1/* Optimized version of the standard strlen() function.
2   This file is part of the GNU C Library.
3   Copyright (C) 2000, 2001, 2003, 2005 Free Software Foundation, Inc.
4   Contributed by Dan Pop <Dan.Pop@cern.ch>.
5
6   The GNU C Library is free software; you can redistribute it and/or
7   modify it under the terms of the GNU Lesser General Public
8   License as published by the Free Software Foundation; either
9   version 2.1 of the License, or (at your option) any later version.
10
11   The GNU C Library is distributed in the hope that it will be useful,
12   but WITHOUT ANY WARRANTY; without even the implied warranty of
13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14   Lesser General Public License for more details.
15
16   You should have received a copy of the GNU Lesser General Public
17   License along with the GNU C Library; if not, see
18   <http://www.gnu.org/licenses/>.  */
19
20/* Return: the length of the input string
21
22   Input:
23        in0:    str
24
25   Look for the null character byte by byte, until we reach a word aligned
26   address, then search word by word, using the czx instruction.  We're
27   also doing one word of read ahead, which could cause problems if the
28   null character is on the last word of a page and the next page is not
29   mapped in the process address space.  Hence the use of the speculative
30   load.
31
32   This implementation assumes little endian mode.  For big endian mode,
33   the instruction czx1.r should be replaced by czx1.l.  */
34
35#include <sysdep.h>
36#undef ret
37
38#define saved_lc	r18
39#define str		r19
40#define pos0		r20
41#define val1		r21
42#define val2		r22
43#define origadd		r23
44#define tmp		r24
45#define loopcnt		r30
46#define len		ret0
47
48ENTRY(strlen)
49	.prologue
50	alloc r2 = ar.pfs, 1, 0, 0, 0
51	.save ar.lc, saved_lc
52        mov 	saved_lc = ar.lc 	/* save the loop counter */
53	.body
54	mov 	str = in0
55	mov 	len = r0		/* len = 0 */
56	and 	tmp = 7, in0		/* tmp = str % 8 */
57	;;
58	sub	loopcnt = 8, tmp	/* loopcnt = 8 - tmp */
59	cmp.eq	p6, p0 = tmp, r0
60(p6)	br.cond.sptk	.str_aligned;;
61	adds	loopcnt = -1, loopcnt;;
62	mov	ar.lc = loopcnt
63.l1:
64	ld1	val2 = [str], 1
65	;;
66	cmp.eq	p6, p0 = val2, r0
67(p6)	br.cond.spnt	.restore_and_exit
68	adds	len = 1, len
69	br.cloop.dptk	.l1
70.str_aligned:
71	mov	origadd = str		/* origadd = orig */
72	ld8	val1 = [str], 8;;
73	nop.b	0
74	nop.b 	0
75.l2:	ld8.s	val2 = [str], 8		/* don't bomb out here */
76	czx1.r	pos0 = val1
77	;;
78	cmp.ne	p6, p0 = 8, pos0
79(p6)	br.cond.spnt .foundit
80	chk.s	val2, .recovery
81.back:
82	mov	val1 = val2
83	br.cond.dptk	.l2
84.foundit:
85	sub	tmp = str, origadd	/* tmp = crt address - orig */
86	add	len = len, pos0;;
87	add	len = len, tmp;;
88	adds	len = -16, len
89.restore_and_exit:
90	mov ar.lc = saved_lc		/* restore the loop counter */
91	br.ret.sptk.many b0
92.recovery:
93	adds	str = -8, str;;
94	ld8	val2 = [str], 8		/* bomb out here */
95	br.cond.sptk	.back
96END(strlen)
97libc_hidden_def (strlen)
98