gcc/ada/s-valllu.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                       S Y S T E M . V A L _ L L U                        --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2009, 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_LLU is
  36
  37    ---------------------------------
  38    -- Scan_Raw_Long_Long_Unsigned --
  39    ---------------------------------
  40
  41    function Scan_Raw_Long_Long_Unsigned
  42      (Str : String;
  43       Ptr : not null access Integer;
  44       Max : Integer) return Long_Long_Unsigned
  45    is
  46       P : Integer;
  47       --  Local copy of the pointer
  48
  49       Uval : Long_Long_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 : Long_Long_Unsigned := 10;
  62       --  Base value (reset in based case)
  63
  64       Digit : Long_Long_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 := (Long_Long_Unsigned'Last - 9) / 10;
  77          --  Max value which cannot overflow on accumulating next digit
  78
  79          Umax10 : constant := Long_Long_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 Long_Long_Unsigned :=
 144                      (Long_Long_Unsigned'Last - Base + 1) / Base;
 145             --  Max value which cannot overflow on accumulating next digit
 146
 147             UmaxB : constant Long_Long_Unsigned :=
 148                       Long_Long_Unsigned'Last / Base;
 149             --  Numbers bigger than UmaxB overflow if multiplied by base
 150
 151          begin
 152             --  Loop to scan out based integer value
 153
 154             loop
 155                --  We require a digit at this stage
 156
 157                if Str (P) in '0' .. '9' then
 158                   Digit := Character'Pos (Str (P)) - Character'Pos ('0');
 159
 160                elsif Str (P) in 'A' .. 'F' then
 161                   Digit :=
 162                     Character'Pos (Str (P)) - (Character'Pos ('A') - 10);
 163
 164                elsif Str (P) in 'a' .. 'f' then
 165                   Digit :=
 166                     Character'Pos (Str (P)) - (Character'Pos ('a') - 10);
 167
 168                --  If we don't have a digit, then this is not a based number
 169                --  after all, so we use the value we scanned out as the base
 170                --  (now in Base), and the pointer to the base character was
 171                --  already stored in Ptr.all.
 172
 173                else
 174                   Uval := Base;
 175                   exit;
 176                end if;
 177
 178                --  If digit is too large, just signal overflow and continue.
 179                --  The idea here is to keep scanning as long as the input is
 180                --  syntactically valid, even if we have detected overflow
 181
 182                if Digit >= Base then
 183                   Overflow := True;
 184
 185                --  Here we accumulate the value, checking overflow
 186
 187                elsif Uval <= Umax then
 188                   Uval := Base * Uval + Digit;
 189
 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;
 200
 201                --  If at end of string with no base char, not a based number
 202                --  but we signal Constraint_Error and set the pointer past
 203                --  the end of the field, since this is what the ACVC tests
 204                --  seem to require, see CE3704N, line 204.
 205
 206                P := P + 1;
 207
 208                if P > Max then
 209                   Ptr.all := P;
 210                   raise Constraint_Error;
 211                end if;
 212
 213                --  If terminating base character, we are done with loop
 214
 215                if Str (P) = Base_Char then
 216                   Ptr.all := P + 1;
 217                   exit;
 218
 219                --  Deal with underscore
 220
 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.
 231
 232       Expon := Scan_Exponent (Str, Ptr, Max);
 233
 234       if Expon /= 0 and then Uval /= 0 then
 235
 236          --  For non-zero value, scale by exponent value. No need to do this
 237          --  efficiently, since use of exponent in integer literals is rare,
 238          --  and in any case the exponent cannot be very large.
 239
 240          declare
 241             UmaxB : constant Long_Long_Unsigned :=
 242                       Long_Long_Unsigned'Last / Base;
 243             --  Numbers bigger than UmaxB overflow if multiplied by base
 244
 245          begin
 246             for J in 1 .. Expon loop
 247                if Uval > UmaxB then
 248                   Overflow := True;
 249                   exit;
 250                end if;
 251
 252                Uval := Uval * Base;
 253             end loop;
 254          end;
 255       end if;
 256
 257       --  Return result, dealing with sign and overflow
 258
 259       if Overflow then
 260          raise Constraint_Error;
 261       else
 262          return Uval;
 263       end if;
 264    end Scan_Raw_Long_Long_Unsigned;
 265
 266    -----------------------------
 267    -- 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;
 285
 286       return Scan_Raw_Long_Long_Unsigned (Str, Ptr, Max);
 287    end Scan_Long_Long_Unsigned;
 288
 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;
 303
 304 end System.Val_LLU;