Merge pull request #394 from c-cube/ccbv_bytes2

(continued) use bytes for CCBV

Author: c-cube

Makefile

@@ -6,7 +6,7 @@ build:
 	dune build @install -p $(PACKAGES)
 
 test: build
-	dune runtest --cache=disabled --no-buffer --force
+	dune runtest --display=quiet --cache=disabled --no-buffer --force
 
 clean:
 	dune clean

src/core/CCInt32.ml

@@ -27,6 +27,20 @@ let pow a b =
     raise (Invalid_argument "pow: can't raise int to negative power")
   | b -> aux a b
 
+(* see {!CCInt.popcount} for more details *)
+let[@inline] popcount (b : t) : int =
+  let m1 = 0x55555555l in
+  let m2 = 0x33333333l in
+  let m4 = 0x0f0f0f0fl in
+
+  let b = sub b (logand (shift_right_logical b 1) m1) in
+  let b = add (logand b m2) (logand (shift_right_logical b 2) m2) in
+  let b = logand (add b (shift_right_logical b 4)) m4 in
+  let b = add b (shift_right_logical b 8) in
+  let b = add b (shift_right_logical b 16) in
+  let b = logand b 0x7fl in
+  to_int b
+
 let floor_div a n =
   if compare a 0l < 0 && compare n 0l >= 0 then
     sub (div (add a 1l) n) 1l

src/core/CCInt32.mli

@@ -41,6 +41,10 @@ val pow : t -> t -> t
     Raises [Invalid_argument] if [x = y = 0] or [y] < 0.
     @since 0.11 *)
 
+val popcount : t -> int
+(** Number of bits set to 1.
+    @since NEXT_RELEASE *)
+
 val floor_div : t -> t -> t
 (** [floor_div x n] is integer division rounding towards negative infinity.
     It satisfies [x = m * floor_div x n + rem x n].

src/core/CCInt64.ml

@@ -8,6 +8,21 @@ let max : t -> t -> t = Stdlib.max
 let hash x = Stdlib.abs (to_int x)
 let sign i = compare i zero
 
+(* see {!CCInt.popcount} for more details *)
+let[@inline] popcount (b : t) : int =
+  let m1 = 0x5555555555555555L in
+  let m2 = 0x3333333333333333L in
+  let m4 = 0x0f0f0f0f0f0f0f0fL in
+
+  let b = sub b (logand (shift_right_logical b 1) m1) in
+  let b = add (logand b m2) (logand (shift_right_logical b 2) m2) in
+  let b = logand (add b (shift_right_logical b 4)) m4 in
+  let b = add b (shift_right_logical b 8) in
+  let b = add b (shift_right_logical b 16) in
+  let b = add b (shift_right_logical b 32) in
+  let b = logand b 0x7fL in
+  to_int b
+
 let pow a b =
   let rec aux acc = function
     | 1L -> acc

src/core/CCInt64.mli

@@ -30,6 +30,10 @@ val hash : t -> int
 (** [hash x] computes the hash of [x].
     Like {!Stdlib.abs (to_int x)}. *)
 
+val popcount : t -> int
+(** Number of bits set to 1.
+    @since NEXT_RELEASE *)
+
 val sign : t -> int
 (** [sign x] return [0] if [x = 0], [-1] if [x < 0] and [1] if [x > 0].
     Same as [compare x zero].