unikernel/duniverse/base/test/test_int64_pow2.ml

@@ -0,0 +1,113 @@
+open! Import
+open! Int64
+
+let examples = [ -1L; 0L; 1L; 2L; 3L; 4L; 5L; 7L; 8L; 9L; 63L; 64L; 65L ]
+let examples_64_bit = [ min_value; succ min_value; pred max_value; max_value ]
+
+let print_for ints f =
+  List.iter ints ~f:(fun i ->
+    print_s
+      [%message "" ~_:(i : int64) ~_:(Or_error.try_with (fun () -> f i) : int Or_error.t)])
+;;
+
+let%expect_test "[floor_log2]" =
+  print_for examples floor_log2;
+  [%expect
+    {|
+    (-1 (Error ("[Int64.floor_log2] got invalid input" -1)))
+    (0 (Error ("[Int64.floor_log2] got invalid input" 0)))
+    (1 (Ok 0))
+    (2 (Ok 1))
+    (3 (Ok 1))
+    (4 (Ok 2))
+    (5 (Ok 2))
+    (7 (Ok 2))
+    (8 (Ok 3))
+    (9 (Ok 3))
+    (63 (Ok 5))
+    (64 (Ok 6))
+    (65 (Ok 6))
+    |}]
+;;
+
+let%expect_test ("[floor_log2]" [@tags "64-bits-only"]) =
+  print_for examples_64_bit floor_log2;
+  [%expect
+    {|
+    (-9_223_372_036_854_775_808 (
+      Error ("[Int64.floor_log2] got invalid input" -9223372036854775808)))
+    (-9_223_372_036_854_775_807 (
+      Error ("[Int64.floor_log2] got invalid input" -9223372036854775807)))
+    (9_223_372_036_854_775_806 (Ok 62))
+    (9_223_372_036_854_775_807 (Ok 62))
+    |}]
+;;
+
+let%expect_test "[ceil_log2]" =
+  print_for examples ceil_log2;
+  [%expect
+    {|
+    (-1 (Error ("[Int64.ceil_log2] got invalid input" -1)))
+    (0 (Error ("[Int64.ceil_log2] got invalid input" 0)))
+    (1 (Ok 0))
+    (2 (Ok 1))
+    (3 (Ok 2))
+    (4 (Ok 2))
+    (5 (Ok 3))
+    (7 (Ok 3))
+    (8 (Ok 3))
+    (9 (Ok 4))
+    (63 (Ok 6))
+    (64 (Ok 6))
+    (65 (Ok 7))
+    |}]
+;;
+
+let%expect_test ("[ceil_log2]" [@tags "64-bits-only"]) =
+  print_for examples_64_bit ceil_log2;
+  [%expect
+    {|
+    (-9_223_372_036_854_775_808 (
+      Error ("[Int64.ceil_log2] got invalid input" -9223372036854775808)))
+    (-9_223_372_036_854_775_807 (
+      Error ("[Int64.ceil_log2] got invalid input" -9223372036854775807)))
+    (9_223_372_036_854_775_806 (Ok 63))
+    (9_223_372_036_854_775_807 (Ok 63))
+    |}]
+;;
+
+let%test_module "int64_math" =
+  (module struct
+    let test_cases () =
+      let cases =
+        [ 0b10101010L
+        ; 0b1010101010101010L
+        ; 0b101010101010101010101010L
+        ; 0b10000000L
+        ; 0b1000000000001000L
+        ; 0b100000000000000000001000L
+        ]
+      in
+      let cases =
+        cases
+        @ [ (0b1010101010101010L lsl 16) lor 0b1010101010101010L
+          ; (0b1000000000000000L lsl 16) lor 0b0000000000001000L
+          ]
+      in
+      let added_cases = List.map cases ~f:(fun x -> x lsl 16) in
+      List.concat [ cases; added_cases ]
+    ;;
+
+    let%test_unit "ceil_pow2" =
+      List.iter (test_cases ()) ~f:(fun x ->
+        let p2 = ceil_pow2 x in
+        assert (is_pow2 p2 && p2 >= x && x >= p2 / 2L))
+    ;;
+
+    let%test_unit "floor_pow2" =
+      List.iter (test_cases ()) ~f:(fun x ->
+        let p2 = floor_pow2 x in
+        assert (is_pow2 p2 && 2L * p2 >= x && x >= p2))
+    ;;
+  end)
+;;