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[/] [openrisc/] [trunk/] [gnu-src/] [gcc-4.5.1/] [gcc/] [ada/] [s-valllu.adb] - Blame information for rev 410

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1 281 jeremybenn
------------------------------------------------------------------------------
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--                                                                          --
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--                         GNAT COMPILER COMPONENTS                         --
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--                                                                          --
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--                       S Y S T E M . V A L _ L L U                        --
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--                                                                          --
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--                                 B o d y                                  --
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--                                                                          --
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--          Copyright (C) 1992-2009, Free Software Foundation, Inc.         --
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--                                                                          --
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-- GNAT is free software;  you can  redistribute it  and/or modify it under --
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-- terms of the  GNU General Public License as published  by the Free Soft- --
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-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
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-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
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-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
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-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
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--                                                                          --
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-- As a special exception under Section 7 of GPL version 3, you are granted --
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-- additional permissions described in the GCC Runtime Library Exception,   --
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-- version 3.1, as published by the Free Software Foundation.               --
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--                                                                          --
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-- You should have received a copy of the GNU General Public License and    --
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-- a copy of the GCC Runtime Library Exception along with this program;     --
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-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
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-- <http://www.gnu.org/licenses/>.                                          --
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--                                                                          --
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-- GNAT was originally developed  by the GNAT team at  New York University. --
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-- Extensive contributions were provided by Ada Core Technologies Inc.      --
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--                                                                          --
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------------------------------------------------------------------------------
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with System.Unsigned_Types; use System.Unsigned_Types;
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with System.Val_Util;       use System.Val_Util;
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package body System.Val_LLU is
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   ---------------------------------
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   -- Scan_Raw_Long_Long_Unsigned --
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   ---------------------------------
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   function Scan_Raw_Long_Long_Unsigned
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     (Str : String;
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      Ptr : not null access Integer;
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      Max : Integer) return Long_Long_Unsigned
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   is
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      P : Integer;
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      --  Local copy of the pointer
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      Uval : Long_Long_Unsigned;
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      --  Accumulated unsigned integer result
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      Expon : Integer;
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      --  Exponent value
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      Overflow : Boolean := False;
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      --  Set True if overflow is detected at any point
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      Base_Char : Character;
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      --  Base character (# or :) in based case
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      Base : Long_Long_Unsigned := 10;
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      --  Base value (reset in based case)
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      Digit : Long_Long_Unsigned;
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      --  Digit value
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   begin
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      P := Ptr.all;
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      Uval := Character'Pos (Str (P)) - Character'Pos ('0');
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      P := P + 1;
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      --  Scan out digits of what is either the number or the base.
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      --  In either case, we are definitely scanning out in base 10.
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      declare
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         Umax : constant := (Long_Long_Unsigned'Last - 9) / 10;
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         --  Max value which cannot overflow on accumulating next digit
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         Umax10 : constant := Long_Long_Unsigned'Last / 10;
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         --  Numbers bigger than Umax10 overflow if multiplied by 10
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      begin
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         --  Loop through decimal digits
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         loop
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            exit when P > Max;
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            Digit := Character'Pos (Str (P)) - Character'Pos ('0');
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            --  Non-digit encountered
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            if Digit > 9 then
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               if Str (P) = '_' then
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                  Scan_Underscore (Str, P, Ptr, Max, False);
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               else
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                  exit;
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               end if;
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            --  Accumulate result, checking for overflow
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            else
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               if Uval <= Umax then
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                  Uval := 10 * Uval + Digit;
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               elsif Uval > Umax10 then
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                  Overflow := True;
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               else
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                  Uval := 10 * Uval + Digit;
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                  if Uval < Umax10 then
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                     Overflow := True;
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                  end if;
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               end if;
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               P := P + 1;
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            end if;
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         end loop;
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      end;
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      Ptr.all := P;
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      --  Deal with based case
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      if P < Max and then (Str (P) = ':' or else Str (P) = '#') then
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         Base_Char := Str (P);
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         P := P + 1;
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         Base := Uval;
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         Uval := 0;
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         --  Check base value. Overflow is set True if we find a bad base, or
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         --  a digit that is out of range of the base. That way, we scan out
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         --  the numeral that is still syntactically correct, though illegal.
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         --  We use a safe base of 16 for this scan, to avoid zero divide.
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         if Base not in 2 .. 16 then
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            Overflow := True;
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            Base :=  16;
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         end if;
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         --  Scan out based integer
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         declare
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            Umax : constant Long_Long_Unsigned :=
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                     (Long_Long_Unsigned'Last - Base + 1) / Base;
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            --  Max value which cannot overflow on accumulating next digit
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            UmaxB : constant Long_Long_Unsigned :=
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                      Long_Long_Unsigned'Last / Base;
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            --  Numbers bigger than UmaxB overflow if multiplied by base
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         begin
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            --  Loop to scan out based integer value
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            loop
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               --  We require a digit at this stage
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               if Str (P) in '0' .. '9' then
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                  Digit := Character'Pos (Str (P)) - Character'Pos ('0');
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               elsif Str (P) in 'A' .. 'F' then
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                  Digit :=
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                    Character'Pos (Str (P)) - (Character'Pos ('A') - 10);
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               elsif Str (P) in 'a' .. 'f' then
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                  Digit :=
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                    Character'Pos (Str (P)) - (Character'Pos ('a') - 10);
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               --  If we don't have a digit, then this is not a based number
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               --  after all, so we use the value we scanned out as the base
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               --  (now in Base), and the pointer to the base character was
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               --  already stored in Ptr.all.
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173
               else
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                  Uval := Base;
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                  exit;
176
               end if;
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               --  If digit is too large, just signal overflow and continue.
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               --  The idea here is to keep scanning as long as the input is
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               --  syntactically valid, even if we have detected overflow
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182
               if Digit >= Base then
183
                  Overflow := True;
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185
               --  Here we accumulate the value, checking overflow
186
 
