code: /*
   * Copyright (c) 2014, Aleksander Osman
   * All rights reserved.
   * 
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are met:
   * 
   * * Redistributions of source code must retain the above copyright notice, this
   *   list of conditions and the following disclaimer.
   * 
   * * Redistributions in binary form must reproduce the above copyright notice,
   *   this list of conditions and the following disclaimer in the documentation
   *   and/or other materials provided with the distribution.
   * 
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
   * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
   * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  package ao486.test.branch;
  
  import ao486.test.TestUnit;
  import ao486.test.layers.FlagsLayer;
  import ao486.test.layers.GeneralRegisterLayer;
  import ao486.test.layers.HandleModeChangeLayer;
  import ao486.test.layers.IOLayer;
  import ao486.test.layers.InstructionLayer;
  import ao486.test.layers.Layer;
  import ao486.test.layers.MemoryLayer;
  import ao486.test.layers.MemoryPatchLayer;
  import ao486.test.layers.OtherLayer;
  import ao486.test.layers.Pair;
  import ao486.test.layers.SegmentLayer;
  import ao486.test.layers.StackLayer;
  import java.io.*;
  import java.util.LinkedList;
  import java.util.Random;
  
  
  public class TestRET_far_real_v8086 extends TestUnit implements Serializable {
      public static void main(String args[]) throws Exception {
          run_test(TestRET_far_real_v8086.class);
      }
      
      //--------------------------------------------------------------------------
      @Override
      public int get_test_count() throws Exception {
          return 100;
      }
      
      @Override
      public void init() throws Exception {
          
          random = new Random(1 + index);
          
          String instruction;
          while(true) {
              layers.clear();
              
              LinkedList<Pair<Long, Long>> prohibited_list = new LinkedList<>();
              
              InstructionLayer instr  = new InstructionLayer(random, prohibited_list);
              layers.add(instr);
              StackLayer stack        = new StackLayer(random, prohibited_list);
              layers.add(stack);
              layers.add(new OtherLayer(random));
              layers.add(new FlagsLayer(random));
              layers.add(new GeneralRegisterLayer(random));
              layers.add(new SegmentLayer(random));
              layers.add(new MemoryLayer(random));
              layers.add(new IOLayer(random));
              layers.addFirst(new HandleModeChangeLayer(
                      getInput("cr0_pe"),
                      getInput("vmflag"),
                      getInput("cs_rpl"),
                      getInput("cs_p"),
                      getInput("cs_s"),
                      getInput("cs_type")
              ));
              
              // instruction size
              boolean cs_d_b = getInput("cs_d_b") == 1;
              
              boolean a32 = random.nextBoolean();
              boolean o32 = random.nextBoolean();
              
              // destination
              long cs  = random.nextInt(0xFFFF+1);
              long eip = Layer.norm(random.nextInt());
              
              if(o32 == false) eip &= 0xFFFF;
  
              long dest = (cs << 4) + eip;
  
              boolean can_add = Layer.collides(prohibited_list, (int)dest, (int)(dest+1));
              
              if(can_add == false) continue;
              
              MemoryPatchLayer patch = new MemoryPatchLayer(random, prohibited_list, (int)dest, 0x0F,0x0F);
              layers.addFirst(patch);
              
              // stack
              if(o32) {
                  stack.push_dword((int)eip); //eip
                  stack.push_dword((int)cs);  //cs
              }
              else {
                  stack.push_word((int)eip); //eip
                  stack.push_word((int)cs);  //cs
              }
              
              // add instruction
              boolean cr0_pe  = getInput("cr0_pe") == 1;
              boolean flag_vm = getInput("vmflag") == 1;
              
              instruction = prepare_instr(cs_d_b, a32, o32);
              instr.add_instruction(instruction);
              
              // end condition
              if(cr0_pe == false || flag_vm == true) {
  System.out.printf("cs: %x, eip: %x, dst: %x\n", cs, eip, dest);
                  break;
              }
          }
          
          System.out.println("Instruction: [" + instruction + "]");
      }
  
      int imm_len(boolean a32, boolean o32, int opcode) {
          return opcode == 0xCA ? 2 : 0;
      }
      String prepare_instr(boolean cs_d_b, boolean a32, boolean o32) throws Exception {
          int opcodes[] = {
              0xCA,0xCB
          };
          
          String prefix = "";
          if(cs_d_b != o32) { prefix = "66" + prefix; }
          if(cs_d_b != a32) { prefix = "67" + prefix; }
          
          int     opcode      = opcodes[random.nextInt(opcodes.length)];
          boolean is_modregrm = false;
          
          byte possible_modregrm = (byte)random.nextInt();
          byte possible_sib      = (byte)random.nextInt();
        
          int len = (is_modregrm == false)? 1 : 1 + modregrm_len(!cs_d_b, unsigned(possible_modregrm), unsigned(possible_sib));
          len += imm_len(a32, o32, opcode);
  
          
          byte instr[] = new byte[len];
          instr[0] = (byte)opcode;
          for(int i=1; i<len; i++) {
              if(i==1)        instr[1] = possible_modregrm;
              else if(i==2)   instr[2] = possible_sib;
              else            instr[i] = (byte)random.nextInt();
          }
          
          return prefix + bytesToHex(instr);
      }
  
  }