From 707e317bb860328fac0f349a5fa199c771ee9329 Mon Sep 17 00:00:00 2001
From: Colin Leroy-Mira <colin@colino.net>
Date: Sat, 25 Oct 2025 11:23:01 +0200
Subject: [PATCH] Apple2: spare 10 bytes on I/O

---
 libsrc/apple2/rwcommon.s | 22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/libsrc/apple2/rwcommon.s b/libsrc/apple2/rwcommon.s
index 769247e63..fbe3d70f5 100644
--- a/libsrc/apple2/rwcommon.s
+++ b/libsrc/apple2/rwcommon.s
@@ -27,17 +27,19 @@ rwcommon:
         ; Set fd
         sta     mliparam + MLI::RW::REF_NUM
 
-        ; Set buf
-        lda     ptr1
-        ldx     ptr1+1
-        sta     mliparam + MLI::RW::DATA_BUFFER
-        stx     mliparam + MLI::RW::DATA_BUFFER+1
+        ; Set buf and count
+        ; buf (ptr1) goes to mliparam + MLI::RW::DATA_BUFFER,
+        ; count (ptr2) goes to mliparam + MLI::RW::REQUEST_COUNT
+        ; Make sure both are at expected offset so we can copy them
+        ; in a small loop.
+        .assert ptr2 = ptr1 + 2, error
+        .assert MLI::RW::REQUEST_COUNT = MLI::RW::DATA_BUFFER + 2, error
 
-        ; Set count
-        lda     ptr2
-        ldx     ptr2+1
-        sta     mliparam + MLI::RW::REQUEST_COUNT
-        stx     mliparam + MLI::RW::REQUEST_COUNT+1
+        ldx     #$03
+:       lda     ptr1,x
+        sta     mliparam + MLI::RW::DATA_BUFFER,x
+        dex
+        bpl     :-
 
         ; Call read or write
         tya