gcc/ada/s-caun64.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                    GNAT RUN-TIME LIBRARY COMPONENTS                      --
   4 --                                                                          --
   5 --      S Y S T E M . C O M P A R E _ A R R A Y _ U N S I G N E D _ 6 4     --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --          Copyright (C) 2002-2005 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- --
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  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,  51  Franklin  Street,  Fifth  Floor, --
  20 -- Boston, MA 02110-1301, 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 System.Address_Operations; use System.Address_Operations;
  35
  36 with Unchecked_Conversion;
  37
  38 package body System.Compare_Array_Unsigned_64 is
  39
  40    type Word is mod 2 ** 64;
  41    --  Used to process operands by words
  42
  43    type Uword is record
  44       W : Word;
  45    end record;
  46    pragma Pack (Uword);
  47    for Uword'Alignment use 1;
  48    --  Used to process operands when unaligned
  49
  50    type WP is access Word;
  51    type UP is access Uword;
  52
  53    function W is new Unchecked_Conversion (Address, WP);
  54    function U is new Unchecked_Conversion (Address, UP);
  55
  56    -----------------------
  57    -- Compare_Array_U64 --
  58    -----------------------
  59
  60    function Compare_Array_U64
  61      (Left      : System.Address;
  62       Right     : System.Address;
  63       Left_Len  : Natural;
  64       Right_Len : Natural) return Integer
  65    is
  66       Clen : Natural := Natural'Min (Left_Len, Right_Len);
  67       --  Number of elements left to compare
  68
  69       L : Address := Left;
  70       R : Address := Right;
  71       --  Pointers to next elements to compare
  72
  73    begin
  74       --  Case of going by aligned double words
  75
  76       if ModA (OrA (Left, Right), 8) = 0 then
  77          while Clen /= 0 loop
  78             if W (L).all /= W (R).all then
  79                if W (L).all > W (R).all then
  80                   return +1;
  81                else
  82                   return -1;
  83                end if;
  84             end if;
  85
  86             Clen := Clen - 1;
  87             L := AddA (L, 8);
  88             R := AddA (R, 8);
  89          end loop;
  90
  91       --  Case of going by unaligned double words
  92
  93       else
  94          while Clen /= 0 loop
  95             if U (L).W /= U (R).W then
  96                if U (L).W > U (R).W then
  97                   return +1;
  98                else
  99                   return -1;
 100                end if;
 101             end if;
 102
 103             Clen := Clen - 1;
 104             L := AddA (L, 8);
 105             R := AddA (R, 8);
 106          end loop;
 107       end if;
 108
 109       --  Here if common section equal, result decided by lengths
 110
 111       if Left_Len = Right_Len then
 112          return 0;
 113       elsif Left_Len > Right_Len then
 114          return +1;
 115       else
 116          return -1;
 117       end if;
 118    end Compare_Array_U64;
 119
 120 end System.Compare_Array_Unsigned_64;