1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.nabla.forward.arithmetic;
18
19 import org.apache.commons.nabla.DifferentiationException;
20 import org.apache.commons.nabla.forward.analysis.InstructionsTransformer;
21 import org.apache.commons.nabla.forward.analysis.MethodDifferentiator;
22 import org.objectweb.asm.Opcodes;
23 import org.objectweb.asm.Type;
24 import org.objectweb.asm.tree.AbstractInsnNode;
25 import org.objectweb.asm.tree.InsnList;
26 import org.objectweb.asm.tree.InsnNode;
27 import org.objectweb.asm.tree.MethodInsnNode;
28
29 /** Differentiation transformer for DSUB instructions.
30 * @version $Id$
31 */
32 public class DSubTransformer implements InstructionsTransformer {
33
34 /** Name of the {@link org.apache.commons.math3.analysis.differentiation.DerivativeStructure} method corresponding to the subtraction. */
35 private static final String SUBTRACT_METHOD = "subtract";
36
37 /** Name of the {@link org.apache.commons.math3.analysis.differentiation.DerivativeStructure} method corresponding to the negation. */
38 private static final String NEGATE_METHOD = "negate";
39
40 /** Indicator for top stack element conversion. */
41 private final boolean stack0Converted;
42
43 /** Indicator for next to top stack element conversion. */
44 private final boolean stack1Converted;
45
46 /** Simple constructor.
47 * @param stack0Converted if true, the top level stack element has already been converted
48 * @param stack1Converted if true, the next to top level stack element has already been converted
49 */
50 public DSubTransformer(final boolean stack0Converted, final boolean stack1Converted) {
51 this.stack0Converted = stack0Converted;
52 this.stack1Converted = stack1Converted;
53 }
54
55 /** {@inheritDoc} */
56 public InsnList getReplacement(final AbstractInsnNode insn,
57 final MethodDifferentiator methodDifferentiator)
58 throws DifferentiationException {
59
60 final InsnList list = new InsnList();
61
62 if (stack1Converted) {
63 if (stack0Converted) {
64 list.add(new MethodInsnNode(Opcodes.INVOKEVIRTUAL, DS_TYPE.getInternalName(),
65 SUBTRACT_METHOD,
66 Type.getMethodDescriptor(DS_TYPE, DS_TYPE)));
67 } else {
68 list.add(new MethodInsnNode(Opcodes.INVOKEVIRTUAL, DS_TYPE.getInternalName(),
69 SUBTRACT_METHOD,
70 Type.getMethodDescriptor(DS_TYPE, Type.DOUBLE_TYPE)));
71 }
72 } else {
73 list.add(new InsnNode(Opcodes.DUP_X2));
74 list.add(new InsnNode(Opcodes.POP));
75 list.add(new MethodInsnNode(Opcodes.INVOKEVIRTUAL, DS_TYPE.getInternalName(),
76 SUBTRACT_METHOD,
77 Type.getMethodDescriptor(DS_TYPE, Type.DOUBLE_TYPE)));
78 list.add(new MethodInsnNode(Opcodes.INVOKEVIRTUAL, DS_TYPE.getInternalName(),
79 NEGATE_METHOD,
80 Type.getMethodDescriptor(DS_TYPE)));
81 }
82
83 return list;
84
85 }
86
87 }