48 lines
954 B
Modula-2
48 lines
954 B
Modula-2
(*
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(c) copyright 1988 by the Vrije Universiteit, Amsterdam, The Netherlands.
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See the copyright notice in the ACK home directory, in the file "Copyright".
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*)
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(*$R-*)
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IMPLEMENTATION MODULE random;
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(*
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Module: random numbers
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Author: Ceriel J.H. Jacobs
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Version: $Header$
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*)
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FROM Unix IMPORT getpid, time;
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TYPE index = [0..54];
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VAR X: ARRAY index OF CARDINAL;
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k, j: index;
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PROCEDURE Random(): CARDINAL;
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BEGIN
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IF k+1 > 54 THEN k := 0; ELSE INC(k) END;
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IF j+1 > 54 THEN j := 0; ELSE INC(j) END;
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X[k] := X[k] + X[j];
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RETURN X[k]
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END Random;
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PROCEDURE Uniform (lwb, upb: CARDINAL): CARDINAL;
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BEGIN
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IF upb <= lwb THEN RETURN lwb; END;
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RETURN lwb + (Random() MOD (upb - lwb + 1));
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END Uniform;
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PROCEDURE StartSeed(seed: CARDINAL);
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BEGIN
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X[0] := seed;
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FOR k := 1 TO 54 DO
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X[k] := X[k-1] * 1297;
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END;
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k := 54;
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j := 30;
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END StartSeed;
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BEGIN
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X[0] := time(NIL);
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StartSeed(CARDINAL(getpid()) * X[0]);
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END random.
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