From 7f5fa5ddf05052d2cd74240bb7e893495dd6cd5e Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Wed, 16 Jul 1997 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 1997-07-16

---
 pc/vgaclgd542x.c | 204 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 204 insertions(+)

diff --git a/pc/vgaclgd542x.c b/pc/vgaclgd542x.c
index f1e7693f70a16eb404b8e2bcaf62f715e90a2c7c..ac9cb7d81eec5929ceabb555bb2e3eaf24adff9b 100644
--- a/pc/vgaclgd542x.c
+++ b/pc/vgaclgd542x.c
@@ -9,7 +9,11 @@
 #include "screen.h"
 #include "vga.h"
 
+extern Bitmap gscreen;
+extern Cursor curcursor;
+
 static Lock clgd542xlock;
+static ulong storage;
 
 static void
 clgd542xpage(int page)
@@ -19,6 +23,205 @@ clgd542xpage(int page)
 	unlock(&clgd542xlock);
 }
 
+static void
+disable(void)
+{
+	uchar sr12;
+
+	lock(&clgd542xlock);
+	sr12 = vgaxi(Seqx, 0x12);
+	vgaxo(Seqx, 0x12, sr12 & ~0x01);
+	unlock(&clgd542xlock);
+}
+
+static void
+enable(void)
+{
+	uchar sr12;
+ 
+	/*
+	 * Disable the cursor.
+	 */
+	lock(&clgd542xlock);
+	sr12 = vgaxi(Seqx, 0x12);
+	vgaxo(Seqx, 0x12, sr12 & ~0x01);
+
+	/*
+	 * Cursor colours.  
+	 */
+	vgaxo(Seqx, 0x12, sr12|0x02);
+	setcolor(0x00, Pwhite<<(32-6), Pwhite<<(32-6), Pwhite<<(32-6));
+	setcolor(0x0F, Pblack<<(32-6), Pblack<<(32-6), Pblack<<(32-6));
+	vgaxo(Seqx, 0x12, sr12);
+
+	/*
+	 * Memory size. The BIOS leaves this in Seq0A, bits 4 and 3.
+	 * See Technical Reference Manual Appendix E1, Section 1.3.2.
+	 *
+	 * The storage area for the 64x64 cursors is the last 16Kb of
+	 * display memory.
+	 */
+	switch((vgaxi(Seqx, 0x0A)>>3) & 0x03){
+
+	case 0:
+		storage = (256-16)*1024;
+		break;
+
+	case 1:
+		storage = (512-16)*1024;
+		break;
+
+	case 2:
+		storage = (1024-16)*1024;
+		break;
+
+	case 3:
+		storage = (2048-16)*1024;
+		break;
+	}
+ 
+	/*
+	 * Set the current cursor to index 0
+	 * and turn the 64x64 cursor on.
+	 */
+	vgaxo(Seqx, 0x13, 0);
+	vgaxo(Seqx, 0x12, sr12|0x05);
+
+	unlock(&clgd542xlock);
+}
+
+static void
+initcursor(Cursor* c, int xo, int yo, int index)
+{
+	uchar *p;
+	uint p0, p1;
+	int x, y;
+
+	/*
+	 * Is linear addressing turned on? This will determine
+	 * how we access the cursor storage.
+	 */
+	if(vgaxi(Seqx, 0x07) & 0xF0)
+		p = ((uchar*)gscreen.base) + storage;
+	else {
+		vgaxo(Grx, 0x09, (storage>>16)<<4);
+		p = ((uchar*)gscreen.base) + (storage & 0xFFFF);
+	}
+	p += index*1024;
+
+	for(y = yo; y < 16; y++){
+		p0 = c->clr[2*y];
+		p1 = c->clr[2*y+1];
+		if(xo){
+			p0 = (p0<<xo)|(p1>>(8-xo));
+			p1 <<= xo;
+		}
+		*p++ = p0;
+		*p++ = p1;
+
+		for(x = 16; x < 64; x += 8)
+			*p++ = 0x00;
+
+		p0 = c->clr[2*y]|c->set[2*y];
+		p1 = c->clr[2*y+1]|c->set[2*y+1];
+		if(xo){
+			p0 = (p0<<xo)|(p1>>(8-xo));
+			p1 <<= xo;
+		}
+		*p++ = p0;
+		*p++ = p1;
+
+		for(x = 16; x < 64; x += 8)
+			*p++ = 0x00;
+	}
+	while(y < 64+yo){
+		for(x = 0; x < 64; x += 8){
+			*p++ = 0x00;
+			*p++ = 0x00;
+		}
+		y++;
+	}
+}
+
+static void
+load(Cursor* c)
+{
+	uchar sr12;
+
+	/*
+	 * Lock the display memory so we can update the
+	 * cursor bitmap if necessary.
+	 * Disable the cursor.
+	 * If it's the same as the last cursor loaded,
+	 * just make sure it's enabled and index 0.
+	 */
+	lock(&clgd542xlock);
+	sr12 = vgaxi(Seqx, 0x12);
+	vgaxo(Seqx, 0x12, sr12 & ~0x01);
+
+	if(memcmp(c, &curcursor, sizeof(Cursor)) == 0){
+		vgaxo(Seqx, 0x13, 0);
+		vgaxo(Seqx, 0x12, sr12|0x05);
+		unlock(&clgd542xlock);
+		return;
+	}
+	memmove(&curcursor, c, sizeof(Cursor));
+	initcursor(c, 0, 0, 0);
+
+	/*
+	 * Enable the cursor.
+	 */
+	vgaxo(Seqx, 0x13, 0);
+	vgaxo(Seqx, 0x12, sr12|0x05);
+
+	unlock(&clgd542xlock);
+}
+
+static int
+move(Point p)
+{
+	int index, x, xo, y, yo;
+
+	if(canlock(&clgd542xlock) == 0)
+		return 1;
+
+	index = 0;
+	if((x = p.x+curcursor.offset.x) < 0){
+		xo = -x;
+		x = 0;
+	}
+	else
+		xo = 0;
+	if((y = p.y+curcursor.offset.y) < 0){
+		yo = -y;
+		y = 0;
+	}
+	else
+		yo = 0;
+
+	if(xo || yo){
+		initcursor(&curcursor, xo, yo, 1);
+		index = 1;
+	}
+	vgaxo(Seqx, 0x13, index<<2);
+	
+	vgaxo(Seqx, 0x10|((x & 0x07)<<5), (x>>3) & 0xFF);
+	vgaxo(Seqx, 0x11|((y & 0x07)<<5), (y>>3) & 0xFF);
+
+	unlock(&clgd542xlock);
+	return 0;
+}
+
+static Hwgc clgd542xhwgc = {
+	"clgd542xhwgc",
+	enable,
+	load,
+	move,
+	disable,
+
+	0,
+};
+
 static Vgac clgd542x = {
 	"clgd542x",
 	clgd542xpage,
@@ -30,4 +233,5 @@ void
 vgaclgd542xlink(void)
 {
 	addvgaclink(&clgd542x);
+	addhwgclink(&clgd542xhwgc);
 }