diff options
| -rw-r--r-- | mergesort.c | 31 |
1 files changed, 15 insertions, 16 deletions
diff --git a/mergesort.c b/mergesort.c index bd9c6ef8ee..92150c4101 100644 --- a/mergesort.c +++ b/mergesort.c @@ -57,28 +57,27 @@ void *llist_mergesort(void *list, { void *ranks[bitsizeof(void *)]; size_t n = 0; - int i; - while (list) { + if (!list) + return NULL; + + for (;;) { + int i; + size_t m; void *next = get_next_fn(list); if (next) set_next_fn(list, NULL); - for (i = 0; n & ((size_t)1 << i); i++) - list = llist_merge(ranks[i], list, get_next_fn, - set_next_fn, compare_fn); + for (i = 0, m = n;; i++, m >>= 1) { + if (m & 1) + list = llist_merge(ranks[i], list, get_next_fn, + set_next_fn, compare_fn); + else if (next) + break; + else if (!m) + return list; + } n++; ranks[i] = list; list = next; } - - for (i = 0; n; i++, n >>= 1) { - if (!(n & 1)) - continue; - if (list) - list = llist_merge(ranks[i], list, get_next_fn, - set_next_fn, compare_fn); - else - list = ranks[i]; - } - return list; } |