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
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20 * the software and documentation in terms of correctness, accuracy,
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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#include <picolibc.h>
32
33	.file "strch_ca.s"
34#ifdef	__PIC
35	.pic
36#endif
37#ifdef	__PID
38	.pid
39#endif
40/*
41 * (c) copyright 1988,1993 Intel Corp., all rights reserved
42 */
43
44/*
45	procedure strchr  (optimized assembler version for the CA)
46
47	src_addr = strchr (src_addr, char)
48
49	return a pointer to the first byte that contains the indicated
50	byte in the source string.  Return null if the byte is not found.
51
52	Undefined behavior will occur if the end of the source string (i.e.
53	the terminating null byte) is in the last two words of the program's
54	allocated memory space.  This is so because, in several cases, strchr
55	will fetch ahead.  Disallowing the fetch ahead would impose a severe
56	performance penalty.
57
58	This program handles two cases:
59
60	1) the argument starts on a word boundary
61	2) the argument doesn't start on a word boundary
62
63	At the time of this writing, only g0 thru g7 and g13 are available
64	for use in this leafproc;  other registers would have to be saved and
65	restored.  These nine registers, plus tricky use of g14 are sufficient
66	to implement the routine.  The registers are used as follows:
67
68	g0  src ptr;  upon return it is a pointer to the matching byte, or null
69	g1  char to seek
70	g2  mask to avoid unimportant bytes in first word
71	g3  char to seek, broadcast to all four bytes
72	g4  word of the source string
73	g5  copy of the word
74	g6  extracted character
75	g7  byte extraction mask
76	g13 return address
77	g14
78*/
79
80	.globl	_strchr
81	.globl	__strchr
82	.leafproc	_strchr, __strchr
83	.align	2
84_strchr:
85#ifndef __PIC
86	lda 	Lrett,g14
87#else
88	lda 	Lrett-(.+8)(ip),g14
89#endif
90__strchr:
91
92	lda	0xff,g7		# byte extraction mask
93	and	g1,g7,g1	# make char an 8-bit ordinal
94	shlo	8,g1,g2		# broadcast the char to four bytes
95	or	g1,g2,g2
96	shlo	16,g2,g4
97	cmpo	g1,g7		# is char being sought 0xff?
98	or	g4,g2,g3
99	 lda	(g14),g13	# preserve return address
100	notand	g0,3,g5		# extract word addr of start of src
101	 lda	0,g14		# conform to register linkage standard
102	and	g0,3,g6		# extract byte offset of src
103	 ld	(g5),g4		# fetch word containing at least first byte
104	shlo	3,g6,g6		# get shift count for making mask for first word
105	 lda	4(g5),g0	# post-increment src word pointer
106	subi	1,0,g5		# mask initially all ones
107#if __i960_BIG_ENDIAN__
108	shro	g6,g5,g5	# get mask for bytes needed from first word
109#else
110	shlo	g6,g5,g5	# get mask for bytes needed from first word
111#endif
112	notor	g4,g5,g4	# set unneeded bytes to all ones
113	 be.f	Lsearch_for_0xff	# branch if seeking 0xff
114
115Lsearch_for_word_with_char_or_null:
116	scanbyte g3,g4		# check for byte with char
117	 lda	(g4),g5		# copy word
118	ld	(g0),g4		# fetch next word of src
119	 bo.f	Lsearch_for_char	# branch if null found
120	scanbyte 0,g5		# check for null byte
121	 lda	4(g0),g0	# post-increment src word pointer
122	bno.t	Lsearch_for_word_with_char_or_null	# branch if not null
123
124Lnot_found:
125	mov	0,g0		# char not found.  Return null
126Lexit_code:
127	bx	(g13)		# g0 = addr of char in src (or null);  g14 = 0
128Lrett:
129	ret
130
131Lsearch_for_char:
132	subo	5,g0,g0		# back up the byte pointer
133Lsearch_for_char.a:
134#if __i960_BIG_ENDIAN__
135	rotate	8,g5,g5		# shift word to position next byte
136#endif
137	and	g5,g7,g6	# extract byte
138	cmpo	g1,g6		# is it char?
139	 lda	1(g0),g0	# bump src byte ptr
140#if ! __i960_BIG_ENDIAN__
141	shro	8,g5,g5		# shift word to position next byte
142#endif
143	 be.f	Lexit_code
144	cmpobne.t 0,g6,Lsearch_for_char.a	# quit if null comes before char
145	b	Lnot_found
146
147Lsearch_for_0xff:
148	lda	0xf0f0f0f0,g2	# make first comparison mask for char=-1 case.
149	or	g5,g2,g2
150	and	g4,g2,g4	# make unimportant bytes of first word 0x0f
151	 b	Lsearch_for_word_with_char_or_null
152
153/* end of strchr */
154
155