1 ------------------------------------------------------------------------------
3 -- GNAT RUNTIME COMPONENTS --
5 -- S Y S T E M . W C H _ J I S --
11 -- Copyright (C) 1992,1993,1994 Free Software Foundation, Inc. --
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. --
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. --
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). --
34 ------------------------------------------------------------------------------
36 package body System.WCh_JIS is
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#).
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);
51 if EUC2B not in 16#A0# .. 16#FE# then
52 raise Constraint_Error;
55 if EUC1B = EUC_Hankaku_Kana then
56 return Wide_Character'Val (EUC2B);
59 if EUC1B not in 16#A0# .. 16#FE# then
60 raise Constraint_Error;
62 return Wide_Character'Val
63 (256 * Natural (EUC1B and 16#7F#) + Natural (EUC2B and 16#7F#));
73 (J : in Wide_Character;
77 JIS1 : constant Natural := Wide_Character'Pos (J) / 256;
78 JIS2 : constant Natural := Wide_Character'Pos (J) rem 256;
82 EUC1 := Character'Val (EUC_Hankaku_Kana);
83 EUC2 := Character'Val (JIS2);
86 EUC1 := Character'Val (JIS1 + 16#80#);
87 EUC2 := Character'Val (JIS2 + 16#80#);
91 ----------------------
92 -- JIS_To_Shift_JIS --
93 ----------------------
95 procedure JIS_To_Shift_JIS
96 (J : in Wide_Character;
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).
108 JIS1 := Byte (Natural (Wide_Character'Pos (J) / 256));
109 JIS2 := Byte (Natural (Wide_Character'Pos (J) rem 256));
111 if JIS1 > 16#5F# then
112 JIS1 := JIS1 + 16#80#;
115 if (JIS1 mod 2) = 0 then
116 SJ1 := Character'Val ((JIS1 - 16#30#) / 2 + 16#88#);
117 SJ2 := Character'Val (JIS2 + 16#7E#);
120 if JIS2 >= 16#60# then
121 JIS2 := JIS2 + 16#01#;
124 SJ1 := Character'Val ((JIS1 - 16#31#) / 2 + 16#89#);
125 SJ2 := Character'Val (JIS2 + 16#1F#);
127 end JIS_To_Shift_JIS;
129 ----------------------
130 -- Shift_JIS_To_JIS --
131 ----------------------
133 function Shift_JIS_To_JIS (SJ1, SJ2 : Character) return Wide_Character is
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.
144 SJIS1 := Character'Pos (SJ1);
145 SJIS2 := Character'Pos (SJ2);
147 if SJIS1 >= 16#E0# then
148 SJIS1 := SJIS1 - 16#40#;
151 if SJIS2 >= 16#9F# then
152 JIS1 := (SJIS1 - 16#88#) * 2 + 16#30#;
153 JIS2 := SJIS2 - 16#7E#;
156 if SJIS2 >= 16#7F# then
157 SJIS2 := SJIS2 - 16#01#;
160 JIS1 := (SJIS1 - 16#89#) * 2 + 16#31#;
161 JIS2 := SJIS2 - 16#1F#;
164 if JIS1 not in 16#20# .. 16#7E#
165 or else JIS2 not in 16#20# .. 16#7E#
167 raise Constraint_Error;
169 return Wide_Character'Val (256 * Natural (JIS1) + Natural (JIS2));
171 end Shift_JIS_To_JIS;