[NotLKH]

I'm not sure how to approach this, but here's my problem.

I'm trying to hash some job administration data files, made on a UNIX platform, with either some C flavor, or JAVA program.

These files consist of properties of print jobs, and I've got 80 % of them defined. Now I'm working on an apparent single precision data type, but in a half hour I've gotten relatively nowhere. I figure the best method would be to 2's complement the values and analyze the relationship between the unaltered sequence, the 2's complement sequence, and the VB Single byte sequence, but I won't be able to get to this for anther day or two.

So, perhaps one of the Geni here might have some quick insight.

Here's some values:



Can anyone explain a way for mapping the extracted data back to its decimal equivalent, or suggest a good way to google for a way?

-Lou

[kedaman]

try IEEE 754 standard

[NotLKH]

Great!
You Got it in 1!

Turns out to be a 64 bit Double precision version.
Also found a cool Macro Page to convert from the Hex Notation to Decimal.

http://babbage.cs.qc.edu/courses/cs3...-754hex64.html

-Thanks
-Lou

[NotLKH]

from http://www.psc.edu/general/software/...ieee/ieee.html
Double Precision
The IEEE double precision floating point standard representation requires a 64 bit word, which may be represented as numbered from 0 to 63, left to right. The first bit is the sign bit, S, the next eleven bits are the exponent bits, 'E', and the final 52 bits are the fraction 'F':

S EEEEEEEEEEE FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
0 1________11 12________________________________________________63

The value V represented by the word may be determined as follows:


If E=2047 and F is nonzero, then V=NaN ("Not a number")
If E=2047 and F is zero and S is 1, then V=-Infinity
If E=2047 and F is zero and S is 0, then V=Infinity
If 0<E<2047 then V=(-1)**S * 2 ** (E-1023) * (1.F) where "1.F" is intended to represent the binary number created by prefixing F with an implicit leading 1 and a binary point.
If E=0 and F is nonzero, then V=(-1)**S * 2 ** (-1022) * (0.F) These are "unnormalized" values.
If E=0 and F is zero and S is 1, then V=-0
If E=0 and F is zero and S is 0, then V=0