git_oid_cmp: inline memcmp by hand to optimize

git.git uses an inlined hashcmp function instead of memcmp, since it
performes much better when comparing hashes (most hashes compared
diverge within the first byte).

Measurements and rationale for the curious reader:
http://thread.gmane.org/gmane.comp.version-control.git/172286

1 files changed, 25 insertions, 1 deletions

diff --git a/include/git2/oid.h b/include/git2/oid.h
index a05b40a37..d6b2d1e7f 100644
--- a/include/git2/oid.h
+++ b/include/git2/oid.h
@@ -136,7 +136,31 @@ GIT_EXTERN(void) git_oid_cpy(git_oid *out, const git_oid *src);
  * @param b second oid structure.
  * @return <0, 0, >0 if a < b, a == b, a > b.
  */
-GIT_EXTERN(int) git_oid_cmp(const git_oid *a, const git_oid *b);
+GIT_INLINE(int) git_oid_cmp(const git_oid *a, const git_oid *b)
+{
+	const unsigned char *sha1 = a->id;
+	const unsigned char *sha2 = b->id;
+	int i;
+
+	for (i = 0; i < GIT_OID_RAWSZ; i++, sha1++, sha2++) {
+		if (*sha1 != *sha2)
+			return *sha1 - *sha2;
+	}
+
+	return 0;
+}
+
+/**
+ * Compare two oid structures for equality
+ *
+ * @param a first oid structure.
+ * @param b second oid structure.
+ * @return true if equal, false otherwise
+ */
+GIT_INLINE(int) git_oid_equal(const git_oid *a, const git_oid *b)
+{
+	return !git_oid_cmp(a, b);
+}
 
 /**
  * Compare the first 'len' hexadecimal characters (packets of 4 bits)