Fix logarithm of 2 (#10275)

* Fix logarithm of 2

* add regression test

* Update encoding/ssz/merkleize.go

Co-authored-by: Nishant Das <nishdas93@gmail.com>

Co-authored-by: Nishant Das <nishdas93@gmail.com>

encoding/ssz/merkleize.go

@@ -34,8 +34,8 @@ func Depth(v uint64) (out uint8) {
 	// Then adding 1 to it to not get the index of the first bit, but the length of the bits (depth of tree)
 	// Zero is a special case, it has a 0 depth.
 	// Example:
-	//  (in out): (0 0), (1 1), (2 1), (3 2), (4 2), (5 3), (6 3), (7 3), (8 3), (9 4)
-	if v == 0 {
+	//  (in out): (0 0), (1 0), (2 1), (3 2), (4 2), (5 3), (6 3), (7 3), (8 3), (9 4)
+	if v <= 1 {
 		return 0
 	}
 	v--

encoding/ssz/merkleize_test.go

@@ -112,3 +112,7 @@ func TestConstructProofNormalPath(t *testing.T) {
 		assert.DeepEqual(t, result[i], v)
 	}
 }
+
+func TestDepthOfOne(t *testing.T) {
+	assert.Equal(t, uint8(0), ssz.Depth(1))
+}