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410 lines
13 KiB
PHP
410 lines
13 KiB
PHP
{
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$Id$
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This file is part of the Free Pascal run time library.
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Copyright (c) 1999-2000 by Michael Van Canneyt,
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member of the Free Pascal development team
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See the file COPYING.FPC, included in this distribution,
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for details about the copyright.
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This program 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.
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**********************************************************************}
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type
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{ See symdefh.inc tfloattyp }
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treal_type = (rt_s32real,rt_s64real,rt_s80real,rt_c64bit,rt_f16bit,rt_f32bit);
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{ corresponding to single double extended fixed comp for i386 }
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Procedure str_real (len,f : longint; d : ValReal; real_type :treal_type; var s : string);
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{$ifdef SUPPORT_EXTENDED}
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type
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TSplitExtended = packed record
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case byte of
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0: (bytes: Array[0..9] of byte);
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1: (words: Array[0..4] of word);
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2: (cards: Array[0..1] of cardinal; w: word);
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end;
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const
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maxDigits = 17;
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{$else}
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{$ifdef SUPPORT_DOUBLE}
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type
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TSplitDouble = packed record
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case byte of
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0: (bytes: Array[0..7] of byte);
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1: (words: Array[0..3] of word);
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2: (cards: Array[0..1] of cardinal);
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end;
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const
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maxDigits = 14;
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{$else}
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{$ifdef SUPPORT_SINGLE}
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type
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TSplitSingle = packed record
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case byte of
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0: (bytes: Array[0..3] of byte);
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1: (words: Array[0..1] of word);
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2: (cards: Array[0..0] of cardinal);
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end;
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const
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maxDigits = 9;
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{$endif SUPPORT_SINGLE}
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{$endif SUPPORT_DOUBLE}
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{$endif SUPPORT_EXTENDED}
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type
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{ the value in the last position is used for rounding }
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TIntPartStack = array[1..maxDigits+1] of valReal;
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var
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roundCorr, corrVal: valReal;
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intPart, spos, endpos, fracCount: longint;
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correct, currprec: longint;
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temp : string;
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power : string[10];
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sign : boolean;
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dot : byte;
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mantZero, expMaximal: boolean;
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procedure RoundStr(var s: string; lastPos: byte);
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var carry: longint;
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begin
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carry := 1;
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repeat
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s[lastPos] := chr(ord(s[lastPos])+carry);
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carry := 0;
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if s[lastPos] > '9' then
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begin
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s[lastPos] := '0';
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carry := 1;
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end;
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dec(lastPos);
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until carry = 0;
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end;
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procedure getIntPart(d: extended);
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var
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intPartStack: TIntPartStack;
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stackPtr, endStackPtr, digits: longint;
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overflow: boolean;
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begin
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{ position in the stack (gets increased before first write) }
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stackPtr := 0;
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{ number of digits processed }
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digits := 0;
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{ did we wrap around in the stack? Necessary to know whether we should round }
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overflow :=false;
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{ generate a list consisting of d, d/10, d/100, ... until d < 1.0 }
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while d > 1.0-roundCorr do
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begin
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inc(stackPtr);
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inc(digits);
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if stackPtr > maxDigits+1 then
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begin
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stackPtr := 1;
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overflow := true;
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end;
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intPartStack[stackPtr] := d;
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d := d / 10.0;
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end;
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{ if no integer part, exit }
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if digits = 0 then
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exit;
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endStackPtr := stackPtr+1;
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if endStackPtr > maxDigits + 1 then
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endStackPtr := 1;
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{ now, all digits are calculated using trunc(d*10^(-n)-int(d*10^(-n-1))*10) }
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corrVal := 0.0;
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{ the power of 10 with which the resulting string has to be "multiplied" }
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{ if the decimal point is placed after the first significant digit }
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correct := digits-1;
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repeat
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if (currprec > 0) then
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begin
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intPart:= trunc(intPartStack[stackPtr]-corrVal);
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dec(currPrec);
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inc(spos);
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temp[spos] := chr(intPart+ord('0'));
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if temp[spos] > '9' then
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begin
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temp[spos] := chr(ord(temp[spos])-10);
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roundStr(temp,spos-1);
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end;
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end;
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corrVal := int(intPartStack[stackPtr]) * 10.0;
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dec(stackPtr);
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if stackPtr = 0 then
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stackPtr := maxDigits+1;
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until (overflow and (stackPtr = endStackPtr)) or
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(not overflow and (stackPtr = maxDigits+1)) or (currPrec = 0);
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{ round if we didn't use all available digits yet and if the }
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{ remainder is > 5 }
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if overflow and
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(trunc(intPartStack[stackPtr]-corrVal) > 5.0 - roundCorr) then
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roundStr(temp,spos);
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end;
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var maxlen : longint; { Maximal length of string for float }
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minlen : longint; { Minimal length of string for float }
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explen : longint; { Length of exponent, including E and sign.
