From 27fa333ea16e6635a0b7172b023ba7106f927505 Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Thu, 4 Aug 1994 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 1994-08-04

---
 pc/vgas3.c     | 70 +++++++++++++++++++++++++++++++++++---------------
 port/devpipe.c | 24 ++++-------------
 port/qio.c     |  9 +++++--
 3 files changed, 61 insertions(+), 42 deletions(-)

diff --git a/pc/vgas3.c b/pc/vgas3.c
index fab090d20e1b935713bb4cce964f051df0930544..b85e43f3bff21888fd3a0c6701cb457163a21273 100644
--- a/pc/vgas3.c
+++ b/pc/vgas3.c
@@ -16,6 +16,7 @@
  */
 static Lock s3pagelock;
 static ulong storage;
+static Point hotpoint;
 
 extern Bitmap gscreen;
 
@@ -80,15 +81,16 @@ enable(void)
 	/*
 	 * Cursor colours. Set both the CR0[EF] and the colour
 	 * stack in case we are using a 16-bit RAMDAC.
+	 * Why are these colours reversed?
 	 */
-	vgaxo(Crtx, 0x0E, 0x00);
-	vgaxo(Crtx, 0x0F, 0xFF);
+	vgaxo(Crtx, 0x0E, 0xFF);
+	vgaxo(Crtx, 0x0F, 0x00);
 	vgaxi(Crtx, 0x45);
 	for(i = 0; i < 4; i++)
-		vgaxo(Crtx, 0x4A, 0x00);
+		vgaxo(Crtx, 0x4A, 0xFF);
 	vgaxi(Crtx, 0x45);
 	for(i = 0; i < 4; i++)
-		vgaxo(Crtx, 0x4B, 0xFF);
+		vgaxo(Crtx, 0x4B, 0x00);
 
 	/*
 	 * Find a place for the cursor data in display memory.
@@ -110,7 +112,7 @@ enable(void)
 static void
 load(Cursor *c)
 {
-	uchar *and, *xor;
+	uchar *p;
 	int x, y;
 
 	/*
@@ -118,14 +120,14 @@ load(Cursor *c)
 	 * memory so we can update the cursor bitmap.
 	 * Set the display page (do we need to restore
 	 * the current contents when done?) and the
-	 * pointers to the two planes.
+	 * pointer to the two planes. What if this crosses
+	 * into a new page?
 	 */
 	disable();
 	lock(&s3pagelock);
 
 	sets3page(storage>>16);
-	and = ((uchar*)gscreen.base) + (storage & 0xFFFF);
-	xor = and + 512;
+	p = ((uchar*)gscreen.base) + (storage & 0xFFFF);
 
 	/*
 	 * The cursor is set in X11 mode which gives the following
@@ -138,24 +140,27 @@ load(Cursor *c)
 	 * Put the cursor into the top-left of the 64x64 array.
 	 */
 	for(y = 0; y < 64; y++){
-		for(x = 0; x < 8; x++){
-			if(y < 16 && x < 2){
-				and[8*y + x] = c->clr[2*y + x]^c->set[2*y + x];
-				xor[8*y + x] = c->set[2*y + x];
+		for(x = 0; x < 64/8; x += 2){
+			if(x < 16/8 && y < 16){
+				*p++ = c->clr[2*y + x]|c->set[2*y + x];
+				*p++ = c->clr[2*y + x+1]|c->set[2*y + x+1];
+				*p++ = c->set[2*y + x];
+				*p++ = c->set[2*y + x+1];
 			}
 			else {
-				and[8*y + x] = 0;
-				xor[8*y + x] = 0;
+				*p++ = 0x00;
+				*p++ = 0x00;
+				*p++ = 0x00;
+				*p++ = 0x00;
 			}
 		}
 	}
 	unlock(&s3pagelock);
 
 	/*
-	 * Set the cursor offset and enable the cursor.
+	 * Set the cursor hotpoint and enable the cursor.
 	 */
-	vgaxo(Crtx, 0x4E, -c->offset.x);
-	vgaxo(Crtx, 0x4F, -c->offset.y);
+	hotpoint = c->offset;
 	vsyncactive();
 	vgaxo(Crtx, 0x45, 0x01);
 }
@@ -163,10 +168,33 @@ load(Cursor *c)
 static int
 move(Point p)
 {
-	vgaxo(Crtx, 0x46, (p.x>>8) & 0x07);
-	vgaxo(Crtx, 0x47, p.x & 0xFF);
-	vgaxo(Crtx, 0x49, p.y & 0xFF);
-	vgaxo(Crtx, 0x48, (p.y>>8) & 0x07);
+	int x, xo, y, yo;
+
+	/*
+	 * Mustn't position the cursor offscreen even partially,
+	 * or it disappears. Therefore, if x or y is -ve, adjust the
+	 * cursor offset instead.
+	 */
+	if((x = p.x+hotpoint.x) < 0){
+		xo = -x;
+		xo = ((xo+1)/2)*2;
+		x = 0;
+	}
+	else
+		xo = 0;
+	if((y = p.y+hotpoint.y) < 0){
+		yo = -y;
+		y = 0;
+	}
+	else
+		yo = 0;
+
+	vgaxo(Crtx, 0x46, (x>>8) & 0x07);
+	vgaxo(Crtx, 0x47, x & 0xFF);
+	vgaxo(Crtx, 0x49, y & 0xFF);
+	vgaxo(Crtx, 0x4E, xo);
+	vgaxo(Crtx, 0x4F, yo);
+	vgaxo(Crtx, 0x48, (y>>8) & 0x07);
 
