thodg/libgit2

diff --git a/src/pack.c b/src/pack.c
index d7e6a1e..e7fb9f1 100644
--- a/src/pack.c
+++ b/src/pack.c
@@ -1110,8 +1110,11 @@ static int pack_entry_find_offset(
 		short_oid->id[0], short_oid->id[1], short_oid->id[2], lo, hi, p->num_objects);
 #endif
 
-	/* Use git.git lookup code */
+#ifdef GIT_USE_LOOKUP
 	pos = sha1_entry_pos(index, stride, 0, lo, hi, p->num_objects, short_oid->id);
+#else
+	pos = sha1_position(index, stride, lo, hi, short_oid->id);
+#endif
 
 	if (pos >= 0) {
 		/* An object matching exactly the oid was found */
diff --git a/src/sha1_lookup.c b/src/sha1_lookup.c
index b7e66cc..8aca863 100644
--- a/src/sha1_lookup.c
+++ b/src/sha1_lookup.c
@@ -9,6 +9,7 @@
 
 #include "sha1_lookup.h"
 #include "common.h"
+#include "oid.h"
 
 /*
  * Conventional binary search loop looks like this:
@@ -123,7 +124,7 @@ int sha1_entry_pos(const void *table,
 			lov = (lov << 8) | lo_key[ofs_0+1];
 			kyv = (kyv << 8) | key[ofs_0+1];
 		}
-		assert(lov < hiv);
+		assert(lov <= hiv);
 
 		if (kyv < lov)
 			return -1 - lo;
@@ -176,3 +177,24 @@ int sha1_entry_pos(const void *table,
 	} while (lo < hi);
 	return -((int)lo)-1;
 }
+
+int sha1_position(const void *table,
+			size_t stride,
+			unsigned lo, unsigned hi,
+			const unsigned char *key)
+{
+	do {
+		unsigned mi = (lo + hi) / 2;
+		int cmp = git_oid__cmp(table + mi * stride, (git_oid *)key);
+
+		if (!cmp)
+			return mi;
+
+		if (cmp > 0)
+			hi = mi;
+		else
+			lo = mi+1;
+	} while (lo < hi);
+
+	return -((int)lo)-1;
+}
diff --git a/src/sha1_lookup.h b/src/sha1_lookup.h
index 9a35372..3799620 100644
--- a/src/sha1_lookup.h
+++ b/src/sha1_lookup.h
@@ -15,4 +15,9 @@ int sha1_entry_pos(const void *table,
 			unsigned lo, unsigned hi, unsigned nr,
 			const unsigned char *key);
 
+int sha1_position(const void *table,
+			size_t stride,
+			unsigned lo, unsigned hi,
+			const unsigned char *key);
+
 #endif