    001/*
    002 *  Licensed to the Apache Software Foundation (ASF) under one or more
    003 *  contributor license agreements.  See the NOTICE file distributed with
    004 *  this work for additional information regarding copyright ownership.
    005 *  The ASF licenses this file to You under the Apache License, Version 2.0
    006 *  (the "License"); you may not use this file except in compliance with
    007 *  the License.  You may obtain a copy of the License at
    008 *
    009 *     http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 *  Unless required by applicable law or agreed to in writing, software
    012 *  distributed under the License is distributed on an "AS IS" BASIS,
    013 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 *  See the License for the specific language governing permissions and
    015 *  limitations under the License.
    016 */
    017package org.apache.commons.compress.harmony.unpack200.bytecode.forms;
    018
    019import java.util.Arrays;
    020import java.util.HashMap;
    021import java.util.Map;
    022
    023import org.apache.commons.compress.harmony.unpack200.bytecode.ByteCode;
    024import org.apache.commons.compress.harmony.unpack200.bytecode.CodeAttribute;
    025import org.apache.commons.compress.harmony.unpack200.bytecode.OperandManager;
    026
    027public abstract class ByteCodeForm {
    028
    029    protected static final boolean WIDENED = true;
    030
    031    protected static final ByteCodeForm[] byteCodeArray = new ByteCodeForm[256];
    032    protected static final Map<String, ByteCodeForm> byteCodesByName = new HashMap<>(256);
    033    static {
    034        byteCodeArray[0] = new NoArgumentForm(0, "nop");
    035        byteCodeArray[1] = new NoArgumentForm(1, "aconst_null");
    036        byteCodeArray[2] = new NoArgumentForm(2, "iconst_m1");
    037        byteCodeArray[3] = new NoArgumentForm(3, "iconst_0");
    038        byteCodeArray[4] = new NoArgumentForm(4, "iconst_1");
    039        byteCodeArray[5] = new NoArgumentForm(5, "iconst_2");
    040        byteCodeArray[6] = new NoArgumentForm(6, "iconst_3");
    041        byteCodeArray[7] = new NoArgumentForm(7, "iconst_4");
    042        byteCodeArray[8] = new NoArgumentForm(8, "iconst_5");
    043        byteCodeArray[9] = new NoArgumentForm(9, "lconst_0");
    044        byteCodeArray[10] = new NoArgumentForm(10, "lconst_1");
    045        byteCodeArray[11] = new NoArgumentForm(11, "fconst_0");
    046        byteCodeArray[12] = new NoArgumentForm(12, "fconst_1");
    047        byteCodeArray[13] = new NoArgumentForm(13, "fconst_2");
    048        byteCodeArray[14] = new NoArgumentForm(14, "dconst_0");
    049        byteCodeArray[15] = new NoArgumentForm(15, "dconst_1");
    050        byteCodeArray[16] = new ByteForm(16, "bipush", new int[] {16, -1});
    051        byteCodeArray[17] = new ShortForm(17, "sipush", new int[] {17, -1, -1});
    052        byteCodeArray[18] = new StringRefForm(18, "ldc", new int[] {18, -1});
    053        byteCodeArray[19] = new StringRefForm(19, "ldc_w", new int[] {19, -1, -1}, WIDENED);
    054        byteCodeArray[20] = new LongForm(20, "ldc2_w", new int[] {20, -1, -1});
    055        byteCodeArray[21] = new LocalForm(21, "iload", new int[] {21, -1});
    056        byteCodeArray[22] = new LocalForm(22, "lload", new int[] {22, -1});
    057        byteCodeArray[23] = new LocalForm(23, "fload", new int[] {23, -1});
    058        byteCodeArray[24] = new LocalForm(24, "dload", new int[] {24, -1});
    059        byteCodeArray[25] = new LocalForm(25, "aload", new int[] {25, -1});
    060        byteCodeArray[26] = new NoArgumentForm(26, "iload_0");
    061        byteCodeArray[27] = new NoArgumentForm(27, "iload_1");
    062        byteCodeArray[28] = new NoArgumentForm(28, "iload_2");
