gcc/ada/s-wchjis.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT RUN-TIME 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) 1992-2007, 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,  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 pragma Warnings (Off);
  35 pragma Compiler_Unit;
  36 pragma Warnings (On);
  37
  38 package body System.WCh_JIS is
  39
  40    type Byte is mod 256;
  41
  42    EUC_Hankaku_Kana : constant Byte := 16#8E#;
  43    --  Prefix byte in EUC for Hankaku Kana (small Katakana). Such characters
  44    --  in EUC are represented by a prefix byte followed by the code, which
  45    --  is in the upper half (the corresponding JIS internal code is in the
  46    --  range 16#0080# - 16#00FF#).
  47
  48    function EUC_To_JIS (EUC1, EUC2 : Character) return Wide_Character is
  49       EUC1B  : constant Byte := Character'Pos (EUC1);
  50       EUC2B  : constant Byte := Character'Pos (EUC2);
  51
  52    begin
  53       if EUC2B not in 16#A0# .. 16#FE# then
  54          raise Constraint_Error;
  55       end if;
  56
  57       if EUC1B = EUC_Hankaku_Kana then
  58          return Wide_Character'Val (EUC2B);
  59
  60       else
  61          if EUC1B not in 16#A0# .. 16#FE# then
  62             raise Constraint_Error;
  63          else
  64             return Wide_Character'Val
  65               (256 * Natural (EUC1B and 16#7F#) + Natural (EUC2B and 16#7F#));
  66          end if;
  67       end if;
  68    end EUC_To_JIS;
  69
  70    ----------------
  71    -- JIS_To_EUC --
  72    ----------------
  73
  74    procedure JIS_To_EUC
  75      (J    : Wide_Character;
  76       EUC1 : out Character;
  77       EUC2 : out Character)
  78    is
  79       JIS1 : constant Natural := Wide_Character'Pos (J) / 256;
  80       JIS2 : constant Natural := Wide_Character'Pos (J) rem 256;
  81
  82    begin
  83       --  Special case of small Katakana
  84
  85       if JIS1 = 0 then
  86
  87          --  The value must be in the range 16#80# to 16#FF# so that the upper
  88          --  bit is set in both bytes.
  89
  90          if JIS2 < 16#80# then
  91             raise Constraint_Error;
  92          end if;
  93
  94          EUC1 := Character'Val (EUC_Hankaku_Kana);
  95          EUC2 := Character'Val (JIS2);
  96
  97       --  The upper bit of both characters must be clear, or this is not
  98       --  a valid character for representation in EUC form.
  99
 100       elsif JIS1 > 16#7F# or else JIS2 > 16#7F# then
 101          raise Constraint_Error;
 102
 103       --  Result is just the two characters with upper bits set
 104
 105       else
 106          EUC1 := Character'Val (JIS1 + 16#80#);
 107          EUC2 := Character'Val (JIS2 + 16#80#);
 108       end if;
 109    end JIS_To_EUC;
 110
 111    ----------------------
 112    -- JIS_To_Shift_JIS --
 113    ----------------------
 114
 115    procedure JIS_To_Shift_JIS
 116      (J   : Wide_Character;
 117       SJ1 : out Character;
 118       SJ2 : out Character)
 119    is
 120       JIS1 : Byte;
 121       JIS2 : Byte;
 122
 123    begin
 124       --  The following is the required algorithm, it's hard to make any
 125       --  more intelligent comments! This was copied from a public domain
 126       --  C program called etos.c (author unknown).
 127
 128       JIS1 := Byte (Natural (Wide_Character'Pos (J) / 256));
 129       JIS2 := Byte (Natural (Wide_Character'Pos (J) rem 256));
 130
 131       if JIS1 > 16#5F# then
 132          JIS1 := JIS1 + 16#80#;
 133       end if;
 134
 135       if (JIS1 mod 2) = 0 then
 136          SJ1 := Character'Val ((JIS1 - 16#30#) / 2 + 16#88#);
 137          SJ2 := Character'Val (JIS2 + 16#7E#);
 138
 139       else
 140          if JIS2 >= 16#60# then
 141             JIS2 := JIS2 + 16#01#;
 142          end if;
 143
 144          SJ1 := Character'Val ((JIS1 - 16#31#) / 2 + 16#89#);
 145          SJ2 := Character'Val (JIS2 + 16#1F#);
 146       end if;
 147    end JIS_To_Shift_JIS;
 148
 149    ----------------------
 150    -- Shift_JIS_To_JIS --
 151    ----------------------
 152
 153    function Shift_JIS_To_JIS (SJ1, SJ2 : Character) return Wide_Character is
 154       SJIS1 : Byte;
 155       SJIS2 : Byte;
 156       JIS1  : Byte;
 157       JIS2  : Byte;
 158
 159    begin
 160       --  The following is the required algorithm, it's hard to make any
 161       --  more intelligent comments! This was copied from a public domain
 162       --  C program called stoj.c written by shige@csk.JUNET.
 163
 164       SJIS1 := Character'Pos (SJ1);
 165       SJIS2 := Character'Pos (SJ2);
 166
 167       if SJIS1 >= 16#E0# then
 168          SJIS1 := SJIS1 - 16#40#;
 169       end if;
 170
 171       if SJIS2 >= 16#9F# then
 172          JIS1 := (SJIS1 - 16#88#) * 2 + 16#30#;
 173          JIS2 := SJIS2 - 16#7E#;
 174
 175       else
 176          if SJIS2 >= 16#7F# then
 177             SJIS2 := SJIS2 - 16#01#;
 178          end if;
 179
 180          JIS1 := (SJIS1 - 16#89#) * 2 + 16#31#;
 181          JIS2 := SJIS2 - 16#1F#;
 182       end if;
 183
 184       if JIS1 not in 16#20# .. 16#7E#
 185         or else JIS2 not in 16#20# .. 16#7E#
 186       then
 187          raise Constraint_Error;
 188       else
 189          return Wide_Character'Val (256 * Natural (JIS1) + Natural (JIS2));
 190       end if;
 191    end Shift_JIS_To_JIS;
 192
 193 end System.WCh_JIS;