ARMSmlalXYTranslator.java

/*
Copyright 2011-2016 Google Inc. All Rights Reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package com.google.security.zynamics.reil.translators.arm;

import com.google.security.zynamics.reil.OperandSize;
import com.google.security.zynamics.reil.ReilHelpers;
import com.google.security.zynamics.reil.ReilInstruction;
import com.google.security.zynamics.reil.translators.ITranslationEnvironment;
import com.google.security.zynamics.reil.translators.InternalTranslationException;
import com.google.security.zynamics.reil.translators.TranslationHelpers;
import com.google.security.zynamics.zylib.disassembly.IInstruction;
import com.google.security.zynamics.zylib.disassembly.IOperandTreeNode;

import java.util.List;


public class ARMSmlalXYTranslator extends ARMBaseTranslator {
  @Override
  protected void translateCore(final ITranslationEnvironment environment,
      final IInstruction instruction, final List<ReilInstruction> instructions) {
    final IOperandTreeNode registerOperand1 =
        instruction.getOperands().get(0).getRootNode().getChildren().get(0);
    final IOperandTreeNode registerOperand2 =
        instruction.getOperands().get(1).getRootNode().getChildren().get(0);
    final IOperandTreeNode registerOperand3 =
        instruction.getOperands().get(2).getRootNode().getChildren().get(0);
    final IOperandTreeNode registerOperand4 =
        instruction.getOperands().get(3).getRootNode().getChildren().get(0);

    final String sourceRegister1 = (registerOperand1.getValue());
    final String sourceRegister2 = (registerOperand2.getValue());
    final String sourceRegister3 = (registerOperand3.getValue());
    final String sourceRegister4 = (registerOperand4.getValue());

    final OperandSize bt = OperandSize.BYTE;
    final OperandSize wd = OperandSize.WORD;
    final OperandSize dw = OperandSize.DWORD;
    final OperandSize qw = OperandSize.QWORD;

    long baseOffset = ReilHelpers.nextReilAddress(instruction, instructions);

    final String carryBit = environment.getNextVariableString();
    final String operand1 = environment.getNextVariableString();
    final String operand2 = environment.getNextVariableString();
    final String tmpVar1 = environment.getNextVariableString();
    final String tmpVar2 = environment.getNextVariableString();
    final String tmpVar3 = environment.getNextVariableString();
    final String tmpVar4 = environment.getNextVariableString();
    final String tmpVar5 = environment.getNextVariableString();
    final String tmpVar6 = environment.getNextVariableString();
    final String tmpVar7 = environment.getNextVariableString();
    final String tmpVar8 = environment.getNextVariableString();
    final String tmpVar9 = environment.getNextVariableString();
    final String isLessCondition = environment.getNextVariableString();

    if (instruction.getMnemonic().contains("BB")) {
      Helpers.signExtend(baseOffset, environment, instruction, instructions, dw, sourceRegister3,
          dw, operand1, 16);
      baseOffset = ReilHelpers.nextReilAddress(instruction, instructions);
      Helpers.signExtend(baseOffset, environment, instruction, instructions, dw, sourceRegister4,
          dw, operand2, 16);

