4181

1 files changed, 258 insertions, 0 deletions

diff --git a/subx/016jump_relative.cc b/subx/016jump_relative.cc
new file mode 100644
index 00000000..c4d92030
--- /dev/null
+++ b/subx/016jump_relative.cc
@@ -0,0 +1,258 @@
+//: jump to 16-bit offset
+
+//:: jump
+
+:(scenario jump_rel16)
+# op  ModRM   SIB   displacement  immediate
+  e9                05 00                     # skip 1 instruction
+  05                              00 00 00 01
+  05                              00 00 00 02
++run: inst: 0x00000001
++run: jump 5
++run: inst: 0x00000009
+-run: inst: 0x00000003
+
+:(before "End Single-Byte Opcodes")
+case 0xe9: {  // jump rel8
+  int16_t offset = imm16();
+  trace(2, "run") << "jump " << offset << end();
+  EIP += offset;
+  break;
+}
+:(code)
+int16_t imm16() {
+  int16_t result = next();
+  result |= (next()<<8);
+  return result;
+}
+
+//:: jump if equal/zero
+
+:(scenario je_rel16_success)
+% ZF = true;
+# op      ModRM   SIB   displacement  immediate
+  0f 84                 05 00                     # skip 1 instruction
+  05                                  00 00 00 01
+  05                                  00 00 00 02
++run: inst: 0x00000001
++run: jump 5
++run: inst: 0x0000000a
+-run: inst: 0x00000005
+
+:(before "End Two-Byte Opcodes Starting With 0f")
+case 0x84: {  // jump rel16 if ZF
+  int8_t offset = imm16();
+  if (ZF) {
+    trace(2, "run") << "jump " << NUM(offset) << end();
+    EIP += offset;
+  }
+  break;
+}
+
+:(scenario je_rel16_fail)
+% ZF = false;
+# op      ModRM   SIB   displacement  immediate
+  0f 84                 05 00                     # skip 1 instruction
+  05                                  00 00 00 01
+  05                                  00 00 00 02
++run: inst: 0x00000001
++run: inst: 0x00000005
++run: inst: 0x0000000a
+-run: jump 5
+
+//:: jump if not equal/not zero
+
+:(scenario jne_rel16_success)
+% ZF = false;
+# op      ModRM   SIB   displacement  immediate
+  0f 85                 05 00                     # skip 1 instruction
+  05                                  00 00 00 01
+  05                                  00 00 00 02
++run: inst: 0x00000001
++run: jump 5
++run: inst: 0x0000000a
+-run: inst: 0x00000005
+
+:(before "End Two-Byte Opcodes Starting With 0f")
+case 0x85: {  // jump rel16 unless ZF
+  int8_t offset = imm16();
+  if (!ZF) {
+    trace(2, "run") << "jump " << NUM(offset) << end();
+    EIP += offset;
+  }
+  break;
+}
+
+:(scenario jne_rel16_fail)
+% ZF = true;
+# op      ModRM   SIB   displacement  immediate
+  0f 85                 05 00                     # skip 1 instruction
+  05                                  00 00 00 01
+  05                                  00 00 00 02
++run: inst: 0x00000001
++run: inst: 0x00000005
++run: inst: 0x0000000a
+-run: jump 5
+
+//:: jump if greater
+
+:(scenario jg_rel16_success)
+% ZF = false;
+% SF = false;
+% OF = false;
+# op      ModRM   SIB   displacement  immediate
+  0f 8f                 05 00                     # skip 1 instruction
+  05                                  00 00 00 01
+  05                                  00 00 00 02
++run: inst: 0x00000001
++run: jump 5
++run: inst: 0x0000000a
+-run: inst: 0x00000005
+
+:(before "End Two-Byte Opcodes Starting With 0f")
+case 0x8f: {  // jump rel16 if !SF and !ZF
+  int8_t offset = imm16();
+  if (!ZF && SF == OF) {
+    trace(2, "run") << "jump " << NUM(offset) << end();
+    EIP += offset;
+  }
+  break;
+}
+
+:(scenario jg_rel16_fail)
+% ZF = false;
+% SF = true;
+% OF = false;
+# op      ModRM   SIB   displacement  immediate
+  0f 8f                 05 00                     # skip 1 instruction
