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(************************************************************************)
(* * The Coq Proof Assistant / The Coq Development Team *)
(* v * INRIA, CNRS and contributors - Copyright 1999-2018 *)
(* <O___,, * (see CREDITS file for the list of authors) *)
(* \VV/ **************************************************************)
(* // * This file is distributed under the terms of the *)
(* * GNU Lesser General Public License Version 2.1 *)
(* * (see LICENSE file for the text of the license) *)
(************************************************************************)
type t = int
let _ = assert (Sys.word_size = 64)
let uint_size = 63
let maxuint63 = Int64.of_string "0x7FFFFFFFFFFFFFFF"
let maxuint31 = 0x7FFFFFFF
(* conversion from an int *)
let to_uint64 i = Int64.logand (Int64.of_int i) maxuint63
let of_int i = i
[@@ocaml.inline always]
let to_int2 i = (0,i)
let of_int64 _i = assert false
let hash i = i
[@@ocaml.inline always]
(* conversion of an uint63 to a string *)
let to_string i = Int64.to_string (to_uint64 i)
let of_string s =
let i64 = Int64.of_string s in
if Int64.compare Int64.zero i64 <= 0
&& Int64.compare i64 maxuint63 <= 0
then Int64.to_int i64
else raise (Failure "Int64.of_string")
(* Compiles an unsigned int to OCaml code *)
let compile i = Printf.sprintf "Uint63.of_int (%i)" i
let zero = 0
let one = 1
(* logical shift *)
let l_sl x y =
if 0 <= y && y < 63 then x lsl y else 0
let l_sr x y =
if 0 <= y && y < 63 then x lsr y else 0
let l_and x y = x land y
[@@ocaml.inline always]
let l_or x y = x lor y
[@@ocaml.inline always]
let l_xor x y = x lxor y
[@@ocaml.inline always]
(* addition of int63 *)
let add x y = x + y
[@@ocaml.inline always]
(* subtraction *)
let sub x y = x - y
[@@ocaml.inline always]
(* multiplication *)
let mul x y = x * y
[@@ocaml.inline always]
(* division *)
let div (x : int) (y : int) =
if y = 0 then 0 else Int64.to_int (Int64.div (to_uint64 x) (to_uint64 y))
(* modulo *)
let rem (x : int) (y : int) =
if y = 0 then 0 else Int64.to_int (Int64.rem (to_uint64 x) (to_uint64 y))
let diveucl x y = (div x y, rem x y)
let addmuldiv p x y =
l_or (l_sl x p) (l_sr y (uint_size - p))
(* comparison *)
let lt (x : int) (y : int) =
(x lxor 0x4000000000000000) < (y lxor 0x4000000000000000)
[@@ocaml.inline always]
let le (x : int) (y : int) =
(x lxor 0x4000000000000000) <= (y lxor 0x4000000000000000)
[@@ocaml.inline always]
(* division of two numbers by one *)
(* precondition: xh < y *)
(* outputs: q, r s.t. x = q * y + r, r < y *)
let div21 xh xl y =
(* nh might temporarily grow as large as 2*y - 1 in the loop body,
so we store it as a 64-bit unsigned integer *)
let nh = ref xh in
let nl = ref xl in
let q = ref 0 in
for _i = 0 to 62 do
(* invariants: 0 <= nh < y, nl = (xl*2^i) % 2^63,
(q*y + nh) * 2^(63-i) + (xl % 2^(63-i)) = (xh%y) * 2^63 + xl *)
nh := Int64.logor (Int64.shift_left !nh 1) (Int64.of_int (!nl lsr 62));
nl := !nl lsl 1;
q := !q lsl 1;
(* TODO: use "Int64.unsigned_compare !nh y >= 0",
once OCaml 4.08 becomes the minimal required version *)
