From 8a1b63fe23b7d10774f06ac4923175de701c10fe Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Mon, 9 Nov 1992 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 1992-11-09

---
 pc/devconfig.c | 10 ++++++----
 pc/l.s         | 24 ++++++++++--------------
 pc/vga.c       | 23 +++++++++++++++++------
 3 files changed, 33 insertions(+), 24 deletions(-)

diff --git a/pc/devconfig.c b/pc/devconfig.c
index c2a5bf25df3d851d4965d013cbad1de5eb9bf69d..64ecf65e3118088e15f28e6836d1c77d24fb7978 100644
--- a/pc/devconfig.c
+++ b/pc/devconfig.c
@@ -146,7 +146,7 @@ long
 configwrite(Chan *c, void *buf, long n, ulong offset)
 {
 	char cbuf[20], *cp;
-	int port, maxx, maxy;
+	int port, maxx, maxy, ldepth;
 
 	switch(c->qid.path&~CHDIR){
 	case Qdir:
@@ -165,10 +165,12 @@ configwrite(Chan *c, void *buf, long n, ulong offset)
 		cp = cbuf;
 		maxx = strtoul(cp, &cp, 0);
 		maxy = strtoul(cp, &cp, 0);
-		if (maxx == 0 || maxy == 0 ||
-		    maxx > 1280 || maxy > 1024)
+		ldepth = strtoul(cp, &cp, 0);
+		if(maxx == 0 || maxy == 0
+		|| maxx > 1280 || maxy > 1024
+		|| ldepth > 3 || ldepth < 0)
 			error(Ebadarg);
-		setscreen(maxx, maxy, 1);
+		setscreen(maxx, maxy, ldepth);
 		return n;
 	case Qvgaport:
 		cp = buf;
diff --git a/pc/l.s b/pc/l.s
index 87374d4bdd2f6204f78203f6f3e79e18f4039987..1c9d408f7302707a22d36806470364b60e35033b 100644
--- a/pc/l.s
+++ b/pc/l.s
@@ -662,25 +662,21 @@ TEXT	l1update(SB),$0
 	MOVL	from+0(FP),SI
 	MOVL	to+4(FP),DI
 	MOVL	len+8(FP),CX
-l10:
-	XORL	DX,DX
-	MOVB	-2(SI)(CX*2),DL		/* high order nibbles */
-	MOVW	l1revsep(SB)(DX*2),BX
-	SHLW	$4,BX
-	MOVB	-1(SI)(CX*2),DL		/* low order nibbles */
-	ORW	l1revsep(SB)(DX*2),BX
-	MOVB	$(Smmask),AL		/* write hi order bits to bit planes 0 & 2 */
+	MOVB	$(Smmask),AL
 	MOVW	$(SRX),DX
 	OUTB
-	MOVB	$0xA,AL
 	MOVW	$(SR),DX
+l10:
+	XORL	AX,AX
+	MOVB	-2(SI)(CX*2),AL		/* high order nibbles */
+	MOVW	l1revsep(SB)(AX*2),BX
+	SHLW	$4,BX
+	MOVB	-1(SI)(CX*2),AL		/* low order nibbles */
+	ORW	l1revsep(SB)(AX*2),BX
+	MOVB	$0xA,AL			/* write hi order bits to bit planes 0 & 2 */
 	OUTB
 	MOVB	BH,-1(DI)(CX*1)
-	MOVB	$(Smmask),AL		/* write lo order bits to bit planes 1 & 3 */
-	MOVW	$(SRX),DX
-	OUTB
-	MOVB	$0x5,AL
-	MOVW	$(SR),DX
+	MOVB	$0x5,AL			/* write lo order bits to bit planes 1 & 3 */
 	OUTB
 	MOVB	BL,-1(DI)(CX*1)
 	LOOP	l10
diff --git a/pc/vga.c b/pc/vga.c
index a31944d6b4c0007370923d2818aed171f9d60f33..4d0993db091fe3524b25ac0948acc130778c0f5a 100644
--- a/pc/vga.c
+++ b/pc/vga.c
@@ -233,24 +233,31 @@ setscreen(int maxx, int maxy, int ldepth)
 	mbb = NULLMBB;
 
 	/*
-	 *  zero hard screen
+	 *  zero hard screen and setup a bitmap for the new size
 	 */
 	memset((void*)SCREENMEM, 0xff, 64*1024);
-	vgascreen.ldepth = 0;
+	if(ldepth == 3)
+		vgascreen.ldepth = 3;
+	else
+		vgascreen.ldepth = 0;
 	vgascreen.base = (void*)SCREENMEM;
 	vgascreen.width = (maxx*(1<<ldepth))/32;
 	vgascreen.r.max = Pt(maxx, maxy);
 	vgascreen.clipr.max = vgascreen.r.max;
 
 	/*
-	 *  setup new soft screen
+	 *  setup new soft screen, free memory for old screen
 	 */
 	gscreen.ldepth = ldepth;
 	gscreen.width = (maxx*(1<<ldepth))/32;
 	gscreen.r.max = Pt(maxx, maxy);
 	gscreen.clipr.max = gscreen.r.max;
 	len = gscreen.width * 4 * maxy;
-	gscreen.base = ((ulong*)malloc(len+2*1024))+256;
+	if(gscreen.base){
+		free(gscreen.base);
+		gscreen.base = ((ulong*)smalloc(len+2*1024))+256;
+	} else
+		gscreen.base = ((ulong*)malloc(len+2*1024))+256;
 	memset((char*)gscreen.base, 0xff, len);
 
 	/*
@@ -334,7 +341,7 @@ void
 screenupdate(void)
 {
 	uchar *sp, *hp;
-	int y, len, incs, inch;
+	int y, len, incs, inch, bits;
 	Rectangle r;
 
 	r = mbb;
@@ -352,9 +359,10 @@ screenupdate(void)
 	if(r.max.y > gscreen.r.max.y)
 		r.max.y = gscreen.r.max.y;
 
+	bits = 1<<vgascreen.ldepth;
 	sp = (uchar*)gaddr(&gscreen, r.min);
 	hp = (uchar*)gaddr(&vgascreen, r.min);
-	len = (r.max.x + 31)/32 - r.min.x/32;
+	len = (r.max.x*bits + 31)/32 - (r.min.x*bits)/32;
 	len *= BY2WD;
 	if(len <= 0)
 		return;
@@ -364,6 +372,8 @@ screenupdate(void)
 
 	switch(gscreen.ldepth){
 	case 0:
+	case 3:
+		/* reverse the bits */
 		for (y = r.min.y; y < r.max.y; y++){
 			l0update(sp, hp, len);
 			sp += incs;
@@ -371,6 +381,7 @@ screenupdate(void)
 		}
 		break;
 	case 1:
+		/* reverse the bits and split into 2 bitmaps */
 		for (y = r.min.y; y < r.max.y; y++){
 			l1update(sp, hp, len);
 			sp += incs;