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(* Random.mod provides a Logitech-3.0 compatible library.
Copyright (C) 2005-2025 Free Software Foundation, Inc.
Contributed by Gaius Mulley <gaius.mulley@southwales.ac.uk>.
This file is part of GNU Modula-2.
GNU Modula-2 is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.
GNU Modula-2 is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.
You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
<http://www.gnu.org/licenses/>. *)
IMPLEMENTATION MODULE Random ;
FROM libc IMPORT rand, srand ;
FROM Selective IMPORT Timeval, InitTime, KillTime, GetTime, GetTimeOfDay ;
(*
Randomize - initialize the random number generator with a seed
based on the microseconds.
*)
PROCEDURE Randomize ;
VAR
t : Timeval ;
sec, usec: CARDINAL ;
BEGIN
t := InitTime (0, 0) ;
IF GetTimeOfDay (t) = 0
THEN
END ;
GetTime (t, sec, usec) ;
RandomInit (usec) ;
t := KillTime (t)
END Randomize ;
(*
RandomInit - initialize the random number generator with value, seed.
*)
PROCEDURE RandomInit (seed: CARDINAL) ;
BEGIN
srand (seed)
END RandomInit ;
(*
RandomBytes - fills in an array with random values.
*)
PROCEDURE RandomBytes (VAR a: ARRAY OF BYTE) ;
VAR
i, h: CARDINAL ;
BEGIN
h := HIGH (a) ;
i := 0 ;
WHILE i <= h DO
a[i] := VAL (BYTE, rand ()) ;
INC (i)
END
END RandomBytes ;
(*
RandomInt - return an INTEGER in the range 0..bound-1
*)
PROCEDURE RandomInt (bound: INTEGER) : INTEGER ;
BEGIN
IF bound=0
THEN
RETURN rand ()
ELSE
RETURN rand () MOD bound
END
END RandomInt ;
(*
RandomCard - return a CARDINAL in the range 0..bound-1
*)
PROCEDURE RandomCard (bound: CARDINAL) : CARDINAL ;
VAR
c: CARDINAL ;
BEGIN
RandomBytes (c) ;
RETURN c MOD bound
END RandomCard ;
(*
RandomReal - return a REAL number in the range 0.0..1.0
*)
PROCEDURE RandomReal () : REAL ;
BEGIN
RETURN RandomLongReal ()
END RandomReal ;
(*
RandomLongReal - return a LONGREAL number in the range 0.0..1.0
*)
PROCEDURE RandomLongReal () : LONGREAL ;
VAR
l: LONGCARD ;
BEGIN
RandomBytes (l) ;
RETURN VAL (LONGREAL, l) / VAL (LONGREAL, MAX (LONGCARD))
END RandomLongReal ;
BEGIN
Randomize
END Random.
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