[CPU] Add syscall handler.

src/xenia/cpu/ppc/ppc_emit_control.cc

@@ -426,6 +426,10 @@ int InstrEmit_sc(PPCHIRBuilder& f, const InstrData& i) {
   // Game code should only ever use LEV=0.
   // LEV=2 is to signify 'call import' from Xenia.
   // TODO(gibbed): syscalls!
+  if (i.SC.LEV == 0) {
+    f.CallExtern(f.builtins()->syscall_handler);
+    return 0;
+  }
   if (i.SC.LEV == 2) {
     f.CallExtern(f.function());
     return 0;

src/xenia/cpu/ppc/ppc_frontend.cc

@@ -10,6 +10,7 @@
 #include "xenia/cpu/ppc/ppc_frontend.h"
 
 #include "xenia/base/atomic.h"
+#include "xenia/base/logging.h"
 #include "xenia/cpu/ppc/ppc_context.h"
 #include "xenia/cpu/ppc/ppc_emit.h"
 #include "xenia/cpu/ppc/ppc_opcode_info.h"
@@ -78,6 +79,16 @@ void LeaveGlobalLock(PPCContext* ppc_context, void* arg0, void* arg1) {
   global_mutex->unlock();
 }
 
+void SyscallHandler(PPCContext* ppc_context, void* arg0, void* arg1) {
+  uint64_t syscall_number = ppc_context->r[0];
+  switch (syscall_number) {
+    default:
+      assert_unhandled_case(syscall_number);
+      XELOGE("Unhandled syscall {}!", syscall_number);
+      break;
+  }
+}
+
 bool PPCFrontend::Initialize() {
   void* arg0 = reinterpret_cast<void*>(&xe::global_critical_region::mutex());
   void* arg1 = reinterpret_cast<void*>(&builtins_.global_lock_count);
@@ -87,6 +98,8 @@ bool PPCFrontend::Initialize() {
       processor_->DefineBuiltin("EnterGlobalLock", EnterGlobalLock, arg0, arg1);
   builtins_.leave_global_lock =
       processor_->DefineBuiltin("LeaveGlobalLock", LeaveGlobalLock, arg0, arg1);
+  builtins_.syscall_handler = processor_->DefineBuiltin(
+      "SyscallHandler", SyscallHandler, nullptr, nullptr);
   return true;
 }
 

src/xenia/cpu/ppc/ppc_frontend.h

@@ -33,6 +33,7 @@ struct PPCBuiltins {
   Function* check_global_lock;
   Function* enter_global_lock;
   Function* leave_global_lock;
+  Function* syscall_handler;
 };
 
 class PPCFrontend {