minor optimization

1 files changed, 5 insertions, 3 deletions

diff --git a/ht.c b/ht.c
index 09eec3e..a2845f0 100644
--- a/ht.c
+++ b/ht.c
@@ -24,15 +24,17 @@ Ht ht_new() {
 }
 
 static HtEntry *find(HtEntry *b, size_t cap, ObjString *k) {
-	size_t ix = k->hash % cap;
+	// cap is guaranteed to be power of 2
+	size_t mask = cap - 1;
+	size_t ix = k->hash & mask;
 	if (cap == 0) return NULL;
 	for (;;) {
 		HtEntry *ent = &b[ix];
 		// XXX tombstones
-		if (ent->k == k || ent->k == NULL) {
+		if (ent->k == NULL || ent->k == k) {
 			return ent;
 		}
-		ix = (ix+1)%cap;
+		ix = (ix+1) & mask;
 	}
 }