    063        byteCodeArray[29] = new NoArgumentForm(29, "iload_3");
    064        byteCodeArray[30] = new NoArgumentForm(30, "lload_0");
    065        byteCodeArray[31] = new NoArgumentForm(31, "lload_1");
    066        byteCodeArray[32] = new NoArgumentForm(32, "lload_2");
    067        byteCodeArray[33] = new NoArgumentForm(33, "lload_3");
    068        byteCodeArray[34] = new NoArgumentForm(34, "fload_0");
    069        byteCodeArray[35] = new NoArgumentForm(35, "fload_1");
    070        byteCodeArray[36] = new NoArgumentForm(36, "fload_2");
    071        byteCodeArray[37] = new NoArgumentForm(37, "fload_3");
    072        byteCodeArray[38] = new NoArgumentForm(38, "dload_0");
    073        byteCodeArray[39] = new NoArgumentForm(39, "dload_1");
    074        byteCodeArray[40] = new NoArgumentForm(40, "dload_2");
    075        byteCodeArray[41] = new NoArgumentForm(41, "dload_3");
    076        byteCodeArray[42] = new NoArgumentForm(42, "aload_0");
    077        byteCodeArray[43] = new NoArgumentForm(43, "aload_1");
    078        byteCodeArray[44] = new NoArgumentForm(44, "aload_2");
    079        byteCodeArray[45] = new NoArgumentForm(45, "aload_3");
    080        byteCodeArray[46] = new NoArgumentForm(46, "iaload");
    081        byteCodeArray[47] = new NoArgumentForm(47, "laload");
    082        byteCodeArray[48] = new NoArgumentForm(48, "faload");
    083        byteCodeArray[49] = new NoArgumentForm(49, "daload");
    084        byteCodeArray[50] = new NoArgumentForm(50, "aaload");
    085        byteCodeArray[51] = new NoArgumentForm(51, "baload");
    086        byteCodeArray[52] = new NoArgumentForm(52, "caload");
    087        byteCodeArray[53] = new NoArgumentForm(53, "saload");
    088        byteCodeArray[54] = new LocalForm(54, "istore", new int[] {54, -1});
    089        byteCodeArray[55] = new LocalForm(55, "lstore", new int[] {55, -1});
    090        byteCodeArray[56] = new LocalForm(56, "fstore", new int[] {56, -1});
    091        byteCodeArray[57] = new LocalForm(57, "dstore", new int[] {57, -1});
    092        byteCodeArray[58] = new LocalForm(58, "astore", new int[] {58, -1});
    093        byteCodeArray[59] = new NoArgumentForm(59, "istore_0");
    094        byteCodeArray[60] = new NoArgumentForm(60, "istore_1");
    095        byteCodeArray[61] = new NoArgumentForm(61, "istore_2");
    096        byteCodeArray[62] = new NoArgumentForm(62, "istore_3");
    097        byteCodeArray[63] = new NoArgumentForm(63, "lstore_0");
    098        byteCodeArray[64] = new NoArgumentForm(64, "lstore_1");
    099        byteCodeArray[65] = new NoArgumentForm(65, "lstore_2");
    100        byteCodeArray[66] = new NoArgumentForm(66, "lstore_3");
    101        byteCodeArray[67] = new NoArgumentForm(67, "fstore_0");
    102        byteCodeArray[68] = new NoArgumentForm(68, "fstore_1");
    103        byteCodeArray[69] = new NoArgumentForm(69, "fstore_2");
    104        byteCodeArray[70] = new NoArgumentForm(70, "fstore_3");
    105        byteCodeArray[71] = new NoArgumentForm(71, "dstore_0");
    106        byteCodeArray[72] = new NoArgumentForm(72, "dstore_1");
    107        byteCodeArray[73] = new NoArgumentForm(73, "dstore_2");
    108        byteCodeArray[74] = new NoArgumentForm(74, "dstore_3");
    109        byteCodeArray[75] = new NoArgumentForm(75, "astore_0");
    110        byteCodeArray[76] = new NoArgumentForm(76, "astore_1");
    111        byteCodeArray[77] = new NoArgumentForm(77, "astore_2");
    112        byteCodeArray[78] = new NoArgumentForm(78, "astore_3");
    113        byteCodeArray[79] = new NoArgumentForm(79, "iastore");
    114        byteCodeArray[80] = new NoArgumentForm(80, "lastore");
    115        byteCodeArray[81] = new NoArgumentForm(81, "fastore");
    116        byteCodeArray[82] = new NoArgumentForm(82, "dastore");
