Implemented optimize()

3 files changed, 48 insertions, 5 deletions

diff --git a/asm/chunk.h b/asm/chunk.h
index 43cf54e..fb3f303 100644
--- a/asm/chunk.h
+++ b/asm/chunk.h
@@ -25,12 +25,12 @@ struct AddressFeature
  bool relativeAddressing{true};
 
  std::vector<uint8_t> machine_code;
- size_t addr_size;
- size_t addr_offs; ///< offset inside code
+ size_t addr_size{0};
+ size_t addr_offs{0}; ///< offset inside code
 
  std::vector<uint8_t> alternative_code;
- size_t alternative_size;
- size_t alternative_offs; ///< offset inside code
+ size_t alternative_size{0};
+ size_t alternative_offs{0}; ///< offset inside code
 };
 
 class Label: public Chunk
diff --git a/asm/segment.cpp b/asm/segment.cpp
index a4544f2..d3050bb 100644
--- a/asm/segment.cpp
+++ b/asm/segment.cpp
@@ -79,6 +79,35 @@ void Segment::insertAddresses()
 
 void Segment::optimize()
 {
- // TODO
+ bool changed{false};
+
+ for (size_t i = 0; i < this->size(); i++) {
+  try {
+   AddressFeature& af { dynamic_cast<AddressFeature&>(*((*this)[i]))};
+
+   if (af.relativeAddressing == false)
+    throw std::runtime_error("Error: Absolute Addressing not supported.");
+
+   if (!af.alternative_code.empty()) {
+    int64_t target_address = getAddressOfLabel(af.label); // throws if label not found
+    int64_t start_address = getAddressOfIndex(i); // throws if out of range
+    int64_t diff = target_address - start_address;
+    if (af.addr_size == 4 && af.alternative_size == 1 && diff >= -128 && diff <= 127) {
+     af.machine_code = af.alternative_code;
+     af.addr_size = af.alternative_size;
+     af.addr_offs = af.alternative_offs;
+     af.alternative_code.clear();
+     af.alternative_size = 0;
+     af.alternative_offs = 0;
+     changed = true;
+    }
+   }
+  } catch (const std::bad_cast& ex) {
+   // ignore, expected for non-addressing chunks
+  }
+ }
+
+ if (changed)
+  insertAddresses(); // renumber
 }
 
diff --git a/test-asm.cpp b/test-asm.cpp
index efdeab9..1d4634e 100644
--- a/test-asm.cpp
+++ b/test-asm.cpp
@@ -115,4 +115,18 @@ TEST_F(AsmTest, Intel64_multiple) {
    0xE9, 0xFF, 0xFF, 0xFF, 0xFF, // jmp data1
    0x01, 0x02, 0x03 // data
   }));
+ 
+ segment.optimize();
+ 
+ ASSERT_EQ(segment.size(), 7);
+ ASSERT_EQ(segment.getCode(), std::vector<uint8_t>(
+  {
+   0x90, // nop
+   0xCD, 0x05, // int 5
+   0xC3, // ret
+   // data1:
+   0xC3, // ret
+   0xEB, 0xFF, // jmp data1
+   0x01, 0x02, 0x03 // data
+  }));
 }