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Subject[PATCH v1]] lib/btree.c: optimise the code by previously getpos function
Date
This patch optimized the code by previously getpos function call.
Therefore, It's takes the convenience to understand logic of code.

Signed-off-by: Leno Hou <lenohou@gmail.com>
---
lib/btree.c | 41 +++++++++++++++++------------------------
1 file changed, 17 insertions(+), 24 deletions(-)

diff --git a/lib/btree.c b/lib/btree.c
index f93a945..87d690f 100644
--- a/lib/btree.c
+++ b/lib/btree.c
@@ -238,6 +238,19 @@ static int keyzero(struct btree_geo *geo, unsigned long *key)
return 1;
}

+static int getpos(struct btree_geo *geo, unsigned long *node,
+ unsigned long *key)
+{
+ int i;
+
+ for (i = 0; i < geo->no_pairs; i++) {
+ if (keycmp(geo, node, i, key) <= 0)
+ break;
+ }
+ return i;
+}
+
+
void *btree_lookup(struct btree_head *head, struct btree_geo *geo,
unsigned long *key)
{
@@ -248,9 +261,7 @@ void *btree_lookup(struct btree_head *head, struct btree_geo *geo,
return NULL;

for ( ; height > 1; height--) {
- for (i = 0; i < geo->no_pairs; i++)
- if (keycmp(geo, node, i, key) <= 0)
- break;
+ i = getpos(geo, node, key);
if (i == geo->no_pairs)
return NULL;
node = bval(geo, node, i);
@@ -278,9 +289,7 @@ int btree_update(struct btree_head *head, struct btree_geo *geo,
return -ENOENT;

for ( ; height > 1; height--) {
- for (i = 0; i < geo->no_pairs; i++)
- if (keycmp(geo, node, i, key) <= 0)
- break;
+ i = getpos(geo, node, key);
if (i == geo->no_pairs)
return -ENOENT;
node = bval(geo, node, i);
@@ -326,9 +335,7 @@ void *btree_get_prev(struct btree_head *head, struct btree_geo *geo,

node = head->node;
for (height = head->height ; height > 1; height--) {
- for (i = 0; i < geo->no_pairs; i++)
- if (keycmp(geo, node, i, key) <= 0)
- break;
+ i = getpos(geo, node, key);
if (i == geo->no_pairs)
goto miss;
oldnode = node;
@@ -360,18 +367,6 @@ void *btree_get_prev(struct btree_head *head, struct btree_geo *geo,
}
EXPORT_SYMBOL_GPL(btree_get_prev);

-static int getpos(struct btree_geo *geo, unsigned long *node,
- unsigned long *key)
-{
- int i;
-
- for (i = 0; i < geo->no_pairs; i++) {
- if (keycmp(geo, node, i, key) <= 0)
- break;
- }
- return i;
-}
-
static int getfill(struct btree_geo *geo, unsigned long *node, int start)
{
int i;
@@ -392,9 +387,7 @@ static unsigned long *find_level(struct btree_head *head, struct btree_geo *geo,
int i, height;

for (height = head->height; height > level; height--) {
- for (i = 0; i < geo->no_pairs; i++)
- if (keycmp(geo, node, i, key) <= 0)
- break;
+ i = getpos(geo, node, key);

if ((i == geo->no_pairs) || !bval(geo, node, i)) {
/* right-most key is too large, update it */
--
1.8.3.1
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