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PiperOrigin-RevId: 194583126
Change-Id: Ica1d8821a90f74e7e745962d71801c598c652463

1 files changed, 55 insertions, 0 deletions

diff --git a/pkg/bits/uint64_arch_generic.go b/pkg/bits/uint64_arch_generic.go
new file mode 100644
index 000000000..862033a4b
--- /dev/null
+++ b/pkg/bits/uint64_arch_generic.go
@@ -0,0 +1,55 @@
+// Copyright 2018 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build !amd64
+
+package bits
+
+// TrailingZeros64 returns the number of bits before the least significant 1
+// bit in x; in other words, it returns the index of the least significant 1
+// bit in x. If x is 0, TrailingZeros64 returns 64.
+func TrailingZeros64(x uint64) int {
+	if x == 0 {
+		return 64
+	}
+	i := 0
+	for ; x&1 == 0; i++ {
+		x >>= 1
+	}
+	return i
+}
+
+// MostSignificantOne64 returns the index of the most significant 1 bit in
+// x. If x is 0, MostSignificantOne64 returns 64.
+func MostSignificantOne64(x uint64) int {
+	if x == 0 {
+		return 64
+	}
+	i := 63
+	for ; x&(1<<63) == 0; i-- {
+		x <<= 1
+	}
+	return i
+}
+
+// ForEachSetBit64 calls f once for each set bit in x, with argument i equal to
+// the set bit's index.
+func ForEachSetBit64(x uint64, f func(i int)) {
+	for i := 0; x != 0; i++ {
+		if x&1 != 0 {
+			f(i)
+		}
+		x >>= 1
+	}
+}