strsep.s

早期freebsd实现

/*-
 * Copyright (c) 1990, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#if defined(LIBC_SCCS) && !defined(lint)
	.asciz "@(#)strsep.s	8.1 (Berkeley) 6/4/93"
#endif /* LIBC_SCCS and not lint */

/*
 * Get next word from string *stringp, where words are
 * strings separated by characters from delim.
 *
 * Writes NULs into the string at *stringp to end tokens.
 * On return, *stringp points past the last NUL written (if there might
 * be further tokens), or is NULL (if there are definitely no more tokens).
 *
 * If *stringp is NULL, strtoken returns NULL.
 *
 * char *
 * strtoken(stringp, delim)
 *	register char **stringp;
 *	register char const *delim;
 */
#include "DEFS.h"

ENTRY(strsep, 0)
	tstl	*4(ap)		/* if (*stringp == NULL) */
	bneq	0f
	clrl	r0		#	return (NULL);
	ret

0:
	subl2	$32,sp		/* make room for 256 bit table */
	movc5	$0,(sp),$0,$32,(sp)
	movq	4(ap),r1	/* r1 = stringp, r2 = delim */

	/* turn on bit for each character in s2, including '\0' */
1:
	movzbl	(r2)+,r0
	bbss	r0,(sp),1b
	bneq	1b

	movl	(r1),r3		/* r3 = s = *stringp */
	movl	r3,r0		/* save return value */

	/* scan for delimiters */
2:
	movzbl	(r3)+,r2	/* c = *s++ */
	bbc	r2,(sp),2b	/* loop until c is in table */
	beql	3f
	clrb	-1(r3)		/* if c!='\0', s[-1] = 0 */
	movl	r3,(r1)		/* and *stringp = s */
	ret
3:
	clrl	(r1)		/* else *stringp = NULL */
	ret