Clear all arm9 cpu registers before jumping to the arm9 entry point. Fixes Cake Ninja DSiWare titles.

arm9/source/jumpToArm9EntryPoint.h

@@ -0,0 +1,5 @@
+#pragma once
+
+/// @brief Clears all cpu registers and jumps to the specified \p arm9EntryPoint.
+/// @param arm9EntryPoint The arm9 entry point to jump to.
+extern "C" void jumpToArm9EntryPoint(void* arm9EntryPoint);

arm9/source/jumpToArm9EntryPoint.s

@@ -0,0 +1,29 @@
+.section ".itcm", "ax"
+.arm
+
+// r0: arm9EntryPoint
+.global jumpToArm9EntryPoint
+.type jumpToArm9EntryPoint, %function
+jumpToArm9EntryPoint:
+    str r0, entry_point
+    // Clear all registers
+    mov r0, #0
+    mov r1, #0
+    mov r2, #0
+    mov r3, #0
+    mov r4, #0
+    mov r5, #0
+    mov r6, #0
+    mov r7, #0
+    mov r8, #0
+    mov r9, #0
+    mov r10, #0
+    mov r11, #0
+    mov r12, #0
+    mov sp, #0
+    mov lr, #0
+    // Jump to the arm9 entry point
+    ldr pc, entry_point
+
+entry_point:
+    .word 0

arm9/source/main.cpp

@@ -26,6 +26,7 @@
 #include "arm9Clock.h"
 #include "errorDisplay/ErrorDisplay.h"
 #include "LoaderInfo.h"
+#include "jumpToArm9EntryPoint.h"
 
 typedef void (*entrypoint_t)(void);
 
@@ -109,7 +110,7 @@ static void bootArm9()
     while (gfx_getVCount() == 191);
     REG_IF = ~0u; // final clear of REG_IF bits
     auto romHeader = (const nds_header_ntr_t*)TWL_SHARED_MEMORY->ntrSharedMem.romHeader;
-    ((entrypoint_t)romHeader->arm9EntryAddress)();
+    jumpToArm9EntryPoint((void*)romHeader->arm9EntryAddress);
 }
 
 static void handleInitializeSdCardCommand()