 	return 0;
 }
diff --git a/port/devpipe.c b/port/devpipe.c
index 847255b525bdeede8218c7091130682d51aefaca..8f99eeefbb52ad3bc2f2de47bca61dfe618b7dd6 100644
--- a/port/devpipe.c
+++ b/port/devpipe.c
@@ -22,7 +22,6 @@ struct Pipe
 struct
 {
 	Lock;
-	Pipe	*pipe;
 	ulong	path;
 } pipealloc;
 
@@ -85,8 +84,6 @@ pipeattach(char *spec)
 
 	lock(&pipealloc);
 	p->path = ++pipealloc.path;
-	p->next = pipealloc.pipe;
-	pipealloc.pipe = p;
 	unlock(&pipealloc);
 
 	c->qid = (Qid){CHDIR|NETQID(2*p->path, Qdir), 0};
@@ -223,7 +220,7 @@ pipewstat(Chan *c, char *db)
 void
 pipeclose(Chan *c)
 {
-	Pipe *p, *f, **l;
+	Pipe *p;
 
 	p = c->aux;
 	qlock(p);
@@ -236,15 +233,15 @@ pipeclose(Chan *c)
 		case Qdata0:
 			p->qref[0]--;
 			if(p->qref[0] == 0){
-				qclose(p->q[0]);
 				qhangup(p->q[1]);
+				qclose(p->q[0]);
 			}
 			break;
 		case Qdata1:
 			p->qref[1]--;
 			if(p->qref[1] == 0){
-				qclose(p->q[1]);
 				qhangup(p->q[0]);
+				qclose(p->q[1]);
 			}
 			break;
 		}
@@ -265,22 +262,11 @@ pipeclose(Chan *c)
 	p->ref--;
 	if(p->ref == 0){
 		qunlock(p);
-		lock(&pipealloc);
-		l = &pipealloc.pipe;
-		for(f = *l; f; f = f->next) {
-			if(f == p) {
-				*l = p->next;
-				break;
-			}
-			l = &f->next;
-		}
-		unlock(&pipealloc);
 		free(p->q[0]);
 		free(p->q[1]);
 		free(p);
-	}
-
-	qunlock(p);
+	} else
+		qunlock(p);
 }
 
 long
diff --git a/port/qio.c b/port/qio.c
index c0e57b5b8dfdf3df1bd1d9933af4cd507c2556a8..75e0a8a9cc0fd3c370caab92a882e9f55b7821aa 100644
--- a/port/qio.c
+++ b/port/qio.c
@@ -337,7 +337,6 @@ qopen(int limit, int msg, void (*kick)(void*), void *arg)
 	if(q == 0)
 		return 0;
 
-	memset(q, 0, sizeof(Queue));
 	q->limit = limit;
 	q->kick = kick;
 	q->arg = arg;
@@ -494,7 +493,7 @@ qwrite(Queue *q, void *vp, int len, int nowait)
 	if(waserror()){
 		qunlock(&q->wlock);
 		nexterror();
-	};
+	}
 	qlock(&q->wlock);
 
 	sofar = 0;
@@ -522,6 +521,10 @@ qwrite(Queue *q, void *vp, int len, int nowait)
 			n = 128*1024;
 
 		b = allocb(n);
+		if(waserror()){
+			freeb(b);
+			nexterror();
+		}
 		memmove(b->wp, p+sofar, n);
 		b->wp += n;
 	
@@ -531,6 +534,7 @@ qwrite(Queue *q, void *vp, int len, int nowait)
 				freeb(b);
 				qunlock(&q->wlock);
 				poperror();
+				poperror();
 				return len;
 			}
 			q->state |= Qflow;
@@ -543,6 +547,7 @@ qwrite(Queue *q, void *vp, int len, int nowait)
 			iunlock(q);
 			error(Ehungup);
 		}
+		poperror();
 
 checkb(b, "qwrite");
 		if(q->syncbuf){