1 ------------------------------------------------------------------------------
3 -- GNAT RUN-TIME COMPONENTS --
5 -- S Y S T E M . W C H _ J I S --
9 -- Copyright (C) 1992-2023, Free Software Foundation, Inc. --
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 3, 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. --
18 -- As a special exception under Section 7 of GPL version 3, you are granted --
19 -- additional permissions described in the GCC Runtime Library Exception, --
20 -- version 3.1, as published by the Free Software Foundation. --
22 -- You should have received a copy of the GNU General Public License and --
23 -- a copy of the GCC Runtime Library Exception along with this program; --
24 -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
25 -- <http://www.gnu.org/licenses/>. --
27 -- GNAT was originally developed by the GNAT team at New York University. --
28 -- Extensive contributions were provided by Ada Core Technologies Inc. --
30 ------------------------------------------------------------------------------
32 package body System
.WCh_JIS
is
36 EUC_Hankaku_Kana
: constant Byte
:= 16#
8E#
;
37 -- Prefix byte in EUC for Hankaku Kana (small Katakana). Such characters
38 -- in EUC are represented by a prefix byte followed by the code, which
39 -- is in the upper half (the corresponding JIS internal code is in the
40 -- range 16#0080# - 16#00FF#).
42 function EUC_To_JIS
(EUC1
, EUC2
: Character) return Wide_Character is
43 EUC1B
: constant Byte
:= Character'Pos (EUC1
);
44 EUC2B
: constant Byte
:= Character'Pos (EUC2
);
47 if EUC2B
not in 16#A0#
.. 16#FE#
then
48 raise Constraint_Error
;
51 if EUC1B
= EUC_Hankaku_Kana
then
52 return Wide_Character'Val (EUC2B
);
55 if EUC1B
not in 16#A0#
.. 16#FE#
then
56 raise Constraint_Error
;
58 return Wide_Character'Val
59 (256 * Natural (EUC1B
and 16#
7F#
) + Natural (EUC2B
and 16#
7F#
));
73 JIS1
: constant Natural := Wide_Character'Pos (J
) / 256;
74 JIS2
: constant Natural := Wide_Character'Pos (J
) rem 256;
77 -- Special case of small Katakana
81 -- The value must be in the range 16#80# to 16#FF# so that the upper
82 -- bit is set in both bytes.
85 raise Constraint_Error
;
88 EUC1
:= Character'Val (EUC_Hankaku_Kana
);
89 EUC2
:= Character'Val (JIS2
);
91 -- The upper bit of both characters must be clear, or this is not
92 -- a valid character for representation in EUC form.
94 elsif JIS1
> 16#
7F#
or else JIS2
> 16#
7F#
then
95 raise Constraint_Error
;
97 -- Result is just the two characters with upper bits set
100 EUC1
:= Character'Val (JIS1
+ 16#
80#
);
101 EUC2
:= Character'Val (JIS2
+ 16#
80#
);
105 ----------------------
106 -- JIS_To_Shift_JIS --
107 ----------------------
109 procedure JIS_To_Shift_JIS
118 -- The following is the required algorithm, it's hard to make any
119 -- more intelligent comments. This was copied from a public domain
120 -- C program called etos.c (author unknown).
122 JIS1
:= Byte
(Natural (Wide_Character'Pos (J
) / 256));
123 JIS2
:= Byte
(Natural (Wide_Character'Pos (J
) rem 256));
125 if JIS1
> 16#
5F#
then
126 JIS1
:= JIS1
+ 16#
80#
;
129 if (JIS1
mod 2) = 0 then
130 SJ1
:= Character'Val ((JIS1
- 16#
30#
) / 2 + 16#
88#
);
131 SJ2
:= Character'Val (JIS2
+ 16#
7E#
);
134 if JIS2
>= 16#
60#
then
135 JIS2
:= JIS2
+ 16#
01#
;
138 SJ1
:= Character'Val ((JIS1
- 16#
31#
) / 2 + 16#
89#
);
139 SJ2
:= Character'Val (JIS2
+ 16#
1F#
);
141 end JIS_To_Shift_JIS
;
143 ----------------------
144 -- Shift_JIS_To_JIS --
145 ----------------------
147 function Shift_JIS_To_JIS
(SJ1
, SJ2
: Character) return Wide_Character is
154 -- The following is the required algorithm, it's hard to make any
155 -- more intelligent comments. This was copied from a public domain
156 -- C program called stoj.c written by shige@csk.JUNET.
158 SJIS1
:= Character'Pos (SJ1
);
159 SJIS2
:= Character'Pos (SJ2
);
161 if SJIS1
>= 16#E0#
then
162 SJIS1
:= SJIS1
- 16#
40#
;
165 if SJIS2
>= 16#
9F#
then
166 JIS1
:= (SJIS1
- 16#
88#
) * 2 + 16#
30#
;
167 JIS2
:= SJIS2
- 16#
7E#
;
170 if SJIS2
>= 16#
7F#
then
171 SJIS2
:= SJIS2
- 16#
01#
;
174 JIS1
:= (SJIS1
- 16#
89#
) * 2 + 16#
31#
;
175 JIS2
:= SJIS2
- 16#
1F#
;
178 if JIS1
not in 16#
20#
.. 16#
7E#
179 or else JIS2
not in 16#
20#
.. 16#
7E#
181 raise Constraint_Error
;
183 return Wide_Character'Val (256 * Natural (JIS1
) + Natural (JIS2
));
185 end Shift_JIS_To_JIS
;