From 7813a2e4a8bc4b3453911e811f3e196936ea2a3b Mon Sep 17 00:00:00 2001
From: Leo C <erbl259-lmu@yahoo.de>
Date: Fri, 11 Dec 2015 15:09:23 +0100
Subject: [PATCH] Bugfix in outmdm (output buffer flush)

---
 cpxac.asm | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/cpxac.asm b/cpxac.asm
index f8763c8..0b15d21 100644
--- a/cpxac.asm
+++ b/cpxac.asm
@@ -707,7 +707,7 @@ outcon:
 outmdm:
 	push	hl
 	ld	hl,(outptr)
-	ld	(hl),e			;return buffered char
+	ld	(hl),e			;save char in buffer
 	inc	hl
 	ld	(outptr),hl
 	ld	a,(outcnt)
@@ -750,22 +750,23 @@ omf_2:
 	ld	a,2			;start write transaction
 	out	(VI2C_CTRL),a
 
-	ld	hl,outbuf+2
-	ld	(outptr),hl
+	ld	hl,outbuf+2		;buffer start
 	ld	a,(outcnt)
-	sub	c
+	sub	c			;buffer now empty?
 	ld	(outcnt),a
 	jr	z,omfex
 
-	push	de
-	ld	d,h
+	push	de			;no, shift remaining chars down
+	ld	d,h			;dest = buffer start
 	ld	e,l
 	ld	b,0
-	add	hl,bc
+	add	hl,bc			;src = buffer start + num chars last transmitted
 	ld	c,a
 	ldir
+	ex	de,hl
 	pop	de
 omfex:
+	ld	(outptr),hl
 	pop	bc
 	pop	hl
 	ret
-- 
2.39.2