Initial revision

1 files changed, 958 insertions, 0 deletions

diff --git a/gdb/ser-go32.c b/gdb/ser-go32.c
new file mode 100644
index 00000000000..f776161964a
--- /dev/null
+++ b/gdb/ser-go32.c
@@ -0,0 +1,958 @@
+/* Remote serial interface for local (hardwired) serial ports for
+   GO32.  Copyright 1992, 1993 Free Software Foundation, Inc.
+
+   Contributed by Nigel Stephens, Algorithmics Ltd. (nigel@algor.co.uk).
+
+   This version uses DPMI interrupts to handle buffered i/o 
+   without the separate "asynctsr" program.
+
+   This file is part of GDB.  
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
+
+#include "defs.h"
+#include "gdbcmd.h"
+#include "serial.h"
+
+
+/*
+ * NS16550 UART registers
+ */
+
+#define COM1ADDR	0x3f8
+#define COM2ADDR	0x2f8
+#define COM3ADDR	0x3e8
+#define COM4ADDR	0x3e0
+
+#define	com_data	0	/* data register (R/W) */
+#define	com_dlbl	0	/* divisor latch low (W) */
+#define	com_ier		1	/* interrupt enable (W) */
+#define	com_dlbh	1	/* divisor latch high (W) */
+#define	com_iir		2	/* interrupt identification (R) */
+#define	com_fifo	2	/* FIFO control (W) */
+#define	com_lctl	3	/* line control register (R/W) */
+#define	com_cfcr	3	/* line control register (R/W) */
+#define	com_mcr		4	/* modem control register (R/W) */
+#define	com_lsr		5	/* line status register (R/W) */
+#define	com_msr		6	/* modem status register (R/W) */
+
+/*
+ * Constants for computing 16 bit baud rate divisor (lower byte
+ * in com_dlbl, upper in com_dlbh) from 1.8432MHz crystal.  Divisor is
+ * 1.8432 MHz / (16 * X) for X bps.  If the baud rate can't be set
+ * to within +- (desired_rate*SPEED_TOLERANCE/1000) bps, we fail.
+ */
+#define COMTICK		(1843200/16)
+#define SPEED_TOLERANCE	30	/* thousandths; real == desired +- 3.0% */
+
+/* interrupt enable register */
+#define	IER_ERXRDY	0x1	/* int on rx ready */
+#define	IER_ETXRDY	0x2	/* int on tx ready */
+#define	IER_ERLS	0x4	/* int on line status change */
+#define	IER_EMSC	0x8	/* int on modem status change */
+
+/* interrupt identification register */
+#define	IIR_FIFO_MASK	0xc0	/* set if FIFOs are enabled */
+#define	IIR_IMASK	0xf	/* interrupt cause mask */
+#define	IIR_NOPEND	0x1	/* nothing pending */
+#define	IIR_RLS		0x6	/* receive line status */
+#define	IIR_RXRDY	0x4	/* receive ready */
+#define	IIR_RXTOUT	0xc	/* receive timeout */
+#define	IIR_TXRDY	0x2	/* transmit ready */
+#define	IIR_MLSC	0x0	/* modem status */
+
+
+/* fifo control register */
+#define	FIFO_ENABLE	0x01	/* enable fifo */
+#define	FIFO_RCV_RST	0x02	/* reset receive fifo */
+#define	FIFO_XMT_RST	0x04	/* reset transmit fifo */
+#define	FIFO_DMA_MODE	0x08	/* enable dma mode */
+#define	FIFO_TRIGGER_1	0x00	/* trigger at 1 char */
+#define	FIFO_TRIGGER_4	0x40	/* trigger at 4 chars */
+#define	FIFO_TRIGGER_8	0x80	/* trigger at 8 chars */
+#define	FIFO_TRIGGER_14	0xc0	/* trigger at 14 chars */
+
+/* character format control register */
+#define	CFCR_DLAB	0x80	/* divisor latch */
+#define	CFCR_SBREAK	0x40	/* send break */
+#define	CFCR_PZERO	0x30	/* zero parity */
+#define	CFCR_PONE	0x20	/* one parity */
+#define	CFCR_PEVEN	0x10	/* even parity */
+#define	CFCR_PODD	0x00	/* odd parity */
