324 lines
6.8 KiB
Modula-2
324 lines
6.8 KiB
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 RealConversions;
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(*
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Module: string-to-real and real-to-string conversions
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Author: Ceriel J.H. Jacobs
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Version: $Header$
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*)
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PROCEDURE RealToString(arg: REAL;
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width, digits: INTEGER;
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VAR str: ARRAY OF CHAR;
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VAR ok: BOOLEAN);
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BEGIN
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LongRealToString(LONG(arg), width, digits, str, ok);
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END RealToString;
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TYPE
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Powers = RECORD
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pval: LONGREAL;
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rpval: LONGREAL;
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exp: INTEGER
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END;
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VAR Powers10: ARRAY[1..6] OF Powers;
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PROCEDURE LongRealToString(arg: LONGREAL;
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width, digits: INTEGER;
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VAR str: ARRAY OF CHAR;
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VAR ok: BOOLEAN);
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VAR pointpos: INTEGER;
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i: CARDINAL;
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ecvtflag: BOOLEAN;
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r: LONGREAL;
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ind1, ind2 : CARDINAL;
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sign: BOOLEAN;
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ndigits: CARDINAL;
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BEGIN
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r := arg;
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IF digits < 0 THEN
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ecvtflag := TRUE;
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ndigits := -digits;
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ELSE
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ecvtflag := FALSE;
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ndigits := digits;
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END;
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IF (HIGH(str) < ndigits + 3) THEN
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str[0] := 0C; ok := FALSE; RETURN
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END;
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pointpos := 0;
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sign := r < 0.0D;
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IF sign THEN r := -r END;
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IF r # 0.0D THEN
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IF r >= 10.0D THEN
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FOR i := 1 TO 6 DO
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WITH Powers10[i] DO
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WHILE r >= pval DO
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r := r * rpval;
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INC(pointpos, exp)
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END;
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END;
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END;
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END;
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IF r < 1.0D THEN
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FOR i := 1 TO 6 DO
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WITH Powers10[i] DO
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WHILE r*pval < 10.0D DO
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r := r * pval;
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DEC(pointpos, exp)
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END;
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END;
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END;
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END;
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(* Now, we have r in [1.0, 10.0) *)
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INC(pointpos);
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END;
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ind1 := 0;
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ok := TRUE;
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ind2 := ndigits+1;
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IF NOT ecvtflag THEN
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IF INTEGER(ind2) + pointpos < 0 THEN
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ind2 := 0;
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ELSE
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ind2 := INTEGER(ind2) + pointpos
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END;
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END;
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IF ind2 > HIGH(str) THEN
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ok := FALSE;
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str[0] := 0C;
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RETURN;
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END;
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WHILE ind1 < ind2 DO
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str[ind1] := CHR(TRUNC(r)+ORD('0'));
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r := 10.0D * (r - FLOATD(TRUNC(r)));
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INC(ind1);
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END;
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IF ind2 > 0 THEN
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DEC(ind2);
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ind1 := ind2;
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str[ind2] := CHR(ORD(str[ind2])+5);
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WHILE str[ind2] > '9' DO
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str[ind2] := '0';
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IF ind2 > 0 THEN
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DEC(ind2);
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str[ind2] := CHR(ORD(str[ind2])+1);
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ELSE
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str[ind2] := '1';
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INC(pointpos);
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IF NOT ecvtflag THEN
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IF ind1 > 0 THEN str[ind1] := '0'; END;
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INC(ind1);
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END;
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END;
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END;
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END;
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IF ecvtflag THEN
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FOR i := ind1 TO 2 BY -1 DO
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str[i] := str[i-1];
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END;
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str[1] := '.';
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INC(ind1);
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IF sign THEN
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FOR i := ind1 TO 1 BY -1 DO
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str[i] := str[i-1];
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END;
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INC(ind1);
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str[0] := '-';
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END;
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IF (ind1 + 4) > HIGH(str) THEN
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str[0] := 0C;
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ok := FALSE;
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RETURN;
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END;
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str[ind1] := 'E'; INC(ind1);
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IF arg # 0.0D THEN DEC(pointpos); END;
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IF pointpos < 0 THEN
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pointpos := -pointpos;
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str[ind1] := '-';
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ELSE
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str[ind1] := '+';
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END;
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INC(ind1);
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str[ind1] := CHR(ORD('0') + CARDINAL(pointpos DIV 100));
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pointpos := pointpos MOD 100;
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INC(ind1);
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str[ind1] := CHR(ORD('0') + CARDINAL(pointpos DIV 10));
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INC(ind1);
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str[ind1] := CHR(ORD('0') + CARDINAL(pointpos MOD 10));
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ELSE
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IF pointpos <= 0 THEN
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FOR i := ind1 TO 1 BY -1 DO
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str[i+CARDINAL(-pointpos)] := str[i-1];
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END;
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FOR i := 0 TO CARDINAL(-pointpos) DO
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str[i] := '0';
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END;
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ind1 := ind1 + CARDINAL(1 - pointpos);
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pointpos := 1;
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END;
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FOR i := ind1 TO CARDINAL(pointpos+1) BY -1 DO
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str[i] := str[i-1];
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END;
