From: Alan Cox <alan@linux.intel.com>
Date: Mon, 5 Oct 2015 12:43:30 +0000 (+0100)
Subject: nc100: draw in the right location
X-Git-Url: https://git.ndcode.org/public/gitweb.cgi?a=commitdiff_plain;h=3468c2d5631884aaabffe9ba36390de60d120c0d;p=FUZIX.git

nc100: draw in the right location
---

diff --git a/Kernel/platform-nc100/nc100.s b/Kernel/platform-nc100/nc100.s
index b3c19660..82b31d8d 100644
--- a/Kernel/platform-nc100/nc100.s
+++ b/Kernel/platform-nc100/nc100.s
@@ -560,6 +560,27 @@ _cursor_off:
 	    jr cursor_do
 
 
+;
+;	Turn a co-ordinate pair in DE into an address in DE
+;	and map the video. Unlike the font version we work in bytes across
+;	(for NC100, NC200 needs doing)
+;
+addr_de_pix:
+	    ld a, #0x43
+	    out (0x11), a
+
+	    ld b, d	; save X
+	    ld a, e	; turn Y into a pixel row
+	    sla d	; X is in 0-63, rotate it left twice
+	    sla d
+	    srl a	; multiple by 64 A into DE
+	    rr  d	; roll two bits into D pushing the X bits
+	    srl a	; back where they came from
+	    rr  d
+	    add #VIDEO_BASEH	; screen start (0x7000 or 0x6000 for NC200)
+	    ld  e, d
+	    ld  d, a
+	    ret
 ;
 ;	For NC100 (NC200 needs doing)
 ;
@@ -578,7 +599,7 @@ _video_cmd:
 	    ld d,(hl)
 	    inc hl
 	    inc hl
-	    call addr_de	; turn DE into screen address (HL is kept)
+	    call addr_de_pix	; turn DE into screen address (HL is kept)
 nextline:
 	    push de
 nextop: