path: root/gdb/remote.c

/* Memory-access and commands for inferior process, for GDB.
   Copyright (C)  1988 Free Software Foundation, Inc.

GDB is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY.  No author or distributor accepts responsibility to anyone
for the consequences of using it or for whether it serves any
particular purpose or works at all, unless he says so in writing.
Refer to the GDB General Public License for full details.

Everyone is granted permission to copy, modify and redistribute GDB,
but only under the conditions described in the GDB General Public
License.  A copy of this license is supposed to have been given to you
along with GDB so you can know your rights and responsibilities.  It
should be in a file named COPYING.  Among other things, the copyright
notice and this notice must be preserved on all copies.

In other words, go ahead and share GDB, but don't try to stop
anyone else from sharing it farther.  Help stamp out software hoarding!
*/

/* Remote communication protocol.
   All values are encoded in ascii hex digits.

	Request		Packet

	read registers  g
	reply		XX....X		Each byte of register data
					is described by two hex digits.
					Registers are in the internal order
					for GDB, and the bytes in a register
					are in the same order the machine uses.
			or ENN		for an error.

	write regs	GXX..XX		Each byte of register data
					is described by two hex digits.
	reply		OK		for success
			ENN		for an error

	read mem	mAA..AA,LLLL	AA..AA is address, LLLL is length.
	reply		XX..XX		XX..XX is mem contents
			or ENN		NN is errno

	write mem	MAA..AA,LLLL:XX..XX
					AA..AA is address,
					LLLL is number of bytes,
					XX..XX is data
	reply		OK		for success
			ENN		for an error

	cont		cAA..AA		AA..AA is address to resume
					If AA..AA is omitted,
					resume at same address.

	step		sAA..AA		AA..AA is address to resume
					If AA..AA is omitted,
					resume at same address.

	There is no immediate reply to step or cont.
	The reply comes when the machine stops.
	It is		SAA		AA is the "signal number"

	kill req	k
*/

#include <stdio.h>
#include <signal.h>

#include "defs.h"
#include "initialize.h"
#include "param.h"
#include "frame.h"
#include "inferior.h"

#include <sys/wait.h>
#include <sys/ioctl.h>
#include <a.out.h>
#include <sys/file.h>
#include <sgtty.h>

int kiodebug;

int icache;

/* Descriptor for I/O to remote machine.  */
int remote_desc;

#define	PBUFSIZ	300

static void remote_send ();
static void putpkt ();
static void getpkt ();
static void dcache_flush ();

START_FILE

/* Open a connection to a remote debugger.
   NAME is the filename used for communication.  */

void
remote_open (name, from_tty)
     char *name;
     int from_tty;
{
  struct sgttyb sg;

  remote_debugging = 0;
  dcache_init ();

  remote_desc = open (name, O_RDWR);
  if (remote_desc < 0)
    perror_with_name (name);

  ioctl (remote_desc, TIOCGETP, &sg);
  sg.sg_flags = RAW;
  ioctl (remote_desc, TIOCSETP, &sg);

  if (from_tty)
    printf ("Remote debugging using %s\n", name);
  remote_debugging = 1;
}

/* Convert hex digit A to a number.  */

static int
fromhex (a)
     int a;
{
  if (a >= '0' && a <= '9')
    return a - '0';
  else if (a >= 'a' && a <= 'f')
    return a - 'a' + 10;
  else
    error ("Reply contains invalid hex digit");
}

/* Convert number NIB to a hex digit.  */

static int
tohex (nib)
     int nib;
{
  if (nib < 10)
    return '0'+nib;
  else
    return 'a'+nib-10;
}

/* Tell the remote machine to resume.  */

int
remote_resume (step, signal)
     int step, signal;
{
  char buf[PBUFSIZ];

  dcache_flush ();

  strcpy (buf, step ? "s": "c");

  putpkt (buf);
}

/* Wait until the remote machine stops, then return,
   storing status in STATUS just as `wait' would.  */

int
remote_wait (status)
     union wait *status;
{
  char buf[PBUFSIZ];

  status->w_status = 0;
  getpkt (buf);
  if (buf[0] == 'E')
    error ("Remote failure reply: %s", buf);
  if (buf[0] != 'S')
    error ("Invalid remote reply: %s", buf);
  status->w_stopval = WSTOPPED;
  status->w_stopsig = (fromhex (buf[1]) << 4) + fromhex (buf[2]);
}

/* Read the remote registers into the block REGS.  */

void
remote_fetch_registers (regs)
     char *regs;
{
  char buf[PBUFSIZ];
  int i;
  char *p;

  sprintf (buf, "g");
  remote_send (buf);

