190 lines
6.6 KiB
Ada
190 lines
6.6 KiB
Ada
------------------------------------------------------------------------------
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-- --
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-- GNAT RUN-TIME COMPONENTS --
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-- --
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-- S Y S T E M . W C H _ J I S --
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-- --
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-- B o d y --
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-- --
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-- Copyright (C) 1992-2013, Free Software Foundation, Inc. --
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-- --
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-- GNAT is free software; you can redistribute it and/or modify it under --
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-- terms of the GNU General Public License as published by the Free Soft- --
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-- ware Foundation; either version 3, or (at your option) any later ver- --
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-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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-- or FITNESS FOR A PARTICULAR PURPOSE. --
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-- --
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-- As a special exception under Section 7 of GPL version 3, you are granted --
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-- additional permissions described in the GCC Runtime Library Exception, --
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-- version 3.1, as published by the Free Software Foundation. --
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-- --
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-- You should have received a copy of the GNU General Public License and --
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-- a copy of the GCC Runtime Library Exception along with this program; --
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-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
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-- <http://www.gnu.org/licenses/>. --
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-- --
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-- GNAT was originally developed by the GNAT team at New York University. --
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-- Extensive contributions were provided by Ada Core Technologies Inc. --
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-- --
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------------------------------------------------------------------------------
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pragma Compiler_Unit_Warning;
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package body System.WCh_JIS is
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type Byte is mod 256;
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EUC_Hankaku_Kana : constant Byte := 16#8E#;
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-- Prefix byte in EUC for Hankaku Kana (small Katakana). Such characters
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-- in EUC are represented by a prefix byte followed by the code, which
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-- is in the upper half (the corresponding JIS internal code is in the
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-- range 16#0080# - 16#00FF#).
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function EUC_To_JIS (EUC1, EUC2 : Character) return Wide_Character is
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EUC1B : constant Byte := Character'Pos (EUC1);
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EUC2B : constant Byte := Character'Pos (EUC2);
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begin
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if EUC2B not in 16#A0# .. 16#FE# then
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raise Constraint_Error;
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end if;
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if EUC1B = EUC_Hankaku_Kana then
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return Wide_Character'Val (EUC2B);
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else
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if EUC1B not in 16#A0# .. 16#FE# then
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raise Constraint_Error;
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else
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return Wide_Character'Val
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(256 * Natural (EUC1B and 16#7F#) + Natural (EUC2B and 16#7F#));
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end if;
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end if;
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end EUC_To_JIS;
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----------------
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-- JIS_To_EUC --
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----------------
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procedure JIS_To_EUC
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(J : Wide_Character;
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EUC1 : out Character;
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EUC2 : out Character)
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is
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JIS1 : constant Natural := Wide_Character'Pos (J) / 256;
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JIS2 : constant Natural := Wide_Character'Pos (J) rem 256;
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begin
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-- Special case of small Katakana
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if JIS1 = 0 then
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-- The value must be in the range 16#80# to 16#FF# so that the upper
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-- bit is set in both bytes.
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if JIS2 < 16#80# then
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raise Constraint_Error;
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end if;
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EUC1 := Character'Val (EUC_Hankaku_Kana);
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EUC2 := Character'Val (JIS2);
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-- The upper bit of both characters must be clear, or this is not
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-- a valid character for representation in EUC form.
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elsif JIS1 > 16#7F# or else JIS2 > 16#7F# then
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raise Constraint_Error;
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-- Result is just the two characters with upper bits set
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else
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EUC1 := Character'Val (JIS1 + 16#80#);
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EUC2 := Character'Val (JIS2 + 16#80#);
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end if;
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end JIS_To_EUC;
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----------------------
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-- JIS_To_Shift_JIS --
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----------------------
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procedure JIS_To_Shift_JIS
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(J : Wide_Character;
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SJ1 : out Character;
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SJ2 : out Character)
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is
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JIS1 : Byte;
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JIS2 : Byte;
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begin
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-- The following is the required algorithm, it's hard to make any
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-- more intelligent comments. This was copied from a public domain
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-- C program called etos.c (author unknown).
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JIS1 := Byte (Natural (Wide_Character'Pos (J) / 256));
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JIS2 := Byte (Natural (Wide_Character'Pos (J) rem 256));
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if JIS1 > 16#5F# then
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JIS1 := JIS1 + 16#80#;
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end if;
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if (JIS1 mod 2) = 0 then
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SJ1 := Character'Val ((JIS1 - 16#30#) / 2 + 16#88#);
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SJ2 := Character'Val (JIS2 + 16#7E#);
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else
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if JIS2 >= 16#60# then
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JIS2 := JIS2 + 16#01#;
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end if;
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SJ1 := Character'Val ((JIS1 - 16#31#) / 2 + 16#89#);
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SJ2 := Character'Val (JIS2 + 16#1F#);
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end if;
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end JIS_To_Shift_JIS;
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----------------------
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-- Shift_JIS_To_JIS --
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----------------------
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function Shift_JIS_To_JIS (SJ1, SJ2 : Character) return Wide_Character is
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SJIS1 : Byte;
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SJIS2 : Byte;
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JIS1 : Byte;
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JIS2 : Byte;
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begin
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-- The following is the required algorithm, it's hard to make any
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-- more intelligent comments. This was copied from a public domain
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-- C program called stoj.c written by shige@csk.JUNET.
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SJIS1 := Character'Pos (SJ1);
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SJIS2 := Character'Pos (SJ2);
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if SJIS1 >= 16#E0# then
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SJIS1 := SJIS1 - 16#40#;
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end if;
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if SJIS2 >= 16#9F# then
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JIS1 := (SJIS1 - 16#88#) * 2 + 16#30#;
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JIS2 := SJIS2 - 16#7E#;
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else
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if SJIS2 >= 16#7F# then
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SJIS2 := SJIS2 - 16#01#;
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end if;
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JIS1 := (SJIS1 - 16#89#) * 2 + 16#31#;
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JIS2 := SJIS2 - 16#1F#;
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end if;
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if JIS1 not in 16#20# .. 16#7E#
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or else JIS2 not in 16#20# .. 16#7E#
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then
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raise Constraint_Error;
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else
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return Wide_Character'Val (256 * Natural (JIS1) + Natural (JIS2));
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end if;
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end Shift_JIS_To_JIS;
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end System.WCh_JIS;
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