Add new ROM function: poweroff

fox32rom.def

@@ -13,6 +13,7 @@ scancode_to_ascii:                        jmp [0xF0040020]
 shift_pressed:                            jmp [0xF0040024]
 shift_released:                           jmp [0xF0040028]
 caps_pressed:                             jmp [0xF004002C]
+poweroff:                                 jmp [0xF0040030]
 
 ; generic drawing jump table
 draw_str_generic:                         jmp [0xF0041000]

main.asm

@@ -169,6 +169,13 @@ get_rom_version:
     mov r2, FOX32ROM_VERSION_PATCH
     ret
 
+poweroff:
+    mov r0, 0x80010000
+    mov r1, 0
+    out r0, r1
+poweroff_wait:
+    jmp poweroff_wait
+
     ; code
     #include "audio.asm"
     #include "background.asm"
@@ -216,6 +223,7 @@ get_rom_version:
     data.32 shift_pressed
     data.32 shift_released
     data.32 caps_pressed
+    data.32 poweroff
 
     ; generic drawing jump table
     org.pad 0xF0041000