+#define	CFCR_PENAB	0x08	/* parity enable */
+#define	CFCR_STOPB	0x04	/* 2 stop bits */
+#define	CFCR_8BITS	0x03	/* 8 data bits */
+#define	CFCR_7BITS	0x02	/* 7 data bits */
+#define	CFCR_6BITS	0x01	/* 6 data bits */
+#define	CFCR_5BITS	0x00	/* 5 data bits */
+
+/* modem control register */
+#define	MCR_LOOPBACK	0x10	/* loopback */
+#define	MCR_IENABLE	0x08	/* output 2 = int enable */
+#define	MCR_DRS		0x04	/* output 1 = xxx */
+#define	MCR_RTS		0x02	/* enable RTS */
+#define	MCR_DTR		0x01	/* enable DTR */
+
+/* line status register */
+#define	LSR_RCV_FIFO	0x80	/* error in receive fifo */
+#define	LSR_TSRE	0x40	/* transmitter empty */
+#define	LSR_TXRDY	0x20	/* transmitter ready */
+#define	LSR_BI		0x10	/* break detected */
+#define	LSR_FE		0x08	/* framing error */
+#define	LSR_PE		0x04	/* parity error */
+#define	LSR_OE		0x02	/* overrun error */
+#define	LSR_RXRDY	0x01	/* receiver ready */
+#define	LSR_RCV_MASK	0x1f
+
+/* modem status register */
+#define	MSR_DCD		0x80
+#define	MSR_RI		0x40
+#define	MSR_DSR		0x20
+#define	MSR_CTS		0x10
+#define	MSR_DDCD	0x08
+#define	MSR_TERI	0x04
+#define	MSR_DDSR	0x02
+#define	MSR_DCTS	0x01
+
+#include <sys/dos.h>
+#include <sys/go32.h>
+#include <sys/dpmi.h>
+
+/* DPMI Communication */
+static union REGS dpmi_regs;
+static struct SREGS dpmi_sregs;
+
+/* 16550 rx fifo trigger point */
+#define FIFO_TRIGGER	FIFO_TRIGGER_4
+
+/* input buffer size */
+#define CBSIZE	4096
+
+/* return raw 18Hz clock count */
+extern long rawclock (void);
+
+#define RAWHZ	18
+
+#ifdef DOS_STATS
+#define CNT_RX		16
+#define CNT_TX		17
+#define CNT_STRAY	18
+#define CNT_ORUN	19
+#define NCNT		20
+
+static int	intrcnt;
+static int	cnts[NCNT];
+static char	*cntnames[NCNT] = {
+  /* h/w interrupt counts. */
+  "mlsc",	"nopend",	"txrdy",	"?3",
+  "rxrdy",	"?5",		"rls", 		"?7", 
+  "?8", 	"?9", 		"?a", 		"?b", 
+  "rxtout", 	"?d", 		"?e",		"?f", 
+  /* s/w counts. */
+  "rxcnt",	"txcnt",	"stray",	"swoflo"
+};
+
+#define COUNT(x) cnts[x]++
+#else
+#define COUNT(x) 
+#endif
+
+/* Main interrupt controller port addresses. */
+#define ICU_BASE	0x20
+#define ICU_OCW2	(ICU_BASE + 0)
+#define ICU_MASK	(ICU_BASE + 1)
+
+/* Original interrupt controller mask register. */
+unsigned char	icu_oldmask;
+
+/* Maximum of 8 interrupts (we don't handle the slave icu yet). */
+#define NINTR	8
+
+static struct intrupt
+{  
+  char			inuse;
+  struct dos_ttystate	*port;
+  _go32_dpmi_seginfo	old_rmhandler;
+  _go32_dpmi_seginfo	old_pmhandler;
+  _go32_dpmi_seginfo	new_rmhandler;
+  _go32_dpmi_seginfo	new_pmhandler;
+  _go32_dpmi_registers	regs;
+} intrupts[NINTR];
+
+
+static struct dos_ttystate
+{
+  int		base;
+  int		irq;
+  int		refcnt;
+  struct intrupt *intrupt;
+  int		fifo;
+  int		baudrate;
+  unsigned char	cbuf[CBSIZE];
+  unsigned int	first;
+  unsigned int	count;
+  int		txbusy;
+  unsigned char	old_mcr;
+  int		ferr;
+  int		perr;
+  int		oflo;
+  int		msr;
+} ports[4] = {
+  {COM1ADDR, 4}, 
+  {COM2ADDR, 3}, 
+  {COM3ADDR, 4}, 
+  {COM4ADDR, 3}
+};
+
+static int dos_open PARAMS ((serial_t scb, const char *name));
+static void dos_raw PARAMS ((serial_t scb));