    117        byteCodeArray[83] = new NoArgumentForm(83, "aastore");
    118        byteCodeArray[84] = new NoArgumentForm(84, "bastore");
    119        byteCodeArray[85] = new NoArgumentForm(85, "castore");
    120        byteCodeArray[86] = new NoArgumentForm(86, "sastore");
    121        byteCodeArray[87] = new NoArgumentForm(87, "pop");
    122        byteCodeArray[88] = new NoArgumentForm(88, "pop2");
    123        byteCodeArray[89] = new NoArgumentForm(89, "dup");
    124        byteCodeArray[90] = new NoArgumentForm(90, "dup_x1");
    125        byteCodeArray[91] = new NoArgumentForm(91, "dup_x2");
    126        byteCodeArray[92] = new NoArgumentForm(92, "dup2");
    127        byteCodeArray[93] = new NoArgumentForm(93, "dup2_x1");
    128        byteCodeArray[94] = new NoArgumentForm(94, "dup2_x2");
    129        byteCodeArray[95] = new NoArgumentForm(95, "swap");
    130        byteCodeArray[96] = new NoArgumentForm(96, "iadd");
    131        byteCodeArray[97] = new NoArgumentForm(97, "ladd");
    132        byteCodeArray[98] = new NoArgumentForm(98, "fadd");
    133        byteCodeArray[99] = new NoArgumentForm(99, "dadd");
    134        byteCodeArray[100] = new NoArgumentForm(100, "isub");
    135        byteCodeArray[101] = new NoArgumentForm(101, "lsub");
    136        byteCodeArray[102] = new NoArgumentForm(102, "fsub");
    137        byteCodeArray[103] = new NoArgumentForm(103, "dsub");
    138        byteCodeArray[104] = new NoArgumentForm(104, "imul");
    139        byteCodeArray[105] = new NoArgumentForm(105, "lmul");
    140        byteCodeArray[106] = new NoArgumentForm(106, "fmul");
    141        byteCodeArray[107] = new NoArgumentForm(107, "dmul");
    142        byteCodeArray[108] = new NoArgumentForm(108, "idiv");
    143        byteCodeArray[109] = new NoArgumentForm(109, "ldiv");
    144        byteCodeArray[110] = new NoArgumentForm(110, "fdiv");
    145        byteCodeArray[111] = new NoArgumentForm(111, "ddiv");
    146        byteCodeArray[112] = new NoArgumentForm(112, "irem");
    147        byteCodeArray[113] = new NoArgumentForm(113, "lrem");
    148        byteCodeArray[114] = new NoArgumentForm(114, "frem");
    149        byteCodeArray[115] = new NoArgumentForm(115, "drem");
    150        byteCodeArray[116] = new NoArgumentForm(116, "");
    151        byteCodeArray[117] = new NoArgumentForm(117, "lneg");
    152        byteCodeArray[118] = new NoArgumentForm(118, "fneg");
    153        byteCodeArray[119] = new NoArgumentForm(119, "dneg");
    154        byteCodeArray[120] = new NoArgumentForm(120, "ishl");
    155        byteCodeArray[121] = new NoArgumentForm(121, "lshl");
    156        byteCodeArray[122] = new NoArgumentForm(122, "ishr");
    157        byteCodeArray[123] = new NoArgumentForm(123, "lshr");
    158        byteCodeArray[124] = new NoArgumentForm(124, "iushr");
    159        byteCodeArray[125] = new NoArgumentForm(125, "lushr");
    160        byteCodeArray[126] = new NoArgumentForm(126, "iand");
    161        byteCodeArray[127] = new NoArgumentForm(127, "land");
    162        byteCodeArray[128] = new NoArgumentForm(128, "ior");
    163        byteCodeArray[129] = new NoArgumentForm(129, "lor");
    164        byteCodeArray[130] = new NoArgumentForm(130, "ixor");
    165        byteCodeArray[131] = new NoArgumentForm(131, "lxor");
    166        byteCodeArray[132] = new IincForm(132, "iinc", new int[] {132, -1, -1});
    167        byteCodeArray[133] = new NoArgumentForm(133, "i2l");
    168        byteCodeArray[134] = new NoArgumentForm(134, "i2f");
    169        byteCodeArray[135] = new NoArgumentForm(135, "i2d");
    170        byteCodeArray[136] = new NoArgumentForm(136, "l2i");
    171        byteCodeArray[137] = new NoArgumentForm(137, "l2f");
    172        byteCodeArray[138] = new NoArgumentForm(138, "l2d");
