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 --                                                                          --
  10 --          Copyright (C) 1992-2001 Free Software Foundation, Inc.          --
  11 --                                                                          --
  12 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  13 -- terms of the  GNU General Public License as published  by the Free Soft- --
  14 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  15 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  16 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  17 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  18 -- for  more details.  You should have  received  a copy of the GNU General --
  19 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
  20 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  21 -- MA 02111-1307, USA.                                                      --
  22 --                                                                          --
  23 -- As a special exception,  if other files  instantiate  generics from this --
  24 -- unit, or you link  this unit with other files  to produce an executable, --
  25 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  26 -- covered  by the  GNU  General  Public  License.  This exception does not --
  27 -- however invalidate  any other reasons why  the executable file  might be --
  28 -- covered by the  GNU Public License.                                      --
  29 --                                                                          --
  30 -- GNAT was originally developed  by the GNAT team at  New York University. --
  31 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  32 --                                                                          --
  33 ------------------------------------------------------------------------------
  34
  35 with Debug;   use Debug;
  36 with Opt;
  37 with Output;        use Output;
  38 pragma Elaborate_All (Output);
  39 with System;        use System;
  40 with Tree_IO;       use Tree_IO;
  41 with System.Memory; use System.Memory;
  42 with System.Address_To_Access_Conversions;
  43
  44 package body Table is
  45    package body Table is
  46
  47       Min : constant Int := Int (Table_Low_Bound);
  48       --  Subscript of the minimum entry in the currently allocated table
  49
  50       Length : Int := 0;
  51       --  Number of entries in currently allocated table. The value of zero
  52       --  ensures that we initially allocate the table.
  53
  54       -----------------------
  55       -- Local Subprograms --
  56       -----------------------
  57
  58       procedure Reallocate;
  59       --  Reallocate the existing table according to the current value stored
  60       --  in Max. Works correctly to do an initial allocation if the table
  61       --  is currently null.
  62
  63       function Tree_Get_Table_Address return Address;
  64       --  Return Null_Address if the table length is zero,
  65       --  Table (First)'Address if not.
  66
  67       package Table_Conversions is
  68          new System.Address_To_Access_Conversions (Big_Table_Type);
  69       --  Address and Access conversions for a Table object.
  70
  71       function To_Address (Table : Table_Ptr) return Address;
  72       pragma Inline (To_Address);
  73       --  Returns the Address for the Table object.
  74
  75       function To_Pointer (Table : Address) return Table_Ptr;
  76       pragma Inline (To_Pointer);
  77       --  Returns the Access pointer for the Table object.
  78
  79       ------------
  80       -- Append --
  81       ------------
  82
  83       procedure Append (New_Val : Table_Component_Type) is
  84       begin
  85          Increment_Last;
  86          Table (Table_Index_Type (Last_Val)) := New_Val;
  87       end Append;
  88
  89       --------------------
  90       -- Decrement_Last --
  91       --------------------
  92
  93       procedure Decrement_Last is
  94       begin
  95          Last_Val := Last_Val - 1;
  96       end Decrement_Last;
  97
  98       ----------
  99       -- Free --
 100       ----------
 101
 102       procedure Free is
 103       begin
 104          Free (To_Address (Table));
 105          Table := null;
 106          Length := 0;
 107       end Free;
 108
 109       --------------------
 110       -- Increment_Last --
 111       --------------------
 112
 113       procedure Increment_Last is
 114       begin
 115          Last_Val := Last_Val + 1;
 116
 117          if Last_Val > Max then
 118             Reallocate;
 119          end if;
 120       end Increment_Last;
 121
 122       ----------
 123       -- Init --
 124       ----------
 125
 126       procedure Init is
 127          Old_Length : Int := Length;
 128
 129       begin
 130          Last_Val := Min - 1;
 131          Max      := Min + (Table_Initial * Opt.Table_Factor) - 1;
 132          Length   := Max - Min + 1;
 133
 134          --  If table is same size as before (happens when table is never
 135          --  expanded which is a common case), then simply reuse it. Note
 136          --  that this also means that an explicit Init call right after
 137          --  the implicit one in the package body is harmless.
 138
 139          if Old_Length = Length then
 140             return;
 141
 142          --  Otherwise we can use Reallocate to get a table of the right size.
 143          --  Note that Reallocate works fine to allocate a table of the right
 144          --  initial size when it is first allocated.
 145
 146          else
 147             Reallocate;
 148          end if;
 149       end Init;
 150
 151       ----------
 152       -- Last --
 153       ----------
 154
 155       function Last return Table_Index_Type is
 156       begin
 157          return Table_Index_Type (Last_Val);
 158       end Last;
 159
 160       ----------------
 161       -- Reallocate --
 162       ----------------
 163
 164       procedure Reallocate is
 165          New_Size : Memory.size_t;
 166
 167       begin
 168          if Max < Last_Val then
 169             pragma Assert (not Locked);
 170
 171             --  Make sure that we have at least the initial allocation. This
 172             --  is needed in cases where a zero length table is written out.
