On Nov 29, 2013, at 12:58 PM, Graham Cox <graham....@bigpond.com> wrote:
> Another general question. > > Does anyone have a quick-and-dirty (but functional) way to hash NSData? I’m > currently using SHA-1 but it’s quite slow. All I need is a way to determine > whether one block of data is identical to another or not - but every bit > counts. It doesn’t need to be of crypto-standard, but SHA-1 was convenient. > Note that this can’t be the same as simply seeing whether one object is the > same as another - I really do need to know if two different objects hold the > same data bytes, and to derive a short, unique value that can be used as a > key. > > I’ve previously written my own quick-and-dirty hash that was basically a > weighted sum of the bytes, modulo some number, but it turned out to have > collisions more often than I expected, so SHA-1 was then used to fix that > problem. Now it’s causing quite a noticeable performance hit in some cases. I recently (last week, no kidding) investigated this question, and went with murmur hash. _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
