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/*
* 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.android.dx.dex.code.form;
import com.android.dx.dex.code.CstInsn;
import com.android.dx.dex.code.DalvInsn;
import com.android.dx.dex.code.InsnFormat;
import com.android.dx.rop.code.RegisterSpec;
import com.android.dx.rop.code.RegisterSpecList;
import com.android.dx.rop.cst.Constant;
import com.android.dx.rop.cst.CstMethodRef;
import com.android.dx.rop.cst.CstType;
import com.android.dx.rop.type.Type;
import com.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;
}
}
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