First program: Can add 2 integers and return result via exit code

1 files changed, 33 insertions, 13 deletions

diff --git a/asm/intel64/codes.cpp b/asm/intel64/codes.cpp
index 66a08dd..5d93a57 100644
--- a/asm/intel64/codes.cpp
+++ b/asm/intel64/codes.cpp
@@ -29,14 +29,14 @@ namespace {
   {"dl", 2}, {"dh", 6},
 
   {"ax", 0}, {"sp", 4},
-  {"bx", 3}, {"bp", 7},
-  {"cx", 1}, {"si", 5},
-  {"dx", 2}, {"di", 6},
+  {"bx", 3}, {"bp", 5},
+  {"cx", 1}, {"si", 6},
+  {"dx", 2}, {"di", 7},
 
   {"eax", 0}, {"esp", 4},
-  {"ebx", 3}, {"ebp", 7},
-  {"ecx", 1}, {"esi", 5},
-  {"edx", 2}, {"edi", 6},
+  {"ebx", 3}, {"ebp", 5},
+  {"ecx", 1}, {"esi", 6},
+  {"edx", 2}, {"edi", 7},
  };
 
 }
@@ -44,15 +44,26 @@ namespace {
 // Manual, page 530
 // Reg + Reg/Memory
 uint8_t ModRM(const std::string& reg, const std::string& rm) {
- // TODO: extend
  uint8_t result{0b11000000};
 
- auto index1{ IndexOfRegister.find(reg) };
- if (index1 == IndexOfRegister.end())
-  throw std::runtime_error("Unknown register for arg1: "s + reg);
-
- result |= (index1->second << 3);
-
+ size_t val_reg{};
+ // reg
+ if (reg.size() > 0 && reg[0] == '/') { // "/digit"
+  try {
+   val_reg = stoull(reg.substr(1));
+  } catch (const std::exception& ex) {
+   throw std::runtime_error("ModRM: Bad digit in arg1: "s + reg);
+  }
+ } else { // reg
+  auto index1{ IndexOfRegister.find(reg) };
+  if (index1 == IndexOfRegister.end())
+   throw std::runtime_error("ModRM: Unknown register for arg1: "s + reg);
+  val_reg = index1->second;
+ }
+
+ result |= (val_reg << 3);
+
+ // rm
  auto index2{ IndexOfRegister.find(rm) };
  if (index2 == IndexOfRegister.end())
   throw std::runtime_error("Unknown register for arg2: "s + rm);
@@ -62,6 +73,15 @@ uint8_t ModRM(const std::string& reg, const std::string& rm) {
  return result;
 }
 
+uint8_t RegNo(const std::string& reg)
+{
+ auto index{ IndexOfRegister.find(reg) };
+ if (index == IndexOfRegister.end())
+  throw std::runtime_error("Reg: Unknown register for arg: "s + reg);
+
+ return index->second;
+}
+
 #if 0
  prefixes{
   "lock", 0xf0,