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 // basic instruction decoder class 30 abstract class InstructionDecoder implements /* imports */ SPARCOpcodes , RTLDataTypes, RTLOperations { 31 // some general utility functions - for format 2, 3 & 3A instructions 32 33 static int extractSignedIntFromNBits(int value, int num_bits) { 34 return (value << (32 - num_bits)) >> (32 - num_bits); 35 } 36 37 // "rs1" 38 static int getSourceRegister1(int instruction) { 39 return (instruction & RS1_MASK) >>> RS1_START_BIT; 40 } 41 42 // "rs2" 43 static int getSourceRegister2(int instruction) { 44 return (instruction & RS2_MASK); 45 } 46 47 // "rd" 48 static int getDestinationRegister(int instruction) { 49 return (instruction & RD_MASK) >>> RD_START_BIT; 50 } 51 52 static int getConditionCode(int instruction) { 53 return (instruction & CONDITION_CODE_MASK) >>> CONDITION_CODE_START_BIT; 54 } 55 56 // "i" bit - used to indicate whether second component in an indirect 57 // address is immediate value or a register. (format 3 & 3A). 58 59 static boolean isIBitSet(int instruction) { 60 return (instruction & I_MASK) != 0; 61 } 62 63 static ImmediateOrRegister getOperand2(int instruction) { 64 boolean iBit = isIBitSet(instruction); 65 ImmediateOrRegister operand2 = null; 66 if (iBit) { 67 operand2 = new Immediate(new Short((short)extractSignedIntFromNBits(instruction, 13))); 68 } else { 69 operand2 = SPARCRegisters.getRegister(getSourceRegister2(instruction)); 70 } 71 return operand2; 72 } 73 74 // "opf" - floating point operation code. 75 static int getOpf(int instruction) { 76 return (instruction & OPF_MASK) >>> OPF_START_BIT; 77 } 78 79 abstract Instruction decode(int instruction, SPARCInstructionFactory factory); 80 }