gcc/ada/libgnat/s-pack36.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT RUN-TIME COMPONENTS                         --
   4 --                                                                          --
   5 --                       S Y S T E M . P A C K _ 3 6                        --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2024, 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.Storage_Elements;
  33 with System.Unsigned_Types;
  34
  35 package body System.Pack_36 is
  36
  37    subtype Bit_Order is System.Bit_Order;
  38    Reverse_Bit_Order : constant Bit_Order :=
  39      Bit_Order'Val (1 - Bit_Order'Pos (System.Default_Bit_Order));
  40
  41    subtype Ofs is System.Storage_Elements.Storage_Offset;
  42    subtype Uns is System.Unsigned_Types.Unsigned;
  43    subtype N07 is System.Unsigned_Types.Unsigned range 0 .. 7;
  44
  45    use type System.Storage_Elements.Storage_Offset;
  46    use type System.Unsigned_Types.Unsigned;
  47
  48    type Cluster is record
  49       E0, E1, E2, E3, E4, E5, E6, E7 : Bits_36;
  50    end record;
  51
  52    for Cluster use record
  53       E0 at 0 range 0 * Bits .. 0 * Bits + Bits - 1;
  54       E1 at 0 range 1 * Bits .. 1 * Bits + Bits - 1;
  55       E2 at 0 range 2 * Bits .. 2 * Bits + Bits - 1;
  56       E3 at 0 range 3 * Bits .. 3 * Bits + Bits - 1;
  57       E4 at 0 range 4 * Bits .. 4 * Bits + Bits - 1;
  58       E5 at 0 range 5 * Bits .. 5 * Bits + Bits - 1;
  59       E6 at 0 range 6 * Bits .. 6 * Bits + Bits - 1;
  60       E7 at 0 range 7 * Bits .. 7 * Bits + Bits - 1;
  61    end record;
  62
  63    for Cluster'Size use Bits * 8;
  64
  65    for Cluster'Alignment use Integer'Min (Standard'Maximum_Alignment,
  66      1 +
  67      1 * Boolean'Pos (Bits mod 2 = 0) +
  68      2 * Boolean'Pos (Bits mod 4 = 0));
  69    --  Use maximum possible alignment, given the bit field size, since this
  70    --  will result in the most efficient code possible for the field.
  71
  72    type Cluster_Ref is access Cluster;
  73
  74    type Rev_Cluster is new Cluster
  75      with Bit_Order            => Reverse_Bit_Order,
  76           Scalar_Storage_Order => Reverse_Bit_Order;
  77    type Rev_Cluster_Ref is access Rev_Cluster;
  78
  79    --  The following declarations are for the case where the address
  80    --  passed to GetU_36 or SetU_36 is not guaranteed to be aligned.
  81    --  These routines are used when the packed array is itself a
  82    --  component of a packed record, and therefore may not be aligned.
  83
  84    type ClusterU is new Cluster;
  85    for ClusterU'Alignment use 1;
  86
  87    type ClusterU_Ref is access ClusterU;
  88
  89    type Rev_ClusterU is new ClusterU
  90      with Bit_Order            => Reverse_Bit_Order,
  91           Scalar_Storage_Order => Reverse_Bit_Order;
  92    type Rev_ClusterU_Ref is access Rev_ClusterU;
  93
  94    ------------
  95    -- Get_36 --
  96    ------------
  97
  98    function Get_36
  99      (Arr     : System.Address;
 100       N       : Natural;
 101       Rev_SSO : Boolean) return Bits_36
 102    is
 103       A  : constant System.Address := Arr + Bits * Ofs (Uns (N) / 8);
 104       C  : Cluster_Ref     with Address => A'Address, Import;
 105       RC : Rev_Cluster_Ref with Address => A'Address, Import;
 106    begin
 107       return
 108          (if Rev_SSO then
 109             (case N07 (Uns (N) mod 8) is
 110                when 0 => RC.E0,
 111                when 1 => RC.E1,
 112                when 2 => RC.E2,
 113                when 3 => RC.E3,
 114                when 4 => RC.E4,
 115                when 5 => RC.E5,
 116                when 6 => RC.E6,
 117                when 7 => RC.E7)
 118
 119          else
 120             (case N07 (Uns (N) mod 8) is
 121                when 0 => C.E0,
 122                when 1 => C.E1,
 123                when 2 => C.E2,
 124                when 3 => C.E3,
 125                when 4 => C.E4,
