4071

subx: conditional jump instructions

Lots of boilerplate here. This commit really strains my 'copyista'
ethic. But I think it's still clearer to see each instruction
implemented independently than to try to create a macro or something
like that.

1 files changed, 252 insertions, 0 deletions

diff --git a/subx/014jump_relative.cc b/subx/014jump_relative.cc
new file mode 100644
index 00000000..c9cdcd1b
--- /dev/null
+++ b/subx/014jump_relative.cc
@@ -0,0 +1,252 @@
+//: jump to 8-bit offset
+
+//:: jump
+
+:(scenario jump_rel8)
+# op  ModRM   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  ModRM   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  ModRM   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  ModRM   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  ModRM   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  ModRM   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  ModRM   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  ModRM   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  ModRM   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  ModRM   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  ModRM   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  ModRM   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  ModRM   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  ModRM   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