_ Git - BearSSL/blob - T0/CodeElement.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
  27 abstract 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 }