From b7580c6011dc9909c6d1aac06bd81fbc38349e61 Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Tue, 9 Jul 1991 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 1991-07-09

---
 gnot/trap.c    |  4 +---
 pc/clock.c     | 29 ++++++++++++++++++---------
 pc/fns.h       |  4 ++--
 pc/io.h        | 11 +----------
 pc/main.c      |  7 ++++++-
 pc/mem.h       | 11 +++++------
 pc/trap.c      | 53 ++++++++++++++++++++++++++++++++++++++------------
 port/fault.c   |  4 ++--
 port/sysproc.c | 18 ++++++-----------
 power/trap.c   |  1 -
 ss/trap.c      |  4 ++--
 11 files changed, 86 insertions(+), 60 deletions(-)

diff --git a/gnot/trap.c b/gnot/trap.c
index efb629af7ad332823b5ceb13ab851024a17f08e1..18cfda3e9d77dd9fdb33b64865db5242ec91b0e7 100644
--- a/gnot/trap.c
+++ b/gnot/trap.c
@@ -306,14 +306,12 @@ syscall(Ureg *aur)
 		poperror();
 	}
 
-#ifdef Check
 	if(u->nerrlab){
 		print("bad errstack [%d]: %d extra\n", r0, u->nerrlab);
 		for(i = 0; i < NERR; i++)
 			print("sp=%lux pc=%lux\n", u->errlab[i].sp, u->errlab[i].pc);
-		panic("bad rob");
+		panic("error stack");
 	}
-#endif
 
 	u->p->insyscall = 0;
 
diff --git a/pc/clock.c b/pc/clock.c
index 5c6facc0a4e491134fb79ac2258ec1491bd8af75..769e8bfdb4402c2b70eeb0220aa04d2602927458 100644
--- a/pc/clock.c
+++ b/pc/clock.c
@@ -11,23 +11,39 @@
  */
 enum
 {
-	Timerctl=	0x43,		/* control port */
-	Timercnt=	0x40,		/* timer count port (outb count-1) */
-	Timericnt=	0x41,		/* timer count input port */
+	T0cntr=	0x40,		/* counter ports */
+	T1cntr=	0x41,		/* ... */
+	T2cntr=	0x42,		/* ... */
+	Tmode=	0x43,		/* mode port */
 
-	Timerlatch=	0x40,		/* latch count into Timericnt */
+	Load0square=	0x36,		/*  load counter 0 with 2 bytes,
+					 *  output a square wave whose
+					 *  period is the counter period
+					 */
+	Freq=		1193182,	/* Real clock frequency */
 };
 
 void
 clockinit(void)
 {
+	/*
+	 *  set vector for clock interrupts
+	 */
 	setvec(Clockvec, clock, SEGIG);
+
+	/*
+	 *  make clock output a square wave with a 1/HZ period
+	 */
+	outb(Tmode, Load0square);
+	outb(T0cntr, (Freq/HZ));	/* low byte */
+	outb(T0cntr, (Freq/HZ)>>8);	/* high byte */
 }
 
 void
 clock(Ureg *ur)
 {
 	Proc *p;
+	static int last;
 
 	m->ticks++;
 	p = m->proc;
@@ -36,9 +52,4 @@ clock(Ureg *ur)
 		if (p->state==Running)
 			p->time[p->insyscall]++;
 	}
-
-	if((m->ticks%185) == 92)
-		floppystart();
-	else if((m->ticks%185) == 0)
-		floppystop();
 }
diff --git a/pc/fns.h b/pc/fns.h
index af6544ce00cbf0379da4813f6d1a8404694f7894..492f2c36fe094c1e5c4807f1b26761b3e293b529 100644
--- a/pc/fns.h
+++ b/pc/fns.h
@@ -5,8 +5,8 @@ void	clockinit(void);
 void	delay(int);
 void	floppyinit(void);
 void	floppyintr(Ureg*);
-void	floppystart(void);
-void	floppystop(void);
+void	floppystart(int);
+void	floppystop(int);
 void	idle(void);
 int	inb(int);
 void	intr0(void);
diff --git a/pc/io.h b/pc/io.h
index b9f3cb7c43770d1ac19011dc799ec68de48273ae..948fc0e41188fb0e03a92580cda1dcc987ff2be8 100644
--- a/pc/io.h
+++ b/pc/io.h
@@ -1,21 +1,12 @@
 /*
- *  8259 interrupt controllers
+ *  programmable interrupt vectors (for the 8259)
  */
 enum
 {
-	Int0ctl=	0x20,		/* control port */
-	Int0aux=	0x21,		/* everything else port */
-	Int1ctl=	0xA0,		/* control port */
-	Int1aux=	0xA1,		/* everything else port */
-
-	Intena=		0x20,		/* written to Intctlport, enables next int */
-
 	Int0vec=	16,		/* first interrupt vector used by the 8259 */
 	Clockvec=	Int0vec+0,	/* clock interrupts */
 	Kbdvec=		Int0vec+1,	/* keyboard interrupts */
 };
-#define	INT0ENABLE	outb(Int0ctl, Intena)
-#define	INT1ENABLE	outb(Int1ctl, Intena)
 
