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crc32 with RtlComputeCrc32 (ntdll.dll)
Posted: Thu Mar 15, 2007 10:59 am
by bingo
Code: Select all
Import "ntdll.lib"
RtlComputeCrc32(dwInitial.l,pData.l,iLen.l)
EndImport
buffer.s = "1234567" + Space(512) + "1234567"
lenbuffer.l = Len(buffer)
counter.l = 999999
For s=1 To 3
timer = GetTickCount_()
For i=1 To counter
CRC32Fingerprint(@buffer,lenbuffer)
Next
Debug "pb... " + Str(GetTickCount_() - timer)
Debug Hex(CRC32Fingerprint(@buffer,lenbuffer))
timer = GetTickCount_()
For i=1 To counter
RtlComputeCrc32(0,@buffer,lenbuffer)
Next
Debug "api..." + Str(GetTickCount_() - timer)
Debug Hex(RtlComputeCrc32(0,@buffer,lenbuffer))
Next
pb... 1860
D359D67E
api...1484
D359D67E
pb... 1844
D359D67E
api...1484
D359D67E
pb... 1828
D359D67E
api...1485
D359D67E
my vista pc:
pb... 2247
D359D67E
api...1903
D359D67E
pb... 2199
D359D67E
api...1857
D359D67E
pb... 2215
D359D67E
api...1872
D359D67E
RtlComputeCrc32 15-20% faster as CRC32Fingerprint ?
Posted: Thu Mar 15, 2007 1:20 pm
by SFSxOI
hmmm...nice idea but doesn't work here on my Vista Pc. Unresolved External Symbol - RtlComputeCrc32.
Posted: Thu Mar 15, 2007 1:43 pm
by Rescator
That function is not in the PSDK, also ntdll is not documented "officially".
I would not rely on anything in it as it could change from Windows release/build to the next.
PS! The reason it is faster is that it most likely use file memory mapping,
not to mention being on a kernel level I think?
Posted: Thu Mar 15, 2007 1:47 pm
by bingo
RtlComputeCrc32 is not in pb-standard ntdll.lib ! create a new or use
http://kyf.net/tmp/ntdll.zip and it works ...
Posted: Mon Mar 19, 2007 1:56 pm
by okasvi
or just use LoadLibrary/GetProcAddress...
Posted: Mon Mar 19, 2007 2:33 pm
by Rings
Did not work with w2k, works with win-xp
here is a more friendly version:
Code: Select all
LibName.s="ntdll.dll"
FuncName.s="RtlComputeCrc32"
Prototype PrototypeRtlComputeCrc32(dwInitial.l,pData.l,iLen.l)
LibNR=LoadLibrary_(Libname)
If LibNR
FuncPointer=GetProcAddress_(LibNR,FuncName)
If FuncPointer
RtlComputeCrc32.PrototypeRtlComputeCrc32=FuncPointer
buffer.s = "1234567" + Space(512) + "1234567"
lenbuffer.l = Len(buffer)
counter.l = 999999
For s=1 To 3
timer = GetTickCount_()
For i=1 To counter
CRC32Fingerprint(@buffer,lenbuffer)
Next
Debug "pb... " + Str(GetTickCount_() - timer)
Debug Hex(CRC32Fingerprint(@buffer,lenbuffer))
timer = GetTickCount_()
For i=1 To counter
RtlComputeCrc32(0,@buffer,lenbuffer)
Next
Debug "api..." + Str(GetTickCount_() - timer)
Debug Hex(RtlComputeCrc32(0,@buffer,lenbuffer))
Next
Else
Debug "Cannot find entrypoint for " + Funcname
EndIf
FreeLibrary_(LibNR)
Else
Debug "Cannot open library " + Libname
EndIf
Posted: Mon Mar 19, 2007 3:02 pm
by blueznl
Highly distracting signature, Rings...
Posted: Fri Mar 23, 2007 9:44 am
by Seldon
Hi ! What are the specs for the Vista PC ? I hope it is slower than the one with XP because of a slower CPU and not for the OS.