-- --
-- S Y S T E M . V A L _ R E A L --
-- --
--- S p e c --
+-- B o d y --
-- --
--- $Revision: 1.18 $
--- --
--- Copyright (C) 1992-2000 Free Software Foundation, Inc. --
+-- Copyright (C) 1992-2005, Free Software Foundation, Inc. --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
-- for more details. You should have received a copy of the GNU General --
-- Public License distributed with GNAT; see file COPYING. If not, write --
--- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
--- MA 02111-1307, USA. --
+-- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, --
+-- Boston, MA 02110-1301, USA. --
-- --
-- As a special exception, if other files instantiate generics from this --
-- unit, or you link this unit with other files to produce an executable, --
-- covered by the GNU Public License. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
--- It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). --
+-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
---------------
function Scan_Real
- (Str : String;
- Ptr : access Integer;
- Max : Integer)
- return Long_Long_Float
+ (Str : String;
+ Ptr : access Integer;
+ Max : Integer) return Long_Long_Float
is
procedure Reset;
pragma Import (C, Reset, "__gnat_init_float");
After_Point : Natural := 0;
-- Set to 1 after the point
+ Num_Saved_Zeroes : Natural := 0;
+ -- This counts zeroes after the decimal point. A non-zero value means
+ -- that this number of previously scanned digits are zero. if the end
+ -- of the number is reached, these zeroes are simply discarded, which
+ -- ensures that trailing zeroes after the point never affect the value
+ -- (which might otherwise happen as a result of rounding). With this
+ -- processing in place, we can ensure that, for example, we get the
+ -- same exact result from 1.0E+49 and 1.0000000E+49. This is not
+ -- necessarily required in a case like this where the result is not
+ -- a machine number, but it is certainly a desirable behavior.
+
procedure Scanf;
-- Scans integer literal value starting at current character position.
-- For each digit encountered, Uval is multiplied by 10.0, and the new
-- return P points past the last character. On entry, the current
-- character is known to be a digit, so a numeral is definitely present.
+ -----------
+ -- Scanf --
+ -----------
+
procedure Scanf is
Digit : Natural;
begin
loop
Digit := Character'Pos (Str (P)) - Character'Pos ('0');
- Uval := Uval * 10.0 + Long_Long_Float (Digit);
P := P + 1;
- Scale := Scale - After_Point;
+
+ -- Save up trailing zeroes after the decimal point
+
+ if Digit = 0 and After_Point = 1 then
+ Num_Saved_Zeroes := Num_Saved_Zeroes + 1;
+
+ -- Here for a non-zero digit
+
+ else
+ -- First deal with any previously saved zeroes
+
+ if Num_Saved_Zeroes /= 0 then
+ while Num_Saved_Zeroes > Maxpow loop
+ Uval := Uval * Powten (Maxpow);
+ Num_Saved_Zeroes := Num_Saved_Zeroes - Maxpow;
+ Scale := Scale - Maxpow;
+ end loop;
+
+ Uval := Uval * Powten (Num_Saved_Zeroes);
+ Scale := Scale - Num_Saved_Zeroes;
+
+ Num_Saved_Zeroes := 0;
+ end if;
+
+ -- Accumulate new digit
+
+ Uval := Uval * 10.0 + Long_Long_Float (Digit);
+ Scale := Scale - After_Point;
+ end if;
-- Done if end of input field
raise Constraint_Error;
end if;
- P := P + 1;
- Fdigit := Long_Long_Float (Digit);
+ -- Save up trailing zeroes after the decimal point
+
+ if Digit = 0 and After_Point = 1 then
+ Num_Saved_Zeroes := Num_Saved_Zeroes + 1;
+
+ -- Here for a non-zero digit
- if Fdigit >= Base then
- Bad_Base := True;
else
- Scale := Scale - After_Point;
- Uval := Uval * Base + Fdigit;
+ -- First deal with any previously saved zeroes
+
+ if Num_Saved_Zeroes /= 0 then
+ Uval := Uval * Base ** Num_Saved_Zeroes;
+ Scale := Scale - Num_Saved_Zeroes;
+ Num_Saved_Zeroes := 0;
+ end if;
+
+ -- Now accumulate the new digit
+
+ Fdigit := Long_Long_Float (Digit);
+
+ if Fdigit >= Base then
+ Bad_Base := True;
+ else
+ Scale := Scale - After_Point;
+ Uval := Uval * Base + Fdigit;
+ end if;
end if;
+ P := P + 1;
+
if P > Max then
raise Constraint_Error;
if Base /= 10.0 then
Uval := Uval * Base ** Scale;
- -- For base 10, use power of ten table, repeatedly if necessary.
+ -- For base 10, use power of ten table, repeatedly if necessary
elsif Scale > 0 then
-
while Scale > Maxpow loop
Uval := Uval * Powten (Maxpow);
Scale := Scale - Maxpow;
end if;
elsif Scale < 0 then
-
while (-Scale) > Maxpow loop
Uval := Uval / Powten (Maxpow);
Scale := Scale + Maxpow;
return Uval;
end if;
end if;
-
end Scan_Real;
----------------
function Value_Real (Str : String) return Long_Long_Float is
V : Long_Long_Float;
P : aliased Integer := Str'First;
-
begin
V := Scan_Real (Str, P'Access, Str'Last);
Scan_Trailing_Blanks (Str, P);
return V;
-
end Value_Real;
end System.Val_Real;
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