Messages in this thread | | | Date | Sat, 3 Apr 2004 23:04:49 -0800 | From | William Lee Irwin III <> | Subject | Re: remove bitmap_shift_*() bitmap length limits |
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On Sat, Apr 03, 2004 at 10:57:12PM -0800, Paul Jackson wrote: > There was one bug in my untested code for simple bitmap shifts, > the left shift needs to scan downwards, not upwards, so as to > avoid clobbering the input if shifting inplace. > The total text size of my user level test program is actually > made smaller with this per-bit simple implementation, as compared > to the implementation currently in the kernel, by 80 bytes. > Bill Irwin's more sophisticated version grows the text size, > over the current implementation, by 304 bytes. This is on > Pentium pc, gcc version 3.3.2, compiled -O2. > Given the very rare usage this bitmap shift routines receive, > I cast my vote for small and simple. > The more sophisticated logic of Bill's implementation is > impressive, but unjustified in this situation, in my view. > My fixed shift functions are:
I don't see this as a hard problem or why you call the implementation I brewed up impressive. I don't personally have a preference as to what implementation is used so long as it's not got fixed-size arrays in it, though I am somewhat puzzled as to why you bothered.
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