/* old_eh.c
   Extracted from libgcc2.c and modified by Eberhard Mattes, Jul 1995 */

/* Copyright (C) 1989, 1992, 1993, 1994, 1995 Free Software Foundation, Inc.

This file is part of GNU CC.

GNU CC 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, or (at your option)
any later version.

GNU CC 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 GNU CC; see the file COPYING.  If not, write to
the Free Software Foundation, 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */

/* As a special exception, if you link this library with other files,
   some of which are compiled with GCC, to produce an executable,
   this library does not by itself cause the resulting executable
   to be covered by the GNU General Public License.
   This exception does not however invalidate any other reasons why
   the executable file might be covered by the GNU General Public License.  */


#include <stdlib.h>

typedef struct {
  void *start;
  void *end;
  void *exception_handler;
} exception_table;

struct exception_table_node {
  exception_table *table;
  void *start;
  void *end;
  struct exception_table_node *next;
};

static int except_table_pos;
static void *except_pc;
static struct exception_table_node *exception_table_list;

static exception_table *
find_exception_table (pc)
     void* pc;
{
  register struct exception_table_node *table = exception_table_list;
  for ( ; table != 0; table = table->next)
    {
      if (table->start <= pc && table->end > pc)
	return table->table;
    }
  return 0;
}

/* this routine takes a pc, and the address of the exception handler associated
   with the closest exception table handler entry associated with that PC,
   or 0 if there are no table entries the PC fits in.  The algorithm works
   something like this:

    while(current_entry exists) {
        if(current_entry.start < pc )
            current_entry = next_entry;
        else {
            if(prev_entry.start <= pc && prev_entry.end > pc) {
                save pointer to prev_entry;
                return prev_entry.exception_handler;
             }
            else return 0;
         }
     }
    return 0;

   Assuming a correctly sorted table (ascending order) this routine should
   return the tightest match...

   In the advent of a tie, we have to give the last entry, as it represents
   an inner block.
 */


void *
__find_first_exception_table_match(pc)
void *pc;
{
  exception_table *table = find_exception_table (pc);
  int pos = 0;
  int best = 0;
  if (table == 0)
    return (void*)0;
#if 0
  printf("find_first_exception_table_match(): pc = %x!\n",pc);
#endif

  except_pc = pc;

#if 0
  /* We can't do this yet, as we don't know that the table is sorted.  */
  do {
    ++pos;
    if (table[pos].start > except_pc)
      /* found the first table[pos].start > except_pc, so the previous
	 entry better be the one we want! */
      break;
  } while(table[pos].exception_handler != (void*)-1);

  --pos;
  if (table[pos].start <= except_pc && table[pos].end > except_pc)
    {
      except_table_pos = pos;
#if 0
      printf("find_first_eh_table_match(): found match: %x\n",table[pos].exception_handler);
#endif
      return table[pos].exception_handler;
    }
#else
  while (table[++pos].exception_handler != (void*)-1) {
    if (table[pos].start <= except_pc && table[pos].end > except_pc)
      {
	/* This can apply.  Make sure it is better or as good as the previous
	   best.  */
	/* The best one ends first. */
	if (best == 0 || (table[pos].end <= table[best].end
			  /* The best one starts last.  */
			  && table[pos].start >= table[best].start))
	  best = pos;
      }
  }
  if (best != 0)
    return table[best].exception_handler;
#endif

#if 0
  printf("find_first_eh_table_match(): else: returning NULL!\n");
#endif
  return (void*)0;
}

#ifndef EMX     /* Also defined in gcc/eh.c */
void *
__throw_type_match (void *catch_type, void *throw_type, void* obj)
{
#if 0
 printf("__throw_type_match (): catch_type = %s, throw_type = %s\n",
	catch_type, throw_type);
#endif
 if (strcmp ((const char *)catch_type, (const char *)throw_type) == 0)
   return obj;
 return 0;
}
#endif

void
__register_exceptions (exception_table *table)
{
  struct exception_table_node *node;
  exception_table *range = table + 1;

  if (range->start == (void*)-1)
    return;

  node = (struct exception_table_node*)
    malloc (sizeof (struct exception_table_node));
  node->table = table;

  /* This look can be optimized away either if the table
     is sorted, or if we pass in extra parameters. */
  node->start = range->start;
  node->end = range->end;
  for (range++ ; range->start != (void*)(-1); range++)
    {
      if (range->start < node->start)
	node->start = range->start;
      if (range->end > node->end)
	node->end = range->end;
    }

  node->next = exception_table_list;
  exception_table_list = node;
}

#if #machine(i386)
void
__unwind_function(void *ptr)
{
  asm("movl 8(%esp),%ecx");
  /* Undo current frame */
  asm("movl %ebp,%esp");
  asm("popl %ebp");
  /* like ret, but stay here */
  asm("addl $4,%esp");
  
  /* Now, undo previous frame. */
  /* This is a test routine, as we have to dynamically probe to find out
     what to pop for certain, this is just a guess. */
  asm("leal -16(%ebp),%esp");
  asm("pop %ebx");
  asm("pop %esi");
  asm("pop %edi");
  asm("movl %ebp,%esp");
  asm("popl %ebp");

  asm("movl %ecx,0(%esp)");
  asm("ret");
}
#elif #machine(rs6000)
__unwind_function(void *ptr)
{
  asm("mr 31,1");
  asm("l 1,0(1)");
  asm("l 31,-4(1)");
  asm("# br");

  asm("mr 31,1");
  asm("l 1,0(1)");
  /* use 31 as a scratch register to restore the link register. */
  asm("l 31, 8(1);mtlr 31 # l lr,8(1)");
  asm("l 31,-4(1)");
  asm("# br");
  asm("mtctr 3;bctr # b 3");
}
#elif #machine(powerpc)
__unwind_function(void *ptr)
{
  asm("mr 31,1");
  asm("lwz 1,0(1)");
  asm("lwz 31,-4(1)");
  asm("# br");

  asm("mr 31,1");
  asm("lwz 1,0(1)");
  /* use 31 as a scratch register to restore the link register. */
  asm("lwz 31, 8(1);mtlr 31 # l lr,8(1)");
  asm("lwz 31,-4(1)");
  asm("# br");
  asm("mtctr 3;bctr # b 3");
}
#elif #machine(vax)
__unwind_function(void *ptr)
{
  __label__ return_again;

  /* Replace our frame's return address with the label below.
     During execution, we will first return here instead of to
     caller, then second return takes caller's frame off the stack.
     Two returns matches two actual calls, so is less likely to
     confuse debuggers.  `16' corresponds to RETURN_ADDRESS_OFFSET.  */
  __asm ("movl %0,16(fp)" : : "p" (&& return_again));
  return;

 return_again:
  return;
}
#else
__unwind_function(void *ptr)
{
  abort ();
}
#endif /* powerpc */