    173        byteCodeArray[139] = new NoArgumentForm(139, "f2i");
    174        byteCodeArray[140] = new NoArgumentForm(140, "f2l");
    175        byteCodeArray[141] = new NoArgumentForm(141, "f2d");
    176        byteCodeArray[142] = new NoArgumentForm(142, "d2i");
    177        byteCodeArray[143] = new NoArgumentForm(143, "d2l");
    178        byteCodeArray[144] = new NoArgumentForm(144, "d2f");
    179        byteCodeArray[145] = new NoArgumentForm(145, "i2b");
    180        byteCodeArray[146] = new NoArgumentForm(146, "i2c");
    181        byteCodeArray[147] = new NoArgumentForm(147, "i2s");
    182        byteCodeArray[148] = new NoArgumentForm(148, "lcmp");
    183        byteCodeArray[149] = new NoArgumentForm(149, "fcmpl");
    184        byteCodeArray[150] = new NoArgumentForm(150, "fcmpg");
    185        byteCodeArray[151] = new NoArgumentForm(151, "dcmpl");
    186        byteCodeArray[152] = new NoArgumentForm(152, "dcmpg");
    187        byteCodeArray[153] = new LabelForm(153, "ifeq", new int[] {153, -1, -1});
    188        byteCodeArray[154] = new LabelForm(154, "ifne", new int[] {154, -1, -1});
    189        byteCodeArray[155] = new LabelForm(155, "iflt", new int[] {155, -1, -1});
    190        byteCodeArray[156] = new LabelForm(156, "ifge", new int[] {156, -1, -1});
    191        byteCodeArray[157] = new LabelForm(157, "ifgt", new int[] {157, -1, -1});
    192        byteCodeArray[158] = new LabelForm(158, "ifle", new int[] {158, -1, -1});
    193        byteCodeArray[159] = new LabelForm(159, "if_icmpeq", new int[] {159, -1, -1});
    194        byteCodeArray[160] = new LabelForm(160, "if_icmpne", new int[] {160, -1, -1});
    195        byteCodeArray[161] = new LabelForm(161, "if_icmplt", new int[] {161, -1, -1});
    196        byteCodeArray[162] = new LabelForm(162, "if_icmpge", new int[] {162, -1, -1});
    197        byteCodeArray[163] = new LabelForm(163, "if_icmpgt", new int[] {163, -1, -1});
    198        byteCodeArray[164] = new LabelForm(164, "if_icmple", new int[] {164, -1, -1});
    199        byteCodeArray[165] = new LabelForm(165, "if_acmpeq", new int[] {165, -1, -1});
    200        byteCodeArray[166] = new LabelForm(166, "if_acmpne", new int[] {166, -1, -1});
    201        byteCodeArray[167] = new LabelForm(167, "goto", new int[] {167, -1, -1});
    202        byteCodeArray[168] = new LabelForm(168, "jsr", new int[] {168, -1, -1});
    203        byteCodeArray[169] = new LocalForm(169, "ret", new int[] {169, -1});
    204        byteCodeArray[170] = new TableSwitchForm(170, "tableswitch");
    205        byteCodeArray[171] = new LookupSwitchForm(171, "lookupswitch");
    206        byteCodeArray[172] = new NoArgumentForm(172, "ireturn");
    207        byteCodeArray[173] = new NoArgumentForm(173, "lreturn");
    208        byteCodeArray[174] = new NoArgumentForm(174, "freturn");
    209        byteCodeArray[175] = new NoArgumentForm(175, "dreturn");
    210        byteCodeArray[176] = new NoArgumentForm(176, "areturn");
    211        byteCodeArray[177] = new NoArgumentForm(177, "return");
    212        byteCodeArray[178] = new FieldRefForm(178, "getstatic", new int[] {178, -1, -1});
    213        byteCodeArray[179] = new FieldRefForm(179, "putstatic", new int[] {179, -1, -1});
    214        byteCodeArray[180] = new FieldRefForm(180, "getfield", new int[] {180, -1, -1});
    215        byteCodeArray[181] = new FieldRefForm(181, "putfield", new int[] {181, -1, -1});
    216        byteCodeArray[182] = new MethodRefForm(182, "invokevirtual", new int[] {182, -1, -1});
    217        byteCodeArray[183] = new MethodRefForm(183, "invokespecial", new int[] {183, -1, -1});
    218        byteCodeArray[184] = new MethodRefForm(184, "invokestatic", new int[] {184, -1, -1});
    219        byteCodeArray[185] = new IMethodRefForm(185, "invokeinterface", new int[] {185, -1, -1, /* count */-1, 0});