 173
 174             Length := Int'Max (Length, Table_Initial);
 175
 176             --  Now increment table length until it is sufficiently large
 177
 178             while Max < Last_Val loop
 179                Length := Length * (100 + Table_Increment) / 100;
 180                Max := Min + Length - 1;
 181             end loop;
 182
 183             if Debug_Flag_D then
 184                Write_Str ("--> Allocating new ");
 185                Write_Str (Table_Name);
 186                Write_Str (" table, size = ");
 187                Write_Int (Max - Min + 1);
 188                Write_Eol;
 189             end if;
 190          end if;
 191
 192          New_Size :=
 193            Memory.size_t ((Max - Min + 1) *
 194                           (Table_Type'Component_Size / Storage_Unit));
 195
 196          if Table = null then
 197             Table := To_Pointer (Alloc (New_Size));
 198
 199          elsif New_Size > 0 then
 200             Table :=
 201               To_Pointer (Realloc (Ptr  => To_Address (Table),
 202                                    Size => New_Size));
 203          end if;
 204
 205          if Length /= 0 and then Table = null then
 206             Set_Standard_Error;
 207             Write_Str ("available memory exhausted");
 208             Write_Eol;
 209             Set_Standard_Output;
 210             raise Unrecoverable_Error;
 211          end if;
 212
 213       end Reallocate;
 214
 215       -------------
 216       -- Release --
 217       -------------
 218
 219       procedure Release is
 220       begin
 221          Length := Last_Val - Int (Table_Low_Bound) + 1;
 222          Max    := Last_Val;
 223          Reallocate;
 224       end Release;
 225
 226       -------------
 227       -- Restore --
 228       -------------
 229
 230       procedure Restore (T : Saved_Table) is
 231       begin
 232          Free (To_Address (Table));
 233          Last_Val := T.Last_Val;
 234          Max      := T.Max;
 235          Table    := T.Table;
 236          Length   := Max - Min + 1;
 237       end Restore;
 238
 239       ----------
 240       -- Save --
 241       ----------
 242
 243       function Save return Saved_Table is
 244          Res : Saved_Table;
 245
 246       begin
 247          Res.Last_Val := Last_Val;
 248          Res.Max      := Max;
 249          Res.Table    := Table;
 250
 251          Table  := null;
 252          Length := 0;
 253          Init;
 254          return Res;
 255       end Save;
 256
 257       --------------
 258       -- Set_Item --
 259       --------------
 260
 261       procedure Set_Item
 262          (Index : Table_Index_Type;
 263           Item  : Table_Component_Type)
 264       is
 265       begin
 266          if Int (Index) > Max then
 267             Set_Last (Index);
 268          end if;
 269
 270          Table (Index) := Item;
 271       end Set_Item;
 272
 273       --------------
 274       -- Set_Last --
 275       --------------
 276
 277       procedure Set_Last (New_Val : Table_Index_Type) is
 278       begin
 279          if Int (New_Val) < Last_Val then
 280             Last_Val := Int (New_Val);
 281          else
 282             Last_Val := Int (New_Val);
 283
 284             if Last_Val > Max then
 285                Reallocate;
 286             end if;
 287          end if;
 288       end Set_Last;
 289
 290       ----------------
 291       -- To_Address --
 292       ----------------
 293
 294       function To_Address (Table : Table_Ptr) return Address is
 295       begin
 296          return Table_Conversions.To_Address
 297            (Table_Conversions.Object_Pointer (Table));
 298       end To_Address;
 299
 300       ----------------
 301       -- To_Pointer --
 302       ----------------
 303
 304       function To_Pointer (Table : Address) return Table_Ptr is
 305       begin
 306          return Table_Ptr (Table_Conversions.To_Pointer (Table));
 307       end To_Pointer;
 308
 309       ----------------------------
 310       -- Tree_Get_Table_Address --
 311       ----------------------------
 312
 313       function Tree_Get_Table_Address return Address is
 314       begin
 315          if Length = 0 then
 316             return Null_Address;
 317          else
 318             return Table (First)'Address;
 319          end if;
 320       end Tree_Get_Table_Address;
 321
 322       ---------------
 323       -- Tree_Read --
 324       ---------------
 325
 326       --  Note: we allocate only the space required to accommodate the data
 327       --  actually written, which means that a Tree_Write/Tree_Read sequence
 328       --  does an implicit Release.
 329
 330       procedure Tree_Read is
 331       begin
 332          Tree_Read_Int (Max);
 333          Last_Val := Max;
 334          Length := Max - Min + 1;
 335          Reallocate;
 336
 337          Tree_Read_Data
 338            (Tree_Get_Table_Address,
 339              (Last_Val - Int (First) + 1) *
 340                Table_Type'Component_Size / Storage_Unit);
 341       end Tree_Read;
 342
 343       ----------------
 344       -- Tree_Write --
 345       ----------------
 346
 347       --  Note: we write out only the currently valid data, not the entire
 348       --  contents of the allocated array. See note above on Tree_Read.
 349
 350       procedure Tree_Write is
 351       begin
 352          Tree_Write_Int (Int (Last));
 353          Tree_Write_Data
 354            (Tree_Get_Table_Address,
 355             (Last_Val - Int (First) + 1) *
 356               Table_Type'Component_Size / Storage_Unit);
 357       end Tree_Write;
 358
 359    begin
 360       Init;
 361    end Table;
 362 end Table;