+static int dos_readchar PARAMS ((serial_t scb, int timeout));
+static int dos_setbaudrate PARAMS ((serial_t scb, int rate));
+static int dos_write PARAMS ((serial_t scb, const char *str, int len));
+static void dos_close PARAMS ((serial_t scb));
+static serial_ttystate dos_get_tty_state PARAMS ((serial_t scb));
+static int dos_set_tty_state PARAMS ((serial_t scb, serial_ttystate state));
+static int dos_baudconv PARAMS ((int rate));
+
+#define inb(p,a)	inportb((p)->base + (a))
+#define outb(p,a,v)	outportb((p)->base + (a), (v))
+#define disable()	asm volatile ("cli");
+#define enable()	asm volatile ("sti");
+
+
+static int
+dos_getc (port)
+     volatile struct dos_ttystate *port;
+{
+    int c;
+
+    if (port->count == 0)
+      return -1;
+
+    c = port->cbuf[port->first];
+    disable ();
+    port->first = (port->first + 1) & (CBSIZE - 1);
+    port->count--;
+    enable ();
+    return c;
+}
+    
+
+static int 
+dos_putc (c, port)
+     int c;
+     struct dos_ttystate *port;
+{
+    if (port->count >= CBSIZE - 1)
+	return -1;
+    port->cbuf[(port->first + port->count) & (CBSIZE - 1)] = c;
+    port->count++;
+    return 0;
+}
+
+
+
+static void
+dos_comisr (irq)
+     int irq;
+{
+  struct dos_ttystate *port;
+  unsigned char iir, lsr, c;
+
+  disable ();			/* Paranoia */
+  outportb (ICU_OCW2, 0x20);	/* End-Of-Interrupt */
+#ifdef DOS_STATS
+  ++intrcnt;
+#endif
+
+  port = intrupts[irq].port;
+  if (!port) 
+    {
+      COUNT (CNT_STRAY);
+      return;		/* not open */
+    }
+
+  while (1)
+    {
+      iir = inb (port, com_iir) & IIR_IMASK;
+      switch (iir) 
+	{
+	  
+	case IIR_RLS:
+	  lsr = inb (port, com_lsr);
+	  goto rx;
+	  
+	case IIR_RXTOUT:
+	case IIR_RXRDY:
+	  lsr = 0;
+	  
+      rx:
+	  do 
+	    {
+	      c = inb (port, com_data);
+	      if (lsr & (LSR_BI | LSR_FE | LSR_PE | LSR_OE))
+		{
+		  if (lsr & (LSR_BI | LSR_FE))
+		    port->ferr++;
+		  else if (lsr & LSR_PE)
+		    port->perr++;
+		  if (lsr & LSR_OE)
+		    port->oflo++;
+		}
+
+	      if (dos_putc (c, port) < 0)
+		{
+		  COUNT (CNT_ORUN);
+		}
+	      else
+		{
+		  COUNT (CNT_RX);
+		}
+	    }
+	  while ((lsr = inb (port, com_lsr)) & LSR_RXRDY);
+	  break;
+	  
+	case IIR_MLSC:
+	  /* could be used to flowcontrol Tx */
+	  port->msr = inb (port, com_msr);
+	  break;
+	  
+	case IIR_TXRDY:
+	  port->txbusy = 0;
+	  break;
+
+	case IIR_NOPEND:
+	  /* no more pending interrupts, all done */
+	  return;
+
+	default:
+	  /* unexpected interrupt, ignore */
+	  break;
+	}
+      COUNT (iir);
+    } 
+}
+
+#ifdef __STDC__
+#define ISRNAME(x) dos_comisr##x
+#else
+#define ISRNAME(x) dos_comisr/**/x
+#endif
+#define ISR(x) static void ISRNAME(x)() {dos_comisr(x);}
+
+ISR(0) ISR(1) ISR(2) ISR(3)
+ISR(4) ISR(5) ISR(6) ISR(7)
+
+typedef void (*isr_t)();
+
+static isr_t isrs[NINTR] = {
+  ISRNAME(0), ISRNAME(1), ISRNAME(2), ISRNAME(3),
+  ISRNAME(4), ISRNAME(5), ISRNAME(6), ISRNAME(7)
+};
+
+
+
+static struct intrupt *
+dos_hookirq (irq)
+     unsigned int irq;
+{
+  struct intrupt *intr;
+  unsigned int vec;
+  isr_t isr;
+
+  if (irq >= NINTR)
+    return 0;
+
+  intr = &intrupts[irq];
+  if (intr->inuse)
+    return 0;
+  
