gcc/ada/s-valuns.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                       S Y S T E M . V A L _ U N S                        --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2012, Free Software Foundation, Inc.         --
  10 --                                                                          --
  11 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  12 -- terms of the  GNU General Public License as published  by the Free Soft- --
  13 -- ware  Foundation;  either version 3,  or (at your option) any later ver- --
  14 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  15 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  16 -- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
  17 --                                                                          --
  18 -- As a special exception under Section 7 of GPL version 3, you are granted --
  19 -- additional permissions described in the GCC Runtime Library Exception,   --
  20 -- version 3.1, as published by the Free Software Foundation.               --
  21 --                                                                          --
  22 -- You should have received a copy of the GNU General Public License and    --
  23 -- a copy of the GCC Runtime Library Exception along with this program;     --
  24 -- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
  25 -- <http://www.gnu.org/licenses/>.                                          --
  26 --                                                                          --
  27 -- GNAT was originally developed  by the GNAT team at  New York University. --
  28 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  29 --                                                                          --
  30 ------------------------------------------------------------------------------
  31
  32 with System.Unsigned_Types; use System.Unsigned_Types;
  33 with System.Val_Util;       use System.Val_Util;
  34
  35 package body System.Val_Uns is
  36
  37    -----------------------
  38    -- Scan_Raw_Unsigned --
  39    -----------------------
  40
  41    function Scan_Raw_Unsigned
  42      (Str : String;
  43       Ptr : not null access Integer;
  44       Max : Integer) return Unsigned
  45    is
  46       P : Integer;
  47       --  Local copy of the pointer
  48
  49       Uval : Unsigned;
  50       --  Accumulated unsigned integer result
  51
  52       Expon : Integer;
  53       --  Exponent value
  54
  55       Overflow : Boolean := False;
  56       --  Set True if overflow is detected at any point
  57
  58       Base_Char : Character;
  59       --  Base character (# or :) in based case
  60
  61       Base : Unsigned := 10;
  62       --  Base value (reset in based case)
  63
  64       Digit : Unsigned;
  65       --  Digit value
  66
  67    begin
  68       P := Ptr.all;
  69       Uval := Character'Pos (Str (P)) - Character'Pos ('0');
  70       P := P + 1;
  71
  72       --  Scan out digits of what is either the number or the base.
  73       --  In either case, we are definitely scanning out in base 10.
  74
  75       declare
  76          Umax : constant := (Unsigned'Last - 9) / 10;
  77          --  Max value which cannot overflow on accumulating next digit
  78
  79          Umax10 : constant := Unsigned'Last / 10;
  80          --  Numbers bigger than Umax10 overflow if multiplied by 10
  81
  82       begin
  83          --  Loop through decimal digits
  84          loop
  85             exit when P > Max;
  86
  87             Digit := Character'Pos (Str (P)) - Character'Pos ('0');
  88
  89             --  Non-digit encountered
  90
  91             if Digit > 9 then
  92                if Str (P) = '_' then
  93                   Scan_Underscore (Str, P, Ptr, Max, False);
  94                else
  95                   exit;
  96                end if;
  97
  98             --  Accumulate result, checking for overflow
  99
 100             else
 101                if Uval <= Umax then
 102                   Uval := 10 * Uval + Digit;
 103
 104                elsif Uval > Umax10 then
 105                   Overflow := True;
 106
 107                else
 108                   Uval := 10 * Uval + Digit;
 109
 110                   if Uval < Umax10 then
 111                      Overflow := True;
 112                   end if;
 113                end if;
 114
 115                P := P + 1;
 116             end if;
 117          end loop;
 118       end;
 119
 120       Ptr.all := P;
 121
 122       --  Deal with based case
 123
 124       if P < Max and then (Str (P) = ':' or else Str (P) = '#') then
 125          Base_Char := Str (P);
 126          P := P + 1;
 127          Base := Uval;
 128          Uval := 0;
 129
 130          --  Check base value. Overflow is set True if we find a bad base, or
 131          --  a digit that is out of range of the base. That way, we scan out
 132          --  the numeral that is still syntactically correct, though illegal.
 133          --  We use a safe base of 16 for this scan, to avoid zero divide.