    220        byteCodeArray[186] = new NoArgumentForm(186, "xxxunusedxxx");
    221        byteCodeArray[187] = new NewClassRefForm(187, "new", new int[] {187, -1, -1});
    222        byteCodeArray[188] = new ByteForm(188, "newarray", new int[] {188, -1});
    223        byteCodeArray[189] = new ClassRefForm(189, "anewarray", new int[] {189, -1, -1});
    224        byteCodeArray[190] = new NoArgumentForm(190, "arraylength");
    225        byteCodeArray[191] = new NoArgumentForm(191, "athrow");
    226        byteCodeArray[192] = new ClassRefForm(192, "checkcast", new int[] {192, -1, -1});
    227        byteCodeArray[193] = new ClassRefForm(193, "instanceof", new int[] {193, -1, -1});
    228        byteCodeArray[194] = new NoArgumentForm(194, "monitorenter");
    229        byteCodeArray[195] = new NoArgumentForm(195, "monitorexit");
    230        byteCodeArray[196] = new WideForm(196, "wide");
    231        byteCodeArray[197] = new MultiANewArrayForm(197, "multianewarray", new int[] {197, -1, -1, -1});
    232        byteCodeArray[198] = new LabelForm(198, "ifnull", new int[] {198, -1, -1});
    233        byteCodeArray[199] = new LabelForm(199, "ifnonnull", new int[] {199, -1, -1});
    234        byteCodeArray[200] = new LabelForm(200, "goto_w", new int[] {200, -1, -1, -1, -1}, WIDENED);
    235        byteCodeArray[201] = new LabelForm(201, "jsr_w", new int[] {201, -1, -1, -1, -1}, WIDENED);
    236
    237        // Extra ones defined by pack200
    238        byteCodeArray[202] = new ThisFieldRefForm(202, "getstatic_this", new int[] {178, -1, -1});
    239        byteCodeArray[203] = new ThisFieldRefForm(203, "putstatic_this", new int[] {179, -1, -1});
    240        byteCodeArray[204] = new ThisFieldRefForm(204, "getfield_this", new int[] {180, -1, -1});
    241        byteCodeArray[205] = new ThisFieldRefForm(205, "putfield_this", new int[] {181, -1, -1});
    242        byteCodeArray[206] = new ThisMethodRefForm(206, "invokevirtual_this", new int[] {182, -1, -1});
    243        byteCodeArray[207] = new ThisMethodRefForm(207, "invokespecial_this", new int[] {183, -1, -1});
    244        byteCodeArray[208] = new ThisMethodRefForm(208, "invokestatic_this", new int[] {184, -1, -1});
    245        byteCodeArray[209] = new ThisFieldRefForm(209, "aload_0_getstatic_this", new int[] {42, 178, -1, -1});
    246        byteCodeArray[210] = new ThisFieldRefForm(210, "aload_0_putstatic_this", new int[] {42, 179, -1, -1});
    247        byteCodeArray[211] = new ThisFieldRefForm(211, "aload_0_getfield_this", new int[] {42, 180, -1, -1});
    248        byteCodeArray[212] = new ThisFieldRefForm(212, "aload_0_putfield_this", new int[] {42, 181, -1, -1});
    249        byteCodeArray[213] = new ThisMethodRefForm(213, "aload_0_invokevirtual_this", new int[] {42, 182, -1, -1});
    250        byteCodeArray[214] = new ThisMethodRefForm(214, "aload_0_invokespecial_this", new int[] {42, 183, -1, -1});
    251        byteCodeArray[215] = new ThisMethodRefForm(215, "aload_0_invokestatic_this", new int[] {42, 184, -1, -1});
    252        byteCodeArray[216] = new SuperFieldRefForm(216, "getstatic_super", new int[] {178, -1, -1});
    253        byteCodeArray[217] = new SuperFieldRefForm(217, "putstatic_super", new int[] {179, -1, -1});
    254        byteCodeArray[218] = new SuperFieldRefForm(218, "getfield_super", new int[] {180, -1, -1});
    255        byteCodeArray[219] = new SuperFieldRefForm(219, "putfield_super", new int[] {181, -1, -1});
    256        byteCodeArray[220] = new SuperMethodRefForm(220, "invokevirtual_super", new int[] {182, -1, -1});
    257        byteCodeArray[221] = new SuperMethodRefForm(221, "invokespecial_super", new int[] {183, -1, -1});
    258        byteCodeArray[222] = new SuperMethodRefForm(222, "invokestatic_super", new int[] {184, -1, -1});
