with Interfaces; use Interfaces;
package body Natools.S_Expressions.Printers.Pretty.Config.Commands.CE is
P : constant array (0 .. 2) of Natural :=
(1, 4, 6);
T1 : constant array (0 .. 2) of Unsigned_8 :=
(20, 19, 0);
T2 : constant array (0 .. 2) of Unsigned_8 :=
(9, 10, 8);
G : constant array (0 .. 20) of Unsigned_8 :=
(0, 0, 9, 6, 0, 5, 1, 0, 0, 0, 0, 0, 0, 0, 5, 0, 4, 9, 2, 0, 1);
function Hash (S : String) return Natural is
F : constant Natural := S'First - 1;
L : constant Natural := S'Length;
F1, F2 : Natural := 0;
J : Natural;
begin
for K in P'Range loop
exit when L < P (K);
J := Character'Pos (S (P (K) + F));
F1 := (F1 + Natural (T1 (K)) * J) mod 21;
F2 := (F2 + Natural (T2 (K)) * J) mod 21;
end loop;
return (Natural (G (F1)) + Natural (G (F2))) mod 10;
end Hash;
end Natools.S_Expressions.Printers.Pretty.Config.Commands.CE;