Messages in this thread | | | Date | Mon, 8 Mar 1999 22:52:17 -0600 (CST) | From | Oliver Xymoron <> | Subject | Re: Linux/IA-64 byte order |
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On Tue, 9 Mar 1999, Richard Gooch wrote:
> I write visualisation software for astronomy. This software is used > all over the world, and often has to deal with very large > datasets. It's not uncommon to "load" a dataset (a cube) but only view > a small portion of it (a single plane (channel) of the cube). On > big-endian machines I can avoid loading data and instead use memory > mapping, because all the portable binary data formats are big-endian > (FITS, Miriad and my own). > > Being able to memory map a gigabyte dataset makes "loading" extremely > fast. It also means you don't need stacks of swap space.
Make an empty map for little-endian direct access and make a backing map with the actual file. Then install a signal handler to catch reads in the empty map, copy a page (or more) with byteswapping, and you're done. "Loading" is still extremely fast.
As David Miller suggests, this might be a complete non-issue. We can for instance speculate that the processor has a byteswap micro-op that can be added to an instruction pipeline with little or no cost. Or other such magic. Remember, we're talking about a fairly novel architecture.
-- "Love the dolphins," she advised him. "Write by W.A.S.T.E.."
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