content: package mars.mips.instructions.syscalls;
  
  import mars.Globals;
  import mars.ProcessingException;
  import mars.ProgramStatement;
  import mars.mips.hardware.RegisterFile;
  import mars.simulator.Exceptions;
  
  /*
   * Copyright (c) 2003-2006, Pete Sanderson and Kenneth Vollmar
   *
   * Developed by Pete Sanderson (psanderson@otterbein.edu) and Kenneth Vollmar
   * (kenvollmar@missouristate.edu)
   *
   * Permission is hereby granted, free of charge, to any person obtaining a copy
   * of this software and associated documentation files (the "Software"), to deal
   * in the Software without restriction, including without limitation the rights
   * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   * copies of the Software, and to permit persons to whom the Software is
   * furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in
   * all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
   * SOFTWARE.
   *
   * (MIT license, http://www.opensource.org/licenses/mit-license.html)
   */
  
  /**
   * Service to allocate amount of heap memory specified in $a0, putting address
   * into $v0.
   */
  
  public class SyscallSbrk extends AbstractSyscall {
  
  	/**
  	 * Build an instance of the Sbrk syscall. Default service number is 9 and name
  	 * is "Sbrk".
  	 */
  	public SyscallSbrk() {
  		super(9, "Sbrk");
  	}
  
  	/**
  	 * Performs syscall function to allocate amount of heap memory specified in $a0,
  	 * putting address into $v0.
  	 */
  	@Override
  	public void simulate(final ProgramStatement statement) throws ProcessingException {
  		int address = 0;
  		try {
  			address = Globals.memory.allocateBytesFromHeap(RegisterFile.getValue(4));
  		} catch (final IllegalArgumentException iae) {
  			throw new ProcessingException(statement, iae.getMessage() + " (syscall " + getNumber() + ")",
  					Exceptions.SYSCALL_EXCEPTION);
  		}
  		RegisterFile.updateRegister(2, address);
  	}
  }
  