6 Commits

Author	SHA1	Message	Date
Christopher Haster	0825d34f3d	Adopted alternative implementation for lfs_ctz_index ... Same runtime cost, however reduces the logic and avoids one of the two big branches. See the DESIGN.md for more info. Now uses these equations instead of the messy guess and correct method: n = (N - w/8(popcount(N/(B-2w/8)) + 2)) / (B-2w/8) off = N - (B-w2/8)n - w/8popcount(n)	2017-10-30 12:03:33 -05:00
Christopher Haster	46e22b2a38	Adopted lfs_ctz_index implementation using popcount ... This reduces the O(n^2logn) runtime to read a file to only O(nlog). The extra O(n) did not touch the disk, so it isn't a problem until the files become very large, but this solution comes with very little cost. Long story short, you can find the block index + offset pair for a CTZ linked-list with this series of formulas: n' = floor(N / (B - 2w/8)) N' = (B - 2w/8)n' + (w/8)popcount(n') off' = N - N' n, off = n'-1, off'+B if off' < 0 n', off'+(w/8)(ctz(n')+1) if off' >= 0 For the long story, you will need to see the updated DESIGN.md	2017-10-18 00:44:30 -05:00
Christopher Haster	454b588f73	Updated SPEC.md and DESIGN.md based on recent changes ... - Added math behind CTZ limits - Added documentation over atomic moves	2017-10-12 20:31:33 -05:00
Christopher Haster	476915fee6	Removed a few "what"s from the documentation	2017-07-16 12:41:47 -05:00
Christopher Haster	0d66f9f991	Cleaned up design documentation	2017-06-28 15:50:29 -05:00
Christopher Haster	d2bf2bbc72	Added documentation over the underlying design	2017-05-18 23:44:18 -05:00