  /* Reply describes registers byte by byte,
     each byte encoded as two hex characters.  */

  p = buf;
  for (i = 0; i < REGISTER_BYTES; i++)
    {
      if (p[0] == 0 || p[1] == 0)
	error ("Remote reply is too short: %s", buf);
      regs[i] = fromhex (p[0]) * 16 + fromhex (p[1]);
      p += 2;
    }
}

/* Store the remote registers from the contents of the block REGS.  */

void
remote_store_registers (regs)
     char *regs;
{
  char buf[PBUFSIZ];
  int i;
  char *p;

  buf[0] = 'G';
  
  /* Command describes registers byte by byte,
     each byte encoded as two hex characters.  */

  p = buf + 1;
  for (i = 0; i < REGISTER_BYTES; i++)
    {
      *p++ = (regs[i] > 4) & 0xf;
      *p++ = regs[i] & 0xf;
    }

  remote_send (buf);
}

/* Read a word from remote address ADDR and return it.
   This goes through the data cache.  */

int
remote_fetch_word (addr)
     CORE_ADDR addr;
{
  if (icache)
    {
      extern CORE_ADDR text_start, text_end;

      if (addr >= text_start && addr < text_end)
	{
	  int buffer;
	  xfer_core_file (addr, &buffer, sizeof (int));
	  return buffer;
	}
    }
  return dcache_fetch (addr);
}

/* Write a word WORD into remote address ADDR.
   This goes through the data cache.  */

void
remote_store_word (addr, word)
     CORE_ADDR addr;
     int word;
{
  dcache_poke (addr, word);
}

/* Write memory data directly to the remote machine.
   This does not inform the data cache; the data cache uses this.
   MEMADDR is the address in the remote memory space.
   MYADDR is the address of the buffer in our space.
   LEN is the number of bytes.  */

void
remote_write_bytes (memaddr, myaddr, len)
     CORE_ADDR memaddr;
     char *myaddr;
     int len;
{
  char buf[PBUFSIZ];
  int i;
  char *p;

  if (len > PBUFSIZ / 2 - 20)
    abort ();

  sprintf (buf, "M%x,%x:", memaddr, len);

  /* Command describes registers byte by byte,
     each byte encoded as two hex characters.  */

  p = buf + strlen (buf);
  for (i = 0; i < len; i++)
    {
      *p++ = (myaddr[i] > 4) & 0xf;
      *p++ = myaddr[i] & 0xf;
    }

  remote_send (buf);
}

/* Read memory data directly from the remote machine.
   This does not use the data cache; the data cache uses this.
   MEMADDR is the address in the remote memory space.
   MYADDR is the address of the buffer in our space.
   LEN is the number of bytes.  */

void
remote_read_bytes (memaddr, myaddr, len)
     CORE_ADDR memaddr;
     char *myaddr;
     int len;
{
  char buf[PBUFSIZ];
  int i;
  char *p;

  if (len > PBUFSIZ / 2 - 1)
    abort ();

  sprintf (buf, "m%x,%x", memaddr, len);
  remote_send (buf);

  /* Reply describes registers byte by byte,
     each byte encoded as two hex characters.  */

  p = buf;
  for (i = 0; i < REGISTER_BYTES; i++)
    {
      if (p[0] == 0 || p[1] == 0)
	error ("Remote reply is too short: %s", buf);
      myaddr[i] = fromhex (p[0]) * 16 + fromhex (p[1]);
      p += 2;
    }
}

/*

A debug packet whose contents are <data>
is encapsulated for transmission in the form:

	$ <data> # CSUM1 CSUM2

	<data> must be ASCII alphanumeric and cannot include characters
	'$' or '#'

	CSUM1 and CSUM2 are ascii hex representation of an 8-bit 
	checksum of <data>, the most significant nibble is sent first.
	the hex digits 0-9,a-f are used.

Receiver responds with:

	+	- if CSUM is correct and ready for next packet
	-	- if CSUM is incorrect

*/

/* Send the command in BUF to the remote machine,
   and read the reply into BUF.
   Report an error if we get an error reply.  */

static void
remote_send (buf)
     char *buf;
{
  int i;
  putpkt (buf);
  getpkt (buf);

  if (buf[0] == 'E')
    error ("Remote failure reply: %s", buf);
}

/* Send a packet to the remote machine, with error checking.
   The data of the packet is in BUF.  */

static void
putpkt (buf)
     char *buf;
{
  int i;
  char csum = 0;
  char buf2[500];
  char buf3[1];
  int cnt = strlen (buf);
  char *p;

  if (kiodebug)
    fprintf (stderr, "Sending packet: %s\n", buf);

  /* Copy the packet into buffer BUF2, encapsulating it
     and giving it a checksum.  */

  p = buf2;
  *p++ = '$';

  for (i = 0; i < cnt; i++)
    {
      csum += buf[i];
      *p++ = buf[i];
    }
  *p++ = '#';
  *p++ = tohex ((csum >> 4) & 0xf);
  *p++ = tohex (csum & 0xf);

