adolphenom
136 lines
4.9 KiB
Java
136 lines
4.9 KiB
Java
package mars.mips.instructions;
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import mars.assembler.*;
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import mars.*;
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import java.util.*;
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/*
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Copyright (c) 2003-2006, Pete Sanderson and Kenneth Vollmar
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Developed by Pete Sanderson (psanderson@otterbein.edu)
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and Kenneth Vollmar (kenvollmar@missouristate.edu)
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Permission is hereby granted, free of charge, to any person obtaining
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a copy of this software and associated documentation files (the
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"Software"), to deal in the Software without restriction, including
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without limitation the rights to use, copy, modify, merge, publish,
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distribute, sublicense, and/or sell copies of the Software, and to
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permit persons to whom the Software is furnished to do so, subject
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to the following conditions:
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The above copyright notice and this permission notice shall be
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included in all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR
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ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
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CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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(MIT license, http://www.opensource.org/licenses/mit-license.html)
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*/
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/**
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* Base class to represent member of MIPS instruction set.
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*
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* @author Pete Sanderson and Ken Vollmar
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* @version August 2003
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*/
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public abstract class Instruction {
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/**
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* Length in bytes of a machine instruction. MIPS is a RISC architecture
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* so all instructions are the same length. Currently set to 4.
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*/
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public static final int INSTRUCTION_LENGTH = 4;
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public static final int INSTRUCTION_LENGTH_BITS = 32;
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/** Characters used in instruction mask to indicate bit positions
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* for 'f'irst, 's'econd, and 't'hird operands.
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**/
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public static char[] operandMask = { 'f', 's', 't'};
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/** The instruction name. **/
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protected String mnemonic;
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/** Example usage of this instruction. Is provided as subclass constructor argument. **/
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protected String exampleFormat;
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/** Description of instruction for display to user **/
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protected String description;
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/** List of tokens generated by tokenizing example usage (see <tt>exampleFormat</tt>). **/
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protected TokenList tokenList;
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/**
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* Get operation mnemonic
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*
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* @return operation mnemonic (e.g. addi, sw)
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*/
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public String getName() {
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return mnemonic;
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}
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/**
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* Get string descriptor of instruction's format. This is an example MIPS
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* assembler instruction usage which contains the operator and all operands.
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* Operands are separated by commas, an operand that begins with a '$'
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* represents a register, and an integer operand represents an immediate value
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* or address. Here are two examples: "nor $1,$2,$3" and "sw $1,100($2)"
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*
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* @return String representing example instruction format.
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*/
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public String getExampleFormat() {
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return exampleFormat;
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}
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/**
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* Get string describing the instruction. This is not used internally by
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* MARS, but is for display to the user.
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*
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* @return String describing the instruction.
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*/
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public String getDescription() {
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return description;
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}
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/**
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* Get TokenList corresponding to correct instruction syntax.
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* For example, the instruction with format "sw $1,100($2)" yields token list
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* <operator><register_number><integer><left_paren><register_number><right_parent>
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*
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* @return TokenList object representing correct instruction usage.
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*/
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public TokenList getTokenList() {
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return tokenList;
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}
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/**
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* Get length in bytes that this instruction requires in its binary form.
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* Default is 4 (holds for all basic instructions), but can be overridden
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* in subclass.
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* @return int length in bytes of corresponding binary instruction(s).
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*/
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public int getInstructionLength() {
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return INSTRUCTION_LENGTH;
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}
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/** Used by subclass constructors to extract operator mnemonic from the
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instruction example. **/
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protected String extractOperator(String example) {
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StringTokenizer st = new StringTokenizer(example, " ,\t");
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return st.nextToken();
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}
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/** Used to build a token list from the example instruction
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provided as constructor argument. Parser uses this for syntax checking. **/
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protected void createExampleTokenList() {
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try {
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tokenList = ((new Tokenizer()).tokenizeExampleInstruction(exampleFormat));
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} catch (ProcessingException pe) {
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System.out.println("CONFIGURATION ERROR: Instruction example \""+exampleFormat+"\" contains invalid token(s).");
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}
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}
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}
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