From: Ben Pfaff <blp@gnu.org>
Date: Thu, 21 Dec 2006 06:15:05 +0000 (+0000)
Subject: Add comment that ll_sort is stable,
X-Git-Tag: v0.6.0~623
X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4e9bb21173b1ee541a7a23358552b68666005f99;p=pspp-builds.git

Add comment that ll_sort is stable,
which is verified by the existing set of tests.
---

diff --git a/src/libpspp/ll.c b/src/libpspp/ll.c
index 25b4462b..525dcc5b 100644
--- a/src/libpspp/ll.c
+++ b/src/libpspp/ll.c
@@ -429,6 +429,8 @@ ll_prev_permutation (struct ll *r0, struct ll *r1,
    In use, keep in mind that R0 may move during the sort, so that
    afterward R0...R1 may denote a different range.
    (On the other hand, R1 is fixed in place.)
+   The sort is stable; that is, it will not change the relative
+   order of nodes that compare equal.
    Runs in O(n lg n) time in the number of nodes in the range. */
 void
 ll_sort (struct ll *r0, struct ll *r1, ll_compare_func *compare, void *aux)