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Wireshark-dev: [Wireshark-dev] ask about wireshark's lua dissectors

From: Javier Aguinaga <el.tio.pastafrola@xxxxxxxxx>
Date: Mon, 25 Nov 2013 13:28:18 -0200
Hi guys, i have been working in a lua dissector for a private protocol
 
the protocol in the dump has a section with the return of the window's API GetSystemTimeAsFileTime in the form
 
6a 0e 2e c2 0c e2 ce 01
 
this is the value of the structure FILETIME
 
in the serve is decoded with
 
import datetime
datetime.datetime.fromtimestamp((0xc22e0e6a + (0x01cee20c << 32)) / 10000000.0 - 11644473600)
 
the hex number 0xc2220e6a is the representation of  "6a 0e 2e c2" and 0x01cee20c is "0c e2 ce 01"
 
i tried to decoded with a lua script:
 
timelow = buffer(0,4):le_uint()
timehihg = buffer(4,4):le_uint()
 
the numbers are correct (i saw it with message())
 
but i have problems with:
 
bit.lshift(timehigh,32)
 
when i did message(bit.lshift(timehigh, 32))
 
i got -1037169046
 
i think that the problem has two reasons:
* timehigh isn't a unsigned value
* or timehigh is a 32 bits integer without the possility to extend to 64 bits
 
i wanna get:
 
>>> "%d" % (0xc22e0e6a << 32)
13992136940716032000
 
is there any way?
 
p.s.: i also tried to get the complete number of 64 bits with le_uint64() but doesn't work
 
thanks for advance
 
Regards