64 lines
1.5 KiB
OCaml
64 lines
1.5 KiB
OCaml
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module type Intlike = sig
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type t
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val logand : t -> t -> t
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val zero : t
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val one : t
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val equal : t -> t -> bool
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val compare : t -> t -> int
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val shift_right_logical : t -> int -> t
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val shift_left : t -> int -> t
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val bitwidth : int
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end
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module Make (Int : Intlike) = struct
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let least_significant_bit n = Int.logand n Int.one
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let is_least_significant_bit_set n =
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let lsb = least_significant_bit n in
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if Int.equal lsb Int.one
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then true
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else if Int.equal lsb Int.zero
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then false
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else assert false
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;;
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let is_most_significant_bit_set n = if Int.compare n Int.zero < 0 then true else false
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let count_trailing_zeros n =
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let rec loop ~acc ~mask =
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if is_least_significant_bit_set mask
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then acc
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else (
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let mask = Int.shift_right_logical mask 1 in
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let acc = acc + 1 in
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loop ~mask ~acc)
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in
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if Int.equal n Int.zero then Int.bitwidth else loop ~acc:0 ~mask:n
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;;
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let count_leading_zeros n =
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let rec loop ~acc ~mask =
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if is_most_significant_bit_set mask
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then acc
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else (
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let mask = Int.shift_left mask 1 in
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let acc = acc + 1 in
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loop ~mask ~acc)
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in
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if Int.equal n Int.zero then Int.bitwidth else loop ~acc:0 ~mask:n
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;;
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let count_set_bits n =
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let rec loop ~acc ~mask =
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if Int.equal mask Int.zero
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then acc
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else (
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let acc = if is_least_significant_bit_set mask then acc + 1 else acc in
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let mask = Int.shift_right_logical mask 1 in
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loop ~mask ~acc)
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in
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loop ~acc:0 ~mask:n
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;;
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end
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