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Must be strictly larger than 2 }
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const
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maxexp = 1e+35; { Maximum value for decimal expressions }
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minexp = 1e-35; { Minimum value for decimal expressions }
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zero = '0000000000000000000000000000000000000000';
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begin
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case real_type of
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rt_s32real :
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begin
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maxlen:=16;
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minlen:=8;
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explen:=4;
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{ correction used with comparing to avoid rounding/precision errors }
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roundCorr := (1/exp((16-4-3)*ln(10)));
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end;
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rt_s64real :
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begin
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{ if the maximum suppported type is double, we can print out one digit }
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{ less, because otherwise we can't round properly and 1e-400 becomes }
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{ 0.99999999999e-400 (JM) }
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{$ifdef support_extended}
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maxlen:=23;
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{ correction used with comparing to avoid rounding/precision errors }
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roundCorr := (1/exp((23-5-3)*ln(10)));
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{$else support_extended}
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{$ifdef support_double}
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maxlen := 22;
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{ correction used with comparing to avoid rounding/precision errors }
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roundCorr := (1/exp((22-4-3)*ln(10)));
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{$endif support_double}
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{$endif support_extended}
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minlen:=9;
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explen:=5;
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end;
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rt_s80real :
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begin
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{ Different in TP help, but this way the output is the same (JM) }
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maxlen:=25;
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minlen:=10;
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explen:=6;
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{ correction used with comparing to avoid rounding/precision errors }
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roundCorr := (1/exp((25-6-3)*ln(10)));
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end;
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rt_c64bit :
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begin
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maxlen:=23;
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minlen:=10;
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{ according to TP (was 5) (FK) }
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explen:=6;
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{ correction used with comparing to avoid rounding/precision errors }
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roundCorr := (1/exp((23-6-3)*ln(10)));
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end;
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rt_f16bit :
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begin
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maxlen:=16;
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minlen:=8;
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explen:=4;
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{ correction used with comparing to avoid rounding/precision errors }
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roundCorr := (1/exp((16-4-3)*ln(10)));
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end;
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rt_f32bit :
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begin
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maxlen:=16;
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minlen:=8;
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explen:=4;
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{ correction used with comparing to avoid rounding/precision errors }
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roundCorr := (1/exp((16-4-3)*ln(10)));
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end;
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end;
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{ check parameters }
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{ default value for length is -32767 }
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if len=-32767 then
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len:=maxlen;
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{ determine sign. before precision, needs 2 less calls to abs() }
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{$ifndef big_endian}
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{$ifdef SUPPORT_EXTENDED}
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{ extended, format (MSB): 1 Sign bit, 15 bit exponent, 64 bit mantissa }
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sign := (TSplitExtended(d).w and $8000) <> 0;
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expMaximal := (TSplitExtended(d).w and $7fff) = 32767;
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mantZero := (TSplitExtended(d).cards[0] = 0) and
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(TSplitExtended(d).cards[1] = 0);
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{$else SUPPORT_EXTENDED}
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{$ifdef SUPPORT_DOUBLE}
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{ double, format (MSB): 1 Sign bit, 11 bit exponent, 52 bit mantissa }
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sign := ((TSplitDouble(d).cards[1] shr 20) and $800) <> 0;
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expMaximal := ((TSplitDouble(d).cards[1] shr 20) and $7ff) = 2047;
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mantZero := (TSplitDouble(d).cards[1] and $fffff = 0) and
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(TSplitDouble(d).cards[0] = 0);
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{$else SUPPORT_DOUBLE}
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{$ifdef SUPPORT_SINGLE}
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{ single, format (MSB): 1 Sign bit, 8 bit exponent, 23 bit mantissa }
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sign := ((TSplitSingle(d).words[1] shr 7) and $100) <> 0;
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expMaximal := ((TSplitSingle(d).words[1] shr 7) and $ff) = 255;
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mantZero := (TSplitSingle(d).cards[0] and $7fffff = 0);
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{$else SUPPORT_SINGLE}
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{$error No big endian floating type supported yet in real2str}
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{$endif SUPPORT_SINGLE}
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{$endif SUPPORT_DOUBLE}
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{$endif SUPPORT_EXTENDED}
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{$else big_endian}
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{$error sign/NaN/Inf not yet supported for big endian CPU's in str_real}
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{$endif big_endian}
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if expMaximal then
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if mantZero then
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if sign then
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temp := '-Inf'
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else temp := 'Inf'
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else temp := 'NaN'
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else
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begin
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{ d:=abs(d); this converts d to double so we loose precision }
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{ for the same reason I converted d:=frac(d) to d:=d-int(d); (PM) }
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if sign then
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d:=-d;
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{ determine precision : maximal precision is : }
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currPrec := maxlen-explen-2;
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{ this is also the maximal number of decimals !!}
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if f>currprec then
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f:=currprec;
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{ when doing a fixed-point, we need less characters.}
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if (f<0) {or ((d<>0) and ((d>maxexp) and (d>minexp)))} then