    259        byteCodeArray[223] = new SuperFieldRefForm(223, "aload_0_getstatic_super", new int[] {42, 178, -1, -1});
    260        byteCodeArray[224] = new SuperFieldRefForm(224, "aload_0_putstatic_super", new int[] {42, 179, -1, -1});
    261        byteCodeArray[225] = new SuperFieldRefForm(225, "aload_0_getfield_super", new int[] {42, 180, -1, -1});
    262        byteCodeArray[226] = new SuperFieldRefForm(226, "aload_0_putfield_super", new int[] {42, 181, -1, -1});
    263        byteCodeArray[227] = new SuperMethodRefForm(227, "aload_0_invokevirtual_super", new int[] {42, 182, -1, -1});
    264        byteCodeArray[228] = new SuperMethodRefForm(228, "aload_0_invokespecial_super", new int[] {42, 183, -1, -1});
    265        byteCodeArray[229] = new SuperMethodRefForm(229, "aload_0_invokestatic_super", new int[] {42, 184, -1, -1});
    266        byteCodeArray[230] = new ThisInitMethodRefForm(230, "invokespecial_this_init", new int[] {183, -1, -1});
    267        byteCodeArray[231] = new SuperInitMethodRefForm(231, "invokespecial_super_init", new int[] {183, -1, -1});
    268        byteCodeArray[232] = new NewInitMethodRefForm(232, "invokespecial_new_init", new int[] {183, -1, -1});
    269        byteCodeArray[233] = new NarrowClassRefForm(233, "cldc", new int[] {18, -1});
    270        byteCodeArray[234] = new IntRefForm(234, "ildc", new int[] {18, -1});
    271        byteCodeArray[235] = new FloatRefForm(235, "fldc", new int[] {18, -1});
    272        byteCodeArray[236] = new NarrowClassRefForm(236, "cldc_w", new int[] {19, -1, -1}, WIDENED);
    273        byteCodeArray[237] = new IntRefForm(237, "ildc_w", new int[] {19, -1, -1}, WIDENED);
    274        byteCodeArray[238] = new FloatRefForm(238, "fldc_w", new int[] {19, -1, -1}, WIDENED);
    275        byteCodeArray[239] = new DoubleForm(239, "dldc2_w", new int[] {20, -1, -1});
    276
    277        // Reserved bytecodes
    278        byteCodeArray[254] = new NoArgumentForm(254, "impdep1");
    279        byteCodeArray[255] = new NoArgumentForm(255, "impdep2");
    280
    281        // Bytecodes that aren't defined in the spec but are useful when
    282        // unpacking (all must be >255)
    283        // maybe wide versions of the others? etc.
    284
    285        // Put all the bytecodes in a HashMap so we can
    286        // get them by either name or number
    287        for (final ByteCodeForm byteCode : byteCodeArray) {
    288            if (byteCode != null) {
    289                byteCodesByName.put(byteCode.getName(), byteCode);
    290            }
    291        }
    292    }
    293
    294    public static ByteCodeForm get(final int opcode) {
    295        return byteCodeArray[opcode];
    296    }
    297    private final int opcode;
    298    private final String name;
    299    private final int[] rewrite;
    300    private int firstOperandIndex;
    301
    302    private int operandLength;
    303
    304    /**
    305     * Answer a new instance of this class with the specified opcode and name. Assume no rewrite.
    306     *
    307     * @param opcode int corresponding to the opcode's value
    308     * @param name String printable name of the opcode
    309     */
    310    public ByteCodeForm(final int opcode, final String name) {
    311        this(opcode, name, new int[] {opcode});
    312    }
    313
    314    /**
    315     * Answer a new instance of this class with the specified opcode, name, operandType and rewrite
    316     *
    317     * @param opcode int corresponding to the opcode's value
    318     * @param name String printable name of the opcode
    319     * @param rewrite int[] Array of ints. Operand positions (which will later be rewritten in ByteCodes) are indicated
    320     *        by -1.
