gcc/ada/s-wchjis.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT RUNTIME COMPONENTS                          --
   4 --                                                                          --
   5 --                       S Y S T E M . W C H _ J I S                        --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --                            $Revision: 1.5 $                              --
  10 --                                                                          --
  11 --        Copyright (C) 1992,1993,1994 Free Software Foundation, Inc.       --
  12 --                                                                          --
  13 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  14 -- terms of the  GNU General Public License as published  by the Free Soft- --
  15 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  16 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  17 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  18 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  19 -- for  more details.  You should have  received  a copy of the GNU General --
  20 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
  21 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  22 -- MA 02111-1307, USA.                                                      --
  23 --                                                                          --
  24 -- As a special exception,  if other files  instantiate  generics from this --
  25 -- unit, or you link  this unit with other files  to produce an executable, --
  26 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  27 -- covered  by the  GNU  General  Public  License.  This exception does not --
  28 -- however invalidate  any other reasons why  the executable file  might be --
  29 -- covered by the  GNU Public License.                                      --
  30 --                                                                          --
  31 -- GNAT was originally developed  by the GNAT team at  New York University. --
  32 -- It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). --
  33 --                                                                          --
  34 ------------------------------------------------------------------------------
  35
  36 package body System.WCh_JIS is
  37
  38    type Byte is mod 256;
  39
  40    EUC_Hankaku_Kana : constant Byte := 16#8E#;
  41    --  Prefix byte in EUC for Hankaku Kana (small Katakana). Such characters
  42    --  in EUC are represented by a prefix byte followed by the code, which
  43    --  is in the upper half (the corresponding JIS internal code is in the
  44    --  range 16#0080# - 16#00FF#).
  45
  46    function EUC_To_JIS (EUC1, EUC2 : Character) return Wide_Character is
  47       EUC1B  : constant Byte := Character'Pos (EUC1);
  48       EUC2B  : constant Byte := Character'Pos (EUC2);
  49
  50    begin
  51       if EUC2B not in 16#A0# .. 16#FE# then
  52          raise Constraint_Error;
  53       end if;
  54
  55       if EUC1B = EUC_Hankaku_Kana then
  56          return Wide_Character'Val (EUC2B);
  57
  58       else
  59          if EUC1B not in 16#A0# .. 16#FE# then
  60             raise Constraint_Error;
  61          else
  62             return Wide_Character'Val
  63               (256 * Natural (EUC1B and 16#7F#) + Natural (EUC2B and 16#7F#));
  64          end if;
  65       end if;
  66    end EUC_To_JIS;
  67
  68    ----------------
  69    -- JIS_To_EUC --
  70    ----------------
  71
  72    procedure JIS_To_EUC
  73      (J    : in Wide_Character;
  74       EUC1 : out Character;
  75       EUC2 : out Character)
  76    is
  77       JIS1 : constant Natural := Wide_Character'Pos (J) / 256;
  78       JIS2 : constant Natural := Wide_Character'Pos (J) rem 256;
  79
  80    begin
  81       if JIS1 = 0 then
  82          EUC1 := Character'Val (EUC_Hankaku_Kana);
  83          EUC2 := Character'Val (JIS2);
  84
  85       else
  86          EUC1 := Character'Val (JIS1 + 16#80#);
  87          EUC2 := Character'Val (JIS2 + 16#80#);
  88       end if;
  89    end JIS_To_EUC;
  90
  91    ----------------------
  92    -- JIS_To_Shift_JIS --
  93    ----------------------
  94
  95    procedure JIS_To_Shift_JIS
  96      (J   : in Wide_Character;
  97       SJ1 : out Character;
  98       SJ2 : out Character)
  99    is
 100       JIS1 : Byte;
 101       JIS2 : Byte;
 102
 103    begin
 104       --  The following is the required algorithm, it's hard to make any
 105       --  more intelligent comments! This was copied from a public domain
 106       --  C program called etos.c (author unknown).
 107
 108       JIS1 := Byte (Natural (Wide_Character'Pos (J) / 256));
 109       JIS2 := Byte (Natural (Wide_Character'Pos (J) rem 256));
 110
 111       if JIS1 > 16#5F# then
 112          JIS1 := JIS1 + 16#80#;
 113       end if;
 114
 115       if (JIS1 mod 2) = 0 then
 116          SJ1 := Character'Val ((JIS1 - 16#30#) / 2 + 16#88#);
 117          SJ2 := Character'Val (JIS2 + 16#7E#);
 118
 119       else
 120          if JIS2 >= 16#60# then
 121             JIS2 := JIS2 + 16#01#;
 122          end if;
 123
 124          SJ1 := Character'Val ((JIS1 - 16#31#) / 2 + 16#89#);
 125          SJ2 := Character'Val (JIS2 + 16#1F#);
 126       end if;
 127    end JIS_To_Shift_JIS;
 128
 129    ----------------------
 130    -- Shift_JIS_To_JIS --
 131    ----------------------
 132
 133    function Shift_JIS_To_JIS (SJ1, SJ2 : Character) return Wide_Character is
 134       SJIS1 : Byte;
 135       SJIS2 : Byte;
 136       JIS1  : Byte;
 137       JIS2  : Byte;
 138
 139    begin
 140       --  The following is the required algorithm, it's hard to make any
 141       --  more intelligent comments! This was copied from a public domain
 142       --  C program called stoj.c written by shige@csk.JUNET.
 143
 144       SJIS1 := Character'Pos (SJ1);
 145       SJIS2 := Character'Pos (SJ2);
 146
 147       if SJIS1 >= 16#E0# then
 148          SJIS1 := SJIS1 - 16#40#;
 149       end if;
 150
 151       if SJIS2 >= 16#9F# then
 152          JIS1 := (SJIS1 - 16#88#) * 2 + 16#30#;
 153          JIS2 := SJIS2 - 16#7E#;
 154
 155       else
 156          if SJIS2 >= 16#7F# then
 157             SJIS2 := SJIS2 - 16#01#;
 158          end if;
 159
 160          JIS1 := (SJIS1 - 16#89#) * 2 + 16#31#;
 161          JIS2 := SJIS2 - 16#1F#;
 162       end if;
 163
 164       if JIS1 not in 16#20# .. 16#7E#
 165         or else JIS2 not in 16#20# .. 16#7E#
 166       then
 167          raise Constraint_Error;
 168       else
 169          return Wide_Character'Val (256 * Natural (JIS1) + Natural (JIS2));
 170       end if;
 171    end Shift_JIS_To_JIS;
 172
 173 end System.WCh_JIS;