From c3eb994b1c642a341b7ba3b0ab4eba5905568ea1 Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Tue, 10 Nov 1992 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 1992-11-10

---
 pc/fns.h  |  1 +
 pc/l.s    |  8 ++++----
 pc/main.c |  1 +
 pc/vga.c  | 32 +++++++++++++++++++++-----------
 pc/vga.h  |  3 +++
 5 files changed, 30 insertions(+), 15 deletions(-)

diff --git a/pc/fns.h b/pc/fns.h
index 2f53c8efda62be0cd98d8198355818e5b7f0dbe0..bf39bd5c080259b3a627bf637eb2b2d78e7a3744 100644
--- a/pc/fns.h
+++ b/pc/fns.h
@@ -35,6 +35,7 @@ void	insl(int, void*, int);
 ulong	isamem(int);
 void	kbdinit(void);
 void	l0update(uchar*, uchar*, int);
+void	l1update(uchar*, uchar*, int);
 void	mathinit(void);
 void	mmuinit(void);
 int	modem(int);
diff --git a/pc/l.s b/pc/l.s
index 1c9d408f7302707a22d36806470364b60e35033b..36d45c57bfe0c23d29bc1030014bb31851481f11 100644
--- a/pc/l.s
+++ b/pc/l.s
@@ -642,12 +642,12 @@ TEXT	config(SB),$0
 TEXT	l0update(SB),$0
 	XORL	AX,AX
 	MOVL	len+8(FP),CX
-	MOVL	from+0(FP),BX
-	MOVL	to+4(FP),DX
+	MOVL	from+0(FP),SI
+	MOVL	to+4(FP),DI
 l00:
-	MOVB	-1(BX)(CX*1),AL
+	MOVB	-2(SI)(CX*2),AL
 	MOVB	bitrevtab(SB)(AX*1),AL
-	MOVB	AL,-1(DX)(CX*1)
+	MOVB	AL,-1(DI)(CX*1)
 	LOOP	l00
 	RET
 
diff --git a/pc/main.c b/pc/main.c
index 0778805878e9985d7a3c7e00e8212534396da0b9..86cecf94b014eb475772cc6a675d0ecb39a0341d 100644
--- a/pc/main.c
+++ b/pc/main.c
@@ -271,6 +271,7 @@ confinit(void)
 	conf.npage1 = (i*MB - conf.base1)/BY2PG;
 	conf.npage = conf.npage0 + conf.npage1;
 
+	conf.ldepth = 1;
 	pcnt = screenbits()-1;		/* Calculate % of memory for page pool */
 	pcnt = 70 - (pcnt*10);
 	conf.upages = (conf.npage*pcnt)/100;
diff --git a/pc/vga.c b/pc/vga.c
index 4d0993db091fe3524b25ac0948acc130778c0f5a..9d9e1b16dc57c868b5ec4e41a0cb008f8e17806f 100644
--- a/pc/vga.c
+++ b/pc/vga.c
@@ -241,7 +241,7 @@ setscreen(int maxx, int maxy, int ldepth)
 	else
 		vgascreen.ldepth = 0;
 	vgascreen.base = (void*)SCREENMEM;
-	vgascreen.width = (maxx*(1<<ldepth))/32;
+	vgascreen.width = (maxx*(1<<vgascreen.ldepth))/32;
 	vgascreen.r.max = Pt(maxx, maxy);
 	vgascreen.clipr.max = vgascreen.r.max;
 
@@ -252,7 +252,7 @@ setscreen(int maxx, int maxy, int ldepth)
 	gscreen.width = (maxx*(1<<ldepth))/32;
 	gscreen.r.max = Pt(maxx, maxy);
 	gscreen.clipr.max = gscreen.r.max;
-	len = gscreen.width * 4 * maxy;
+	len = gscreen.width * BY2WD * maxy;
 	if(gscreen.base){
 		free(gscreen.base);
 		gscreen.base = ((ulong*)smalloc(len+2*1024))+256;
@@ -271,7 +271,7 @@ setscreen(int maxx, int maxy, int ldepth)
 void
 screeninit(void)
 {
-	int i;
+	int i, x;
 	ulong *l;
 
 	setmode(&mode12);
@@ -300,8 +300,18 @@ screeninit(void)
 		conf.maxx = MAXX;
 	if(conf.maxy == 0)
 		conf.maxy = MAXY;
-
 	setscreen(conf.maxx, conf.maxy, conf.ldepth);
+
+	/*
+	 *  set up default grey scale color map
+	 */
+	outb(CMWX, 0);
+	for(i = 0; i < 16; i++){
+		x = (i*63)/15;
+		outb(CM, x);
+		outb(CM, x);
+		outb(CM, x);
+	}
 }
 
 /*
@@ -341,7 +351,7 @@ void
 screenupdate(void)
 {
 	uchar *sp, *hp;
-	int y, len, incs, inch, bits;
+	int y, len, incs, inch, bits, off;
 	Rectangle r;
 
 	r = mbb;
@@ -360,10 +370,11 @@ screenupdate(void)
 		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*bits + 31)/32 - (r.min.x*bits)/32;
-	len *= BY2WD;
+	off = (r.min.x*bits)>>(3-vgascreen.ldepth);
+	hp = (uchar*)(vgascreen.base+(r.min.y*vgascreen.width)) + off;
+	off <<= gscreen.ldepth - vgascreen.ldepth;
+	sp = (uchar*)(gscreen.base+(r.min.y*gscreen.width)) + off;
+	len = (r.max.x*bits + 7)/8 - (r.min.x*bits)/8;
 	if(len <= 0)
 		return;
 
@@ -446,7 +457,6 @@ screenputs(char *s, int n)
 		}
 	}
 	rs.max = Pt(gscreen.r.max.x, out.pos.y+defont0.height);
-	unlock(&screenlock);
 	mbbrect(rs);
 	screenupdate();
 }
@@ -454,7 +464,7 @@ screenputs(char *s, int n)
 int
 screenbits(void)
 {
-	return 1;	/* bits per pixel */
+	return 1<<gscreen.ldepth;	/* bits per pixel */
 }
 
 
diff --git a/pc/vga.h b/pc/vga.h
index 80f5605d808686372d8760197fafb7f307888307..2c5b57818dd2c1bbc5fa6fff579a06b8f3dbd1a5 100644
--- a/pc/vga.h
+++ b/pc/vga.h
@@ -15,6 +15,9 @@ enum
 	 Cvre=		 0x11,		/*  vertical retrace end */
 	ARW=		0x3C0,		/* attribute registers (writing) */
 	ARR=		0x3C1,		/* attribute registers (reading) */
+	CMRX=		0x3C7,		/* color map read index */
+	CMWX=		0x3C8,		/* color map write index */
+	CM=		0x3C9,		/* color map data reg */
 };
 
 #define SCREENMEM	(0xA0000 | KZERO)