+  vec = 0x08 + irq;
+  isr = isrs[irq];
+
+  /* setup real mode handler */
+  _go32_dpmi_get_real_mode_interrupt_vector (vec, &intr->old_rmhandler);
+
+  intr->new_rmhandler.pm_selector = _go32_my_cs();
+  intr->new_rmhandler.pm_offset = (u_long)isr;
+  if (_go32_dpmi_allocate_real_mode_callback_iret (&intr->new_rmhandler,
+						   &intr->regs))
+    {
+      return 0;
+    }
+
+  if (_go32_dpmi_set_real_mode_interrupt_vector (vec, &intr->new_rmhandler))
+    {
+      return 0;
+    }
+      
+  /* setup protected mode handler */
+  _go32_dpmi_get_protected_mode_interrupt_vector(vec, &intr->old_pmhandler);
+
+  intr->new_pmhandler.pm_selector = _go32_my_cs();
+  intr->new_pmhandler.pm_offset = (u_long)isr;
+  _go32_dpmi_allocate_iret_wrapper (&intr->new_pmhandler);
+
+  if (_go32_dpmi_set_protected_mode_interrupt_vector(vec, &intr->new_pmhandler))
+    {
+      return 0;
+    }
+
+  /* setup interrupt controller mask */
+  disable ();
+  outportb (ICU_MASK, inportb (ICU_MASK) & ~(1 << irq));
+  enable ();
+
+  intr->inuse = 1;
+  return intr;
+}
+
+
+static void
+dos_unhookirq (intr)
+     struct intrupt *intr;
+{
+  unsigned int irq, vec;
+  unsigned char mask;
+
+  irq = intr - intrupts;
+  vec = 0x08 + irq;
+
+  /* restore old interrupt mask bit */
+  mask = 1 << irq;
+  disable ();
+  outportb (ICU_MASK, inportb (ICU_MASK) | (mask & icu_oldmask));
+  enable ();
+
+  /* remove real mode handler */
+  _go32_dpmi_set_real_mode_interrupt_vector (vec, &intr->old_rmhandler);
+  _go32_dpmi_free_real_mode_callback (&intr->new_rmhandler);
+      
+  /* remove protected mode handler */
+  _go32_dpmi_set_protected_mode_interrupt_vector (vec, &intr->old_pmhandler);
+  _go32_dpmi_free_iret_wrapper (&intr->new_pmhandler);
+  intr->inuse = 0;
+}
+
+
+
+static int
+dos_open (scb, name)
+     serial_t scb;
+     const char *name;
+{
+  struct dos_ttystate *port;
+  int fd, i;
+
+  if (strncasecmp (name, "/dev/", 5) == 0)
+    name += 5;
+  else if (strncasecmp (name, "\\dev\\", 5) == 0)
+    name += 5;
+
+  if (strlen (name) != 4 || strncasecmp (name, "com", 3) != 0)
+    {
+      errno = ENOENT;
+      return -1;
+    }
+
+  if (name[3] < '1' || name[3] > '4')
+    {
+      errno = ENOENT;
+      return -1;
+    }
+
+  fd = name[3] - '1';
+  port = &ports[fd];
+  if (port->refcnt++ > 0)
+    {
+      /* Device already opened another user.  Just point at it. */
+      scb->fd = fd;
+      return 0;
+    }
+
+  /* force access to ID reg */
+  outb(port, com_cfcr, 0);
+  outb(port, com_iir, 0);
+  for (i = 0; i < 17; i++) {
+    if ((inb(port, com_iir) & 0x38) == 0)
+      goto ok;
+    (void) inb(port, com_data); /* clear recv */
+  }
+  errno = ENODEV;
+  return -1;
+
+ok:
+  /* disable all interrupts in chip */
+  outb(port, com_ier, 0);
+
+  /* tentatively enable 16550 fifo, and see if it responds */
+  outb(port, com_fifo, FIFO_ENABLE|FIFO_RCV_RST|FIFO_XMT_RST|FIFO_TRIGGER);
+  sleep(1);
+  port->fifo = ((inb(port, com_iir) & IIR_FIFO_MASK) == IIR_FIFO_MASK);
+
+  /* clear pending status reports. */
+  (void) inb(port, com_lsr);
+  (void) inb(port, com_msr);
+
+  /* enable external interrupt gate (to avoid floating IRQ) */
