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Go Back   Linux Archive > ArchLinux > ArchLinux Pacman Development

 
 
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Old 01-01-2012, 02:07 AM
Dan McGee
 
Default alpm_list_msort: inline alpm_list_nth() call

This reduces the number of functions we call by log(n) in this function,
and the inlined version is trivial and barely increases the size of the
function.

Signed-off-by: Dan McGee <dan@archlinux.org>
---
lib/libalpm/alpm_list.c | 21 ++++++++++++++-------
1 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/lib/libalpm/alpm_list.c b/lib/libalpm/alpm_list.c
index cad6d09..83ba9dc 100644
--- a/lib/libalpm/alpm_list.c
+++ b/lib/libalpm/alpm_list.c
@@ -204,7 +204,8 @@ alpm_list_t SYMEXPORT *alpm_list_join(alpm_list_t *first, alpm_list_t *second)
*
* @return the resultant list
*/
-alpm_list_t SYMEXPORT *alpm_list_mmerge(alpm_list_t *left, alpm_list_t *right, alpm_list_fn_cmp fn)
+alpm_list_t SYMEXPORT *alpm_list_mmerge(alpm_list_t *left, alpm_list_t *right,
+ alpm_list_fn_cmp fn)
{
alpm_list_t *newlist, *lp, *tail_ptr, *left_tail_ptr, *right_tail_ptr;

@@ -273,17 +274,23 @@ alpm_list_t SYMEXPORT *alpm_list_mmerge(alpm_list_t *left, alpm_list_t *right, a
*
* @return the resultant list
*/
-alpm_list_t SYMEXPORT *alpm_list_msort(alpm_list_t *list, size_t n, alpm_list_fn_cmp fn)
+alpm_list_t SYMEXPORT *alpm_list_msort(alpm_list_t *list, size_t n,
+ alpm_list_fn_cmp fn)
{
if(n > 1) {
- alpm_list_t *left = list;
- alpm_list_t *lastleft = alpm_list_nth(list, n/2 - 1);
- alpm_list_t *right = lastleft->next;
+ size_t half = n / 2;
+ size_t i = half - 1;
+ alpm_list_t *left = list, *lastleft = list, *right;
+
+ while(i--) {
+ lastleft = lastleft->next;
+ }
+ right = lastleft->next;
/* terminate first list */
lastleft->next = NULL;

- left = alpm_list_msort(left, n/2, fn);
- right = alpm_list_msort(right, n - (n/2), fn);
+ left = alpm_list_msort(left, half, fn);
+ right = alpm_list_msort(right, n - half, fn);
list = alpm_list_mmerge(left, right, fn);
}
return list;
--
1.7.8.1
 

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