From 9443499037a67210f4c9282c5b89c280413f4799 Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Fri, 18 Apr 1997 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 1997-04-18

---
 pc/devether.c   |   4 +-
 pc/ether8390.c  | 100 ++++++++++++++++++++++++++++--------------------
 pc/ether8390.h  |   1 +
 pc/etherelnk3.c |   1 -
 4 files changed, 61 insertions(+), 45 deletions(-)

diff --git a/pc/devether.c b/pc/devether.c
index 138c937b7799385539465e2c696d6dc830c1f3ad..33a020de90b18e7b43882f82475437ebb3f26e4f 100644
--- a/pc/devether.c
+++ b/pc/devether.c
@@ -398,9 +398,7 @@ ethercrc(uchar *p, int len)
 	for(i = 0; i < len; i++){
 		b = *p++;
 		for(j = 0; j < 8; j++){
-			crc = (crc>>1);
-			if((crc^b) & 1)
-				crc ^= POLY;
+			crc = (crc>>1) ^ (((crc^b) & 1) ? POLY : 0);
 			b >>= 1;
 		}
 	}
diff --git a/pc/ether8390.c b/pc/ether8390.c
index 1eb53a5536633f500d0e4385ec02b8406adee789..f0fcc85c597bf0258bc8d2e315bec8dd2fadf111 100644
--- a/pc/ether8390.c
+++ b/pc/ether8390.c
@@ -604,77 +604,95 @@ interrupt(Ureg*, void* arg)
 	unlock(ctlr);
 }
 
+static uchar allmar[8] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
+
+static void
+setfilter(Ether *ether, Dp8390 *ctlr)
+{
+	uchar r, cr;
+	int i;
+	uchar *mar;
+
+	r = Ab;
+	mar = 0;
+	if(ether->prom){
+		r |= Pro|Am;
+		mar = allmar;
+	} else if(ether->nmaddr){
+		r |= Am;
+		mar = ctlr->mar;
+	}
+	if(mar){
+		cr = regr(ctlr, Cr) & ~Txp;
+		regw(ctlr, Cr, Page1|(~(Ps1|Ps0) & cr));
+		for(i = 0; i < 8; i++)
+			regw(ctlr, Mar0+i, *(mar++));
+		regw(ctlr, Cr, cr);
+	}
+	regw(ctlr, Rcr, r);
+}
+
 static void
 promiscuous(void *arg, int on)
 {
 	Ether *ether;
 	Dp8390 *ctlr;
-	uchar r;
+
+	USED(on);
 
 	ether = arg;
 	ctlr = ether->ctlr;
 
-	/*
-	 * Set/reset promiscuous mode.
-	 */
-	r = Ab;
-	if(on)
-		r |= Pro;
-	if(ether->nmaddr)
-		r |= Am;
 	ilock(ctlr);
-	regw(ctlr, Rcr, r);
+	setfilter(ether, ctlr);
 	iunlock(ctlr);
 }
 
+static void
+setbit(Dp8390 *ctlr, int bit, int on)
+{
+	int i, h;
+
+	i = bit/8;
+	h = bit%8;
+	if(on){
+		if(++(ctlr->mref[bit]) == 1)
+			ctlr->mar[i] |= 1<<h;
+	} else {
+		if(--(ctlr->mref[bit]) <= 0){
+			ctlr->mref[bit] = 0;
+			ctlr->mar[i] &= ~(1<<h);
+		}
+	}
+}
+
+static uchar reverse[64];
+
 static void
 multicast(void* arg, uchar *addr, int on)
 {
 	Ether *ether;
 	Dp8390 *ctlr;
-	uchar r, cr;
 	int i;
 	ulong h;
 
-	USED(addr, on);
+	USED(on);
 
 	ether = arg;
 	ctlr = ether->ctlr;
+	if(reverse[1] == 0){
+		for(i = 0; i < 64; i++)
+			reverse[i] = ((i&1)<<5) | ((i&2)<<3) | ((i&4)<<1)
+					| ((i&8)>>1) | ((i&16)>>3) | ((i&32)>>5);
+	}
 
 	/*
 	 *  change filter bits
 	 */
 	h = ethercrc(addr, 6);
-	h = h>>(32-6);
-	i = h/8;
-	h = h%8;
 	ilock(ctlr);
-	cr = regr(ctlr, Cr) & ~Txp;
-	regw(ctlr, Cr, Page1|(~(Ps1|Ps0) & cr));
-	r = regr(ctlr, Mar0+i);
-	if(on){
-		if(++(ctlr->mref[h]) == 1)
-			r |= 1<<h;
-	} else {
-		if(--(ctlr->mref[h]) <= 0){
-			ctlr->mref[h] = 0;
-			r &= ~(1<<h);
-		}
-	}	
-	regw(ctlr, Mar0+i, r);
-	regw(ctlr, Cr, cr);
-	iunlock(ctlr);
-
-	/*
-	 * Set/reset promiscuous mode.
-	 */
-	r = Ab;
-	if(ether->nmaddr)
-		r |= Am;
-	if(ether->prom)
-		r |= Pro;
-	ilock(ctlr);
-	regw(ctlr, Rcr, r);
+	setbit(ctlr, reverse[h&0x3f], on);
+	setfilter(ether, ctlr);
 	iunlock(ctlr);
 }
 
diff --git a/pc/ether8390.h b/pc/ether8390.h
index 8fff39432a14275a36fff9be9eb061b0042e4cd6..b5bf6e55528cfd0f9e9e3f3360140a7b218030df 100644
--- a/pc/ether8390.h
+++ b/pc/ether8390.h
@@ -20,6 +20,7 @@ typedef struct {
 	int	txbusy;			/* transmit */
 	uchar	tstart;			/* 8390 ring addresses */
 
+	uchar	mar[8];			/* shadow multicast address registers */
 	int	mref[64];		/* reference counts for multicast groups */
 } Dp8390;
 
diff --git a/pc/etherelnk3.c b/pc/etherelnk3.c
index 647a844510353acb203dab1e7af6464e06ed439a..9e3dd8a43676d5195245ff7c5d5cbcd44d67d90d 100644
--- a/pc/etherelnk3.c
+++ b/pc/etherelnk3.c
@@ -467,7 +467,6 @@ multicast(void* arg, uchar *addr, int on)
 	ether = (Ether*)arg;
 	port = ether->port;
 
-print("multicast nmaddr == %d\n", ether->nmaddr);
 	filter = receiveBroadcast|receiveIndividual;
 	if(ether->nmaddr)
 		filter |= receiveMulticast;