1 /*
   2  * Copyright (c) 2002, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores,
  20  * CA 94065 USA or visit www.oracle.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 class V9ReadDecoder extends InstructionDecoder
  30               implements V9InstructionDecoder {
  31     Instruction decode(int instruction, SPARCInstructionFactory factory) {
  32         SPARCV9InstructionFactory v9factory = (SPARCV9InstructionFactory) factory;
  33         Instruction instr = null;
  34         int specialRegNum = getSourceRegister1(instruction);
  35 
  36         // rs1 values 1, 7-14 are reserved - see page 214, A.44 Read State Register.
  37         if (specialRegNum == 1 || (specialRegNum > 6 && specialRegNum < 15)) {
  38             instr = v9factory.newIllegalInstruction(instruction);
  39         } else {
  40             int rdNum = getDestinationRegister(instruction);
  41             if (specialRegNum == 15) {
  42                 // may be stbar, member or illegal
  43                 if (rdNum == 0) {
  44                     boolean iBit = isIBitSet(instruction);
  45                     if (iBit) {
  46                         instr = v9factory.newV9MembarInstruction((instruction & MMASK_MASK) >>> MMASK_START_BIT,
  47                                                         (instruction & CMASK_MASK) >>> CMASK_START_BIT);
  48                     } else {
  49                         instr = v9factory.newStbarInstruction();
  50                     }
  51                 } else { // rd != 0 && rs1 == 15
  52                     instr = v9factory.newIllegalInstruction(instruction);
  53                 }
  54              } else {
  55                 int asrRegNum = -1;
  56                 if (specialRegNum > 15){
  57                     asrRegNum = specialRegNum;
  58                     specialRegNum = SPARCV9SpecialRegisters.ASR;
  59                 }
  60                 SPARCRegister rd = SPARCRegisters.getRegister(rdNum);
  61                 instr = v9factory.newV9ReadInstruction(specialRegNum, asrRegNum, rd);
  62              }
  63         }
  64         return instr;
  65     }
  66 }