fox32rom: Add copy_string

fox32rom.def

@@ -58,8 +58,9 @@ write_sector:                             jmp [0xF0045004]
 ; memory copy/compare jump table
 copy_memory_bytes:                        jmp [0xF0046000]
 copy_memory_words:                        jmp [0xF0046004]
-compare_memory_bytes:                     jmp [0xF0046008]
-compare_memory_words:                     jmp [0xF004600C]
+copy_string:                              jmp [0xF0046008]
+compare_memory_bytes:                     jmp [0xF004600C]
+compare_memory_words:                     jmp [0xF0046010]
 
 ; event types
 const EVENT_TYPE_MOUSE_CLICK:    0x00000000

main.asm

@@ -155,6 +155,7 @@ get_rom_version:
     #include "overlay.asm"
     #include "panic.asm"
     #include "ryfs.asm"
+    #include "string.asm"
     #include "vsync.asm"
 
 
@@ -227,6 +228,7 @@ get_rom_version:
     org.pad 0xF0046000
     data.32 copy_memory_bytes
     data.32 copy_memory_words
+    data.32 copy_string
     data.32 compare_memory_bytes
     data.32 compare_memory_words
 

string.asm

@@ -0,0 +1,24 @@
+; copy string from source pointer to destination pointer
+; if the source and destination overlap, the behavior is undefined
+; inputs:
+; r0: pointer to source
+; r1: pointer to destinaton
+; outputs:
+; none
+copy_string:
+    push r0
+    push r1
+    push r2
+
+copy_string_loop:
+    mov.8 r2, [r0]
+    mov.8 [r1], r2
+    inc r0
+    inc r1
+    cmp.8 r2, 0
+    ifnz jmp copy_string_loop
+
+    pop r2
+    pop r1
+    pop r0
+    ret