[mkgmap-dev] [PATCH V3]mkgmap performanceFrom GerdP gpetermann_muenchen at hotmail.com on Mon Jan 2 12:16:05 GMT 2012
Hello Steve, Steve Ratcliffe wrote > >> reg. "local information": I totally agree, but I found no better way, >> and it saved a lot of time on my system. > > Personally I think that the way you have done it in the patch is much > more natural than the existing way! > Ok, so than the patch is fine for me as well. > It is also possible to make the Coord structure smaller, since only 24 > bits of the latitude and longitude fields are used, so both of the > byte values could be located in the un-used 16 bits. Also there are > only three values of highwayCount that matter: 0, 1, and > more-than-one, so only two bits are required for that. I originally > did it that way, but because of a mistake I gave up and went back to a > separate field. This would save a bit of memory, but it is only worth > doing if it results in a significant improvement in performance. > I also thought about this, but I wasn't sure how many bits are really used, and I got the feeling that such bitmask tricks are somehow outaged. I think I'll give it a try. I see two ways: 1) Keep the Coord class, but place these bits somewhere in the two interger fields 2) Use a long and map all fields in some mapping routines. This will be more complex, but could allow to use arrays (long) to store coords, and I guess this would mean > 50% memory saving for Coords. Gerd -- View this message in context: http://gis.638310.n2.nabble.com/PATCH-mkgmap-performance-part-2-tp7123938p7143656.html Sent from the Mkgmap Development mailing list archive at Nabble.com.
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