Hykilpikonna
96 lines
3.4 KiB
Java
96 lines
3.4 KiB
Java
package mars.mips.instructions.syscalls;
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import mars.Globals;
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import mars.ProcessingException;
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import mars.ProgramStatement;
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import mars.mips.hardware.AddressErrorException;
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import mars.mips.hardware.RegisterFile;
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import mars.util.SystemIO;
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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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* Service to read console input string into buffer starting at address in $a0.
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*/
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public class SyscallReadString extends AbstractSyscall
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{
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/**
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* Build an instance of the Read String syscall. Default service number is 8 and name is "ReadString".
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*/
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public SyscallReadString()
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{
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super(8, "ReadString");
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}
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/**
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* Performs syscall function to read console input string into buffer starting at address in $a0. Follows semantics
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* of UNIX 'fgets'. For specified length n, string can be no longer than n-1. If less than that, add newline to
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* end. In either case, then pad with null byte.
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*/
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public void simulate(ProgramStatement statement) throws ProcessingException
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{
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String inputString = "";
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int buf = RegisterFile.getValue(4); // buf addr in $a0
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int maxLength = RegisterFile.getValue(5) - 1; // $a1
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boolean addNullByte = true;
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// Guard against negative maxLength. DPS 13-July-2011
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if (maxLength < 0)
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{
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maxLength = 0;
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addNullByte = false;
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}
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inputString = SystemIO.readString(this.getNumber(), maxLength);
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int stringLength = Math.min(maxLength, inputString.length());
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try
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{
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for (int index = 0; index < stringLength; index++)
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{
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Globals.memory.setByte(buf + index,
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inputString.charAt(index));
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}
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if (stringLength < maxLength)
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{
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Globals.memory.setByte(buf + stringLength, '\n');
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stringLength++;
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}
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if (addNullByte)
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{
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Globals.memory.setByte(buf + stringLength, 0);
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}
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}
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catch (AddressErrorException e)
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{
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throw new ProcessingException(statement, e);
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}
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}
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}
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