unikernel/duniverse/base/test/test_int_pow2.ml

@@ -0,0 +1,121 @@
+open! Import
+open! Int
+
+let examples = [ -1; 0; 1; 2; 3; 4; 5; 7; 8; 9; 63; 64; 65 ]
+
+let examples_64_bit =
+  [ Int.min_value; Int.min_value + 1; Int.max_value - 1; Int.max_value ]
+;;
+
+let print_for ints f =
+  List.iter ints ~f:(fun i ->
+    print_s
+      [%message "" ~_:(i : int) ~_:(Or_error.try_with (fun () -> f i) : int Or_error.t)])
+;;
+
+let%expect_test "[floor_log2]" =
+  print_for examples floor_log2;
+  [%expect
+    {|
+    (-1 (Error ("[Int.floor_log2] got invalid input" -1)))
+    (0 (Error ("[Int.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
+    {|
+    (-4_611_686_018_427_387_904 (
+      Error ("[Int.floor_log2] got invalid input" -4611686018427387904)))
+    (-4_611_686_018_427_387_903 (
+      Error ("[Int.floor_log2] got invalid input" -4611686018427387903)))
+    (4_611_686_018_427_387_902 (Ok 61))
+    (4_611_686_018_427_387_903 (Ok 61))
+    |}]
+;;
+
+let%expect_test "[ceil_log2]" =
+  print_for examples ceil_log2;
+  [%expect
+    {|
+    (-1 (Error ("[Int.ceil_log2] got invalid input" -1)))
+    (0 (Error ("[Int.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
+    {|
+    (-4_611_686_018_427_387_904 (
+      Error ("[Int.ceil_log2] got invalid input" -4611686018427387904)))
+    (-4_611_686_018_427_387_903 (
+      Error ("[Int.ceil_log2] got invalid input" -4611686018427387903)))
+    (4_611_686_018_427_387_902 (Ok 62))
+    (4_611_686_018_427_387_903 (Ok 62))
+    |}]
+;;
+
+let%test_module "int_math" =
+  (module struct
+    let test_cases () =
+      let cases =
+        [ 0b10101010
+        ; 0b1010101010101010
+        ; 0b101010101010101010101010
+        ; 0b10000000
+        ; 0b1000000000001000
+        ; 0b100000000000000000001000
+        ]
+      in
+      match Word_size.word_size with
+      | W64 ->
+        (* create some >32 bit values... *)
+        (* We can't use literals directly because the compiler complains on 32 bits. *)
+        let cases =
+          cases
+          @ [ (0b1010101010101010 lsl 16) lor 0b1010101010101010
+            ; (0b1000000000000000 lsl 16) lor 0b0000000000001000
+            ]
+        in
+        let added_cases = List.map cases ~f:(fun x -> x lsl 16) in
+        List.concat [ cases; added_cases ]
+      | W32 -> 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 / 2))
+    ;;
+
+    let%test_unit "floor_pow2" =
+      List.iter (test_cases ()) ~f:(fun x ->
+        let p2 = floor_pow2 x in
+        assert (is_pow2 p2 && 2 * p2 >= x && x >= p2))
+    ;;
+  end)
+;;