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September 2004
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2004.09.17 15:06 "Re: BigTIFF Tag Value Count issue", by Bob Friesenhahn
On Fri, 17 Sep 2004, Joris wrote: > > But I wish you would draw conclusions, as, to me, you seem to be stepping on > your own point. If misaligned data can cause such disasters, and you're memory > mapping the file, you'll have to design your code to check correct alignment > anyway, and be prepared to copy the structures if needed to properly aligned > locations, since we can't trust everyone to align the IFD structure as we lay it > out in the BigTIFF spec. If all this code logic has to be built anyway, does > this not make designing aligment in the spec less important, and is this not > another argument pro regular IO instead of memory mapping for this kind of codec > application? I certainly agree that if other factors make memory alignment impossible to assure, then it is not worth agonizing over it. Unaligned data does not rule out use of memory mapping, it just means that the data needs to be copied first using types which require less alignment (which is what libtiff does). Bob ====================================== Bob Friesenhahn bfriesen@simple.dallas.tx.us http://www.simplesystems.org/users/bfriesen