Added encoded OID for hash functions (for use with PKCS#1 v1.5 signatures) into the...
[BearSSL] / T0 / Opcode.cs
1 /*
2 * Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining
5 * a copy of this software and associated documentation files (the
6 * "Software"), to deal in the Software without restriction, including
7 * without limitation the rights to use, copy, modify, merge, publish,
8 * distribute, sublicense, and/or sell copies of the Software, and to
9 * permit persons to whom the Software is furnished to do so, subject to
10 * the following conditions:
11 *
12 * The above copyright notice and this permission notice shall be
13 * included in all copies or substantial portions of the Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
16 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
17 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
18 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
19 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
20 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
21 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
22 * SOFTWARE.
23 */
24
25 using System;
26 using System.Collections.Generic;
27
28 abstract class Opcode {
29
30 internal Opcode()
31 {
32 }
33
34 /*
35 * Execute this opcode.
36 */
37 internal abstract void Run(CPU cpu);
38
39 /*
40 * Resolve the target (word reference) for this opcode.
41 */
42 internal virtual void ResolveTarget(Word target)
43 {
44 throw new Exception("Not a call opcode");
45 }
46
47 /*
48 * Resolve the jump offset for this opcode. Displacement is
49 * relative to the address of the opcode that immediately follows
50 * the jump code; thus, 0 implies no jump at all.
51 */
52 internal virtual void ResolveJump(int disp)
53 {
54 throw new Exception("Not a jump opcode");
55 }
56
57 /*
58 * Get the Word that this opcode references; this can happen
59 * only with "call" and "const" opcodes. For all other opcodes,
60 * this method returns null.
61 */
62 internal virtual Word GetReference(T0Comp ctx)
63 {
64 return null;
65 }
66
67 /*
68 * Get the data block that this opcode references; this can happen
69 * only with "const" opcodes. For all other opcodes, this method
70 * returns null.
71 */
72 internal virtual ConstData GetDataBlock(T0Comp ctx)
73 {
74 return null;
75 }
76
77 /*
78 * Test whether this opcode may "fall through", i.e. execution
79 * may at least potentially proceed to the next opcode.
80 */
81 internal virtual bool MayFallThrough {
82 get {
83 return true;
84 }
85 }
86
87 /*
88 * Get jump displacement. For non-jump opcodes, this returns 0.
89 */
90 internal virtual int JumpDisp {
91 get {
92 return 0;
93 }
94 }
95
96 /*
97 * Get stack effect for this opcode (number of elements added to
98 * the stack, could be negative). For OpcodeCall, this returns
99 * 0.
100 */
101 internal virtual int StackAction {
102 get {
103 return 0;
104 }
105 }
106
107 internal abstract CodeElement ToCodeElement();
108
109 /*
110 * This method is called for the CodeElement corresponding to
111 * this opcode, at gcode[off]; it is used to compute actual
112 * byte jump offsets when converting code to C.
113 */
114 internal virtual void FixUp(CodeElement[] gcode, int off)
115 {
116 }
117 }