stab.c

<B>Digital的Unix操作系统VAX 4.2源码</B>

#ifndef lint
static	char	*sccsid = "@(#)stab.c	4.1	(ULTRIX)	7/2/90";
#endif lint

/************************************************************************
 *									*
 *			Copyright (c) 1987 by				*
 *		Digital Equipment Corporation, Maynard, MA		*
 *			All rights reserved.				*
 *									*
 *   This software is furnished under a license and may be used and	*
 *   copied  only  in accordance with the terms of such license and	*
 *   with the  inclusion  of  the  above  copyright  notice.   This	*
 *   software  or  any  other copies thereof may not be provided or	*
 *   otherwise made available to any other person.  No title to and	*
 *   ownership of the software is hereby transferred.			*
 *									*
 *   This software is  derived  from  software  received  from  the	*
 *   University    of   California,   Berkeley,   and   from   Bell	*
 *   Laboratories.  Use, duplication, or disclosure is  subject  to	*
 *   restrictions  under  license  agreements  with  University  of	*
 *   California and with AT&T.						*
 *									*
 *   The information in this software is subject to change  without	*
 *   notice  and should not be construed as a commitment by Digital	*
 *   Equipment Corporation.						*
 *									*
 *   Digital assumes no responsibility for the use  or  reliability	*
 *   of its software on equipment which is not supplied by Digital.	*
 *									*
 ************************************************************************/

# include "sendmail.h"

/*
**  STAB -- manage the symbol table
**
**	Parameters:
**		name -- the name to be looked up or inserted.
**		type -- the type of symbol.
**		op -- what to do:
**			ST_ENTER -- enter the name if not
**				already present.
**			ST_FIND -- find it only.
**
**	Returns:
**		pointer to a STAB entry for this name.
**		NULL if not found and not entered.
**
**	Side Effects:
**		can update the symbol table.
*/

# define STABSIZE	400

static STAB	*SymTab[STABSIZE];

STAB *
stab(name, type, op)
	char *name;
	int type;
	int op;
{
	register STAB *s;
	register STAB **ps;
	extern bool sameword();
	register int hfunc;
	register char *p;
	extern char lower();

# ifdef DEBUG
	if (tTd(36, 5))
		printf("STAB: %s %d ", name, type);
# endif DEBUG

	/*
	**  Compute the hashing function
	**
	**	We could probably do better....
	*/

	hfunc = type;
	for (p = name; *p != '\0'; p++)
		hfunc = (((hfunc << 7) | lower(*p)) & 077777) % STABSIZE;

# ifdef DEBUG
	if (tTd(36, 9))
		printf("(hfunc=%d) ", hfunc);
# endif DEBUG

	ps = &SymTab[hfunc];
	while ((s = *ps) != NULL && (!sameword(name, s->s_name) || s->s_type != type))
		ps = &s->s_next;

	/*
	**  Dispose of the entry.
	*/

	if (s != NULL || op == ST_FIND)
	{
# ifdef DEBUG
		if (tTd(36, 5))
		{
			if (s == NULL)
				printf("not found\n");
			else
			{
				long *lp = (long *) s->s_class;

				printf("type %d val %lx %lx %lx %lx\n",
					s->s_type, lp[0], lp[1], lp[2], lp[3]);
			}
		}
# endif DEBUG
		return (s);
	}

	/*
	**  Make a new entry and link it in.
	*/

# ifdef DEBUG
	if (tTd(36, 5))
		printf("entered\n");
# endif DEBUG

	/* make new entry */
	s = (STAB *) xalloc(sizeof *s);
	bzero((char *) s, sizeof *s);
	s->s_name = newstr(name);
	makelower(s->s_name);
	s->s_type = type;

	/* link it in */
	*ps = s;

	return (s);
}