We know our mode entry in our tree objects should be 5 or 6 characters
long. This change both enforces this fact and also unrolls the parsing
of the information giving the compiler more room for optimization of the
operations.
Signed-off-by: Dan McGee <dpmcgee@xxxxxxxxx>
---
tree-walk.c | 41 ++++++++++++++++++++++++++++++++++-------
1 files changed, 34 insertions(+), 7 deletions(-)
diff --git a/tree-walk.c b/tree-walk.c
index f386151..41383b0 100644
--- a/tree-walk.c
+++ b/tree-walk.c
@@ -9,16 +9,43 @@ static const char *get_mode(const char *str, unsigned int *modep)
unsigned char c;
unsigned int mode = 0;
- if (*str == ' ')
- return NULL;
-
- while ((c = *str++) != ' ') {
- if (c < '0' || c > '7')
- return NULL;
+ /*
+ * Unroll what looks like a loop since the bounds are
+ * well-known. There should be at least 5 and at most 6
+ * characters available in any valid mode, as '40000' is the
+ * shortest while '160000' (S_IFGITLINK) is the longest.
+ */
+ /* char 1 */
+ c = *str++;
+ if (c < '0' || c > '7') return NULL;
+ mode = (mode << 3) + (c - '0');
+ /* char 2 */
+ c = *str++;
+ if (c < '0' || c > '7') return NULL;
+ mode = (mode << 3) + (c - '0');
+ /* char 3 */
+ c = *str++;
+ if (c < '0' || c > '7') return NULL;
+ mode = (mode << 3) + (c - '0');
+ /* char 4 */
+ c = *str++;
+ if (c < '0' || c > '7') return NULL;
+ mode = (mode << 3) + (c - '0');
+ /* char 5 */
+ c = *str++;
+ if (c < '0' || c > '7') return NULL;
+ mode = (mode << 3) + (c - '0');
+ /* char 6, optional */
+ if (*str != ' ') {
+ c = *str++;
+ if (c < '0' || c > '7') return NULL;
mode = (mode << 3) + (c - '0');
}
+
+ if (*str != ' ') return NULL;
+
*modep = mode;
- return str;
+ return str + 1;
}
static void decode_tree_entry(struct tree_desc *desc, const char *buf, unsigned long size)
--
1.7.4.2
--
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