/* Memory breakpoint operations for the remote server for GDB.
   Copyright (C) 2002, 2003, 2005, 2007, 2008 Free Software Foundation, Inc.

   Contributed by MontaVista Software.

   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 3 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, see <http://www.gnu.org/licenses/>.  */

#include "server.h"

const unsigned char *breakpoint_data;
int breakpoint_len;

#define MAX_BREAKPOINT_LEN 8

struct breakpoint
{
  struct breakpoint *next;
  CORE_ADDR pc;
  unsigned char old_data[MAX_BREAKPOINT_LEN];

  /* Non-zero iff we are stepping over this breakpoint.  */
  int reinserting;

  /* Non-NULL iff this breakpoint was inserted to step over
     another one.  Points to the other breakpoint (which is also
     in the *next chain somewhere).  */
  struct breakpoint *breakpoint_to_reinsert;

  /* Function to call when we hit this breakpoint.  If it returns 1,
     the breakpoint will be deleted; 0, it will be reinserted for
     another round.  */
  int (*handler) (CORE_ADDR);
};

struct breakpoint *breakpoints;

void
set_breakpoint_at (CORE_ADDR where, int (*handler) (CORE_ADDR))
{
  struct breakpoint *bp;

  if (breakpoint_data == NULL)
    error ("Target does not support breakpoints.");

  bp = malloc (sizeof (struct breakpoint));
  memset (bp, 0, sizeof (struct breakpoint));

  (*the_target->read_memory) (where, bp->old_data,
			      breakpoint_len);
  (*the_target->write_memory) (where, breakpoint_data,
			       breakpoint_len);

  bp->pc = where;
  bp->handler = handler;

  bp->next = breakpoints;
  breakpoints = bp;
}

static void
delete_breakpoint (struct breakpoint *bp)
{
  struct breakpoint *cur;

  if (breakpoints == bp)
    {
      breakpoints = bp->next;
      (*the_target->write_memory) (bp->pc, bp->old_data,
				   breakpoint_len);
      free (bp);
      return;
    }
  cur = breakpoints;
  while (cur->next)
    {
      if (cur->next == bp)
	{
	  cur->next = bp->next;
	  (*the_target->write_memory) (bp->pc, bp->old_data,
				       breakpoint_len);
	  free (bp);
	  return;
	}
    }
  warning ("Could not find breakpoint in list.");
}

static struct breakpoint *
find_breakpoint_at (CORE_ADDR where)
{
  struct breakpoint *bp = breakpoints;

  while (bp != NULL)
    {
      if (bp->pc == where)
	return bp;
      bp = bp->next;
    }

  return NULL;
}

void
delete_breakpoint_at (CORE_ADDR addr)
{
  struct breakpoint *bp = find_breakpoint_at (addr);
  if (bp != NULL)
    delete_breakpoint (bp);
}

static int
reinsert_breakpoint_handler (CORE_ADDR stop_pc)
{
  struct breakpoint *stop_bp, *orig_bp;

  stop_bp = find_breakpoint_at (stop_pc);
  if (stop_bp == NULL)
    error ("lost the stopping breakpoint.");

  orig_bp = stop_bp->breakpoint_to_reinsert;
  if (orig_bp == NULL)
    error ("no breakpoint to reinsert");

  (*the_target->write_memory) (orig_bp->pc, breakpoint_data,
			       breakpoint_len);
  orig_bp->reinserting = 0;
  return 1;
}

void
reinsert_breakpoint_by_bp (CORE_ADDR stop_pc, CORE_ADDR stop_at)
{
  struct breakpoint *bp, *orig_bp;

  orig_bp = find_breakpoint_at (stop_pc);
  if (orig_bp == NULL)
    error ("Could not find original breakpoint in list.");

  set_breakpoint_at (stop_at, reinsert_breakpoint_handler);

  bp = find_breakpoint_at (stop_at);
  if (bp == NULL)
    error ("Could not find breakpoint in list (reinserting by breakpoint).");
  bp->breakpoint_to_reinsert = orig_bp;

  (*the_target->write_memory) (orig_bp->pc, orig_bp->old_data,
			       breakpoint_len);
  orig_bp->reinserting = 1;
}

void
uninsert_breakpoint (CORE_ADDR stopped_at)
{
  struct breakpoint *bp;

  bp = find_breakpoint_at (stopped_at);
  if (bp == NULL)
    error ("Could not find breakpoint in list (uninserting).");

  (*the_target->write_memory) (bp->pc, bp->old_data,
			       breakpoint_len);
  bp->reinserting = 1;
}

void
reinsert_breakpoint (CORE_ADDR stopped_at)
{
  struct breakpoint *bp;

  bp = find_breakpoint_at (stopped_at);
  if (bp == NULL)
    error ("Could not find breakpoint in list (uninserting).");
  if (! bp->reinserting)
    error ("Breakpoint already inserted at reinsert time.");

  (*the_target->write_memory) (bp->pc, breakpoint_data,
			       breakpoint_len);
  bp->reinserting = 0;
}

int
check_breakpoints (CORE_ADDR stop_pc)
{
  struct breakpoint *bp;

  bp = find_breakpoint_at (stop_pc);
  if (bp == NULL)
    return 0;
  if (bp->reinserting)
    {
      warning ("Hit a removed breakpoint?");
      return 0;
    }

  if ((*bp->handler) (bp->pc))
    {
      delete_breakpoint (bp);
      return 2;
    }
  else
    return 1;
}

void
set_breakpoint_data (const unsigned char *bp_data, int bp_len)
{
  breakpoint_data = bp_data;
  breakpoint_len = bp_len;
}

void
check_mem_read (CORE_ADDR mem_addr, unsigned char *buf, int mem_len)
{
  struct breakpoint *bp = breakpoints;
  CORE_ADDR mem_end = mem_addr + mem_len;

  for (; bp != NULL; bp = bp->next)
    {
      CORE_ADDR bp_end = bp->pc + breakpoint_len;
      CORE_ADDR start, end;
      int copy_offset, copy_len, buf_offset;

      if (mem_addr >= bp_end)
	continue;
      if (bp->pc >= mem_end)
	continue;

      start = bp->pc;
      if (mem_addr > start)
	start = mem_addr;

      end = bp_end;
      if (end > mem_end)
	end = mem_end;

      copy_len = end - start;
      copy_offset = start - bp->pc;
      buf_offset = start - mem_addr;

      memcpy (buf + buf_offset, bp->old_data + copy_offset, copy_len);
    }
}

void
check_mem_write (CORE_ADDR mem_addr, unsigned char *buf, int mem_len)
{
  struct breakpoint *bp = breakpoints;
  CORE_ADDR mem_end = mem_addr + mem_len;

  for (; bp != NULL; bp = bp->next)
    {
      CORE_ADDR bp_end = bp->pc + breakpoint_len;
      CORE_ADDR start, end;
      int copy_offset, copy_len, buf_offset;

      if (mem_addr >= bp_end)
	continue;
      if (bp->pc >= mem_end)
	continue;

      start = bp->pc;
      if (mem_addr > start)
	start = mem_addr;

      end = bp_end;
      if (end > mem_end)
	end = mem_end;

      copy_len = end - start;
      copy_offset = start - bp->pc;
      buf_offset = start - mem_addr;

      memcpy (bp->old_data + copy_offset, buf + buf_offset, copy_len);
      if (bp->reinserting == 0)
	memcpy (buf + buf_offset, breakpoint_data + copy_offset, copy_len);
    }
}

/* Delete all breakpoints.  */

void
delete_all_breakpoints (void)
{
  while (breakpoints)
    delete_breakpoint (breakpoints);
}