1 ------------------------------------------------------------------------------
3 -- GNAT RUN-TIME COMPONENTS --
5 -- S Y S T E M . W C H _ J I S --
9 -- Copyright (C) 1992-2006, 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 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. --
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. --
29 -- GNAT was originally developed by the GNAT team at New York University. --
30 -- Extensive contributions were provided by Ada Core Technologies Inc. --
32 ------------------------------------------------------------------------------
34 with System
.Pure_Exceptions
; use System
.Pure_Exceptions
;
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#
));
77 JIS1
: constant Natural := Wide_Character'Pos (J
) / 256;
78 JIS2
: constant Natural := Wide_Character'Pos (J
) rem 256;
81 -- Special case of small Katakana
85 -- The value must be in the range 16#80# to 16#FF# so that the upper
86 -- bit is set in both bytes.
89 Raise_Exception
(CE
, "invalid small Katakana character");
92 EUC1
:= Character'Val (EUC_Hankaku_Kana
);
93 EUC2
:= Character'Val (JIS2
);
95 -- The upper bit of both characters must be clear, or this is not
96 -- a valid character for representation in EUC form.
98 elsif JIS1
> 16#
7F#
or else JIS2
> 16#
7F#
then
99 Raise_Exception
(CE
, "wide character value out of EUC range");
101 -- Result is just the two characters with upper bits set
104 EUC1
:= Character'Val (JIS1
+ 16#
80#
);
105 EUC2
:= Character'Val (JIS2
+ 16#
80#
);
109 ----------------------
110 -- JIS_To_Shift_JIS --
111 ----------------------
113 procedure JIS_To_Shift_JIS
122 -- The following is the required algorithm, it's hard to make any
123 -- more intelligent comments! This was copied from a public domain
124 -- C program called etos.c (author unknown).
126 JIS1
:= Byte
(Natural (Wide_Character'Pos (J
) / 256));
127 JIS2
:= Byte
(Natural (Wide_Character'Pos (J
) rem 256));
129 if JIS1
> 16#
5F#
then
130 JIS1
:= JIS1
+ 16#
80#
;
133 if (JIS1
mod 2) = 0 then
134 SJ1
:= Character'Val ((JIS1
- 16#
30#
) / 2 + 16#
88#
);
135 SJ2
:= Character'Val (JIS2
+ 16#
7E#
);
138 if JIS2
>= 16#
60#
then
139 JIS2
:= JIS2
+ 16#
01#
;
142 SJ1
:= Character'Val ((JIS1
- 16#
31#
) / 2 + 16#
89#
);
143 SJ2
:= Character'Val (JIS2
+ 16#
1F#
);
145 end JIS_To_Shift_JIS
;
147 ----------------------
148 -- Shift_JIS_To_JIS --
149 ----------------------
151 function Shift_JIS_To_JIS
(SJ1
, SJ2
: Character) return Wide_Character is
158 -- The following is the required algorithm, it's hard to make any
159 -- more intelligent comments! This was copied from a public domain
160 -- C program called stoj.c written by shige@csk.JUNET.
162 SJIS1
:= Character'Pos (SJ1
);
163 SJIS2
:= Character'Pos (SJ2
);
165 if SJIS1
>= 16#E0#
then
166 SJIS1
:= SJIS1
- 16#
40#
;
169 if SJIS2
>= 16#
9F#
then
170 JIS1
:= (SJIS1
- 16#
88#
) * 2 + 16#
30#
;
171 JIS2
:= SJIS2
- 16#
7E#
;
174 if SJIS2
>= 16#
7F#
then
175 SJIS2
:= SJIS2
- 16#
01#
;
178 JIS1
:= (SJIS1
- 16#
89#
) * 2 + 16#
31#
;
179 JIS2
:= SJIS2
- 16#
1F#
;
182 if JIS1
not in 16#
20#
.. 16#
7E#
183 or else JIS2
not in 16#
20#
.. 16#
7E#
185 raise Constraint_Error
;
187 return Wide_Character'Val (256 * Natural (JIS1
) + Natural (JIS2
));
189 end Shift_JIS_To_JIS
;