+  outb(port, com_mcr, MCR_IENABLE);
+
+  /* hook up interrupt handler and initialise icu */
+  port->intrupt = dos_hookirq (port->irq);
+  if (!port->intrupt)
+    {
+      outb(port, com_mcr, 0);
+      outb(port, com_fifo, 0);
+      errno = ENODEV;
+      return -1;
+    }
+
+  disable ();
+
+  /* record port */
+  port->intrupt->port = port; 
+  scb->fd = fd;
+
+  /* clear rx buffer, tx busy flag and overflow count */
+  port->first = port->count = 0;
+  port->txbusy = 0;
+  port->oflo = 0;
+
+  /* set default baud rate and mode: 9600,8,n,1 */
+  i = dos_baudconv (port->baudrate = 9600);
+  outb(port, com_cfcr, CFCR_DLAB);
+  outb(port, com_dlbl, i & 0xff);
+  outb(port, com_dlbh, i >> 8);
+  outb(port, com_cfcr, CFCR_8BITS);
+
+  /* enable all interrupts */
+  outb(port, com_ier, IER_ETXRDY | IER_ERXRDY | IER_ERLS | IER_EMSC);
+
+  /* enable DTR & RTS */
+  outb(port, com_mcr, MCR_DTR | MCR_RTS | MCR_IENABLE);
+
+  enable ();
+
+  return 0;
+}
+
+
+static void
+dos_close (scb)
+     serial_t scb;
+{
+    struct dos_ttystate *port;
+    struct intrupt *intrupt;
+
+    if (!scb)
+      return;
+
+    port = &ports[scb->fd];
+
+    if (port->refcnt-- > 1)
+      return;
+
+    if (!(intrupt = port->intrupt))
+      return;
+
+    /* disable interrupts, fifo, flow control */
+    disable ();
+    port->intrupt = 0;
+    intrupt->port = 0;
+    outb(port, com_fifo, 0);
+    outb(port, com_ier, 0);
+    enable ();
+
+    /* unhook handler, and disable interrupt gate */
+    dos_unhookirq (intrupt);
+    outb(port, com_mcr, 0);
+
+    /* Check for overflow errors */
+    if (port->oflo)
+      {
+	fprintf_unfiltered (gdb_stderr,
+			    "Serial input overruns occurred.\n");
+	fprintf_unfiltered (gdb_stderr, "This system %s handle %d baud.\n",
+			    port->fifo ? "cannot" : "needs a 16550 to",
+			    port->baudrate);
+      }
+}
+
+
+
+static int
+dos_noop (scb)
+     serial_t scb;
+{
+  return 0;
+}
+
+static void
+dos_raw (scb)
+     serial_t scb;
+{
+  /* Always in raw mode */
+}
+
+static int
+dos_readchar (scb, timeout)
+     serial_t scb;
+     int timeout;
+{
+  struct dos_ttystate *port = &ports[scb->fd];
+  long then;
+  int c;
+
+  then = rawclock() + (timeout * RAWHZ);
+  while ((c = dos_getc (port)) < 0)
+    {
+      if (timeout >= 0 && (rawclock () - then) >= 0)
+	return SERIAL_TIMEOUT;
+      notice_quit ();
+    }
+
+  return c;
+}
+
+
+static serial_ttystate
+dos_get_tty_state (scb)
+     serial_t scb;
+{
+  struct dos_ttystate *port = &ports[scb->fd];
+  struct dos_ttystate *state;
+
+  state = (struct dos_ttystate *) xmalloc (sizeof *state);
+  *state = *port;
+  return (serial_ttystate) state;
+}
+
+static int
+dos_set_tty_state (scb, ttystate)
+     serial_t scb;
+     serial_ttystate ttystate;
+{
+  struct dos_ttystate *state;
+
+  state = (struct dos_ttystate *) ttystate;
+  dos_setbaudrate (scb, state->baudrate);
+  return 0;
+}
+
+static int
+dos_noflush_set_tty_state (scb, new_ttystate, old_ttystate)
+     serial_t scb;
+     serial_ttystate new_ttystate;
+     serial_ttystate old_ttystate;
+{
+  struct dos_ttystate *state;
+
+  state = (struct dos_ttystate *) new_ttystate;