 126                when 5 => C.E5,
 127                when 6 => C.E6,
 128                when 7 => C.E7)
 129          );
 130    end Get_36;
 131
 132    -------------
 133    -- GetU_36 --
 134    -------------
 135
 136    function GetU_36
 137      (Arr     : System.Address;
 138       N       : Natural;
 139       Rev_SSO : Boolean) return Bits_36
 140    is
 141       A  : constant System.Address := Arr + Bits * Ofs (Uns (N) / 8);
 142       C  : ClusterU_Ref     with Address => A'Address, Import;
 143       RC : Rev_ClusterU_Ref with Address => A'Address, Import;
 144    begin
 145       return
 146          (if Rev_SSO then
 147             (case N07 (Uns (N) mod 8) is
 148                when 0 => RC.E0,
 149                when 1 => RC.E1,
 150                when 2 => RC.E2,
 151                when 3 => RC.E3,
 152                when 4 => RC.E4,
 153                when 5 => RC.E5,
 154                when 6 => RC.E6,
 155                when 7 => RC.E7)
 156
 157          else
 158             (case N07 (Uns (N) mod 8) is
 159                when 0 => C.E0,
 160                when 1 => C.E1,
 161                when 2 => C.E2,
 162                when 3 => C.E3,
 163                when 4 => C.E4,
 164                when 5 => C.E5,
 165                when 6 => C.E6,
 166                when 7 => C.E7)
 167          );
 168    end GetU_36;
 169
 170    ------------
 171    -- Set_36 --
 172    ------------
 173
 174    procedure Set_36
 175      (Arr     : System.Address;
 176       N       : Natural;
 177       E       : Bits_36;
 178       Rev_SSO : Boolean)
 179    is
 180       A  : constant System.Address := Arr + Bits * Ofs (Uns (N) / 8);
 181       C  : Cluster_Ref     with Address => A'Address, Import;
 182       RC : Rev_Cluster_Ref with Address => A'Address, Import;
 183    begin
 184       if Rev_SSO then
 185          case N07 (Uns (N) mod 8) is
 186             when 0 => RC.E0 := E;
 187             when 1 => RC.E1 := E;
 188             when 2 => RC.E2 := E;
 189             when 3 => RC.E3 := E;
 190             when 4 => RC.E4 := E;
 191             when 5 => RC.E5 := E;
 192             when 6 => RC.E6 := E;
 193             when 7 => RC.E7 := E;
 194          end case;
 195       else
 196          case N07 (Uns (N) mod 8) is
 197             when 0 => C.E0 := E;
 198             when 1 => C.E1 := E;
 199             when 2 => C.E2 := E;
 200             when 3 => C.E3 := E;
 201             when 4 => C.E4 := E;
 202             when 5 => C.E5 := E;
 203             when 6 => C.E6 := E;
 204             when 7 => C.E7 := E;
 205          end case;
 206       end if;
 207    end Set_36;
 208
 209    -------------
 210    -- SetU_36 --
 211    -------------
 212
 213    procedure SetU_36
 214      (Arr     : System.Address;
 215       N       : Natural;
 216       E       : Bits_36;
 217       Rev_SSO : Boolean)
 218    is
 219       A  : constant System.Address := Arr + Bits * Ofs (Uns (N) / 8);
 220       C  : ClusterU_Ref     with Address => A'Address, Import;
 221       RC : Rev_ClusterU_Ref with Address => A'Address, Import;
 222    begin
 223       if Rev_SSO then
 224          case N07 (Uns (N) mod 8) is
 225             when 0 => RC.E0 := E;
 226             when 1 => RC.E1 := E;
 227             when 2 => RC.E2 := E;
 228             when 3 => RC.E3 := E;
 229             when 4 => RC.E4 := E;
 230             when 5 => RC.E5 := E;
 231             when 6 => RC.E6 := E;
 232             when 7 => RC.E7 := E;
 233          end case;
 234       else
 235          case N07 (Uns (N) mod 8) is
 236             when 0 => C.E0 := E;
 237             when 1 => C.E1 := E;
 238             when 2 => C.E2 := E;
 239             when 3 => C.E3 := E;
 240             when 4 => C.E4 := E;
 241             when 5 => C.E5 := E;
 242             when 6 => C.E6 := E;
 243             when 7 => C.E7 := E;
 244          end case;
 245       end if;
 246    end SetU_36;
 247
 248 end System.Pack_36;