binutils-gdb/gdb/ser-go32.c

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/* 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
1995-08-02 11:41:12 +08:00
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.");
}