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------------------------------------------------------------------------------
-- --
-- GNAT RUN-TIME COMPONENTS --
-- --
-- S Y S T E M . W C H _ J I S --
-- --
-- B o d y --
-- --
-- Copyright (C) 1992-2024, Free Software Foundation, Inc. --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
-- ware Foundation; either version 3, or (at your option) any later ver- --
-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE. --
-- --
-- As a special exception under Section 7 of GPL version 3, you are granted --
-- additional permissions described in the GCC Runtime Library Exception, --
-- version 3.1, as published by the Free Software Foundation. --
-- --
-- You should have received a copy of the GNU General Public License and --
-- a copy of the GCC Runtime Library Exception along with this program; --
-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
-- <http://www.gnu.org/licenses/>. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
package body System.WCh_JIS is
type Byte is mod 256;
EUC_Hankaku_Kana : constant Byte := 16#8E#;
-- Prefix byte in EUC for Hankaku Kana (small Katakana). Such characters
-- in EUC are represented by a prefix byte followed by the code, which
-- is in the upper half (the corresponding JIS internal code is in the
-- range 16#0080# - 16#00FF#).
function EUC_To_JIS (EUC1, EUC2 : Character) return Wide_Character is
EUC1B : constant Byte := Character'Pos (EUC1);
EUC2B : constant Byte := Character'Pos (EUC2);
begin
if EUC2B not in 16#A0# .. 16#FE# then
raise Constraint_Error;
end if;
if EUC1B = EUC_Hankaku_Kana then
return Wide_Character'Val (EUC2B);
else
if EUC1B not in 16#A0# .. 16#FE# then
raise Constraint_Error;
else
return Wide_Character'Val
(256 * Natural (EUC1B and 16#7F#) + Natural (EUC2B and 16#7F#));
end if;
end if;
end EUC_To_JIS;
----------------
-- JIS_To_EUC --
----------------
procedure JIS_To_EUC
(J : Wide_Character;
EUC1 : out Character;
EUC2 : out Character)
is
JIS1 : constant Natural := Wide_Character'Pos (J) / 256;
JIS2 : constant Natural := Wide_Character'Pos (J) rem 256;
begin
-- Special case of small Katakana
if JIS1 = 0 then
-- The value must be in the range 16#80# to 16#FF# so that the upper
-- bit is set in both bytes.
if JIS2 < 16#80# then
raise Constraint_Error;
end if;
EUC1 := Character'Val (EUC_Hankaku_Kana);
EUC2 := Character'Val (JIS2);
-- The upper bit of both characters must be clear, or this is not
-- a valid character for representation in EUC form.
elsif JIS1 > 16#7F# or else JIS2 > 16#7F# then
raise Constraint_Error;
-- Result is just the two characters with upper bits set
else
EUC1 := Character'Val (JIS1 + 16#80#);
EUC2 := Character'Val (JIS2 + 16#80#);
end if;
end JIS_To_EUC;
----------------------
-- JIS_To_Shift_JIS --
----------------------
procedure JIS_To_Shift_JIS
(J : Wide_Character;
SJ1 : out Character;
SJ2 : out Character)
is
JIS1 : Byte;
JIS2 : Byte;
begin
-- The following is the required algorithm, it's hard to make any
-- more intelligent comments. This was copied from a public domain
-- C program called etos.c (author unknown).
JIS1 := Byte (Natural (Wide_Character'Pos (J) / 256));
JIS2 := Byte (Natural (Wide_Character'Pos (J) rem 256));
if JIS1 > 16#5F# then
JIS1 := JIS1 + 16#80#;
end if;
if (JIS1 mod 2) = 0 then
SJ1 := Character'Val ((JIS1 - 16#30#) / 2 + 16#88#);
SJ2 := Character'Val (JIS2 + 16#7E#);
else
if JIS2 >= 16#60# then
JIS2 := JIS2 + 16#01#;
end if;
SJ1 := Character'Val ((JIS1 - 16#31#) / 2 + 16#89#);
SJ2 := Character'Val (JIS2 + 16#1F#);
end if;
end JIS_To_Shift_JIS;
----------------------
-- Shift_JIS_To_JIS --
----------------------
function Shift_JIS_To_JIS (SJ1, SJ2 : Character) return Wide_Character is
SJIS1 : Byte;
SJIS2 : Byte;
JIS1 : Byte;
JIS2 : Byte;
begin
-- The following is the required algorithm, it's hard to make any
-- more intelligent comments. This was copied from a public domain
-- C program called stoj.c written by shige@csk.JUNET.
SJIS1 := Character'Pos (SJ1);
SJIS2 := Character'Pos (SJ2);
if SJIS1 >= 16#E0# then
SJIS1 := SJIS1 - 16#40#;
end if;
if SJIS2 >= 16#9F# then
JIS1 := (SJIS1 - 16#88#) * 2 + 16#30#;
JIS2 := SJIS2 - 16#7E#;
else
if SJIS2 >= 16#7F# then
SJIS2 := SJIS2 - 16#01#;
end if;
JIS1 := (SJIS1 - 16#89#) * 2 + 16#31#;
JIS2 := SJIS2 - 16#1F#;
end if;
if JIS1 not in 16#20# .. 16#7E#
or else JIS2 not in 16#20# .. 16#7E#
then
raise Constraint_Error;
else
return Wide_Character'Val (256 * Natural (JIS1) + Natural (JIS2));
end if;
end Shift_JIS_To_JIS;
end System.WCh_JIS;
|
