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| author | Paul Eggert <eggert@cs.ucla.edu> | 2018-08-20 15:52:29 -0700 |
|---|---|---|
| committer | Paul Eggert <eggert@cs.ucla.edu> | 2018-08-20 16:01:31 -0700 |
| commit | eb83344fc7c08ec08b51e7700f1ac2632afa462c (patch) | |
| tree | 69c96f89acf42957ed98dc7ce189cb49d04abecd /src/xterm.c | |
| parent | 36de7bd7b0b9fcd038c440b4705e9186bfbaaa41 (diff) | |
| download | emacs-eb83344fc7c08ec08b51e7700f1ac2632afa462c.tar.gz emacs-eb83344fc7c08ec08b51e7700f1ac2632afa462c.tar.bz2 emacs-eb83344fc7c08ec08b51e7700f1ac2632afa462c.zip | |
Speed up (nthcdr N L) when L is circular
Also, fix bug when N is a positive bignum, a problem reported
by Eli Zaretskii and Pip Cet in:
https://lists.gnu.org/r/emacs-devel/2018-08/msg00690.html
* src/fns.c (Fnthcdr): If a cycle is found, reduce the count
modulo the cycle length before continuing. This reduces the
worst-case cost of (nthcdr N L) from N to min(N, C) where C is
the number of distinct cdrs of L. Reducing modulo the cycle
length also allows us to do arithmetic with machine words
instead of with GMP.
* test/src/fns-tests.el (test-nthcdr-circular): New test.
Diffstat (limited to 'src/xterm.c')
0 files changed, 0 insertions, 0 deletions