From 3d545acb5113015c64aa220c28c8c9056dba8b0f Mon Sep 17 00:00:00 2001
From: drochner <drochner@NetBSD.org>
Date: Fri, 24 Jul 1998 16:20:14 +0000
Subject: [PATCH] Overload the generic "copyrows" function by a private one
 which implents a "fast scroll" by setting the display start in memory. (Only
 implemented for "scroll up" because this is more used. "scroll down" is easy
 to add.) This moves the semantics of "copyrows" to something like "moverows";
 the contents of the new visible lines at the bottom is undefined. The
 emulations can live without the original "copy" semantics.

---
 sys/dev/ic/vga.c | 75 ++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 70 insertions(+), 5 deletions(-)

diff --git a/sys/dev/ic/vga.c b/sys/dev/ic/vga.c
index 9e96e0c63a01..5f4d0cba101c 100644
--- a/sys/dev/ic/vga.c
+++ b/sys/dev/ic/vga.c
@@ -1,4 +1,4 @@
-/* $NetBSD: vga.c,v 1.7 1998/06/26 21:05:20 drochner Exp $ */
+/* $NetBSD: vga.c,v 1.8 1998/07/24 16:20:14 drochner Exp $ */
 
 /*
  * Copyright (c) 1995, 1996 Carnegie-Mellon University.
@@ -59,6 +59,8 @@ struct vgascreen {
 	int fontset;
 	/* font data */
 	/* palette */
+
+	int mindispoffset, maxdispoffset;
 };
 
 struct vga_config {
@@ -84,6 +86,7 @@ void vga_init __P((struct vga_config *, bus_space_tag_t,
 		   bus_space_tag_t));
 
 static int	vga_alloc_attr __P((void *, int, int, int, long *));
+void	vga_copyrows __P((void *, int, int, int));
 
 const struct wsdisplay_emulops vga_emulops = {
 	pcdisplay_cursor,
@@ -91,7 +94,7 @@ const struct wsdisplay_emulops vga_emulops = {
 	pcdisplay_putchar,
 	pcdisplay_copycols,
 	pcdisplay_erasecols,
-	pcdisplay_copyrows,
+	vga_copyrows,
 	pcdisplay_eraserows,
 	vga_alloc_attr
 };
@@ -261,13 +264,15 @@ vga_init_screen(vc, scr, type, existing, attrp)
 	int existing;
 	long *attrp;
 {
-	int cpos = 0;
+	int cpos;
 	int res;
 
 	scr->cfg = vc;
 	scr->pcs.hdl = (struct pcdisplay_handle *)&vc->hdl;
 	scr->pcs.type = type;
 	scr->pcs.active = 0;
+	scr->mindispoffset = 0;
+	scr->maxdispoffset = 0x8000 - type->nrows * type->ncols * 2;
 
 	if (existing) {
 		cpos = vga_6845_read(&vc->hdl, cursorh) << 8;
@@ -276,6 +281,17 @@ vga_init_screen(vc, scr, type, existing, attrp)
 		/* make sure we have a valid cursor position */
 		if (cpos < 0 || cpos >= type->nrows * type->ncols)
 			cpos = 0;
+
+		scr->pcs.dispoffset = vga_6845_read(&vc->hdl, startadrh) << 9;
+		scr->pcs.dispoffset |= vga_6845_read(&vc->hdl, startadrl) << 1;
+
+		/* make sure we have a valid memory offset */
+		if (scr->pcs.dispoffset < scr->mindispoffset ||
+		    scr->pcs.dispoffset > scr->maxdispoffset)
+			scr->pcs.dispoffset = scr->mindispoffset;
+	} else {
+		cpos = 0;
+		scr->pcs.dispoffset = scr->mindispoffset;
 	}
 
 	scr->pcs.vc_crow = cpos / type->ncols;
@@ -549,7 +565,7 @@ vga_show_screen(v, cookie)
 
 	for (i = 0; i < oldtype->ncols * oldtype->nrows; i++)
 		oldscr->pcs.mem[i] = bus_space_read_2(vh->vh_memt, vh->vh_memh,
-						      i * 2);
+						oldscr->pcs.dispoffset + i * 2);
 
 	if (oldtype != type)
 		vga_setscreentype(vh, type);
@@ -557,9 +573,16 @@ vga_show_screen(v, cookie)
 		vga_setfontset(vh, scr->fontset);
 	/* swich colours */
 
+	scr->pcs.dispoffset = scr->mindispoffset;
+	if (scr->pcs.dispoffset != oldscr->pcs.dispoffset) {
+		vga_6845_write(vh, startadrh, scr->pcs.dispoffset >> 9);
+		vga_6845_write(vh, startadrl, scr->pcs.dispoffset >> 1);
+	}
+
 	for (i = 0; i < type->ncols * type->nrows; i++)
 		bus_space_write_2(vh->vh_memt, vh->vh_memh,
-				  i * 2, scr->pcs.mem[i]);
+				  scr->pcs.dispoffset + i * 2,
+				  scr->pcs.mem[i]);
 
 	scr->pcs.active = 1;
 	vc->active = scr;
@@ -621,3 +644,45 @@ vga_alloc_attr(id, fg, bg, flags, attrp)
 		*attrp |= FG_BLINK;
 	return (0);
 }
+
+void
+vga_copyrows(id, srcrow, dstrow, nrows)
+	void *id;
+	int srcrow, dstrow, nrows;
+{
+	struct vgascreen *scr = id;
+	bus_space_tag_t memt = scr->pcs.hdl->ph_memt;
+	bus_space_handle_t memh = scr->pcs.hdl->ph_memh;
+	int ncols = scr->pcs.type->ncols;
+	bus_size_t srcoff, dstoff;
+
+	srcoff = srcrow * ncols + 0;
+	dstoff = dstrow * ncols + 0;
+
+	if (scr->pcs.active) {
+		if (dstrow == 0 && (srcrow + nrows == scr->pcs.type->nrows)) {
+			/* scroll up whole screen */
+			if ((scr->pcs.dispoffset + srcrow * ncols * 2)
+			    <= scr->maxdispoffset) {
+				scr->pcs.dispoffset += srcrow * ncols * 2;
+			} else {
+				bus_space_copy_region_2(memt, memh,
+					scr->pcs.dispoffset + srcoff * 2,
+					memh, scr->mindispoffset,
+					nrows * ncols);
+				scr->pcs.dispoffset = scr->mindispoffset;
+			}
+			vga_6845_write(&scr->cfg->hdl, startadrh,
+				       scr->pcs.dispoffset >> 9);
+			vga_6845_write(&scr->cfg->hdl, startadrl,
+				       scr->pcs.dispoffset >> 1);
+		} else {
+			bus_space_copy_region_2(memt, memh,
+					scr->pcs.dispoffset + srcoff * 2,
+					memh, scr->pcs.dispoffset + dstoff * 2,
+					nrows * ncols);
+		}
+	} else
+		bcopy(&scr->pcs.mem[srcoff], &scr->pcs.mem[dstoff],
+		      nrows * ncols * 2);
+}