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begin
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{ determine maximal number of decimals }
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if (len>=0) and (len<minlen) then
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len:=minlen;
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if (len>0) and (len<maxlen) then
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currprec:=len-explen-2;
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end;
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{ leading zero, may be necessary for things like str(9.999:0:2) to }
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{ be able to insert an extra character at the start of the string }
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temp := ' 0';
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{ position in the temporary output string }
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spos := 2;
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{ get the integer part }
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correct := 0;
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GetIntPart(d);
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{ now process the fractional part }
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if d > 1.0- roundCorr then
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d := frac(d);
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{ if we have to round earlier than the amount of available precision, }
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{ only calculate digits up to that point }
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if (f >= 0) and (currPrec > f) then
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currPrec := f;
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{ if integer part was zero, go to the first significant digit of the }
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{ fractional part }
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{ make sure we don't get an endless loop if d = 0 }
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if (spos = 2) and (d <> 0.0) then
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begin
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{ take rounding errors into account }
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while d < 0.1-roundCorr do
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begin
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d := d * 10.0;
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dec(correct);
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{ adjust the precision depending on how many digits we }
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{ already "processed" by multiplying by 10, but only if }
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{ the amount of precision is specified }
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if f >= 0 then
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dec(currPrec);
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end;
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dec(correct);
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end;
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{ current length of the output string in endPos }
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endPos := spos;
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{ always calculate at least 1 fractional digit for rounding }
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if (currPrec >= 0) then
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begin
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corrVal := 0.5;
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for fracCount := 1 to currPrec do
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corrVal := corrVal / 10.0;
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if d >= corrVal then
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d := d + corrVal;
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if int(d) = 1 then
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begin
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roundStr(temp,spos);
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d := frac(d);
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end;
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{ calculate the necessary fractional digits }
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for fracCount := 1 to currPrec do
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begin
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if d > 1.0- roundCorr then
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d := frac(d) * 10.0
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else d := d * 10.0;
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inc(spos);
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temp[spos] := chr(trunc(d)+ord('0'));
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if temp[spos] > '9' then
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{ possible because trunc and the "*10.0" aren't exact :( }
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begin
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temp[spos] := chr(ord(temp[spos]) - 10);
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roundStr(temp,spos-1);
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end;
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end;
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{ new length of string }
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endPos := spos;
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end;
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setLength(temp,endPos);
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{ delete leading zero if we didn't need it while rounding at the }
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{ string level }
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if temp[2] = '0' then
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delete(temp,2,1)
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{ the rounding caused an overflow to the next power of 10 }
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else inc(correct);
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if sign then
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temp[1] := '-';
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if (f<0) or (correct>(round(ln(maxexp)/ln(10)))) then
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begin
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insert ('.',temp,3);
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str(abs(correct),power);
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if length(power)<explen-2 then
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power:=copy(zero,1,explen-2-length(power))+power;
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if correct<0 then
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power:='-'+power
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else
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power:='+'+power;
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temp:=temp+'E'+power;
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end
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else
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begin
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if not sign then
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begin
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delete(temp,1,1);
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dot := 2
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end
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else
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dot := 3;
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{ set zeroes and dot }
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if correct>=0 then
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begin
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if length(temp)<correct+dot+f-1 then
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temp:=temp+copy(zero,1,correct+dot+f-length(temp));
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insert ('.',temp,correct+dot);
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end
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else
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begin
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correct:=abs(correct);
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insert(copy(zero,1,correct),temp,dot-1);
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insert ('.',temp,dot);
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end;
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{ correct length to fit precision }
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if f>0 then
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setlength(temp,pos('.',temp)+f)
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else
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setLength(temp,pos('.',temp)-1);
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end;
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end;
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if length(temp)<len then
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s:=space(len-length(temp))+temp
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else s:=temp;
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end;
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{
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$Log$
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Revision 1.2 2000-07-13 11:33:45 michael
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+ removed logs
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}
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