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(* RandomNumber.mod implement a set of random number procedures for pervasive types.
Copyright (C) 2012-2025 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 RandomNumber ;
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 [low .. high].
*)
PROCEDURE RandomInt (low, high: INTEGER) : INTEGER ;
BEGIN
RETURN VAL(INTEGER, RandomLongInt(low, high))
END RandomInt ;
(*
RandomShortInt - return an SHORTINT in the range [low..high].
*)
PROCEDURE RandomShortInt (low, high: SHORTINT) : SHORTINT ;
BEGIN
RETURN VAL(SHORTINT, RandomInt(low, high))
END RandomShortInt ;
(*
RandomLongInt - return an LONGINT in the range [low..high].
*)
PROCEDURE RandomLongInt (low, high: LONGINT) : LONGINT ;
VAR
random: LONGINT ;
values,
number: LONGCARD ;
BEGIN
RandomBytes(number) ;
IF (low=0) AND (high=0)
THEN
RETURN number
ELSE
values := high-low;
random := number MOD (values+1) ;
RETURN random+low
END
END RandomLongInt ;
(*
RandomLongCard - return an LONGCARD in the range [low..high].
*)
PROCEDURE RandomLongCard (low, high: LONGCARD) : LONGCARD ;
VAR
random,
values,
number: LONGCARD ;
BEGIN
RandomBytes(number) ;
IF (low=0) AND (high=0)
THEN
RETURN number
ELSE
values := high-low;
random := number MOD (values+1) ;
RETURN random+low
END
END RandomLongCard ;
(*
RandomCard - return a CARDINAL in the range [low..high].
*)
PROCEDURE RandomCard (low, high: CARDINAL) : CARDINAL ;
BEGIN
RETURN RandomLongCard(low, high)
END RandomCard ;
(*
RandomShortCard - return a SHORTCARD in the range [low..high].
*)
PROCEDURE RandomShortCard (low, high: CARDINAL) : CARDINAL ;
BEGIN
RETURN RandomLongCard(low, high)
END RandomShortCard ;
(*
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 ;
(*
RandomShortReal - return a SHORTREAL number in the range 0.0..1.0
*)
PROCEDURE RandomShortReal () : SHORTREAL ;
BEGIN
RETURN RandomLongReal()
END RandomShortReal ;
BEGIN
Randomize
END RandomNumber.
|
