From fc0dba6c9ca10bd40bd1210530b88fa8184e4e44 Mon Sep 17 00:00:00 2001
From: "Matthias@Dell" <matthiasqui@protonmail.com>
Date: Wed, 27 Dec 2023 16:55:40 +0100
Subject: [PATCH] add memcopy16

---
 programs/memcopy.s65 | 51 ++++++++++++++++++++++++++++++++++++++------
 1 file changed, 44 insertions(+), 7 deletions(-)

diff --git a/programs/memcopy.s65 b/programs/memcopy.s65
index 53c3fc6..b1b877c 100644
--- a/programs/memcopy.s65
+++ b/programs/memcopy.s65
@@ -3,15 +3,16 @@ INCLUDE_MEMCOPY = 1
 
 .include "system.h65"
 
-.export memcopy
+.export memcopy,memcopy16
 
 .code
-;********************************************************************************
-; @function Copy a block of memory to a different address
-; @param ARG0-1: Source address
-; @param ARG2-3: Target address
-; @param y: Number of bytes to copy
-;********************************************************************************
+;;********************************************************************************
+;; @function Copy a block of memory to a different address
+;; @param ARG0-1: Source address
+;; @param ARG2-3: Target address
+;; @param Y: Number of bytes to copy
+;; @modifies: A,Y
+;;********************************************************************************
 .proc memcopy
     cpy #0
     beq @rts
@@ -24,5 +25,41 @@ INCLUDE_MEMCOPY = 1
 @rts:
     rts
 .endproc
+
+;;********************************************************************************
+;; @function Copy a block of memory to a different address
+;; @param ARG0-1: Source address
+;; @param ARG2-3: Target address
+;; @param ARG5-6: Number of bytes to copy (LE)
+;; @modifies: A,Y
+;;********************************************************************************
+.proc memcopy16
+    lda ARG6
+    beq @last_page  ; no full page
+    ldy #$ff
+    bra @copy_byte
+@next_page:   ; y is 0
+    lda ARG6
+    beq @rts  ; done
+    inc ARG1
+    inc ARG3
+    dec ARG6
+    beq @last_page
+    ldy #$ff
+@copy_byte:
+    lda (ARG0),y
+    sta (ARG2),y
+@dec_y:
+    dey
+    beq @next_page
+    bra @copy_byte
+@last_page:
+    ldy ARG5
+    dey
+    bra @copy_byte
+@rts:
+    rts
+.endproc
+
 .endif  ; guard