gcc/ada/table.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                                T A B L E                                 --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2002 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 2,  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.  See the GNU General Public License --
  17 -- for  more details.  You should have  received  a copy of the GNU General --
  18 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
  19 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  20 -- MA 02111-1307, USA.                                                      --
  21 --                                                                          --
  22 -- As a special exception,  if other files  instantiate  generics from this --
  23 -- unit, or you link  this unit with other files  to produce an executable, --
  24 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  25 -- covered  by the  GNU  General  Public  License.  This exception does not --
  26 -- however invalidate  any other reasons why  the executable file  might be --
  27 -- covered by the  GNU Public License.                                      --
  28 --                                                                          --
  29 -- GNAT was originally developed  by the GNAT team at  New York University. --
  30 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  31 --                                                                          --
  32 ------------------------------------------------------------------------------
  33
  34 with Debug;   use Debug;
  35 with Opt;     use Opt;
  36 with Output;  use Output;
  37 with System;  use System;
  38 with Tree_IO; use Tree_IO;
  39
  40 with System.Memory; use System.Memory;
  41
  42 with Unchecked_Conversion;
  43
  44 pragma Elaborate_All (Output);
  45
  46 package body Table is
  47    package body Table is
  48
  49       Min : constant Int := Int (Table_Low_Bound);
  50       --  Subscript of the minimum entry in the currently allocated table
  51
  52       Length : Int := 0;
  53       --  Number of entries in currently allocated table. The value of zero
  54       --  ensures that we initially allocate the table.
  55
  56       -----------------------
  57       -- Local Subprograms --
  58       -----------------------
  59
  60       procedure Reallocate;
  61       --  Reallocate the existing table according to the current value stored
  62       --  in Max. Works correctly to do an initial allocation if the table
  63       --  is currently null.
  64
  65       function Tree_Get_Table_Address return Address;
  66       --  Return Null_Address if the table length is zero,
  67       --  Table (First)'Address if not.
  68
  69       function To_Address is new Unchecked_Conversion (Table_Ptr, Address);
  70       function To_Pointer is new Unchecked_Conversion (Address, Table_Ptr);
  71
  72       ------------
  73       -- Append --
  74       ------------
  75
  76       procedure Append (New_Val : Table_Component_Type) is
  77       begin
  78          Increment_Last;
  79          Table (Table_Index_Type (Last_Val)) := New_Val;
  80       end Append;
  81
  82       --------------------
  83       -- Decrement_Last --
  84       --------------------
  85
  86       procedure Decrement_Last is
  87       begin
  88          Last_Val := Last_Val - 1;
  89       end Decrement_Last;
  90
  91       ----------
  92       -- Free --
  93       ----------
  94
  95       procedure Free is
  96       begin
  97          Free (To_Address (Table));
  98          Table := null;
  99          Length := 0;
 100       end Free;
 101
 102       --------------------
 103       -- Increment_Last --
 104       --------------------
 105
 106       procedure Increment_Last is
 107       begin
 108          Last_Val := Last_Val + 1;
 109
 110          if Last_Val > Max then
 111             Reallocate;
 112          end if;
 113       end Increment_Last;
 114
 115       ----------
 116       -- Init --
 117       ----------
 118
 119       procedure Init is
 120          Old_Length : constant Int := Length;
 121
 122       begin
 123          Locked   := False;
 124          Last_Val := Min - 1;
 125          Max      := Min + (Table_Initial * Table_Factor) - 1;
 126          Length   := Max - Min + 1;
 127
 128          --  If table is same size as before (happens when table is never
 129          --  expanded which is a common case), then simply reuse it. Note
 130          --  that this also means that an explicit Init call right after
 131          --  the implicit one in the package body is harmless.
 132
 133          if Old_Length = Length then
 134             return;
 135
 136          --  Otherwise we can use Reallocate to get a table of the right size.
 137          --  Note that Reallocate works fine to allocate a table of the right
 138          --  initial size when it is first allocated.
 139
 140          else
 141             Reallocate;
 142          end if;
 143       end Init;
 144
 145       ----------
 146       -- Last --
 147       ----------
 148
 149       function Last return Table_Index_Type is
 150       begin
 151          return Table_Index_Type (Last_Val);
 152       end Last;
 153
 154       ----------------
 155       -- Reallocate --
 156       ----------------
 157
 158       procedure Reallocate is
 159          New_Size : Memory.size_t;
 160
 161       begin
 162          if Max < Last_Val then
 163             pragma Assert (not Locked);
 164
 165             --  Make sure that we have at least the initial allocation. This
 166             --  is needed in cases where a zero length table is written out.
