From 1db1ce63b7f5e67e274849bb03f541f00bc7f6e2 Mon Sep 17 00:00:00 2001
From: Todd Gruben <tgruben@umbel.com>
Date: Fri, 15 Sep 2017 15:27:24 -0500
Subject: [PATCH] optimize intersectionBitmapBitmap

---
 roaring/roaring.go | 22 +++++-----------------
 1 file changed, 5 insertions(+), 17 deletions(-)

diff --git a/roaring/roaring.go b/roaring/roaring.go
index 602fb9c8b..53c07e347 100644
--- a/roaring/roaring.go
+++ b/roaring/roaring.go
@@ -2115,24 +2115,12 @@ func intersectArrayBitmap(a, b *container) *container {
 
 func intersectBitmapBitmap(a, b *container) *container {
 	output := &container{bitmap: make([]uint64, bitmapN), container_type: ContainerBitmap}
-	itr0 := newBitmapIterator(a.bitmap)
-	itr1 := newBitmapIterator(b.bitmap)
-	va, eof1 := itr0.next()
-	vb, eof2 := itr1.next()
-	for {
-		if eof1 || eof2 {
-			break
-		}
 
-		if va < vb {
-			va, eof1 = itr0.next()
-		} else if va > vb {
-			vb, eof2 = itr1.next()
-		} else {
-			output.add(va)
-			va, eof1 = itr0.next()
-			vb, eof2 = itr1.next()
-		}
+	for i := range a.bitmap {
+		v := a.bitmap[i] & b.bitmap[i]
+		output.bitmap[i] = v
+		output.n += int(popcount(v))
+
 	}
 	return output
 }