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101 lines
2.9 KiB
Modula-2
101 lines
2.9 KiB
Modula-2
(* $Id: LongInts.Mod,v 1.3 1999/09/02 13:14:52 acken Exp $ *)
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MODULE oocLongInts;
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(*
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LongInts - Simple extended integer implementation.
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Copyright (C) 1996 Michael Griebling
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This module is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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This module is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*)
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CONST
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B*=8000H;
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TYPE
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LongInt*=ARRAY 170 OF INTEGER;
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PROCEDURE MinDigit * (VAR w: LongInt) : LONGINT;
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VAR min, l: LONGINT;
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BEGIN
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min:=1; l:=LEN(w)-1;
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WHILE (min<l) & (w[min]=0) DO INC(min) END;
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RETURN min
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END MinDigit;
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PROCEDURE MultDigit * (VAR w: LongInt; digit, k: LONGINT);
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VAR i, t, min: LONGINT;
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BEGIN
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i:=LEN(w)-1; min:=MinDigit(w)-2;
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REPEAT
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t:=w[i]*digit+k; (* multiply *)
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w[i]:=SHORT(t MOD B); k:=t DIV B; (* generate result & carry *)
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DEC(i)
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UNTIL i=min
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END MultDigit;
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PROCEDURE AddDigit * (VAR w: LongInt; k: LONGINT);
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VAR i, t, min: LONGINT;
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BEGIN
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i:=LEN(w)-1; min:=MinDigit(w)-2;
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REPEAT
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t:=w[i]+k; (* add *)
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w[i]:=SHORT(t MOD B); k:=t DIV B; (* generate result & carry *)
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DEC(i)
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UNTIL i=min
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END AddDigit;
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PROCEDURE DivDigit * (VAR w: LongInt; digit: LONGINT; VAR r: LONGINT);
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VAR j, t, m: LONGINT;
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BEGIN
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j:=MinDigit(w)-1; r:=0; m:=LEN(w)-1;
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REPEAT
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t:=r*B+w[j];
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w[j]:=SHORT(t DIV digit); r:=t MOD digit; (* generate result & remainder *)
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INC(j)
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UNTIL j>m
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END DivDigit;
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PROCEDURE TenPower * (VAR x: LongInt; power: INTEGER);
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VAR exp, i: INTEGER; d: LONGINT;
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BEGIN
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IF power>0 THEN
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exp:=power DIV 4; power:=power MOD 4;
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FOR i:=1 TO exp DO MultDigit(x, 10000, 0) END;
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FOR i:=1 TO power DO MultDigit(x, 10, 0) END
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ELSIF power<0 THEN
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power:=-power;
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exp:=power DIV 4; power:=power MOD 4;
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FOR i:=1 TO exp DO DivDigit(x, 10000, d) END;
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FOR i:=1 TO power DO DivDigit(x, 10, d) END
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END
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END TenPower;
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PROCEDURE BPower * (VAR x: LongInt; power: INTEGER);
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VAR i, lx: LONGINT;
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BEGIN
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lx:=LEN(x);
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IF power>0 THEN
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FOR i:=1 TO lx-1-power DO x[i]:=x[i+power] END;
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FOR i:=lx-power TO lx-1 DO x[i]:=0 END
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ELSIF power<0 THEN
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power:=-power;
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FOR i:=lx-1-power TO 1 BY -1 DO x[i+power]:=x[i] END;
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FOR i:=1 TO power DO x[i]:=0 END
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END
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END BPower;
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END oocLongInts.
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