 167
 168             Length := Int'Max (Length, Table_Initial);
 169
 170             --  Now increment table length until it is sufficiently large
 171
 172             while Max < Last_Val loop
 173                Length := Length * (100 + Table_Increment) / 100;
 174                Max := Min + Length - 1;
 175             end loop;
 176
 177             if Debug_Flag_D then
 178                Write_Str ("--> Allocating new ");
 179                Write_Str (Table_Name);
 180                Write_Str (" table, size = ");
 181                Write_Int (Max - Min + 1);
 182                Write_Eol;
 183             end if;
 184          end if;
 185
 186          New_Size :=
 187            Memory.size_t ((Max - Min + 1) *
 188                           (Table_Type'Component_Size / Storage_Unit));
 189
 190          if Table = null then
 191             Table := To_Pointer (Alloc (New_Size));
 192
 193          elsif New_Size > 0 then
 194             Table :=
 195               To_Pointer (Realloc (Ptr  => To_Address (Table),
 196                                    Size => New_Size));
 197          end if;
 198
 199          if Length /= 0 and then Table = null then
 200             Set_Standard_Error;
 201             Write_Str ("available memory exhausted");
 202             Write_Eol;
 203             Set_Standard_Output;
 204             raise Unrecoverable_Error;
 205          end if;
 206
 207       end Reallocate;
 208
 209       -------------
 210       -- Release --
 211       -------------
 212
 213       procedure Release is
 214       begin
 215          Length := Last_Val - Int (Table_Low_Bound) + 1;
 216          Max    := Last_Val;
 217          Reallocate;
 218       end Release;
 219
 220       -------------
 221       -- Restore --
 222       -------------
 223
 224       procedure Restore (T : Saved_Table) is
 225       begin
 226          Free (To_Address (Table));
 227          Last_Val := T.Last_Val;
 228          Max      := T.Max;
 229          Table    := T.Table;
 230          Length   := Max - Min + 1;
 231       end Restore;
 232
 233       ----------
 234       -- Save --
 235       ----------
 236
 237       function Save return Saved_Table is
 238          Res : Saved_Table;
 239
 240       begin
 241          Res.Last_Val := Last_Val;
 242          Res.Max      := Max;
 243          Res.Table    := Table;
 244
 245          Table  := null;
 246          Length := 0;
 247          Init;
 248          return Res;
 249       end Save;
 250
 251       --------------
 252       -- Set_Item --
 253       --------------
 254
 255       procedure Set_Item
 256          (Index : Table_Index_Type;
 257           Item  : Table_Component_Type)
 258       is
 259       begin
 260          if Int (Index) > Max then
 261             Set_Last (Index);
 262          end if;
 263
 264          Table (Index) := Item;
 265       end Set_Item;
 266
 267       --------------
 268       -- Set_Last --
 269       --------------
 270
 271       procedure Set_Last (New_Val : Table_Index_Type) is
 272       begin
 273          if Int (New_Val) < Last_Val then
 274             Last_Val := Int (New_Val);
 275          else
 276             Last_Val := Int (New_Val);
 277
 278             if Last_Val > Max then
 279                Reallocate;
 280             end if;
 281          end if;
 282       end Set_Last;
 283
 284       ----------------------------
 285       -- Tree_Get_Table_Address --
 286       ----------------------------
 287
 288       function Tree_Get_Table_Address return Address is
 289       begin
 290          if Length = 0 then
 291             return Null_Address;
 292          else
 293             return Table (First)'Address;
 294          end if;
 295       end Tree_Get_Table_Address;
 296
 297       ---------------
 298       -- Tree_Read --
 299       ---------------
 300
 301       --  Note: we allocate only the space required to accommodate the data
 302       --  actually written, which means that a Tree_Write/Tree_Read sequence
 303       --  does an implicit Release.
 304
 305       procedure Tree_Read is
 306       begin
 307          Tree_Read_Int (Max);
 308          Last_Val := Max;
 309          Length := Max - Min + 1;
 310          Reallocate;
 311
 312          Tree_Read_Data
 313            (Tree_Get_Table_Address,
 314              (Last_Val - Int (First) + 1) *
 315                Table_Type'Component_Size / Storage_Unit);
 316       end Tree_Read;
 317
 318       ----------------
 319       -- Tree_Write --
 320       ----------------
 321
 322       --  Note: we write out only the currently valid data, not the entire
 323       --  contents of the allocated array. See note above on Tree_Read.
 324
 325       procedure Tree_Write is
 326       begin
 327          Tree_Write_Int (Int (Last));
 328          Tree_Write_Data
 329            (Tree_Get_Table_Address,
 330             (Last_Val - Int (First) + 1) *
 331               Table_Type'Component_Size / Storage_Unit);
 332       end Tree_Write;
 333
 334    begin
 335       Init;
 336    end Table;
 337 end Table;