From e21aae6d08b05e8d4fceb0d32d96ea85c1277861 Mon Sep 17 00:00:00 2001
From: ry755 <ryanst755@gmail.com>
Date: Fri, 11 Feb 2022 19:39:33 -0800
Subject: [PATCH] fox32rom: Add some convenience routines for copying memory

---
 main.asm   |  1 +
 memory.asm | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 52 insertions(+)
 create mode 100644 memory.asm

diff --git a/main.asm b/main.asm
index 93fa623..706c425 100644
--- a/main.asm
+++ b/main.asm
@@ -165,6 +165,7 @@ mount_boot_disk:
     #include "boot.asm"
     #include "background.asm"
     #include "overlay.asm"
+    #include "memory.asm"
     #include "menu.asm"
     #include "submenu.asm"
     #include "event.asm"
diff --git a/memory.asm b/memory.asm
new file mode 100644
index 0000000..a94efa7
--- /dev/null
+++ b/memory.asm
@@ -0,0 +1,51 @@
+; memory copy routines
+
+; copy specified number of bytes 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
+; r2: number of bytes to copy
+; outputs:
+; none
+copy_memory_bytes:
+    push r0
+    push r1
+    push r31
+
+    mov r31, r2
+copy_memory_bytes_loop:
+    mov.8 [r1], [r0]
+    inc r0
+    inc r1
+    loop copy_memory_bytes_loop
+
+    pop r31
+    pop r1
+    pop r0
+    ret
+
+; copy specified number of words 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
+; r2: number of words to copy
+; outputs:
+; none
+copy_memory_words:
+    push r0
+    push r1
+    push r31
+
+    mov r31, r2
+copy_memory_words_loop:
+    mov [r1], [r0]
+    add r0, 4
+    add r1, 4
+    loop copy_memory_words_loop
+
+    pop r31
+    pop r1
+    pop r0
+    ret
\ No newline at end of file