gcc/ada/s-caun64.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                   GNU ADA RUNTIME 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 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 Unchecked_Conversion;
  35
  36 package body System.Compare_Array_Unsigned_64 is
  37
  38    type Word is mod 2 ** 64;
  39    --  Used to process operands by words
  40
  41    type Uword is record
  42       W : Word;
  43    end record;
  44    pragma Pack (Uword);
  45    for Uword'Alignment use 1;
  46    --  Used to process operands when unaligned
  47
  48    type WP is access Word;
  49    type UP is access Uword;
  50
  51    function W is new Unchecked_Conversion (Address, WP);
  52    function U is new Unchecked_Conversion (Address, UP);
  53
  54    -----------------------
  55    -- Compare_Array_U64 --
  56    -----------------------
  57
  58    function Compare_Array_U64
  59      (Left      : System.Address;
  60       Right     : System.Address;
  61       Left_Len  : Natural;
  62       Right_Len : Natural)
  63       return      Integer
  64    is
  65       Clen : Natural := Natural'Min (Left_Len, Right_Len);
  66       --  Number of elements left to compare
  67
  68       L : Address := Left;
  69       R : Address := Right;
  70       --  Pointers to next elements to compare
  71
  72    begin
  73       --  Case of going by aligned words
  74
  75       if ((Left or Right) and (8 - 1)) = 0 then
  76          while Clen /= 0 loop
  77             if W (L).all /= W (R).all then
  78                if W (L).all > W (R).all then
  79                   return +1;
  80                else
  81                   return -1;
  82                end if;
  83             end if;
  84
  85             Clen := Clen - 1;
  86             L := L + 8;
  87             R := R + 8;
  88          end loop;
  89
  90       --  Case of going by unaligned words
  91
  92       else
  93          while Clen /= 0 loop
  94             if U (L).W /= U (R).W then
  95                if U (L).W > U (R).W then
  96                   return +1;
  97                else
  98                   return -1;
  99                end if;
 100             end if;
 101
 102             Clen := Clen - 1;
 103             L := L + 8;
 104             R := R + 8;
 105          end loop;
 106       end if;
 107
 108       --  Here if common section equal, result decided by lengths
 109
 110       if Left_Len = Right_Len then
 111          return 0;
 112       elsif Left_Len > Right_Len then
 113          return +1;
 114       else
 115          return -1;
 116       end if;
 117    end Compare_Array_U64;
 118
 119 end System.Compare_Array_Unsigned_64;