/*
 * Copyright (c) 2002, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

package sun.jvm.hotspot.asm.sparc;

import sun.jvm.hotspot.asm.*;

class V9ReadDecoder extends InstructionDecoder
              implements V9InstructionDecoder {
    Instruction decode(int instruction, SPARCInstructionFactory factory) {
        SPARCV9InstructionFactory v9factory = (SPARCV9InstructionFactory) factory;
        Instruction instr = null;
        int specialRegNum = getSourceRegister1(instruction);

        // rs1 values 1, 7-14 are reserved - see page 214, A.44 Read State Register.
        if (specialRegNum == 1 || (specialRegNum > 6 && specialRegNum < 15)) {
            instr = v9factory.newIllegalInstruction(instruction);
        } else {
            int rdNum = getDestinationRegister(instruction);
            if (specialRegNum == 15) {
                // may be stbar, member or illegal
                if (rdNum == 0) {
                    boolean iBit = isIBitSet(instruction);
                    if (iBit) {
                        instr = v9factory.newV9MembarInstruction((instruction & MMASK_MASK) >>> MMASK_START_BIT,
                                                        (instruction & CMASK_MASK) >>> CMASK_START_BIT);
                    } else {
                        instr = v9factory.newStbarInstruction();
                    }
                } else { // rd != 0 && rs1 == 15
                    instr = v9factory.newIllegalInstruction(instruction);
                }
             } else {
                int asrRegNum = -1;
                if (specialRegNum > 15){
                    asrRegNum = specialRegNum;
                    specialRegNum = SPARCV9SpecialRegisters.ASR;
                }
                SPARCRegister rd = SPARCRegisters.getRegister(rdNum);
                instr = v9factory.newV9ReadInstruction(specialRegNum, asrRegNum, rd);
             }
        }
        return instr;
    }
}