+  05                                  00 00 00 01
+  05                                  00 00 00 02
++run: inst: 0x00000001
++run: inst: 0x00000005
++run: inst: 0x0000000a
+-run: jump 5
+
+//:: jump if greater or equal
+
+:(scenario jge_rel16_success)
+% SF = false;
+% OF = false;
+# op      ModRM   SIB   displacement  immediate
+  0f 8d                 05 00                     # skip 1 instruction
+  05                                  00 00 00 01
+  05                                  00 00 00 02
++run: inst: 0x00000001
++run: jump 5
++run: inst: 0x0000000a
+-run: inst: 0x00000005
+
+:(before "End Two-Byte Opcodes Starting With 0f")
+case 0x8d: {  // jump rel16 if !SF
+  int8_t offset = imm16();
+  if (SF == OF) {
+    trace(2, "run") << "jump " << NUM(offset) << end();
+    EIP += offset;
+  }
+  break;
+}
+
+:(scenario jge_rel16_fail)
+% SF = true;
+% OF = false;
+# op      ModRM   SIB   displacement  immediate
+  0f 8d                 05 00                     # skip 1 instruction
+  05                                  00 00 00 01
+  05                                  00 00 00 02
++run: inst: 0x00000001
++run: inst: 0x00000005
++run: inst: 0x0000000a
+-run: jump 5
+
+//:: jump if lesser
+
+:(scenario jl_rel16_success)
+% ZF = false;
+% SF = true;
+% OF = false;
+# op      ModRM   SIB   displacement  immediate
+  0f 8c                 05 00                     # skip 1 instruction
+  05                                  00 00 00 01
+  05                                  00 00 00 02
++run: inst: 0x00000001
++run: jump 5
++run: inst: 0x0000000a
+-run: inst: 0x00000005
+
+:(before "End Two-Byte Opcodes Starting With 0f")
+case 0x8c: {  // jump rel16 if SF and !ZF
+  int8_t offset = imm16();
+  if (SF != OF) {
+    trace(2, "run") << "jump " << NUM(offset) << end();
+    EIP += offset;
+  }
+  break;
+}
+
+:(scenario jl_rel16_fail)
+% ZF = false;
+% SF = false;
+% OF = false;
+# op      ModRM   SIB   displacement  immediate
+  0f 8c                 05 00                     # skip 1 instruction
+  05                                  00 00 00 01
+  05                                  00 00 00 02
++run: inst: 0x00000001
++run: inst: 0x00000005
++run: inst: 0x0000000a
+-run: jump 5
+
+//:: jump if lesser or equal
+
+:(scenario jle_rel16_equal)
+% ZF = true;
+% SF = false;
+% OF = false;
+# op      ModRM   SIB   displacement  immediate
+  0f 8e                 05 00                     # skip 1 instruction
+  05                                  00 00 00 01
+  05                                  00 00 00 02
++run: inst: 0x00000001
++run: jump 5
++run: inst: 0x0000000a
+-run: inst: 0x00000005
+
+:(scenario jle_rel16_lesser)
+% ZF = false;
+% SF = true;
+% OF = false;
+# op      ModRM   SIB   displacement  immediate
+  0f 8e                 05 00                     # skip 1 instruction
+  05                                  00 00 00 01
+  05                                  00 00 00 02
++run: inst: 0x00000001
++run: jump 5
++run: inst: 0x0000000a
+-run: inst: 0x00000005
+
+:(before "End Two-Byte Opcodes Starting With 0f")
+case 0x8e: {  // jump rel16 if SF or ZF
+  int8_t offset = imm16();
+  if (ZF || SF != OF) {
+    trace(2, "run") << "jump " << NUM(offset) << end();
+    EIP += offset;
+  }
+  break;
+}
+
+:(scenario jle_rel16_greater)
+% ZF = false;
+% SF = false;
+% OF = false;
+# op      ModRM   SIB   displacement  immediate
+  0f 8e                 05 00                     # skip 1 instruction
+  05                                  00 00 00 01
+  05                                  00 00 00 02
++run: inst: 0x00000001
++run: inst: 0x00000005
++run: inst: 0x0000000a
+-run: jump 5