.

Make the first instruction described something that doesn't touch flags,
so we don't introduce too much complexity all at once.

1 files changed, 24 insertions, 2 deletions

diff --git a/subx/015immediate_addressing.cc b/subx/015immediate_addressing.cc
index 8a0ba020..f4762c2b 100644
--- a/subx/015immediate_addressing.cc
+++ b/subx/015immediate_addressing.cc
@@ -1,6 +1,29 @@
 //: instructions that (immediately) contain an argument to act with
 
 :(before "End Initialize Op Names")
+put_new(Name, "05", "add imm32 to EAX (add)");
+
+:(before "End Single-Byte Opcodes")
+case 0x05: {  // add imm32 to EAX
+  int32_t signed_arg2 = next32();
+  trace(Callstack_depth+1, "run") << "add imm32 0x" << HEXWORD << signed_arg2 << " to reg EAX" << end();
+  int64_t signed_full_result = Reg[EAX].i + signed_arg2;
+  Reg[EAX].i += signed_arg2;
+  trace(Callstack_depth+1, "run") << "storing 0x" << HEXWORD << Reg[EAX].i << end();
+  SF = (Reg[EAX].i < 0);
+  ZF = (Reg[EAX].i == 0);
+  OF = (Reg[EAX].i != signed_full_result);
+  // set CF
+  uint32_t unsigned_arg1 = static_cast<uint32_t>(Reg[EAX].i);
+  uint32_t unsigned_arg2 = static_cast<uint32_t>(signed_arg2);
+  uint32_t unsigned_result = unsigned_arg1 + unsigned_arg2;
+  uint64_t unsigned_full_result = unsigned_arg1 + unsigned_arg2;
+  CF = (unsigned_result != unsigned_full_result);
+  trace(Callstack_depth+1, "run") << "SF=" << SF << "; ZF=" << ZF << "; CF=" << CF << "; OF=" << OF << end();
+  break;
+}
+
+:(before "End Initialize Op Names")
 put_new(Name, "81", "combine rm32 with imm32 based on subop (add/sub/and/or/xor/cmp)");
 
 :(code)
@@ -832,7 +855,7 @@ void test_compare_imm32_with_mem_at_r32_equal() {
 //:: copy (mov)
 
 :(before "End Initialize Op Names")
-put_new(Name, "b8", "copy imm32 to EAX (mov)");
+// b8 defined earlier to copy imm32 to EAX
 put_new(Name, "b9", "copy imm32 to ECX (mov)");
 put_new(Name, "ba", "copy imm32 to EDX (mov)");
 put_new(Name, "bb", "copy imm32 to EBX (mov)");
@@ -854,7 +877,6 @@ void test_copy_imm32_to_r32() {
 }
 
 :(before "End Single-Byte Opcodes")
-case 0xb8:
 case 0xb9:
 case 0xba:
 case 0xbb: