Exemplo n.º 1
0
static void find_stack_direction()
{
	static char *addr = NULL;	/* Address of first `dummy', once known.  */
	auto char dummy;	/* To get stack address.  */

	if (addr == NULL) {	/* Initial entry.  */
		addr = ADDRESS_FUNCTION(dummy);

		find_stack_direction();	/* Recurse once.  */
	} else {
		/* Second entry.  */
		if (ADDRESS_FUNCTION(dummy) > addr)
			stack_dir = 1;	/* Stack grew upward.  */
		else
			stack_dir = -1;	/* Stack grew downward.  */
	}
}
Exemplo n.º 2
0
static void
find_stack_direction (/* void */)
{
  static char	*addr = NULL;	/* address of first
				   `dummy', once known */
  auto char	dummy;		/* to get stack address */

  if (addr == NULL)
    {				/* initial entry */
      addr = ADDRESS_FUNCTION(dummy);

      find_stack_direction ();	/* recurse once */
    }
  else				/* second entry */
    if (ADDRESS_FUNCTION(dummy) > addr)
      stack_dir = 1;		/* stack grew upward */
    else
      stack_dir = -1;		/* stack grew downward */
}
Exemplo n.º 3
0
Arquivo: alloca.c Projeto: 8l/csolve
static void
find_stack_direction (char **ptr)
{
  auto char dummy;              /* To get stack address.  */

  if (*ptr == NULL)
    {                           /* Initial entry.  */
      *ptr = ADDRESS_FUNCTION (dummy);

      find_stack_direction (ptr);  /* Recurse once.  */
    }
  else
    {
      /* Second entry.  */
      if (ADDRESS_FUNCTION (dummy) > *ptr)
        stack_dir = 1;          /* Stack grew upward.  */
      else
        stack_dir = -1;         /* Stack grew downward.  */
    }
}
Exemplo n.º 4
0
void *
alloca (unsigned size)
{
  auto char probe;		/* Probes stack depth: */
  register char *depth = ADDRESS_FUNCTION (probe);

#if STACK_DIRECTION == 0
  if (STACK_DIR == 0)		/* Unknown growth direction.  */
    find_stack_direction ();
#endif

  /* Reclaim garbage, defined as all alloca'd storage that
     was allocated from deeper in the stack than currently. */

  {
    register header *hp;	/* Traverses linked list.  */

    for (hp = last_alloca_header; hp != NULL;)
      if ((STACK_DIR > 0 && hp->h.deep > depth)
	  || (STACK_DIR < 0 && hp->h.deep < depth))
	{
	  register header *np = hp->h.next;

	  free ((void *) hp);	/* Collect garbage.  */

	  hp = np;		/* -> next header.  */
	}
      else
	break;			/* Rest are not deeper.  */

    last_alloca_header = hp;	/* -> last valid storage.  */
  }

  if (size == 0)
    return NULL;		/* No allocation required.  */

  /* Allocate combined header + user data storage.  */

  {
    register void * newptr = malloc (sizeof (header) + size);
    /* Address of header.  */

    ((header *) newptr)->h.next = last_alloca_header;
    ((header *) newptr)->h.deep = depth;

    last_alloca_header = (header *) newptr;

    /* User storage begins just after header.  */

    return (void *) ((char *) newptr + sizeof (header));
  }
}