gcc/ada/libgnat/s-atopri.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT RUN-TIME COMPONENTS                         --
   4 --                                                                          --
   5 --               S Y S T E M . A T O M I C _ P R I M I T I V E S            --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --              Copyright (C) 2012-2017, 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 package body System.Atomic_Primitives is
  33
  34    ----------------------
  35    -- Lock_Free_Read_8 --
  36    ----------------------
  37
  38    function Lock_Free_Read_8 (Ptr : Address) return uint8 is
  39    begin
  40       if uint8'Atomic_Always_Lock_Free then
  41          return Atomic_Load_8 (Ptr, Acquire);
  42       else
  43          raise Program_Error;
  44       end if;
  45    end Lock_Free_Read_8;
  46
  47    -----------------------
  48    -- Lock_Free_Read_16 --
  49    -----------------------
  50
  51    function Lock_Free_Read_16 (Ptr : Address) return uint16 is
  52    begin
  53       if uint16'Atomic_Always_Lock_Free then
  54          return Atomic_Load_16 (Ptr, Acquire);
  55       else
  56          raise Program_Error;
  57       end if;
  58    end Lock_Free_Read_16;
  59
  60    -----------------------
  61    -- Lock_Free_Read_32 --
  62    -----------------------
  63
  64    function Lock_Free_Read_32 (Ptr : Address) return uint32 is
  65    begin
  66       if uint32'Atomic_Always_Lock_Free then
  67          return Atomic_Load_32 (Ptr, Acquire);
  68       else
  69          raise Program_Error;
  70       end if;
  71    end Lock_Free_Read_32;
  72
  73    -----------------------
  74    -- Lock_Free_Read_64 --
  75    -----------------------
  76
  77    function Lock_Free_Read_64 (Ptr : Address) return uint64 is
  78    begin
  79       if uint64'Atomic_Always_Lock_Free then
  80          return Atomic_Load_64 (Ptr, Acquire);
  81       else
  82          raise Program_Error;
  83       end if;
  84    end Lock_Free_Read_64;
  85
  86    ---------------------------
  87    -- Lock_Free_Try_Write_8 --
  88    ---------------------------
  89
  90    function Lock_Free_Try_Write_8
  91       (Ptr      : Address;
  92        Expected : in out uint8;
  93        Desired  : uint8) return Boolean
  94    is
  95       Actual : uint8;
  96
  97    begin
  98       if Expected /= Desired then
  99
 100          if uint8'Atomic_Always_Lock_Free then
 101             Actual := Sync_Compare_And_Swap_8 (Ptr, Expected, Desired);
 102          else
 103             raise Program_Error;
 104          end if;
 105
 106          if Actual /= Expected then
 107             Expected := Actual;
 108             return False;
 109          end if;
 110       end if;
 111
 112       return True;
 113    end Lock_Free_Try_Write_8;
 114
 115    ----------------------------
 116    -- Lock_Free_Try_Write_16 --
 117    ----------------------------
 118
 119    function Lock_Free_Try_Write_16
 120       (Ptr      : Address;
 121        Expected : in out uint16;
 122        Desired  : uint16) return Boolean
 123    is
 124       Actual : uint16;
 125
 126    begin
 127       if Expected /= Desired then
 128
 129          if uint16'Atomic_Always_Lock_Free then
 130             Actual := Sync_Compare_And_Swap_16 (Ptr, Expected, Desired);
 131          else
 132             raise Program_Error;
 133          end if;
 134
 135          if Actual /= Expected then
 136             Expected := Actual;
 137             return False;
 138          end if;
 139       end if;
 140
 141       return True;
 142    end Lock_Free_Try_Write_16;
 143
 144    ----------------------------
 145    -- Lock_Free_Try_Write_32 --
 146    ----------------------------
 147
 148    function Lock_Free_Try_Write_32
 149       (Ptr      : Address;
 150        Expected : in out uint32;
 151        Desired  : uint32) return Boolean
 152    is
 153       Actual : uint32;
 154
 155    begin
 156       if Expected /= Desired then
 157
 158          if uint32'Atomic_Always_Lock_Free then
 159             Actual := Sync_Compare_And_Swap_32 (Ptr, Expected, Desired);
 160          else
 161             raise Program_Error;
 162          end if;
 163
 164          if Actual /= Expected then
 165             Expected := Actual;
 166             return False;
 167          end if;
 168       end if;
 169
 170       return True;
 171    end Lock_Free_Try_Write_32;
 172
 173    ----------------------------
 174    -- Lock_Free_Try_Write_64 --
 175    ----------------------------
 176
 177    function Lock_Free_Try_Write_64
 178       (Ptr      : Address;
 179        Expected : in out uint64;
 180        Desired  : uint64) return Boolean
 181    is
 182       Actual : uint64;
 183
 184    begin
 185       if Expected /= Desired then
 186
 187          if uint64'Atomic_Always_Lock_Free then
 188             Actual := Sync_Compare_And_Swap_64 (Ptr, Expected, Desired);
 189          else
 190             raise Program_Error;
 191          end if;
 192
 193          if Actual /= Expected then
 194             Expected := Actual;
 195             return False;
 196          end if;
 197       end if;
 198
 199       return True;
 200    end Lock_Free_Try_Write_64;
 201 end System.Atomic_Primitives;