if Int64.compare !nh 0L < 0 || Int64.compare !nh y >= 0 then
begin q := !q lor 1; nh := Int64.sub !nh y; end
done;
!q, Int64.to_int !nh
let div21 xh xl y =
let xh = to_uint64 xh in
let y = to_uint64 y in
if Int64.compare y xh <= 0 then 0, 0 else div21 xh xl y
(* exact multiplication *)
(* TODO: check that none of these additions could be a logical or *)
(* size = 32 + 31
(hx << 31 + lx) * (hy << 31 + ly) =
hxhy << 62 + (hxly + lxhy) << 31 + lxly
*)
(* precondition : (x lsr 62 = 0 || y lsr 62 = 0) *)
let mulc_aux x y =
let lx = x land maxuint31 in
let ly = y land maxuint31 in
let hx = x lsr 31 in
let hy = y lsr 31 in
(* hx and hy are 32 bits value but at most one is 32 *)
let hxy = hx * hy in (* 63 bits *)
let hxly = hx * ly in (* 63 bits *)
let lxhy = lx * hy in (* 63 bits *)
let lxy = lx * ly in (* 62 bits *)
let l = lxy lor (hxy lsl 62) (* 63 bits *) in
let h = hxy lsr 1 in (* 62 bits *)
let hl = hxly + lxhy in (* We can have a carry *)
let h = if lt hl hxly then h + (1 lsl 31) else h in
let hl'= hl lsl 31 in
let l = l + hl' in
let h = if lt l hl' then h + 1 else h in
let h = h + (hl lsr 32) in
(h,l)
let mulc x y =
if (x lsr 62 = 0 || y lsr 62 = 0) then mulc_aux x y
else
let yl = y lxor (1 lsl 62) in
let (h,l) = mulc_aux x yl in
(* h << 63 + l = x * yl
x * y = x * (1 << 62 + yl) =
x << 62 + x*yl = x << 62 + h << 63 + l *)
let l' = l + (x lsl 62) in
let h = if lt l' l then h + 1 else h in
(h + (x lsr 1), l')
let equal (x : int) (y : int) = x = y
[@@ocaml.inline always]
let compare (x:int) (y:int) =
let x = x lxor 0x4000000000000000 in
let y = y lxor 0x4000000000000000 in
if x > y then 1
else if y > x then -1
else 0
(* head tail *)
let head0 x =
let r = ref 0 in
let x = ref x in
if !x land 0x7FFFFFFF00000000 = 0 then r := !r + 31
else x := !x lsr 31;
if !x land 0xFFFF0000 = 0 then (x := !x lsl 16; r := !r + 16);
if !x land 0xFF000000 = 0 then (x := !x lsl 8; r := !r + 8);
if !x land 0xF0000000 = 0 then (x := !x lsl 4; r := !r + 4);
if !x land 0xC0000000 = 0 then (x := !x lsl 2; r := !r + 2);
if !x land 0x80000000 = 0 then (x := !x lsl 1; r := !r + 1);
if !x land 0x80000000 = 0 then ( r := !r + 1);
!r;;
let tail0 x =
let r = ref 0 in
let x = ref x in
if !x land 0xFFFFFFFF = 0 then (x := !x lsr 32; r := !r + 32);
if !x land 0xFFFF = 0 then (x := !x lsr 16; r := !r + 16);
if !x land 0xFF = 0 then (x := !x lsr 8; r := !r + 8);
if !x land 0xF = 0 then (x := !x lsr 4; r := !r + 4);
if !x land 0x3 = 0 then (x := !x lsr 2; r := !r + 2);
if !x land 0x1 = 0 then ( r := !r + 1);
!r
let is_uint63 t =
Obj.is_int t
[@@ocaml.inline always]
(* Arithmetic with explicit carries *)
(* Analog of Numbers.Abstract.Cyclic.carry *)
type 'a carry = C0 of 'a | C1 of 'a
let addc x y =
let r = x + y in
if lt r x then C1 r else C0 r
let addcarryc x y =
let r = x + y + 1 in
if le r x then C1 r else C0 r
let subc x y =
let r = x - y in
if le y x then C0 r else C1 r
let subcarryc x y =
let r = x - y - 1 in
if lt y x then C0 r else C1 r
[ Dauer der Verarbeitung: 0.16 Sekunden
(vorverarbeitet)
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