From 53ff411302fc5a909dc40489998a02f1aebe28f6 Mon Sep 17 00:00:00 2001
From: Forest Belton <65484+forestbelton@users.noreply.github.com>
Date: Fri, 9 Jul 2021 05:22:32 -0400
Subject: [PATCH] Annotate memcpy with performance information

---
 src/util.s | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/src/util.s b/src/util.s
index ee4e838..af0f0c9 100644
--- a/src/util.s
+++ b/src/util.s
@@ -8,18 +8,18 @@ wait_for_vblank::
     jr nz, wait_for_vblank
     ret
 
-; Copy data between two regions
+; Copy data between two regions (takes 40*N+12 cycles)
 ; @param bc Pointer to the destination region
 ; @param hl Pointer to the source region
 ; @param d  Size (in bytes) to copy. Must be >0
 ; @destroy a, b, c, d, h, l
 memcpy::
-    ld a, [hli]
-    ld [bc], a
-    inc bc
-    dec d
-    jr nz, memcpy
-    ret
+    ld a, [hli] ; 8
+    ld [bc], a ; 8
+    inc bc ; 8
+    dec d ; 4
+    jr nz, memcpy ; 12/8
+    ret ; 16
 
 ; Fill a memory region with a value
 ; @param hl Pointer to the destination region