 /*
  *  8237 dma controllers
diff --git a/pc/main.c b/pc/main.c
index d83dd8d4349b14dbc56873cd0330d83570d57d5a..fbdff93b3b3aadb49fe9e4fe098016515e6d06c9 100644
--- a/pc/main.c
+++ b/pc/main.c
@@ -14,6 +14,7 @@ main(void)
 	mmuinit();
 	floppyinit();
 	spllo();
+	floppystart(0);
 	for(;;){
 		int c;
 
@@ -21,6 +22,11 @@ main(void)
 		if(c!=-1)
 			screenputc(c);
 		idle();
+		if((TK2SEC(m->ticks)%5)==0)
+			if((TK2SEC(m->ticks)%10)==0)
+				floppystop(0);
+			else
+				floppystart(0);
 	}
 }
 
@@ -62,7 +68,6 @@ panic(char *fmt, ...)
 	n = doprint(buf, buf+sizeof(buf), fmt, (&fmt+1)) - buf;
 	screenputs(buf, n);
 	screenputs("\n", 1);
-	INT0ENABLE;
 	spllo();
 	for(;;)
 		idle();
diff --git a/pc/mem.h b/pc/mem.h
index a0791e67b8a32c730aca3128539b665e1403df51..2e57b401bf0644e67ce39a4215406696ecb109b4 100644
--- a/pc/mem.h
+++ b/pc/mem.h
@@ -17,13 +17,12 @@
 
 /*
  * Time
- * Clock frequency is ??? HZ
  */
-#define	HZ		(18)			/* clock frequency */
-#define	MS2HZ		(54)			/* millisec per clock tick */
-#define	TK2SEC(t)	((t)*10/185)		/* ticks to seconds */
-#define	TK2MS(t)	((((ulong)(t))*10000)/185)	/* ticks to milliseconds */
-#define	MS2TK(t)	((((ulong)(t))*185)/10000)	/* milliseconds to ticks */
+#define	HZ		(20)			/* clock frequency */
+#define	MS2HZ		(1000/HZ)		/* millisec per clock tick */
+#define	TK2SEC(t)	((t)/HZ)		/* ticks to seconds */
+#define	TK2MS(t)	((((ulong)(t))*1000)/HZ)	/* ticks to milliseconds */
+#define	MS2TK(t)	((((ulong)(t))*HZ)/1000)	/* milliseconds to ticks */
 
 /*
  * Fundamental addresses
diff --git a/pc/trap.c b/pc/trap.c
index bc29fbb69aaac601dca4ac6b11b9e5a22739a12e..933efbb66d7a926c2c9db03088d2e830ccd4305b 100644
--- a/pc/trap.c
+++ b/pc/trap.c
@@ -6,6 +6,22 @@
 #include	"io.h"
 #include	"ureg.h"
 
+/*
+ *  8259 interrupt controllers
+ */
+enum
+{
+	Int0ctl=	0x20,		/* control port (ICW1, OCW2, OCW3) */
+	Int0aux=	0x21,		/* everything else (ICW2, ICW3, ICW4, OCW1) */
+	Int1ctl=	0xA0,		/* control port */
+	Int1aux=	0xA1,		/* everything else (ICW2, ICW3, ICW4, OCW1) */
+
+	EOI=		0x20,		/* non-specific end of interrupt */
+};
+
+int	int0mask = 7;		/* interrupts enabled for first 8259 */
+int	int1mask = 7;		/* interrupts enabled for second 8259 */
+
 /*
  *  trap/interrupt gates
  */
@@ -25,6 +41,14 @@ setvec(int v, void (*r)(Ureg*), int type)
 	ilt[v].d1 &= ~SEGTYPE;
 	ilt[v].d1 |= type;
 	ivec[v] = r;
+
+	/*
+	 *  enable corresponding interrupt in 8259
+	 */
+	if((v&~0x7) == Int0vec){
+		int0mask &= ~(1<<(v&7));
+		outb(Int0aux, int0mask);
+	}
 }
 
 /*
@@ -75,21 +99,18 @@ trapinit(void)
 	lidt(ilt, sizeof(ilt));
 
 	/*
-	 *  Set up the 8259 interrupt processor #1.
-	 *  Make 8259 interrupts starting at vector I8259vec.
-	 *
-	 *  N.B. This is all magic to me.  It comes from the 
-	 *	 IBM technical reference manual.  I just
-	 *	 changed the vector.
+	 *  Set up the first 8259 interrupt processor.
+	 *  Make 8259 interrupts start at CPU vector Int0vec.
+	 *  Set the 8259 as master with edge triggered
+	 *  input with fully nested interrupts.
 	 */
-	outb(Int0ctl, 0x11);		/* ICW1 - edge, master, ICW4 */
-	outb(Int0aux, Int0vec);		/* ICW2 - interrupt vector */
+	outb(Int0ctl, 0x11);		/* ICW1 - edge triggered, master,
+					   ICW4 will be sent */
+	outb(Int0aux, Int0vec);		/* ICW2 - interrupt vector offset */
 	outb(Int0aux, 0x04);		/* ICW3 - master level 2 */
-	outb(Int0aux, 0x01);		/* ICW4 - master, 8086 mode */
-	outb(Int0aux, 0x00);		/* mask - all enabled */
+	outb(Int0aux, 0x01);		/* ICW4 - 8086 mode, not buffered */
 }
 
