1/*******************************************************************************
2 *
3 * Copyright (c) 1993 Intel Corporation
4 *
5 * Intel hereby grants you permission to copy, modify, and distribute this
6 * software and its documentation.  Intel grants this permission provided
7 * that the above copyright notice appears in all copies and that both the
8 * copyright notice and this permission notice appear in supporting
9 * documentation.  In addition, Intel grants this permission provided that
10 * you prominently mark as "not part of the original" any modifications
11 * made to this software or documentation, and that the name of Intel
12 * Corporation not be used in advertising or publicity pertaining to
13 * distribution of the software or the documentation without specific,
14 * written prior permission.
15 *
16 * Intel Corporation provides this AS IS, WITHOUT ANY WARRANTY, EXPRESS OR
17 * IMPLIED, INCLUDING, WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY
18 * OR FITNESS FOR A PARTICULAR PURPOSE.  Intel makes no guarantee or
19 * representations regarding the use of, or the results of the use of,
20 * the software and documentation in terms of correctness, accuracy,
21 * reliability, currentness, or otherwise; and you rely on the software,
22 * documentation and results solely at your own risk.
23 *
24 * IN NO EVENT SHALL INTEL BE LIABLE FOR ANY LOSS OF USE, LOSS OF BUSINESS,
25 * LOSS OF PROFITS, INDIRECT, INCIDENTAL, SPECIAL OR CONSEQUENTIAL DAMAGES
26 * OF ANY KIND.  IN NO EVENT SHALL INTEL'S TOTAL LIABILITY EXCEED THE SUM
27 * PAID TO INTEL FOR THE PRODUCT LICENSED HEREUNDER.
28 *
29 ******************************************************************************/
30
31	.file "strchr.s"
32#ifdef	__PIC
33	.pic
34#endif
35#ifdef	__PID
36	.pid
37#endif
38/*
39 * (c) copyright 1988,1993 Intel Corp., all rights reserved
40 */
41
42/*
43	procedure strchr  (optimized assembler version for the 80960K series)
44
45	src_addr = strchr (src_addr, char)
46
47	return a pointer to the first byte that contains the indicated
48	byte in the source string.  Return null if the byte is not found.
49
50	Undefined behavior will occur if the end of the source string (i.e.
51	the terminating null byte) is in the last two words of the program's
52	allocated memory space.  This is so because strchr fetches ahead.
53	Disallowing the fetch ahead would impose a severe performance penalty.
54
55	Strategy:
56
57	Fetch the source string by words and scanbyte the words for the
58	char until either a word with the byte is found or the null byte is
59	encountered.  In the former case, move through the word to find the
60	matching byte and return its memory address.  In the latter case,
61	return zero (null).
62
63	Tactics:
64
65	1) Do NOT try to fetch the words in a word aligned manner because,
66	in my judgement, the performance degradation experienced due to
67	non-aligned accesses does NOT outweigh the time and complexity added
68	by the preamble that would be necessary to assure alignment.  This
69	is supported by the intuition that most source arrays (even more
70	true of most big source arrays) will be word aligned to begin with.
71*/
72
73	.globl	_strchr
74	.globl	__strchr
75	.leafproc	_strchr, __strchr
76	.align	2
77_strchr:
78#ifndef __PIC
79	lda 	Lrett,g14
80#else
81	lda 	Lrett-(.+8)(ip),g14
82#endif
83__strchr:
84
85	ld	(g0),g4		# fetch first word
86	lda	0xff,g7		# byte extraction mask
87	and	g1,g7,g1	# make char an 8-bit ordinal
88	shlo	8,g1,g2		# broadcast the char to four bytes
89	or	g1,g2,g2
90	shlo	16,g2,g5
91	or	g2,g5,g3
92	mov	g14,g13		# preserve return address
93	addo	4,g0,g0		# post-increment src pointer
94	mov	0,g14		# conform to register linkage standard
95
96Lsearch_for_word_with_char_or_null:
97	mov	g4,g5		# copy word
98	scanbyte g3,g5		# check for byte with char
99	ld	(g0),g4		# fetch next word of src
100	bo	Lsearch_for_char	# branch if char found
101	scanbyte 0,g5		# check for null byte
102	addo	4,g0,g0		# post-increment src pointer
103	bno	Lsearch_for_word_with_char_or_null	# branch if not null
104
105Lnot_found:
106	mov	0,g0		# char not found.  Return null
107Lexit_code:
108	bx	(g13)		# g0 = addr of char in src (or null);  g14 = 0
109Lrett:
110	ret
111
112Lsearch_for_char:
113	subo	5,g0,g0		# back up the byte pointer
114Lsearch_for_char.a:
115	and	g5,g7,g6	# extract byte
116	cmpo	g1,g6		# is it char?
117	addo	1,g0,g0		# bump src byte ptr
118	shro	8,g5,g5		# shift word to position next byte
119	be	Lexit_code
120	cmpobne 0,g6,Lsearch_for_char.a	# quit if null comes before char
121	b	Lnot_found
122
123/* end of strchr */
124