about summary refs log tree commit diff stats
path: root/subx/015jump_relative.cc
blob: 2d3bbb2bc8fe1123ac58c15941052ca65fd17d52 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
//: jump to 8-bit offset

//:: jump

:(scenario jump_rel8)
# op  ModR/M  SIB   displacement  immediate
  eb                05                        # skip 1 instruction
  05                              00 00 00 01
  05                              00 00 00 02
+run: inst: 0x00000001
+run: jump 5
+run: inst: 0x00000008
-run: inst: 0x00000003

:(before "End Single-Byte Opcodes")
case 0xeb: {  // jump rel8
  int8_t offset = static_cast<int>(next());
  trace(2, "run") << "jump " << NUM(offset) << end();
  EIP += offset;
  break;
}

//:: jump if equal/zero

:(scenario je_rel8_success)
% ZF = true;
# op  ModR/M  SIB   displacement  immediate
  74                05                        # skip 1 instruction
  05                              00 00 00 01
  05                              00 00 00 02
+run: inst: 0x00000001
+run: jump 5
+run: inst: 0x00000008
-run: inst: 0x00000003

:(before "End Single-Byte Opcodes")
case 0x74: {  // jump rel8 if ZF
  int8_t offset = static_cast<int>(next());
  if (ZF) {
    trace(2, "run") << "jump " << NUM(offset) << end();
    EIP += offset;
  }
  break;
}

:(scenario je_rel8_fail)
% ZF = false;
# op  ModR/M  SIB   displacement  immediate
  74                05                        # skip 1 instruction
  05                              00 00 00 01
  05                              00 00 00 02
+run: inst: 0x00000001
+run: inst: 0x00000003
+run: inst: 0x00000008
-run: jump 5

//:: jump if not equal/not zero

:(scenario jne_rel8_success)
% ZF = false;
# op  ModR/M  SIB   displacement  immediate
  75                05                        # skip 1 instruction
  05                              00 00 00 01
  05                              00 00 00 02
+run: inst: 0x00000001
+run: jump 5
+run: inst: 0x00000008
-run: inst: 0x00000003

:(before "End Single-Byte Opcodes")
case 0x75: {  // jump rel8 unless ZF
  int8_t offset = static_cast<int>(next());
  if (!ZF) {
    trace(2, "run") << "jump " << NUM(offset) << end();
    EIP += offset;
  }
  break;
}

:(scenario jne_rel8_fail)
% ZF = true;
# op  ModR/M  SIB   displacement  immediate
  75                05                        # skip 1 instruction
  05                              00 00 00 01
  05                              00 00 00 02
+run: inst: 0x00000001
+run: inst: 0x00000003
+run: inst: 0x00000008
-run: jump 5

//:: jump if greater

:(scenario jg_rel8_success)
% ZF = false;
% SF = false;
% OF = false;
# op  ModR/M  SIB   displacement  immediate
  7f                05                        # skip 1 instruction
  05                              00 00 00 01
  05                              00 00 00 02
+run: inst: 0x00000001
+run: jump 5
+run: inst: 0x00000008
-run: inst: 0x00000003

:(before "End Single-Byte Opcodes")
case 0x7f: {  // jump rel8 if !SF and !ZF
  int8_t offset = static_cast<int>(next());
  if (!ZF && SF == OF) {
    trace(2, "run") << "jump " << NUM(offset) << end();
    EIP += offset;
  }
  break;
}

:(scenario jg_rel8_fail)
% ZF = false;
% SF = true;
% OF = false;
# op  ModR/M  SIB   displacement  immediate
  7f                05                        # skip 1 instruction
  05                              00 00 00 01
  05                              00 00 00 02
+run: inst: 0x00000001
+run: inst: 0x00000003
+run: inst: 0x00000008
-run: jump 5

//:: jump if greater or equal

:(scenario jge_rel8_success)
% SF = false;
% OF = false;
# op  ModR/M  SIB   displacement  immediate
  7d                05                        # skip 1 instruction
  05                              00 00 00 01
  05                              00 00 00 02
+run: inst: 0x00000001
+run: jump 5
+run: inst: 0x00000008
-run: inst: 0x00000003

:(before "End Single-Byte Opcodes")
case 0x7d: {  // jump rel8 if !SF
  int8_t offset = static_cast<int>(next());
  if (SF == OF) {
    trace(2, "run") << "jump " << NUM(offset) << end();
    EIP += offset;
  }
  break;
}

:(scenario jge_rel8_fail)
% SF = true;
% OF = false;
# op  ModR/M  SIB   displacement  immediate
  7d                05                        # skip 1 instruction
  05                              00 00 00 01
  05                              00 00 00 02
+run: inst: 0x00000001
+run: inst: 0x00000003
+run: inst: 0x00000008
-run: jump 5

//:: jump if lesser

:(scenario jl_rel8_success)
% ZF = false;
% SF = true;
% OF = false;
# op  ModR/M  SIB   displacement  immediate
  7c                05                        # skip 1 instruction
  05                              00 00 00 01
  05                              00 00 00 02
+run: inst: 0x00000001
+run: jump 5
+run: inst: 0x00000008
-run: inst: 0x00000003

:(before "End Single-Byte Opcodes")
case 0x7c: {  // jump rel8 if SF and !ZF
  int8_t offset = static_cast<int>(next());
  if (SF != OF) {
    trace(2, "run") << "jump " << NUM(offset) << end();
    EIP += offset;
  }
  break;
}

:(scenario jl_rel8_fail)
% ZF = false;
% SF = false;
% OF = false;
# op  ModR/M  SIB   displacement  immediate
  7c                05                        # skip 1 instruction
  05                              00 00 00 01
  05                              00 00 00 02
+run: inst: 0x00000001
+run: inst: 0x00000003
+run: inst: 0x00000008
-run: jump 5

//:: jump if lesser or equal

:(scenario jle_rel8_equal)
% ZF = true;
% SF = false;
% OF = false;
# op  ModR/M  SIB   displacement  immediate
  7e                05                        # skip 1 instruction
  05                              00 00 00 01
  05                              00 00 00 02
+run: inst: 0x00000001
+run: jump 5
+run: inst: 0x00000008
-run: inst: 0x00000003

:(scenario jle_rel8_lesser)
% ZF = false;
% SF = true;
% OF = false;
# op  ModR/M  SIB   displacement  immediate
  7e                05                        # skip 1 instruction
  05                              00 00 00 01
  05                              00 00 00 02
+run: inst: 0x00000001
+run: jump 5
+run: inst: 0x00000008
-run: inst: 0x00000003

:(before "End Single-Byte Opcodes")
case 0x7e: {  // jump rel8 if SF or ZF
  int8_t offset = static_cast<int>(next());
  if (ZF || SF != OF) {
    trace(2, "run") << "jump " << NUM(offset) << end();
    EIP += offset;
  }
  break;
}

:(scenario jle_rel8_greater)
% ZF = false;
% SF = false;
% OF = false;
# op  ModR/M  SIB   displacement  immediate
  7e                05                        # skip 1 instruction
  05                              00 00 00 01
  05                              00 00 00 02
+run: inst: 0x00000001
+run: inst: 0x00000003
+run: inst: 0x00000008
-run: jump 5