+  dos_setbaudrate (scb, state->baudrate);
+  return 0;
+}
+
+static int
+dos_flush_input (scb)
+     serial_t scb;
+{
+  struct dos_ttystate *port = &ports[scb->fd];
+  disable();
+  port->first = port->count = 0;
+  if (port->fifo)
+    outb(port, com_fifo, FIFO_ENABLE|FIFO_RCV_RST|FIFO_TRIGGER);
+  enable();
+}
+
+static void
+dos_print_tty_state (scb, ttystate)
+     serial_t scb;
+     serial_ttystate ttystate;
+{
+  /* Nothing to print */
+  return;
+}
+
+static int
+dos_baudconv (rate)
+     int rate;
+{
+  long x, err;
+  
+  if (rate <= 0) 
+    return -1;
+
+#define divrnd(n, q)	(((n) * 2 / (q) + 1) / 2) /* divide and round off */
+  x = divrnd(COMTICK, rate);
+  if (x <= 0)
+    return -1;
+  
+  err = divrnd(1000 * COMTICK, x * rate) - 1000;
+  if (err < 0)
+    err = -err;
+  if (err > SPEED_TOLERANCE)
+    return -1;
+#undef divrnd
+  return x;
+}
+
+
+static int
+dos_setbaudrate (scb, rate)
+     serial_t scb;
+     int rate;
+{
+    struct dos_ttystate *port = &ports[scb->fd];
+
+    if (port->baudrate != rate) 
+      {
+	int x;
+	unsigned char cfcr;
+
+	x = dos_baudconv (rate);
+	if (x <= 0)
+	  {
+	    fprintf_unfiltered (gdb_stderr, "%d: impossible baudrate\n", rate);
+	    errno = EINVAL;
+	    return -1;
+	  }
+
+	disable ();
+	cfcr = inb (port, com_cfcr);
+
+	outb(port, com_cfcr, CFCR_DLAB);
+	outb(port, com_dlbl, x & 0xff);
+	outb(port, com_dlbh, x >> 8);
+	outb(port, com_cfcr, cfcr);
+	port->baudrate = rate;
+	enable ();
+      }
+
+    return 0;
+}
+
+static int
+dos_setstopbits (scb, num)
+     serial_t scb;
+     int num;
+{
+    struct dos_ttystate *port = &ports[scb->fd];
+    unsigned char cfcr;
+
+    disable ();
+    cfcr = inb (port, com_cfcr);
+
+    switch (num)
+      {
+      case SERIAL_1_STOPBITS:
+	outb (port, com_cfcr, cfcr & ~CFCR_STOPB);
+	break;
+      case SERIAL_1_AND_A_HALF_STOPBITS:
+      case SERIAL_2_STOPBITS:
+	outb (port, com_cfcr, cfcr | CFCR_STOPB);
+	break;
+      default:
+	enable ();
+	return 1;
+      }
+    enable ();
+
+    return 0;
+}
+
+static int
+dos_write (scb, str, len)
+     serial_t scb;
+     const char *str;
+     int len;
+{
+  volatile struct dos_ttystate *port = &ports[scb->fd];
+  int fifosize = port->fifo ? 16 : 1;
+  long then;
+  int cnt;
+
+   while (len > 0) 
+     {
+	/* send the data, fifosize bytes at a time */
+	cnt = fifosize > len ? len : fifosize;
+	port->txbusy = 1;
+	outportsb (port->base + com_data, str, cnt);
+	str += cnt;
+	len -= cnt;
+#ifdef DOS_STATS
+	cnts[CNT_TX] += cnt;
+#endif
+	/* wait for transmission to complete (max 1 sec) */
+	then = rawclock() + RAWHZ;
+	while (port->txbusy)
+	  {
+	    if ((rawclock () - then) >= 0)
+	      {
+		  errno = EIO;
+		  return SERIAL_ERROR;
+	      }
+	  }
+    }
+  return 0;
+}
+
+
+static int
+dos_sendbreak (scb)
+     serial_t scb;
+{
+  volatile struct dos_ttystate *port = &ports[scb->fd];
+  unsigned char cfcr;
+  long then;
+
+  cfcr = inb(port, com_cfcr);
+  outb(port, com_cfcr, cfcr | CFCR_SBREAK);
+
+  /* 0.25 sec delay */
+  then = rawclock () + RAWHZ / 4;
+  while ((rawclock () - then) < 0)
+    continue;
+
+  outb(port, com_cfcr, cfcr);
