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
25using System;
26
27abstract class CodeElement {
28
29	internal int Address { get; set; }
30
31	internal int LastLength { get; set; }
32
33	// internal abstract int Length { get; }
34
35	internal CodeElement()
36	{
37		Address = -1;
38	}
39
40	internal virtual void SetJumpTarget(CodeElement target)
41	{
42		throw new Exception("Code element accepts no target");
43	}
44
45	internal abstract int GetLength(bool oneByteCode);
46
47	internal abstract int Encode(BlobWriter bw, bool oneByteCode);
48
49	internal static int EncodeOneByte(uint val, BlobWriter bw)
50	{
51		if (val > 255) {
52			throw new Exception(string.Format(
53				"Cannot encode '{0}' over one byte", val));
54		}
55		bw.Append((byte)val);
56		return 1;
57	}
58
59	internal static int Encode7EUnsigned(uint val, BlobWriter bw)
60	{
61		int len = 1;
62		for (uint w = val; w >= 0x80; w >>= 7) {
63			len ++;
64		}
65		if (bw != null) {
66			for (int k = (len - 1) * 7; k >= 0; k -= 7) {
67				int x = (int)(val >> k) & 0x7F;
68				if (k > 0) {
69					x |= 0x80;
70				}
71				bw.Append((byte)x);
72			}
73		}
74		return len;
75	}
76
77	internal static int Encode7ESigned(int val, BlobWriter bw)
78	{
79		int len = 1;
80		if (val < 0) {
81			for (int w = val; w < -0x40; w >>= 7) {
82				len ++;
83			}
84		} else {
85			for (int w = val; w >= 0x40; w >>= 7) {
86				len ++;
87			}
88		}
89		if (bw != null) {
90			for (int k = (len - 1) * 7; k >= 0; k -= 7) {
91				int x = (int)(val >> k) & 0x7F;
92				if (k > 0) {
93					x |= 0x80;
94				}
95				bw.Append((byte)x);
96			}
97		}
98		return len;
99	}
100}
101