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 --        Copyright (C) 1992,1993,1994 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 package body System.WCh_JIS is
  35
  36    type Byte is mod 256;
  37
  38    EUC_Hankaku_Kana : constant Byte := 16#8E#;
  39    --  Prefix byte in EUC for Hankaku Kana (small Katakana). Such characters
  40    --  in EUC are represented by a prefix byte followed by the code, which
  41    --  is in the upper half (the corresponding JIS internal code is in the
  42    --  range 16#0080# - 16#00FF#).
  43
  44    function EUC_To_JIS (EUC1, EUC2 : Character) return Wide_Character is
  45       EUC1B  : constant Byte := Character'Pos (EUC1);
  46       EUC2B  : constant Byte := Character'Pos (EUC2);
  47
  48    begin
  49       if EUC2B not in 16#A0# .. 16#FE# then
  50          raise Constraint_Error;
  51       end if;
  52
  53       if EUC1B = EUC_Hankaku_Kana then
  54          return Wide_Character'Val (EUC2B);
  55
  56       else
  57          if EUC1B not in 16#A0# .. 16#FE# then
  58             raise Constraint_Error;
  59          else
  60             return Wide_Character'Val
  61               (256 * Natural (EUC1B and 16#7F#) + Natural (EUC2B and 16#7F#));
  62          end if;
  63       end if;
  64    end EUC_To_JIS;
  65
  66    ----------------
  67    -- JIS_To_EUC --
  68    ----------------
  69
  70    procedure JIS_To_EUC
  71      (J    : in Wide_Character;
  72       EUC1 : out Character;
  73       EUC2 : out Character)
  74    is
  75       JIS1 : constant Natural := Wide_Character'Pos (J) / 256;
  76       JIS2 : constant Natural := Wide_Character'Pos (J) rem 256;
  77
  78    begin
  79       if JIS1 = 0 then
  80          EUC1 := Character'Val (EUC_Hankaku_Kana);
  81          EUC2 := Character'Val (JIS2);
  82
  83       else
  84          EUC1 := Character'Val (JIS1 + 16#80#);
  85          EUC2 := Character'Val (JIS2 + 16#80#);
  86       end if;
  87    end JIS_To_EUC;
  88
  89    ----------------------
  90    -- JIS_To_Shift_JIS --
  91    ----------------------
  92
  93    procedure JIS_To_Shift_JIS
  94      (J   : in Wide_Character;
  95       SJ1 : out Character;
  96       SJ2 : out Character)
  97    is
  98       JIS1 : Byte;
  99       JIS2 : Byte;
 100
 101    begin
 102       --  The following is the required algorithm, it's hard to make any
 103       --  more intelligent comments! This was copied from a public domain
 104       --  C program called etos.c (author unknown).
 105
 106       JIS1 := Byte (Natural (Wide_Character'Pos (J) / 256));
 107       JIS2 := Byte (Natural (Wide_Character'Pos (J) rem 256));
 108
 109       if JIS1 > 16#5F# then
 110          JIS1 := JIS1 + 16#80#;
 111       end if;
 112
 113       if (JIS1 mod 2) = 0 then
 114          SJ1 := Character'Val ((JIS1 - 16#30#) / 2 + 16#88#);
 115          SJ2 := Character'Val (JIS2 + 16#7E#);
 116
 117       else
 118          if JIS2 >= 16#60# then
 119             JIS2 := JIS2 + 16#01#;
 120          end if;
 121
 122          SJ1 := Character'Val ((JIS1 - 16#31#) / 2 + 16#89#);
 123          SJ2 := Character'Val (JIS2 + 16#1F#);
 124       end if;
 125    end JIS_To_Shift_JIS;
 126
 127    ----------------------
 128    -- Shift_JIS_To_JIS --
 129    ----------------------
 130
 131    function Shift_JIS_To_JIS (SJ1, SJ2 : Character) return Wide_Character is
 132       SJIS1 : Byte;
 133       SJIS2 : Byte;
 134       JIS1  : Byte;
 135       JIS2  : Byte;
 136
 137    begin
 138       --  The following is the required algorithm, it's hard to make any
 139       --  more intelligent comments! This was copied from a public domain
 140       --  C program called stoj.c written by shige@csk.JUNET.
 141
 142       SJIS1 := Character'Pos (SJ1);
 143       SJIS2 := Character'Pos (SJ2);
 144
 145       if SJIS1 >= 16#E0# then
 146          SJIS1 := SJIS1 - 16#40#;
 147       end if;
 148
 149       if SJIS2 >= 16#9F# then
 150          JIS1 := (SJIS1 - 16#88#) * 2 + 16#30#;
 151          JIS2 := SJIS2 - 16#7E#;
 152
 153       else
 154          if SJIS2 >= 16#7F# then
 155             SJIS2 := SJIS2 - 16#01#;
 156          end if;
 157
 158          JIS1 := (SJIS1 - 16#89#) * 2 + 16#31#;
 159          JIS2 := SJIS2 - 16#1F#;
 160       end if;
 161
 162       if JIS1 not in 16#20# .. 16#7E#
 163         or else JIS2 not in 16#20# .. 16#7E#
 164       then
 165          raise Constraint_Error;
 166       else
 167          return Wide_Character'Val (256 * Natural (JIS1) + Natural (JIS2));
 168       end if;
 169    end Shift_JIS_To_JIS;
 170
 171 end System.WCh_JIS;