-
 /*
  *  All traps
  */
@@ -98,6 +119,14 @@ trap(Ureg *ur)
 	if(ur->trap>=256 || ivec[ur->trap] == 0)
 		panic("bad trap type %d\n", ur->trap);
 
+	/*
+	 *  call the trap routine
+	 */
 	(*ivec[ur->trap])(ur);
-	INT0ENABLE;
+
+	/*
+	 *  tell the 8259 that we're done with the
+	 *  highest level interrupt
+	 */
+	outb(Int0ctl, EOI);
 }
diff --git a/port/fault.c b/port/fault.c
index d8ab9d52e4c16a4d7b6d0e8ae22b5a41f4d5729f..11084e93a33146371721812dbc8186c219fa4fc4 100644
--- a/port/fault.c
+++ b/port/fault.c
@@ -123,7 +123,7 @@ pio(Segment *s, ulong addr, ulong soff, Page **p)
 
 	loadrec = *p;
 	if(loadrec == 0) {
-		daddr = s->fstart+soff;			/* Compute disc address */
+		daddr = s->fstart+soff;		/* Compute disc address */
 		new = lookpage(s->image, daddr);
 	}
 	else {
@@ -133,7 +133,7 @@ pio(Segment *s, ulong addr, ulong soff, Page **p)
 			putswap(loadrec);
 	}
 
-	if(new) {			/* Page found from cache */
+	if(new) {				/* Page found from cache */
 		*p = new;
 		return;
 	}
diff --git a/port/sysproc.c b/port/sysproc.c
index a13019ebbbe1fea5ca58ffb4dda2bd6ab3e518a9..f5b2e92b679f502542e9cde766ca28ea8be26803 100644
--- a/port/sysproc.c
+++ b/port/sysproc.c
@@ -28,9 +28,7 @@ sysfork(ulong *arg)
 	KMap *k;
 	int n, on, i;
 	int lastvar;	/* used to compute stack address */
-	/*
-	 * Kernel stack
-	 */
+
 	p = newproc();
 
 	/* Page va of upage used as check in mapstack */
@@ -204,7 +202,7 @@ sysexec(ulong *arg)
 	 * Build the stack segment, putting it in kernel virtual for the moment
 	 */
 	if(spage > TSTKSIZ)
-		errors("not enough argument stack space");
+		errors("too many arguments");
 
 	 
 	p->seg[ESEG] = newseg(SG_STACK, TSTKTOP-USTKSIZE, USTKSIZE/BY2PG);
@@ -238,14 +236,10 @@ sysexec(ulong *arg)
 	/*
 	 * Committed.  Free old memory. Special segments are maintained accross exec
 	 */
-	putseg(p->seg[TSEG]);
-	p->seg[TSEG] = 0;	/* prevent a second free if we have an error */
-	putseg(p->seg[DSEG]);
-	p->seg[DSEG] = 0;
-	putseg(p->seg[BSEG]);
-	p->seg[BSEG] = 0;
-	putseg(p->seg[SSEG]);
-	p->seg[SSEG] = 0;
+	for(i = SSEG; i <= BSEG; i++) {
+		putseg(p->seg[i]);
+		p->seg[i] = 0;	    /* prevent a second free if we have an error */
+	}
 
 	/*
 	 * Close on exec
diff --git a/power/trap.c b/power/trap.c
index a3ebf1d1b7e552508faa1d8ebf00d9f0f2e9580f..02907cb49add127e49860ea25d917075663af37e 100644
--- a/power/trap.c
+++ b/power/trap.c
@@ -550,7 +550,6 @@ syscall(Ureg *aur)
 	}
 	ur->pc += 4;
 	u->nerrlab = 0;
-	
 	if(u->p->procctl)
 		procctl(u->p);
 
diff --git a/ss/trap.c b/ss/trap.c
index ac2804dbf5452b0e4895d328a5fb140c4f31af53..a692befe12d86ac85ef9aced5a720775b6ad5fd3 100644
--- a/ss/trap.c
+++ b/ss/trap.c
@@ -358,10 +358,10 @@ syscall(Ureg *aur)
 	ur->pc += 4;
 	ur->npc = ur->pc+4;
 	if(u->nerrlab){
-		print("unbalanced error stack: %d extra\n", u->nerrlab);
+		print("bad error stack [%d]: %d extra\n", r7, u->nerrlab);
 		for(i = 0; i < NERR; i++)
 			print("sp=%lux pc=%lux\n", u->errlab[i].sp, u->errlab[i].pc);
-		panic("bad rob");
+		panic("error stack");
 	}
 	u->p->insyscall = 0;
 	if(r7 == NOTED)	/* ugly hack */