+  return 0;
+}
+
+
+static struct serial_ops dos_ops =
+{
+  "hardwire",
+  0,
+  dos_open,
+  dos_close,
+  dos_readchar,
+  dos_write,
+  dos_noop,			/* flush output */
+  dos_flush_input,
+  dos_sendbreak,
+  dos_raw,
+  dos_get_tty_state,
+  dos_set_tty_state,
+  dos_print_tty_state,
+  dos_noflush_set_tty_state,
+  dos_setbaudrate,
+  dos_setstopbits,
+  dos_noop,			/* wait for output to drain */
+};
+
+
+static void
+dos_info (arg, from_tty)
+     char *arg;
+     int from_tty;
+{
+  struct dos_ttystate *port;
+  int i;
+
+  for (port = ports; port < &ports[4]; port++) 
+    {
+      if (port->baudrate == 0)
+	continue;
+      printf_filtered ("Port:\tCOM%d (%sactive)\n", port - ports + 1,
+		       port->intrupt ? "" : "not ");
+      printf_filtered ("Addr:\t0x%03x (irq %d)\n", port->base, port->irq);
+      printf_filtered ("16550:\t%s\n", port->fifo ? "yes" : "no");
+      printf_filtered ("Speed:\t%d baud\n", port->baudrate);
+      printf_filtered ("Errs:\tframing %d parity %d overflow %d\n\n", 
+		       port->ferr, port->perr, port->oflo);
+    }
+
+#ifdef DOS_STATS
+  printf_filtered ("\nTotal interrupts: %d\n", intrcnt);
+  for (i = 0; i < NCNT; i++)
+    if (cnts[i])
+      printf_filtered ("%s:\t%d\n", cntnames[i], cnts[i]);
+#endif
+}
+
+
+void
+_initialize_ser_dos ()
+{
+  struct cmd_list_element *c;
+
+  serial_add_interface (&dos_ops);
+
+  /* Save original interrupt mask register. */
+  icu_oldmask = inportb (ICU_MASK);
+
+  /* Mark fixed motherboard irqs as inuse. */
+  intrupts[0].inuse =		/* timer tick */
+    intrupts[1].inuse =		/* keyboard */
+      intrupts[2].inuse = 1;	/* slave icu */
+    
+  add_show_from_set (
+    add_set_cmd ("com1base", class_obscure, var_zinteger,
+		 (char *) &ports[0].base,
+		 "Set COM1 base i/o port address.",
+		 &setlist),
+	&showlist);
+
+  add_show_from_set (
+    add_set_cmd ("com1irq", class_obscure, var_zinteger,
+		 (char *) &ports[0].irq,
+		 "Set COM1 interrupt request.",
+		 &setlist),
+	&showlist);
+
+  add_show_from_set (
+    add_set_cmd ("com2base", class_obscure, var_zinteger,
+		 (char *) &ports[1].base,
+		 "Set COM2 base i/o port address.",
+		 &setlist),
+	&showlist);
+
+  add_show_from_set (
+    add_set_cmd ("com2irq", class_obscure, var_zinteger,
+		 (char *) &ports[1].irq,
+		 "Set COM2 interrupt request.",
+		 &setlist),
+	&showlist);
+
+  add_show_from_set (
+    add_set_cmd ("com3base", class_obscure, var_zinteger,
+		 (char *) &ports[2].base,
+		 "Set COM3 base i/o port address.",
+		 &setlist),
+	&showlist);
+
+  add_show_from_set (
+    add_set_cmd ("com3irq", class_obscure, var_zinteger,
+		 (char *) &ports[2].irq,
+		 "Set COM3 interrupt request.",
+		 &setlist),
+	&showlist);
+
+  add_show_from_set (
+    add_set_cmd ("com4base", class_obscure, var_zinteger,
+		 (char *) &ports[3].base,
+		 "Set COM4 base i/o port address.",
+		 &setlist),
+	&showlist);
+
+  add_show_from_set (
+    add_set_cmd ("com4irq", class_obscure, var_zinteger,
+		 (char *) &ports[3].irq,
+		 "Set COM4 interrupt request.",
+		 &setlist),
+	&showlist);
+
+  add_info ("serial", dos_info,
+	    "Print DOS serial port status.");
+}