1 ------------------------------------------------------------------------------
3 -- GNAT RUN-TIME COMPONENTS --
5 -- S Y S T E M . W C H _ J I S --
9 -- Copyright (C) 1992-2007, 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 pragma Warnings (Off);
38 package body System.WCh_JIS is
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#).
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);
53 if EUC2B not in 16#A0# .. 16#FE# then
54 raise Constraint_Error;
57 if EUC1B = EUC_Hankaku_Kana then
58 return Wide_Character'Val (EUC2B);
61 if EUC1B not in 16#A0# .. 16#FE# then
62 raise Constraint_Error;
64 return Wide_Character'Val
65 (256 * Natural (EUC1B and 16#7F#) + Natural (EUC2B and 16#7F#));
79 JIS1 : constant Natural := Wide_Character'Pos (J) / 256;
80 JIS2 : constant Natural := Wide_Character'Pos (J) rem 256;
83 -- Special case of small Katakana
87 -- The value must be in the range 16#80# to 16#FF# so that the upper
88 -- bit is set in both bytes.
91 raise Constraint_Error;
94 EUC1 := Character'Val (EUC_Hankaku_Kana);
95 EUC2 := Character'Val (JIS2);
97 -- The upper bit of both characters must be clear, or this is not
98 -- a valid character for representation in EUC form.
100 elsif JIS1 > 16#7F# or else JIS2 > 16#7F# then
101 raise Constraint_Error;
103 -- Result is just the two characters with upper bits set
106 EUC1 := Character'Val (JIS1 + 16#80#);
107 EUC2 := Character'Val (JIS2 + 16#80#);
111 ----------------------
112 -- JIS_To_Shift_JIS --
113 ----------------------
115 procedure JIS_To_Shift_JIS
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).
128 JIS1 := Byte (Natural (Wide_Character'Pos (J) / 256));
129 JIS2 := Byte (Natural (Wide_Character'Pos (J) rem 256));
131 if JIS1 > 16#5F# then
132 JIS1 := JIS1 + 16#80#;
135 if (JIS1 mod 2) = 0 then
136 SJ1 := Character'Val ((JIS1 - 16#30#) / 2 + 16#88#);
137 SJ2 := Character'Val (JIS2 + 16#7E#);
140 if JIS2 >= 16#60# then
141 JIS2 := JIS2 + 16#01#;
144 SJ1 := Character'Val ((JIS1 - 16#31#) / 2 + 16#89#);
145 SJ2 := Character'Val (JIS2 + 16#1F#);
147 end JIS_To_Shift_JIS;
149 ----------------------
150 -- Shift_JIS_To_JIS --
151 ----------------------
153 function Shift_JIS_To_JIS (SJ1, SJ2 : Character) return Wide_Character is
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.
164 SJIS1 := Character'Pos (SJ1);
165 SJIS2 := Character'Pos (SJ2);
167 if SJIS1 >= 16#E0# then
168 SJIS1 := SJIS1 - 16#40#;
171 if SJIS2 >= 16#9F# then
172 JIS1 := (SJIS1 - 16#88#) * 2 + 16#30#;
173 JIS2 := SJIS2 - 16#7E#;
176 if SJIS2 >= 16#7F# then
177 SJIS2 := SJIS2 - 16#01#;
180 JIS1 := (SJIS1 - 16#89#) * 2 + 16#31#;
181 JIS2 := SJIS2 - 16#1F#;
184 if JIS1 not in 16#20# .. 16#7E#
185 or else JIS2 not in 16#20# .. 16#7E#
187 raise Constraint_Error;
189 return Wide_Character'Val (256 * Natural (JIS1) + Natural (JIS2));
191 end Shift_JIS_To_JIS;