J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 2006 Sun Microsystems, Inc. All Rights Reserved. |
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 4 | * |
| 5 | * This code is free software; you can redistribute it and/or modify it |
| 6 | * under the terms of the GNU General Public License version 2 only, as |
| 7 | * published by the Free Software Foundation. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun in the LICENSE file that accompanied this code. |
| 10 | * |
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT |
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| 14 | * version 2 for more details (a copy is included in the LICENSE file that |
| 15 | * accompanied this code). |
| 16 | * |
| 17 | * You should have received a copy of the GNU General Public License version |
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, |
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| 20 | * |
| 21 | * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any questions. |
| 24 | */ |
| 25 | |
| 26 | package sun.nio.cs.ext; |
| 27 | |
| 28 | import java.nio.ByteBuffer; |
| 29 | import java.nio.CharBuffer; |
| 30 | import java.nio.charset.Charset; |
| 31 | import java.nio.charset.CharsetDecoder; |
| 32 | import java.nio.charset.CoderResult; |
| 33 | |
| 34 | /** |
| 35 | * An abstract base class for subclasses which decode |
| 36 | * IBM double byte only ebcdic host encodings such as ibm |
| 37 | * code pages 834 835 837 300,... etc |
| 38 | * |
| 39 | * The structure of IBM DBCS-only charsets is defined by the |
| 40 | * IBM Character Data Representation Architecture (CDRA) document |
| 41 | * |
| 42 | * http://www-306.ibm.com/software/globalization/cdra/appendix_a.jsp#HDRHEBDBST |
| 43 | * |
| 44 | */ |
| 45 | |
| 46 | public abstract class DBCS_ONLY_IBM_EBCDIC_Decoder extends CharsetDecoder |
| 47 | { |
| 48 | protected static final char REPLACE_CHAR='\uFFFD'; |
| 49 | |
| 50 | protected short index1[]; |
| 51 | protected String index2; |
| 52 | protected int mask1; |
| 53 | protected int mask2; |
| 54 | protected int shift; |
| 55 | |
| 56 | protected DBCS_ONLY_IBM_EBCDIC_Decoder(Charset cs) { |
| 57 | super(cs, 0.5f, 1.0f); |
| 58 | } |
| 59 | |
| 60 | // Check validity of dbcs ebcdic byte pair values |
| 61 | private static boolean isValidDoubleByte(int b1, int b2) { |
| 62 | return (b1 == 0x40 && b2 == 0x40) // DBCS-HOST SPACE |
| 63 | || (0x41 <= b1 && b1 <= 0xfe && |
| 64 | 0x41 <= b2 && b2 <= 0xfe); |
| 65 | } |
| 66 | |
| 67 | private CoderResult decodeArrayLoop(ByteBuffer src, CharBuffer dst) { |
| 68 | byte[] sa = src.array(); |
| 69 | int sp = src.arrayOffset() + src.position(); |
| 70 | int sl = src.arrayOffset() + src.limit(); |
| 71 | assert (sp <= sl); |
| 72 | sp = (sp <= sl ? sp : sl); |
| 73 | char[] da = dst.array(); |
| 74 | int dp = dst.arrayOffset() + dst.position(); |
| 75 | int dl = dst.arrayOffset() + dst.limit(); |
| 76 | assert (dp <= dl); |
| 77 | dp = (dp <= dl ? dp : dl); |
| 78 | |
| 79 | try { |
| 80 | while (sp + 1 < sl) { |
| 81 | int b1 = sa[sp] & 0xff; |
| 82 | int b2 = sa[sp + 1] & 0xff; |
| 83 | |
| 84 | if (!isValidDoubleByte(b1, b2)) { |
| 85 | return CoderResult.malformedForLength(2); |
| 86 | } |
| 87 | // Lookup in the two level index |
| 88 | int v = b1 * 256 + b2; |
| 89 | char outputChar = index2.charAt(index1[((v & mask1) >> shift)] |
| 90 | + (v & mask2)); |
| 91 | if (outputChar == REPLACE_CHAR) |
| 92 | return CoderResult.unmappableForLength(2); |
| 93 | if (dl - dp < 1) |
| 94 | return CoderResult.OVERFLOW; |
| 95 | da[dp++] = outputChar; |
| 96 | sp += 2; |
| 97 | } |
| 98 | return CoderResult.UNDERFLOW; |
| 99 | } finally { |
| 100 | src.position(sp - src.arrayOffset()); |
| 101 | dst.position(dp - dst.arrayOffset()); |
| 102 | } |
| 103 | } |
| 104 | |
| 105 | private CoderResult decodeBufferLoop(ByteBuffer src, CharBuffer dst) { |
| 106 | int mark = src.position(); |
| 107 | try { |
| 108 | while (src.remaining() > 1) { |
| 109 | int b1 = src.get() & 0xff; |
| 110 | int b2 = src.get() & 0xff; |
| 111 | |
| 112 | if (!isValidDoubleByte(b1, b2)) { |
| 113 | return CoderResult.malformedForLength(2); |
| 114 | } |
| 115 | // Lookup in the two level index |
| 116 | int v = b1 * 256 + b2; |
| 117 | char outputChar = index2.charAt(index1[((v & mask1) >> shift)] |
| 118 | + (v & mask2)); |
| 119 | if (outputChar == REPLACE_CHAR) |
| 120 | return CoderResult.unmappableForLength(2); |
| 121 | |
| 122 | if (!dst.hasRemaining()) |
| 123 | return CoderResult.OVERFLOW; |
| 124 | dst.put(outputChar); |
| 125 | mark += 2; |
| 126 | } |
| 127 | return CoderResult.UNDERFLOW; |
| 128 | } finally { |
| 129 | src.position(mark); |
| 130 | } |
| 131 | } |
| 132 | |
| 133 | protected CoderResult decodeLoop(ByteBuffer src, CharBuffer dst) { |
| 134 | if (src.hasArray() && dst.hasArray()) |
| 135 | return decodeArrayLoop(src, dst); |
| 136 | else |
| 137 | return decodeBufferLoop(src, dst); |
| 138 | } |
| 139 | } |