content: /*
   * Copyright (C) 2007 The Android Open Source Project
   *
   * 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.taobao.android.dx.dex.code;
  
  import com.taobao.android.dx.rop.code.RegisterSpec;
  import com.taobao.android.dx.rop.code.RegisterSpecList;
  import com.taobao.android.dx.rop.code.SourcePosition;
  import com.taobao.android.dx.util.AnnotatedOutput;
  
  /**
   * Combination instruction which turns into a variable number of
   * {@code move*} instructions to move a set of registers into
   * registers starting at {@code 0} sequentially. This is used
   * in translating an instruction whose register requirements cannot
   * be met using a straightforward choice of a single opcode.
   */
  public final class HighRegisterPrefix extends VariableSizeInsn {
      /** {@code null-ok;} cached instructions, if constructed */
      private SimpleInsn[] insns;
  
      /**
       * Constructs an instance. The output address of this instance is initially
       * unknown ({@code -1}).
       *
       * @param position {@code non-null;} source position
       * @param registers {@code non-null;} source registers
       */
      public HighRegisterPrefix(SourcePosition position,
                                RegisterSpecList registers) {
          super(position, registers);
  
          if (registers.size() == 0) {
              throw new IllegalArgumentException("registers.size() == 0");
          }
  
          insns = null;
      }
  
      /** {@inheritDoc} */
      @Override
      public int codeSize() {
          int result = 0;
  
          calculateInsnsIfNecessary();
  
          for (SimpleInsn insn : insns) {
              result += insn.codeSize();
          }
  
          return result;
      }
  
      /** {@inheritDoc} */
      @Override
      public void writeTo(AnnotatedOutput out) {
          calculateInsnsIfNecessary();
  
          for (SimpleInsn insn : insns) {
              insn.writeTo(out);
          }
      }
  
      /**
       * Helper for {@link #codeSize} and {@link #writeTo} which sets up
       * {@link #insns} if not already done.
       */
      private void calculateInsnsIfNecessary() {
          if (insns != null) {
              return;
          }
  
          RegisterSpecList registers = getRegisters();
          int sz = registers.size();
  
          insns = new SimpleInsn[sz];
  
          for (int i = 0, outAt = 0; i < sz; i++) {
            RegisterSpec src = registers.get(i);
            insns[i] = moveInsnFor(src, outAt);
            outAt += src.getCategory();
          }
      }
  
      /** {@inheritDoc} */
      @Override
      public DalvInsn withRegisters(RegisterSpecList registers) {
          return new HighRegisterPrefix(getPosition(), registers);
      }
  
      /** {@inheritDoc} */
      @Override
      protected String argString() {
          return null;
      }
  
      /** {@inheritDoc} */
      @Override
      protected String listingString0(boolean noteIndices) {
          RegisterSpecList registers = getRegisters();
          int sz = registers.size();
          StringBuffer sb = new StringBuffer(100);
  
          for (int i = 0, outAt = 0; i < sz; i++) {
              RegisterSpec src = registers.get(i);
              SimpleInsn insn = moveInsnFor(src, outAt);
  
              if (i != 0) {
                  sb.append('\n');
              }
  
              sb.append(insn.listingString0(noteIndices));
  
              outAt += src.getCategory();
          }
  
          return sb.toString();
      }
  
      /**
       * Returns the proper move instruction for the given source spec
       * and destination index.
       *
       * @param src {@code non-null;} the source register spec
       * @param destIndex {@code >= 0;} the destination register index
       * @return {@code non-null;} the appropriate move instruction
       */
      private static SimpleInsn moveInsnFor(RegisterSpec src, int destIndex) {
          return DalvInsn.makeMove(SourcePosition.NO_INFO,
                  RegisterSpec.make(destIndex, src.getType()),
                  src);
      }
  }
  