From c2979df11ddfd717a4c659a0692803f52a6848d5 Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Sat, 31 Aug 1991 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 1991-08-31

---
 pc/devfloppy.c | 20 +++++++++++++++++++-
 port/stream.c  | 26 +++++++-------------------
 2 files changed, 26 insertions(+), 20 deletions(-)

diff --git a/pc/devfloppy.c b/pc/devfloppy.c
index 7e8294b612c034d09214529fcd3ac98792b7578b..71f22be07513b8682acdbb644004c2a5f7092670 100644
--- a/pc/devfloppy.c
+++ b/pc/devfloppy.c
@@ -26,9 +26,12 @@ enum
 	 Fseek=		 0xf,	/* seek cmd */
 	 Fsense=	 0x8,	/* sense cmd */
 	 Fread=		 0x66,	/* read cmd */
-	 Fwrite=	 0x47,	/* write cmd */
+	 Fwrite=	 0x45,	/* write cmd */
 	 Fmulti=	 0x80,	/* or'd with Fread or Fwrite for multi-head */
 
+	Fchanged=	0x3F7,	/* disk changed register */
+	 Fchange=	 0x80,	/* disk has changed */
+
 	DMAchan=	2,	/* floppy dma channel */
 
 	/* status 0 byte */
@@ -280,6 +283,18 @@ ul2user(uchar *a, ulong x)
 	a[3] = x;
 }
 
+/*
+ *  look for a floppy change
+ */
+void
+floppychange(Drive *dp)
+{
+	if((inb(Fchanged) & Fchange) == 0)
+		return;
+
+	
+}
+
 /*
  *  the floppy is so slow, we always read a cylinder
  *  at a time and cache the extra bytes.
@@ -299,6 +314,7 @@ floppyread(Chan *c, void *a, long n)
 	dp = &floppy.d[c->qid.path & ~Qmask];
 	switch ((int)(c->qid.path & Qmask)) {
 	case Qdata:
+		floppychanged(dp);
 		if(c->offset % dp->t->bytes)
 			errors("bad offset");
 		if(n % dp->t->bytes)
@@ -343,6 +359,8 @@ floppywrite(Chan *c, void *a, long n)
 	dp = &floppy.d[c->qid.path & ~Qmask];
 	switch ((int)(c->qid.path & Qmask)) {
 	case Qdata:
+		floppychanged(dp);
+		dp->ccyl = -1;
 		for(rv = 0; rv < n; rv += i){
 			i = floppyxfer(dp, Fwrite, aa+rv, c->offset+rv, n-rv);
 			if(i <= 0)
diff --git a/port/stream.c b/port/stream.c
index 2c4eebd2d79f1d0e1799b80f6dd431755c36dbb3..141aaec972191ec7cf7904029fd9cc664a70bfa9 100644
--- a/port/stream.c
+++ b/port/stream.c
@@ -43,11 +43,8 @@ static Lock garbagelock;
  */
 typedef struct {
 	int	size;
-	int	lim;
 	int	made;
 	Blist;
-	QLock;		/* qlock for sleepers on r */
-	Rendez	r;	/* sleep here waiting for blocks */
 } Bclass;
 Bclass bclass[Nclass]={
 	{ 0 },
@@ -74,14 +71,13 @@ streaminit(void)
 	qlist = (Queue *)ialloc(conf.nqueue * sizeof(Queue), 0);
 
 	/*
-	 *  set limits on blocks
+	 *  set block classes
 	 */
 	n = conf.nblock;
 	for(class = 0; class < Nclass; class++){
 		if(class < Nclass-1)
 			n = n/2;
 		bcp = &bclass[class];
-		bcp->lim = n;
 		bcp->made = 0;
 	}
 
@@ -115,9 +111,6 @@ newblock(Bclass *bcp)
 	Block *bp;
 	uchar *cp;
 
-	if(bcp->made > bcp->lim)
-		return -1;
-
 	page = newpage(1, 0, 0);
 	page->va = VA(kmap(page));
 	if(bcp == bclass){
@@ -149,11 +142,11 @@ newblock(Bclass *bcp)
 			 *  upgrade a level 0 block
 			 */
 			bp = allocb(0);
-			qlock(bclass);
+			lock(bclass);
 			bclass->made--;
 			bcp->made++;
 			bp->flags = bcp - bclass;
-			qunlock(bclass);
+			unlock(bclass);
 
 			/*
 			 *  tack on the data area
@@ -199,18 +192,12 @@ allocb(ulong size)
 	 */
 	lock(bcp);
 	while(bcp->first == 0){
-		if(newblock(bcp) == 0)
-			continue;
-		unlock(bcp);
-		qlock(bcp);
 		if(waserror()){
-			qunlock(bcp);
+			unlock(bcp);
 			nexterror();
 		}
-		tsleep(&bcp->r, isblock, (void *)bcp, 250);
-		qunlock(bcp);
+		newblock(bcp);
 		poperror();
-		lock(bcp);
 	}
 	bp = bcp->first;
 	bcp->first = bp->next;
@@ -1462,7 +1449,8 @@ dumpqueues(void)
 		for(count = 0, bp = bcp->first; bp; count++, bp = bp->next)
 			;
 		unlock(bcp);
-		print("%d blocks of size %d\n", count, bcp->size);
+		print("%d byte blocks: %d made %d free\n", bcp->size,
+			bcp->made, count);
 	}
 	print("\n");
 }