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.form;
  
  import com.taobao.android.dx.dex.code.CstInsn;
  import com.taobao.android.dx.dex.code.DalvInsn;
  import com.taobao.android.dx.dex.code.InsnFormat;
  import com.taobao.android.dx.rop.code.RegisterSpec;
  import com.taobao.android.dx.rop.code.RegisterSpecList;
  import com.taobao.android.dx.rop.cst.Constant;
  import com.taobao.android.dx.rop.cst.CstMethodRef;
  import com.taobao.android.dx.rop.cst.CstType;
  import com.taobao.android.dx.rop.type.Type;
  import com.taobao.android.dx.util.AnnotatedOutput;
  import java.util.BitSet;
  
  /**
   * Instruction format {@code 35c}. See the instruction format spec
   * for details.
   */
  public final class Form35c extends InsnFormat {
      /** {@code non-null;} unique instance of this class */
      public static final InsnFormat THE_ONE = new Form35c();
  
      /** Maximal number of operands */
      private static final int MAX_NUM_OPS = 5;
  
      /**
       * Constructs an instance. This class is not publicly
       * instantiable. Use {@link #THE_ONE}.
       */
      private Form35c() {
          // This space intentionally left blank.
      }
  
      /** {@inheritDoc} */
      @Override
      public String insnArgString(DalvInsn insn) {
          RegisterSpecList regs = explicitize(insn.getRegisters());
          return regListString(regs) + ", " + cstString(insn);
      }
  
      /** {@inheritDoc} */
      @Override
      public String insnCommentString(DalvInsn insn, boolean noteIndices) {
          if (noteIndices) {
              return cstComment(insn);
          } else {
              return "";
          }
      }
  
      /** {@inheritDoc} */
      @Override
      public int codeSize() {
          return 3;
      }
  
      /** {@inheritDoc} */
      @Override
      public boolean isCompatible(DalvInsn insn) {
          if (!(insn instanceof CstInsn)) {
              return false;
          }
  
          CstInsn ci = (CstInsn) insn;
          int cpi = ci.getIndex();
  
          if (! unsignedFitsInShort(cpi)) {
              return false;
          }
  
          Constant cst = ci.getConstant();
          if (!((cst instanceof CstMethodRef) ||
                (cst instanceof CstType))) {
              return false;
          }
  
          RegisterSpecList regs = ci.getRegisters();
          return (wordCount(regs) >= 0);
      }
  
      /** {@inheritDoc} */
      @Override
      public BitSet compatibleRegs(DalvInsn insn) {
          RegisterSpecList regs = insn.getRegisters();
          int sz = regs.size();
          BitSet bits = new BitSet(sz);
  
          for (int i = 0; i < sz; i++) {
              RegisterSpec reg = regs.get(i);
              /*
               * The check below adds (category - 1) to the register, to
               * account for the fact that the second half of a
               * category-2 register has to be represented explicitly in
               * the result.
               */
              bits.set(i, unsignedFitsInNibble(reg.getReg() +
                                               reg.getCategory() - 1));
          }
  
          return bits;
      }
  
      /** {@inheritDoc} */
      @Override
      public void writeTo(AnnotatedOutput out, DalvInsn insn) {
          int cpi = ((CstInsn) insn).getIndex();
          RegisterSpecList regs = explicitize(insn.getRegisters());
          int sz = regs.size();
          int r0 = (sz > 0) ? regs.get(0).getReg() : 0;
          int r1 = (sz > 1) ? regs.get(1).getReg() : 0;
          int r2 = (sz > 2) ? regs.get(2).getReg() : 0;
          int r3 = (sz > 3) ? regs.get(3).getReg() : 0;
          int r4 = (sz > 4) ? regs.get(4).getReg() : 0;
  
          write(out,
                opcodeUnit(insn,
                           makeByte(r4, sz)), // encode the fifth operand here
                (short) cpi,
                codeUnit(r0, r1, r2, r3));
      }
  
      /**
       * Gets the number of words required for the given register list, where
       * category-2 values count as two words. Return {@code -1} if the
       * list requires more than five words or contains registers that need
       * more than a nibble to identify them.
       *
       * @param regs {@code non-null;} the register list in question
       * @return {@code >= -1;} the number of words required, or {@code -1}
       * if the list couldn't possibly fit in this format
       */
      private static int wordCount(RegisterSpecList regs) {
          int sz = regs.size();
  
          if (sz > MAX_NUM_OPS) {
              // It can't possibly fit.
              return -1;
          }
  
          int result = 0;
  
          for (int i = 0; i < sz; i++) {
              RegisterSpec one = regs.get(i);
              result += one.getCategory();
              /*
               * The check below adds (category - 1) to the register, to
               * account for the fact that the second half of a
               * category-2 register has to be represented explicitly in
               * the result.
               */
              if (!unsignedFitsInNibble(one.getReg() + one.getCategory() - 1)) {
                  return -1;
              }
          }
  
          return (result <= MAX_NUM_OPS) ? result : -1;
      }
  
      /**
       * Returns a register list which is equivalent to the given one,
       * except that it splits category-2 registers into two explicit
       * entries. This returns the original list if no modification is
       * required
       *
       * @param orig {@code non-null;} the original list
       * @return {@code non-null;} the list with the described transformation
       */
      private static RegisterSpecList explicitize(RegisterSpecList orig) {
          int wordCount = wordCount(orig);
          int sz = orig.size();
  
          if (wordCount == sz) {
              return orig;
          }
  
          RegisterSpecList result = new RegisterSpecList(wordCount);
          int wordAt = 0;
  
          for (int i = 0; i < sz; i++) {
              RegisterSpec one = orig.get(i);
              result.set(wordAt, one);
              if (one.getCategory() == 2) {
                  result.set(wordAt + 1,
                             RegisterSpec.make(one.getReg() + 1, Type.VOID));
                  wordAt += 2;
              } else {
                  wordAt++;
              }
          }
  
          result.setImmutable();
          return result;
      }
  }
  