  /* Send it over and over until we get a positive ack.  */

  do {
    write (remote_desc, buf2, p - buf2);
    read (remote_desc, buf3, 1);
  } while (buf3[0] != '+');
}

static int
readchar ()
{
  char buf[1];
  while (read (remote_desc, buf, 1) != 1) ;
  return buf[0] & 0x7f;
}

/* Read a packet from the remote machine, with error checking,
   and store it in BUF.  */

static void
getpkt (buf)
     char *buf;
{
  char *bp;
  char csum = 0;
  int c, c1, c2;
  extern kiodebug;

  while (1)
    {
      while ((c = readchar()) != '$');

      bp = buf;
      while (1)
	{
	  c = readchar ();
	  if (c == '#')
	    break;
	  *bp++ = c;
	  csum += c;
	}
      *bp = 0;

      c1 = fromhex (readchar ());
      c2 = fromhex (readchar ());
      if (csum == (c1 << 4) + c2)
	break;
      printf ("Bad checksum, sentsum=0x%x, csum=0x%x, buf=%s\n",
	      (c1 << 4) + c2, csum, buf);
      write (remote_desc, "-", 1);
    }

  write (remote_desc, "+", 1);

  if (kiodebug)
    fprintf (stderr,"Packet received :%s\n", buf);
}

/* The data cache records all the data read from the remote machine
   since the last time it stopped.

   Each cache block holds 16 bytes of data
   starting at a multiple-of-16 address.  */

#define DCACHE_SIZE 64		/* Number of cache blocks */

struct dcache_block {
	struct dcache_block *next, *last;
	unsigned int addr;	/* Address for which data is recorded.  */
	int data[4];
};

struct dcache_block dcache_free, dcache_valid;

/* Free all the data cache blocks, thus discarding all cached data.  */ 

static void
dcache_flush ()
{
  register struct dcache_block *db;

  while ((db = dcache_valid.next) != &dcache_valid)
    {
      remque (db);
      insque (db, &dcache_free);
    }
}

/*
 * If addr is present in the dcache, return the address of the block 
 * containing it.
 */

struct dcache_block *
dcache_hit (addr)
{
  register struct dcache_block *db;

  if (addr & 3)
    abort ();

  /* Search all cache blocks for one that is at this address.  */
  db = dcache_valid.next;
  while (db != &dcache_valid)
    {
      if ((addr & 0xfffffff0) == db->addr)
	return db;
      db = db->next;
    }
  return NULL;
}

/*  Return the int data at address ADDR in dcache block DC.  */

int
dcache_value (db, addr)
     struct dcache_block *db;
     unsigned int addr;
{
  if (addr & 3)
    abort ();
  return (db->data[(addr>>2)&3]);
}

/* Get a free cache block, put it on the valid list,
   and return its address.  The caller should store into the block
   the address and data that it describes.  */

struct dcache_block *
dcache_alloc ()
{
  register struct dcache_block *db;

  if ((db = dcache_free.next) == &dcache_free)
    /* If we can't get one from the free list, take last valid */
    db = dcache_valid.last;

  remque (db);
  insque (db, &dcache_valid);
  return (db);
}

/* Return the contents of the word at address ADDR in the remote machine,
   using the data cache.  */

int
dcache_fetch (addr)
     CORE_ADDR addr;
{
  register struct dcache_block *db;

  db = dcache_hit (addr);
  if (db == 0)
    {
      db = dcache_alloc ();
      remote_read_bytes (addr & ~0xf, db->data, 16);
      db->addr = addr & ~0xf;
    }
  return (dcache_value (db, addr));
}

/* Write the word at ADDR both in the data cache and in the remote machine.  */

dcache_poke (addr, data)
     CORE_ADDR addr;
     int data;
{
  register struct dcache_block *db;

  /* First make sure the word is IN the cache.  DB is its cache block.  */
  db = dcache_hit (addr);
  if (db == 0)
    {
      db = dcache_alloc ();
      remote_read_bytes (addr & ~0xf, db->data, 16);
      db->addr = addr & ~0xf;
    }

  /* Modify the word in the cache.  */
  db->data[(addr>>2)&3] = data;

  /* Send the changed word.  */
  remote_write_bytes (addr, &data, 4);
}

/* Initialize the data cache.  */

dcache_init ()
{
  register i;
  register struct dcache_block *db;

  db = (struct dcache_block *) xmalloc (sizeof (struct dcache_block) * 
					DCACHE_SIZE);
  dcache_free.next = dcache_free.last = &dcache_free;
  dcache_valid.next = dcache_valid.last = &dcache_valid;
  for (i=0;i<DCACHE_SIZE;i++,db++)
    insque (db, &dcache_free);
}

static initialize ()
{
}

END_FILE