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(* $Id: LongInts.Mod,v 1.3 1999/09/02 13:14:52 acken Exp $ *)
MODULE LongInts;
(*
LongInts - Simple extended integer implementation.
Copyright (C) 1996 Michael Griebling
This module is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
This module 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 Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*)
CONST
B*=8000H;
TYPE
LongInt*=ARRAY 170 OF INTEGER;
PROCEDURE MinDigit * (VAR w: LongInt) : LONGINT;
VAR min, l: LONGINT;
BEGIN
min:=1; l:=LEN(w)-1;
WHILE (min<l) & (w[min]=0) DO INC(min) END;
RETURN min
END MinDigit;
PROCEDURE MultDigit * (VAR w: LongInt; digit, k: LONGINT);
VAR i, t, min: LONGINT;
BEGIN
i:=LEN(w)-1; min:=MinDigit(w)-2;
REPEAT
t:=w[i]*digit+k; (* multiply *)
w[i]:=SHORT(t MOD B); k:=t DIV B; (* generate result & carry *)
DEC(i)
UNTIL i=min
END MultDigit;
PROCEDURE AddDigit * (VAR w: LongInt; k: LONGINT);
VAR i, t, min: LONGINT;
BEGIN
i:=LEN(w)-1; min:=MinDigit(w)-2;
REPEAT
t:=w[i]+k; (* add *)
w[i]:=SHORT(t MOD B); k:=t DIV B; (* generate result & carry *)
DEC(i)
UNTIL i=min
END AddDigit;
PROCEDURE DivDigit * (VAR w: LongInt; digit: LONGINT; VAR r: LONGINT);
VAR j, t, m: LONGINT;
BEGIN
j:=MinDigit(w)-1; r:=0; m:=LEN(w)-1;
REPEAT
t:=r*B+w[j];
w[j]:=SHORT(t DIV digit); r:=t MOD digit; (* generate result & remainder *)
INC(j)
UNTIL j>m
END DivDigit;
PROCEDURE TenPower * (VAR x: LongInt; power: INTEGER);
VAR exp, i: INTEGER; d: LONGINT;
BEGIN
IF power>0 THEN
exp:=power DIV 4; power:=power MOD 4;
FOR i:=1 TO exp DO MultDigit(x, 10000, 0) END;
FOR i:=1 TO power DO MultDigit(x, 10, 0) END
ELSIF power<0 THEN
power:=-power;
exp:=power DIV 4; power:=power MOD 4;
FOR i:=1 TO exp DO DivDigit(x, 10000, d) END;
FOR i:=1 TO power DO DivDigit(x, 10, d) END
END
END TenPower;
PROCEDURE BPower * (VAR x: LongInt; power: INTEGER);
VAR i, lx: LONGINT;
BEGIN
lx:=LEN(x);
IF power>0 THEN
FOR i:=1 TO lx-1-power DO x[i]:=x[i+power] END;
FOR i:=lx-power TO lx-1 DO x[i]:=0 END
ELSIF power<0 THEN
power:=-power;
FOR i:=lx-1-power TO 1 BY -1 DO x[i+power]:=x[i] END;
FOR i:=1 TO power DO x[i]:=0 END
END
END BPower;
END LongInts.
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