    } else if (instruction.getMnemonic().contains("BT")) {
      Helpers.signExtend(baseOffset, environment, instruction, instructions, dw, sourceRegister3,
          dw, operand1, 16);
      baseOffset = ReilHelpers.nextReilAddress(instruction, instructions);
      instructions.add(ReilHelpers.createBsh(
          baseOffset++, dw, sourceRegister4, wd, String.valueOf(-16L), dw, tmpVar1));
      Helpers.signExtend(
          baseOffset, environment, instruction, instructions, dw, tmpVar1, dw, operand2, 16);
    } else if (instruction.getMnemonic().contains("TB")) {
      instructions.add(ReilHelpers.createBsh(
          baseOffset++, dw, sourceRegister3, wd, String.valueOf(-16L), dw, tmpVar1));
      Helpers.signExtend(
          baseOffset, environment, instruction, instructions, dw, tmpVar1, dw, operand1, 16);
      baseOffset = ReilHelpers.nextReilAddress(instruction, instructions);
      Helpers.signExtend(baseOffset, environment, instruction, instructions, dw, sourceRegister4,
          dw, operand2, 16);
    } else if (instruction.getMnemonic().contains("TB")) {
      instructions.add(ReilHelpers.createBsh(
          baseOffset++, dw, sourceRegister3, wd, String.valueOf(-16L), dw, tmpVar1));
      Helpers.signExtend(
          baseOffset, environment, instruction, instructions, dw, tmpVar1, dw, operand1, 16);
      baseOffset = ReilHelpers.nextReilAddress(instruction, instructions);
      instructions.add(ReilHelpers.createBsh(
          baseOffset++, dw, sourceRegister4, wd, String.valueOf(-16L), dw, tmpVar2));
      Helpers.signExtend(
          baseOffset, environment, instruction, instructions, dw, tmpVar2, dw, operand2, 16);
    }
    baseOffset = ReilHelpers.nextReilAddress(instruction, instructions);

    // Multiplication is not indicated as signed could be wrong TODO
    instructions.add(ReilHelpers.createMul(baseOffset++, dw, operand1, dw, operand2, qw, tmpVar3));

    // perform low addition
    instructions.add(
        ReilHelpers.createAdd(baseOffset++, dw, sourceRegister1, qw, tmpVar3, qw, tmpVar4));
    instructions.add(ReilHelpers.createAnd(
        baseOffset++, qw, tmpVar4, dw, String.valueOf(0xFFFFFFFFL), dw, sourceRegister1));

    // condition Bit
    instructions.add(
        ReilHelpers.createBsh(baseOffset++, dw, tmpVar3, wd, String.valueOf(-31L), bt, tmpVar5));
    instructions.add(ReilHelpers.createAnd(
        baseOffset++, bt, tmpVar5, bt, String.valueOf(1L), bt, isLessCondition));
    instructions.add(ReilHelpers.createSub(
        baseOffset++, dw, String.valueOf(0L), bt, isLessCondition, dw, tmpVar6));

    // carry Bit
    instructions.add(
        ReilHelpers.createBsh(baseOffset++, dw, tmpVar3, wd, String.valueOf(-32L), bt, tmpVar7));
    instructions.add(
        ReilHelpers.createAnd(baseOffset++, bt, tmpVar7, bt, String.valueOf(1L), bt, carryBit));

    // perform high addition
    instructions.add(ReilHelpers.createAdd(baseOffset++, dw, tmpVar6, bt, carryBit, dw, tmpVar8));
    instructions.add(
        ReilHelpers.createAdd(baseOffset++, dw, sourceRegister2, dw, tmpVar8, dw, tmpVar9));
    instructions.add(ReilHelpers.createAnd(
        baseOffset++, dw, tmpVar9, dw, String.valueOf(0xFFFFFFFFL), dw, sourceRegister2));
  }

  /**
   * SMLAL<x><y>{<cond>} <RdLo>, <RdHi>, <Rm>, <Rs>
   *
   *  TODO: check if the found information about smlal<x><y> is coded with TT TB BT BB as asumed
   *
   *  Operation:
   *
   *  if ConditionPassed(cond) then if (x == 0) then operand1 = SignExtend(Rm[15:0]) else // x == 1
   * operand1 = SignExtend(Rm[31:16]) if (y == 0) then operand2 = SignExtend(Rs[15:0]) else // y ==
   * 1 operand2 = SignExtend(Rs[31:16]) RdLo = RdLo + (operand1 * operand2) RdHi = RdHi + (if
   * (operand1*operand2) < 0 then 0xFFFFFFFF else 0) + CarryFrom(RdLo + (operand1 * operand2))
   */

  @Override
  public void translate(final ITranslationEnvironment environment, final IInstruction instruction,
      final List<ReilInstruction> instructions) throws InternalTranslationException {
    TranslationHelpers.checkTranslationArguments(environment, instruction, instructions, "SMLAL");
    translateAll(environment, instruction, "SMLAL", instructions);
  }
}