首次提交代码

vendor/github.com/RoaringBitmap/roaring/popcnt.go

@@ -0,0 +1,13 @@
+//go:build go1.9
+// +build go1.9
+
+// "go1.9", from Go version 1.9 onward
+// See https://golang.org/pkg/go/build/#hdr-Build_Constraints
+
+package roaring
+
+import "math/bits"
+
+func popcount(x uint64) uint64 {
+	return uint64(bits.OnesCount64(x))
+}