1 /*
   2  * Copyright 2002 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.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  20  * CA 95054 USA or visit www.sun.com if you need additional information or
  21  * have any questions.
  22  *
  23  */
  24 
  25 package sun.jvm.hotspot.asm.sparc;
  26 
  27 import sun.jvm.hotspot.asm.*;
  28 
  29 abstract class BranchDecoder extends InstructionDecoder {
  30 
  31     // format 2 - condition code names.
  32     // Appendix F - Opcodes and Condition Codes - Page 231 - Table F-7.
  33     static final String integerConditionNames[] = {
  34         "bn", "be", "ble", "bl", "bleu", "bcs", "bneg", "bvs",
  35         "ba", "bne", "bg", "bge", "bgu", "bcc", "bpos", "bvc"
  36     };
  37 
  38     static final String integerAnnuledConditionNames[] = {
  39         "bn,a", "be,a", "ble,a", "bl,a", "bleu,a", "bcs,a", "bneg,a", "bvs,a",
  40         "ba,a", "bne,a", "bg,a", "bge,a", "bgu,a", "bcc,a", "bpos,a", "bvc,a"
  41     };
  42 
  43     // format 2 - condition code names.
  44     // Appendix F - Opcodes and Condition Codes - Page 231 - Table F-7.
  45     static final String floatConditionNames[] = {
  46         "fbn", "fbne", "fblg", "fbul", "fbl", "fbug", "fbg", "fbu",
  47         "fba", "fbe",  "fbue", "fbge", "fbuge", "fble", "fbule", "fbo"
  48     };
  49 
  50     static final String floatAnnuledConditionNames[] = {
  51         "fbn,a", "fbne,a", "fblg,a", "fbul,a", "fbl,a", "fbug,a", "fbg,a", "fbu,a",
  52         "fba,a", "fbe,a",  "fbue,a", "fbge,a", "fbuge,a", "fble,a", "fbule,a", "fbo,a"
  53     };
  54 
  55     static boolean getAnnuledBit(int instruction) {
  56         return (instruction & ANNUL_MASK) != 0;
  57     }
  58 
  59     Instruction decode(int instruction, SPARCInstructionFactory factory) {
  60         boolean isAnnuled = getAnnuledBit(instruction);
  61         int conditionCode = getConditionCode(instruction);
  62         String conditionName = getConditionName(conditionCode, isAnnuled);
  63         int offset = extractSignedIntFromNBits(instruction, 22);
  64         // word align the offset by right shifting 2 bits
  65         offset <<= 2;
  66         PCRelativeAddress addr = new PCRelativeAddress(offset);
  67         return factory.newBranchInstruction(conditionName, addr, isAnnuled, conditionCode);
  68     }
  69 
  70     abstract String getConditionName(int conditionCode, boolean isAnnuled);
  71 }