    321     */
    322    public ByteCodeForm(final int opcode, final String name, final int[] rewrite) {
    323        this.opcode = opcode;
    324        this.name = name;
    325        this.rewrite = rewrite;
    326        calculateOperandPosition();
    327    }
    328
    329    protected void calculateOperandPosition() {
    330        firstOperandIndex = -1;
    331        operandLength = -1;
    332
    333        // Find the first negative number in the rewrite array
    334        int iterationIndex = 0;
    335        while (iterationIndex < rewrite.length) {
    336            if (rewrite[iterationIndex] < 0) {
    337                // Found the first opcode to substitute
    338                firstOperandIndex = iterationIndex;
    339                iterationIndex = rewrite.length;
    340            } else {
    341                iterationIndex++;
    342            }
    343        }
    344
    345        if (firstOperandIndex == -1) {
    346            // Nothing more to do since the opcode has no operands
    347            return;
    348        }
    349
    350        // Find the last negative number in the rewrite array
    351        int lastOperandIndex = -1;
    352        iterationIndex = firstOperandIndex;
    353        while (iterationIndex < rewrite.length) {
    354            if (rewrite[iterationIndex] < 0) {
    355                lastOperandIndex = iterationIndex;
    356            }
    357            iterationIndex++;
    358        }
    359
    360        // Now we have the first index and the last index.
    361        final int difference = lastOperandIndex - firstOperandIndex;
    362
    363        // If last < first, something is wrong.
    364        if (difference < 0) {
    365            throw new Error("Logic error: not finding rewrite operands correctly");
    366        }
    367        operandLength = difference + 1;
    368    }
    369
    370    public int firstOperandIndex() {
    371        return firstOperandIndex;
    372    }
    373
    374    /**
    375     * The ByteCodeForm knows how to fix up a bytecode if it needs to be fixed up because it holds a Label bytecode.
    376     *
    377     * @param byteCode a ByteCode to be fixed up
    378     * @param codeAttribute a CodeAttribute used to determine how the ByteCode should be fixed up.
    379     */
    380    public void fixUpByteCodeTargets(final ByteCode byteCode, final CodeAttribute codeAttribute) {
    381        // Most ByteCodeForms don't have any fixing up to do.
    382    }
    383
    384    public String getName() {
    385        return name;
    386    }
    387
    388    public int getOpcode() {
    389        return opcode;
    390    }
    391
    392    public int[] getRewrite() {
    393        return rewrite;
    394    }
    395
    396    public int[] getRewriteCopy() {
    397        return Arrays.copyOf(rewrite, rewrite.length);
    398    }
    399
    400    /**
    401     * This method will answer true if the receiver is a multi-bytecode instruction (such as aload0_putfield_super);
    402     * otherwise, it will answer false.
    403     *
    404     * @return boolean true if multibytecode, false otherwise
    405     */
    406    public boolean hasMultipleByteCodes() {
    407        // Currently, all multi-bytecode instructions
    408        // begin with aload_0, so this is how we test.
    409        if (rewrite.length > 1 && rewrite[0] == 42) {
    410            // If there's an instruction (not a negative
    411            // number, which is an operand) after the
    412            // aload_0, it's a multibytecode instruction.
    413            return rewrite[1] > 0;
    414        }
    415        return false;
    416    }
    417
    418    public boolean hasNoOperand() {
    419        return false;
    420    }
    421
    422    public boolean nestedMustStartClassPool() {
    423        return false;
    424    }
    425
    426    public int operandLength() {
    427        return operandLength;
    428    }
    429
    430    /**
    431     * When passed a byteCode, an OperandTable and a SegmentConstantPool, this method will set the rewrite of the
    432     * byteCode appropriately.
    433     *
    434     * @param byteCode ByteCode to be updated (!)
    435     * @param operandManager OperandTable from which to draw info
    436     * @param codeLength Length of bytes (excluding this bytecode) from the beginning of the method. Used in calculating
    437     *        padding for some variable-length bytecodes (such as lookupswitch, tableswitch).
    438     */
    439    public abstract void setByteCodeOperands(ByteCode byteCode, OperandManager operandManager, int codeLength);
    440
    441    @Override
    442    public String toString() {
    443        return this.getClass().getName() + "(" + getName() + ")";
    444    }
    445}