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