187
               elsif Uval <= Umax then
188
                  Uval := Base * Uval + Digit;
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190
               elsif Uval > UmaxB then
191
                  Overflow := True;
192
 
193
               else
194
                  Uval := Base * Uval + Digit;
195
 
196
                  if Uval < UmaxB then
197
                     Overflow := True;
198
                  end if;
199
               end if;
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201
               --  If at end of string with no base char, not a based number
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               --  but we signal Constraint_Error and set the pointer past
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               --  the end of the field, since this is what the ACVC tests
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               --  seem to require, see CE3704N, line 204.
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               P := P + 1;
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208
               if P > Max then
209
                  Ptr.all := P;
210
                  raise Constraint_Error;
211
               end if;
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               --  If terminating base character, we are done with loop
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               if Str (P) = Base_Char then
216
                  Ptr.all := P + 1;
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                  exit;
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               --  Deal with underscore
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221
               elsif Str (P) = '_' then
222
                  Scan_Underscore (Str, P, Ptr, Max, True);
223
               end if;
224
 
225
            end loop;
226
         end;
227
      end if;
228
 
229
      --  Come here with scanned unsigned value in Uval. The only remaining
230
      --  required step is to deal with exponent if one is present.
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232
      Expon := Scan_Exponent (Str, Ptr, Max);
233
 
234
      if Expon /= 0 and then Uval /= 0 then
235
 
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         --  For non-zero value, scale by exponent value. No need to do this
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         --  efficiently, since use of exponent in integer literals is rare,
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         --  and in any case the exponent cannot be very large.
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         declare
241
            UmaxB : constant Long_Long_Unsigned :=
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                      Long_Long_Unsigned'Last / Base;
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            --  Numbers bigger than UmaxB overflow if multiplied by base
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245
         begin
246
            for J in 1 .. Expon loop
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               if Uval > UmaxB then
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                  Overflow := True;
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                  exit;
250
               end if;
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252
               Uval := Uval * Base;
253
            end loop;
254
         end;
255
      end if;
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257
      --  Return result, dealing with sign and overflow
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259
      if Overflow then
260
         raise Constraint_Error;
261
      else
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         return Uval;
263
      end if;
264
   end Scan_Raw_Long_Long_Unsigned;
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266
   -----------------------------
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   -- Scan_Long_Long_Unsigned --
268
   -----------------------------
269
 
270
   function Scan_Long_Long_Unsigned
271
     (Str : String;
272
      Ptr : not null access Integer;
273
      Max : Integer) return Long_Long_Unsigned
274
   is
275
      Start : Positive;
276
      --  Save location of first non-blank character
277
 
278
   begin
279
      Scan_Plus_Sign (Str, Ptr, Max, Start);
280
 
281
      if Str (Ptr.all) not in '0' .. '9' then
282
         Ptr.all := Start;
283
         raise Constraint_Error;
284
      end if;
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286
      return Scan_Raw_Long_Long_Unsigned (Str, Ptr, Max);
287
   end Scan_Long_Long_Unsigned;
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289
   ------------------------------
290
   -- Value_Long_Long_Unsigned --
291
   ------------------------------
292
 
293
   function Value_Long_Long_Unsigned
294
     (Str : String) return Long_Long_Unsigned
295
   is
296
      V : Long_Long_Unsigned;
297
      P : aliased Integer := Str'First;
298
   begin
299
      V := Scan_Long_Long_Unsigned (Str, P'Access, Str'Last);
300
      Scan_Trailing_Blanks (Str, P);
301
      return V;
302
   end Value_Long_Long_Unsigned;
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end System.Val_LLU;

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