Cross-platformizing MMIO stuff.

MSVC build likely needs some fixes.

src/xenia/cpu/mmio_handler_win.cc

@@ -0,0 +1,91 @@
+/**
+ ******************************************************************************
+ * Xenia : Xbox 360 Emulator Research Project                                 *
+ ******************************************************************************
+ * Copyright 2014 Ben Vanik. All rights reserved.                             *
+ * Released under the BSD license - see LICENSE in the root for more details. *
+ ******************************************************************************
+ */
+
+#include <xenia/cpu/mmio_handler.h>
+
+namespace xe {
+namespace cpu {
+
+LONG CALLBACK MMIOExceptionHandler(PEXCEPTION_POINTERS ex_info);
+
+class WinMMIOHandler : public MMIOHandler {
+ public:
+  WinMMIOHandler() = default;
+
+ protected:
+  bool Initialize() override;
+  void Uninstall() override;
+
+  uint64_t GetThreadStateRip(void* thread_state_ptr) override;
+  void SetThreadStateRip(void* thread_state_ptr, uint64_t rip) override;
+  uint64_t* GetThreadStateRegPtr(void* thread_state_ptr,
+                                 int32_t be_reg_index) override;
+};
+
+std::unique_ptr<MMIOHandler> CreateMMIOHandler() {
+  return std::make_unique<WinMMIOHandler>();
+}
+
+bool WinMMIOHandler::Initialize() {
+  // If there is a debugger attached the normal exception handler will not
+  // fire and we must instead add the continue handler.
+  AddVectoredExceptionHandler(1, MMIOExceptionHandler);
+  if (IsDebuggerPresent()) {
+    // TODO(benvanik): is this really required?
+    // AddVectoredContinueHandler(1, MMIOExceptionHandler);
+  }
+  return true;
+}
+
+void WinMMIOHandler::Uninstall() {
+  // Remove exception handlers.
+  RemoveVectoredExceptionHandler(MMIOExceptionHandler);
+  RemoveVectoredContinueHandler(MMIOExceptionHandler);
+}
+
+// Handles potential accesses to mmio. We look for access violations to
+// addresses in our range and call into the registered handlers, if any.
+// If there are none, we continue.
+LONG CALLBACK MMIOExceptionHandler(PEXCEPTION_POINTERS ex_info) {
+  // http://msdn.microsoft.com/en-us/library/ms679331(v=vs.85).aspx
+  // http://msdn.microsoft.com/en-us/library/aa363082(v=vs.85).aspx
+  auto code = ex_info->ExceptionRecord->ExceptionCode;
+  if (code == STATUS_ACCESS_VIOLATION) {
+    auto fault_address = ex_info->ExceptionRecord->ExceptionInformation[1];
+    if (HandleAccessFault(ex_info->ContextRecord, fault_address)) {
+      // Handled successfully - RIP has been updated and we can continue.
+      return EXCEPTION_CONTINUE_EXECUTION;
+    } else {
+      // Failed to handle; continue search for a handler (and die if no other
+      // handler is found).
+      return EXCEPTION_CONTINUE_SEARCH;
+    }
+  }
+  return EXCEPTION_CONTINUE_SEARCH;
+}
+
+uint64_t WinMMIOHandler::GetThreadStateRip(void* thread_state_ptr) {
+  auto context = reinterpret_cast<LPCONTEXT>(thread_state_ptr);
+  return context->Rip;
+}
+
+void WinMMIOHandler::SetThreadStateRip(void* thread_state_ptr, uint64_t rip) {
+  auto context = reinterpret_cast<LPCONTEXT>(thread_state_ptr);
+  context->Rip = rip;
+}
+
+uint64_t* WinMMIOHandler::GetThreadStateRegPtr(void* thread_state_ptr,
+                                               int32_t be_reg_index) {
+  auto context = reinterpret_cast<LPCONTEXT>(thread_state_ptr);
+  // BeaEngine register indices line up with the CONTEXT structure format.
+  return &context->Rax + be_reg_index;
+}
+
+}  // namespace cpu
+}  // namespace xe