File : 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) 1992-2013, 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 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. --
17 -- --
18 -- --
19 -- --
20 -- --
21 -- --
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/>. --
26 -- --
27 -- GNAT was originally developed by the GNAT team at New York University. --
28 -- Extensive contributions were provided by Ada Core Technologies Inc. --
29 -- --
30 ------------------------------------------------------------------------------
31
32 pragma Compiler_Unit_Warning;
33
34 package body System.WCh_JIS is
35
36 type Byte is mod 256;
37
38 EUC_Hankaku_Kana : constant Byte := 16#8E#;
39 -- Prefix byte in EUC for Hankaku Kana (small Katakana). Such characters
40 -- in EUC are represented by a prefix byte followed by the code, which
41 -- is in the upper half (the corresponding JIS internal code is in the
42 -- range 16#0080# - 16#00FF#).
43
44 function EUC_To_JIS (EUC1, EUC2 : Character) return Wide_Character is
45 EUC1B : constant Byte := Character'Pos (EUC1);
46 EUC2B : constant Byte := Character'Pos (EUC2);
47
48 begin
49 if EUC2B not in 16#A0# .. 16#FE# then
50 raise Constraint_Error;
51 end if;
52
53 if EUC1B = EUC_Hankaku_Kana then
54 return Wide_Character'Val (EUC2B);
55
56 else
57 if EUC1B not in 16#A0# .. 16#FE# then
58 raise Constraint_Error;
59 else
60 return Wide_Character'Val
61 (256 * Natural (EUC1B and 16#7F#) + Natural (EUC2B and 16#7F#));
62 end if;
63 end if;
64 end EUC_To_JIS;
65
66 ----------------
67 -- JIS_To_EUC --
68 ----------------
69
70 procedure JIS_To_EUC
71 (J : Wide_Character;
72 EUC1 : out Character;
73 EUC2 : out Character)
74 is
75 JIS1 : constant Natural := Wide_Character'Pos (J) / 256;
76 JIS2 : constant Natural := Wide_Character'Pos (J) rem 256;
77
78 begin
79 -- Special case of small Katakana
80
81 if JIS1 = 0 then
82
83 -- The value must be in the range 16#80# to 16#FF# so that the upper
84 -- bit is set in both bytes.
85
86 if JIS2 < 16#80# then
87 raise Constraint_Error;
88 end if;
89
90 EUC1 := Character'Val (EUC_Hankaku_Kana);
91 EUC2 := Character'Val (JIS2);
92
93 -- The upper bit of both characters must be clear, or this is not
94 -- a valid character for representation in EUC form.
95
96 elsif JIS1 > 16#7F# or else JIS2 > 16#7F# then
97 raise Constraint_Error;
98
99 -- Result is just the two characters with upper bits set
100
101 else
102 EUC1 := Character'Val (JIS1 + 16#80#);
103 EUC2 := Character'Val (JIS2 + 16#80#);
104 end if;
105 end JIS_To_EUC;
106
107 ----------------------
108 -- JIS_To_Shift_JIS --
109 ----------------------
110
111 procedure JIS_To_Shift_JIS
112 (J : Wide_Character;
113 SJ1 : out Character;
114 SJ2 : out Character)
115 is
116 JIS1 : Byte;
117 JIS2 : Byte;
118
119 begin
120 -- The following is the required algorithm, it's hard to make any
121 -- more intelligent comments. This was copied from a public domain
122 -- C program called etos.c (author unknown).
123
124 JIS1 := Byte (Natural (Wide_Character'Pos (J) / 256));
125 JIS2 := Byte (Natural (Wide_Character'Pos (J) rem 256));
126
127 if JIS1 > 16#5F# then
128 JIS1 := JIS1 + 16#80#;
129 end if;
130
131 if (JIS1 mod 2) = 0 then
132 SJ1 := Character'Val ((JIS1 - 16#30#) / 2 + 16#88#);
133 SJ2 := Character'Val (JIS2 + 16#7E#);
134
135 else
136 if JIS2 >= 16#60# then
137 JIS2 := JIS2 + 16#01#;
138 end if;
139
140 SJ1 := Character'Val ((JIS1 - 16#31#) / 2 + 16#89#);
141 SJ2 := Character'Val (JIS2 + 16#1F#);
142 end if;
143 end JIS_To_Shift_JIS;
144
145 ----------------------
146 -- Shift_JIS_To_JIS --
147 ----------------------
148
149 function Shift_JIS_To_JIS (SJ1, SJ2 : Character) return Wide_Character is
150 SJIS1 : Byte;
151 SJIS2 : Byte;
152 JIS1 : Byte;
153 JIS2 : Byte;
154
155 begin
156 -- The following is the required algorithm, it's hard to make any
157 -- more intelligent comments. This was copied from a public domain
158 -- C program called stoj.c written by shige@csk.JUNET.
159
160 SJIS1 := Character'Pos (SJ1);
161 SJIS2 := Character'Pos (SJ2);
162
163 if SJIS1 >= 16#E0# then
164 SJIS1 := SJIS1 - 16#40#;
165 end if;
166
167 if SJIS2 >= 16#9F# then
168 JIS1 := (SJIS1 - 16#88#) * 2 + 16#30#;
169 JIS2 := SJIS2 - 16#7E#;
170
171 else
172 if SJIS2 >= 16#7F# then
173 SJIS2 := SJIS2 - 16#01#;
174 end if;
175
176 JIS1 := (SJIS1 - 16#89#) * 2 + 16#31#;
177 JIS2 := SJIS2 - 16#1F#;
178 end if;
179
180 if JIS1 not in 16#20# .. 16#7E#
181 or else JIS2 not in 16#20# .. 16#7E#
182 then
183 raise Constraint_Error;
184 else
185 return Wide_Character'Val (256 * Natural (JIS1) + Natural (JIS2));
186 end if;
187 end Shift_JIS_To_JIS;
188
189 end System.WCh_JIS;