From 7e4457f66fce8fd36a31d3607d9f28e56a0d93b5 Mon Sep 17 00:00:00 2001
From: Tony Di Nucci <tony.dinucci@gmail.com>
Date: Sun, 28 Apr 2019 13:16:57 +0100
Subject: [PATCH] Correct page addressing and NOP handler

---
 src/machine/memory.cpp                        |  6 ++++-
 .../system-opcode-handler-container.cpp       |  7 ++++++
 .../handler/system-opcode-handler-container.h | 21 ++++++++++++++++
 src/opcode/opcode-handler-directory.cpp       |  2 ++
 test/system-opcode-handler-test.cpp           | 25 +++++++++++++++++++
 5 files changed, 60 insertions(+), 1 deletion(-)
 create mode 100644 src/opcode/handler/system-opcode-handler-container.cpp
 create mode 100644 src/opcode/handler/system-opcode-handler-container.h
 create mode 100644 test/system-opcode-handler-test.cpp

diff --git a/src/machine/memory.cpp b/src/machine/memory.cpp
index 1047acd..b7f0b93 100644
--- a/src/machine/memory.cpp
+++ b/src/machine/memory.cpp
@@ -2,7 +2,11 @@
 
 namespace emu_6502 {
     inline uint16_t Memory::get_page_offset(uint8_t page) {
-        return page * 0xFF;
+        uint16_t address = page * 0xFF;
+        if (page > 0)
+            address += 1;
+
+        return address;
     }
 
     Memory::Memory() {
diff --git a/src/opcode/handler/system-opcode-handler-container.cpp b/src/opcode/handler/system-opcode-handler-container.cpp
new file mode 100644
index 0000000..d977a85
--- /dev/null
+++ b/src/opcode/handler/system-opcode-handler-container.cpp
@@ -0,0 +1,7 @@
+#include "system-opcode-handler-container.h"
+
+namespace emu_6502 {
+    SystemOpcodeHandlerContainer::SystemOpcodeHandlerContainer() {
+        handlers.insert({Op::NOP, [](Machine&) {}});
+    }
+}
\ No newline at end of file
diff --git a/src/opcode/handler/system-opcode-handler-container.h b/src/opcode/handler/system-opcode-handler-container.h
new file mode 100644
index 0000000..bbaa19f
--- /dev/null
+++ b/src/opcode/handler/system-opcode-handler-container.h
@@ -0,0 +1,21 @@
+#ifndef INC_6502_EMULATOR_SYSTEM_OPCODE_HANDLER_CONTAINER_H
+#define INC_6502_EMULATOR_SYSTEM_OPCODE_HANDLER_CONTAINER_H
+
+#include "opcode-handler-container.h"
+
+namespace emu_6502 {
+    class SystemOpcodeHandlerContainer : public OpcodeHandlerContainer {
+    private:
+        enum Op {
+            NOP = 0xEA
+        };
+
+    public:
+        SystemOpcodeHandlerContainer();
+        SystemOpcodeHandlerContainer(const SystemOpcodeHandlerContainer& other) = delete;
+        SystemOpcodeHandlerContainer operator=(const SystemOpcodeHandlerContainer& other) = delete;
+    };
+}
+
+
+#endif //INC_6502_EMULATOR_SYSTEM_OPCODE_HANDLER_CONTAINER_H
diff --git a/src/opcode/opcode-handler-directory.cpp b/src/opcode/opcode-handler-directory.cpp
index df14a6e..f54442b 100644
--- a/src/opcode/opcode-handler-directory.cpp
+++ b/src/opcode/opcode-handler-directory.cpp
@@ -9,6 +9,7 @@
 #include "handler/stack-opcode-handler-container.h"
 #include "handler/branch-opcode-handler-container.h"
 #include "handler/jump-opcode-handler-container.h"
+#include "handler/system-opcode-handler-container.h"
 #include "../utils.h"
 
 namespace emu_6502 {
@@ -24,6 +25,7 @@ namespace emu_6502 {
         handler_containers.push_back(make_unique<StackOpcodeHandlerContainer>());
         handler_containers.push_back(make_unique<BranchOpcodeHandlerContainer>());
         handler_containers.push_back(make_unique<JumpOpcodeHandlerContainer>());
+        handler_containers.push_back(make_unique<SystemOpcodeHandlerContainer>());
 
         init_handlers();
     }
diff --git a/test/system-opcode-handler-test.cpp b/test/system-opcode-handler-test.cpp
new file mode 100644
index 0000000..b5502cd
--- /dev/null
+++ b/test/system-opcode-handler-test.cpp
@@ -0,0 +1,25 @@
+#include "gtest/gtest.h"
+#include "test-utils.h"
+
+using namespace std;
+using namespace emu_6502;
+
+const uint8_t NOP = 0xEA;
+const uint8_t LDA_IMM = 0xA9;
+
+TEST(SystemOpcodeHandlerContainer, NOP) {
+    auto machine = create_machine({NOP, NOP, NOP, NOP});
+    machine->execute();
+
+    ASSERT_TRUE(are_flags_set(machine->get_cpu().get_ps(), RegisterFlagSet{}));
+    ASSERT_EQ(0x604, machine->get_cpu().get_pc().get_value());
+}
+
+TEST(SystemOpcodeHandlerContainer, NOP2) {
+    auto machine = create_machine({NOP, NOP, NOP, LDA_IMM, 0x35, NOP});
+    machine->execute();
+
+    ASSERT_EQ(0x35, machine->get_cpu().get_a().get_value());
+    ASSERT_TRUE(are_flags_set(machine->get_cpu().get_ps(), RegisterFlagSet{}));
+    ASSERT_EQ(0x606, machine->get_cpu().get_pc().get_value());
+}