 134
 135          if Base not in 2 .. 16 then
 136             Overflow := True;
 137             Base :=  16;
 138          end if;
 139
 140          --  Scan out based integer
 141
 142          declare
 143             Umax : constant Unsigned := (Unsigned'Last - Base + 1) / Base;
 144             --  Max value which cannot overflow on accumulating next digit
 145
 146             UmaxB : constant Unsigned := Unsigned'Last / Base;
 147             --  Numbers bigger than UmaxB overflow if multiplied by base
 148
 149          begin
 150             --  Loop to scan out based integer value
 151
 152             loop
 153                --  We require a digit at this stage
 154
 155                if Str (P) in '0' .. '9' then
 156                   Digit := Character'Pos (Str (P)) - Character'Pos ('0');
 157
 158                elsif Str (P) in 'A' .. 'F' then
 159                   Digit :=
 160                     Character'Pos (Str (P)) - (Character'Pos ('A') - 10);
 161
 162                elsif Str (P) in 'a' .. 'f' then
 163                   Digit :=
 164                     Character'Pos (Str (P)) - (Character'Pos ('a') - 10);
 165
 166                --  If we don't have a digit, then this is not a based number
 167                --  after all, so we use the value we scanned out as the base
 168                --  (now in Base), and the pointer to the base character was
 169                --  already stored in Ptr.all.
 170
 171                else
 172                   Uval := Base;
 173                   exit;
 174                end if;
 175
 176                --  If digit is too large, just signal overflow and continue.
 177                --  The idea here is to keep scanning as long as the input is
 178                --  syntactically valid, even if we have detected overflow
 179
 180                if Digit >= Base then
 181                   Overflow := True;
 182
 183                --  Here we accumulate the value, checking overflow
 184
 185                elsif Uval <= Umax then
 186                   Uval := Base * Uval + Digit;
 187
 188                elsif Uval > UmaxB then
 189                   Overflow := True;
 190
 191                else
 192                   Uval := Base * Uval + Digit;
 193
 194                   if Uval < UmaxB then
 195                      Overflow := True;
 196                   end if;
 197                end if;
 198
 199                --  If at end of string with no base char, not a based number
 200                --  but we signal Constraint_Error and set the pointer past
 201                --  the end of the field, since this is what the ACVC tests
 202                --  seem to require, see CE3704N, line 204.
 203
 204                P := P + 1;
 205
 206                if P > Max then
 207                   Ptr.all := P;
 208                   Bad_Value (Str);
 209                end if;
 210
 211                --  If terminating base character, we are done with loop
 212
 213                if Str (P) = Base_Char then
 214                   Ptr.all := P + 1;
 215                   exit;
 216
 217                --  Deal with underscore
 218
 219                elsif Str (P) = '_' then
 220                   Scan_Underscore (Str, P, Ptr, Max, True);
 221                end if;
 222
 223             end loop;
 224          end;
 225       end if;
 226
 227       --  Come here with scanned unsigned value in Uval. The only remaining
 228       --  required step is to deal with exponent if one is present.
 229
 230       Expon := Scan_Exponent (Str, Ptr, Max);
 231
 232       if Expon /= 0 and then Uval /= 0 then
 233
 234          --  For non-zero value, scale by exponent value. No need to do this
 235          --  efficiently, since use of exponent in integer literals is rare,
 236          --  and in any case the exponent cannot be very large.
 237
 238          declare
 239             UmaxB : constant Unsigned := Unsigned'Last / Base;
 240             --  Numbers bigger than UmaxB overflow if multiplied by base
 241
 242          begin
 243             for J in 1 .. Expon loop
 244                if Uval > UmaxB then
 245                   Overflow := True;
 246                   exit;
 247                end if;
 248
 249                Uval := Uval * Base;
 250             end loop;
 251          end;
 252       end if;
 253
 254       --  Return result, dealing with sign and overflow
 255
 256       if Overflow then
 257          Bad_Value (Str);
 258       else
 259          return Uval;
 260       end if;
 261    end Scan_Raw_Unsigned;
 262
 263    -------------------
 264    -- Scan_Unsigned --
 265    -------------------
 266
 267    function Scan_Unsigned
 268      (Str : String;
 269       Ptr : not null access Integer;
 270       Max : Integer) return Unsigned
 271    is
 272       Start : Positive;
 273       --  Save location of first non-blank character
 274
 275    begin
 276       Scan_Plus_Sign (Str, Ptr, Max, Start);
 277
 278       if Str (Ptr.all) not in '0' .. '9' then
 279          Ptr.all := Start;
 280          Bad_Value (Str);
 281       end if;
 282
 283       return Scan_Raw_Unsigned (Str, Ptr, Max);
 284    end Scan_Unsigned;
 285
 286    --------------------
 287    -- Value_Unsigned --
 288    --------------------
 289
 290    function Value_Unsigned (Str : String) return Unsigned is
 291       V : Unsigned;
 292       P : aliased Integer := Str'First;
 293    begin
 294       V := Scan_Unsigned (Str, P'Access, Str'Last);
 295       Scan_Trailing_Blanks (Str, P);
 296       return V;
 297    end Value_Unsigned;
 298
 299 end System.Val_Uns;