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IF ndigits = 0 THEN
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str[pointpos] := 0C;
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ELSE
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str[pointpos] := '.';
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END;
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IF sign THEN
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FOR i := ind1 TO 0 BY -1 DO
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str[i+1] := str[i];
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END;
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str[0] := '-';
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INC(ind1);
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END;
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END;
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IF (ind1+1) <= HIGH(str) THEN str[ind1+1] := 0C; END;
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IF ind1 >= CARDINAL(width) THEN
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ok := FALSE;
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RETURN;
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END;
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IF width > 0 THEN
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DEC(width);
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END;
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IF (width > 0) AND (ind1 < CARDINAL(width)) THEN
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FOR i := ind1 TO 0 BY -1 DO
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str[i + CARDINAL(width) - ind1] := str[i];
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END;
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FOR i := 0 TO CARDINAL(width)-(ind1+1) DO
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str[i] := ' ';
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END;
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ind1 := CARDINAL(width);
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IF (ind1+1) <= HIGH(str) THEN
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FOR ind1 := ind1+1 TO HIGH(str) DO
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str[ind1] := 0C;
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END;
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END;
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END;
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END LongRealToString;
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PROCEDURE StringToReal(str: ARRAY OF CHAR;
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VAR r: REAL; VAR ok: BOOLEAN);
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VAR x: LONGREAL;
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BEGIN
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StringToLongReal(str, x, ok);
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IF ok THEN
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r := x;
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END;
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END StringToReal;
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PROCEDURE StringToLongReal(str: ARRAY OF CHAR;
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VAR r: LONGREAL; VAR ok: BOOLEAN);
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CONST BIG = 1.0D17;
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TYPE SETOFCHAR = SET OF CHAR;
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VAR pow10 : INTEGER;
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i : INTEGER;
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e : LONGREAL;
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ch : CHAR;
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signed: BOOLEAN;
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signedexp: BOOLEAN;
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iB: CARDINAL;
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BEGIN
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r := 0.0D;
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pow10 := 0;
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iB := 0;
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ok := TRUE;
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signed := FALSE;
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WHILE (str[iB] = ' ') OR (str[iB] = CHR(9)) DO
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INC(iB);
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IF iB > HIGH(str) THEN
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ok := FALSE;
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RETURN;
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END;
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END;
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IF str[iB] = '-' THEN signed := TRUE; INC(iB)
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ELSIF str[iB] = '+' THEN INC(iB)
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END;
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ch := str[iB]; INC(iB);
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IF NOT (ch IN SETOFCHAR{'0'..'9'}) THEN ok := FALSE; RETURN END;
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REPEAT
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IF r>BIG THEN INC(pow10) ELSE r:= 10.0D*r+FLOATD(ORD(ch)-ORD('0')) END;
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IF iB <= HIGH(str) THEN
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ch := str[iB]; INC(iB);
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END;
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UNTIL (iB > HIGH(str)) OR NOT (ch IN SETOFCHAR{'0'..'9'});
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IF (ch = '.') AND (iB <= HIGH(str)) THEN
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ch := str[iB]; INC(iB);
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IF NOT (ch IN SETOFCHAR{'0'..'9'}) THEN ok := FALSE; RETURN END;
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REPEAT
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IF r < BIG THEN
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r := 10.0D * r + FLOATD(ORD(ch)-ORD('0'));
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DEC(pow10);
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END;
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IF iB <= HIGH(str) THEN
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ch := str[iB]; INC(iB);
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END;
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UNTIL (iB > HIGH(str)) OR NOT (ch IN SETOFCHAR{'0'..'9'});
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END;
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IF (ch = 'E') THEN
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IF iB > HIGH(str) THEN
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ok := FALSE;
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RETURN;
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ELSE
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ch := str[iB]; INC(iB);
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END;
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i := 0;
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signedexp := FALSE;
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IF (ch = '-') OR (ch = '+') THEN
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signedexp := ch = '-';
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IF iB > HIGH(str) THEN
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ok := FALSE;
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RETURN;
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ELSE
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ch := str[iB]; INC(iB);
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END;
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END;
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IF NOT (ch IN SETOFCHAR{'0'..'9'}) THEN ok := FALSE; RETURN END;
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REPEAT
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i := i*10 + INTEGER(ORD(ch) - ORD('0'));
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IF iB <= HIGH(str) THEN
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ch := str[iB]; INC(iB);
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END;
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UNTIL (iB > HIGH(str)) OR NOT (ch IN SETOFCHAR{'0'..'9'});
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IF signedexp THEN i := -i END;
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pow10 := pow10 + i;
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END;
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IF pow10 < 0 THEN i := -pow10; ELSE i := pow10; END;
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e := 1.0D;
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DEC(i);
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WHILE i >= 10 DO
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e := e * 10000000000.0D;
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DEC(i,10);
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END;
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WHILE i >= 0 DO
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e := e * 10.0D;
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DEC(i)
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END;
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IF pow10<0 THEN
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r := r / e;
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ELSE
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r := r * e;
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END;
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IF signed THEN r := -r; END;
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IF (iB <= HIGH(str)) AND (ORD(ch) > ORD(' ')) THEN ok := FALSE; END
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END StringToLongReal;
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BEGIN
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WITH Powers10[1] DO pval := 1.0D32; rpval := 1.0D-32; exp := 32 END;
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WITH Powers10[2] DO pval := 1.0D16; rpval := 1.0D-16; exp := 16 END;
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WITH Powers10[3] DO pval := 1.0D8; rpval := 1.0D-8; exp := 8 END;
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WITH Powers10[4] DO pval := 1.0D4; rpval := 1.0D-4; exp := 4 END;
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WITH Powers10[5] DO pval := 1.0D2; rpval := 1.0D-2; exp := 2 END;
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WITH Powers10[6] DO pval := 1.0D1; rpval := 1.0D-1; exp := 1 END;
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END RealConversions.
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