about summary refs log tree commit diff
path: root/sysdeps/ia64/memchr.S
blob: 5ec9b21032095fe14cd803d6404769a7192a4bf6 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
/* Optimized version of the standard memchr() function.
   This file is part of the GNU C Library.
   Copyright (C) 2000 Free Software Foundation, Inc.
   Contributed by Dan Pop <Dan.Pop@cern.ch>.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public License as
   published by the Free Software Foundation; either version 2 of the
   License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with the GNU C Library; see the file COPYING.LIB.  If not,
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

/* Return: the address of the first occurence of chr in str or NULL

   Inputs:
  	in0:	str
  	in1:	chr
  	in2:	byte count

   This implementation assumes little endian mode.  For big endian mode,
   the instruction czx1.r should be replaced by czx1.l.

   The algorithm is fairly straightforward: search byte by byte until we
   we get to a word aligned address, then search word by word as much as
   possible; the remaining few bytes are searched one at a time.

   The word by word search is performed by xor-ing the word with a word
   containing chr in every byte.  If there is a hit, the result will
   contain a zero byte in the corresponding position.  The presence and
   position of that zero byte is detected with a czx instruction.

   All the loops in this function could have had the internal branch removed
   if br.ctop and br.cloop could be predicated :-(.  */

#include <sysdep.h>
#undef ret

#define	saved_pfs	r14
#define saved_pr	r15
#define saved_lc	r16
#define	chr		r17
#define len		r18
#define pos0		r20
#define val		r21
#define tmp		r24
#define chrx8		r25
#define loopcnt		r30

#define str		in0

ENTRY(__memchr)
	alloc saved_pfs = ar.pfs, 3, 0, 29, 32
#include "softpipe.h"
	.rotr	value[MEMLAT+1], addr[MEMLAT+3], aux[2], poschr[2]
	.rotp	p[MEMLAT+3]
        mov 	saved_lc = ar.lc 	// save the loop counter
	mov	saved_pr = pr		// save the predicates
	mov 	ret0 = str
	and 	tmp = 7, str		// tmp = str % 8
	cmp.ne	p7, p0 = r0, r0		// clear p7
	extr.u	chr = in1, 0, 8		// chr = (unsigned char) in1
	mov	len = in2
	cmp.gtu	p6, p0 = 16, in2	// use a simple loop for short
(p6)	br.cond.spnt .srchfew ;;	// searches
	sub	loopcnt = 8, tmp	// loopcnt = 8 - tmp
	cmp.eq	p6, p0 = tmp, r0
(p6)	br.cond.sptk	.str_aligned;;
	sub	len = len, loopcnt
	adds	loopcnt = -1, loopcnt;;
	mov	ar.lc = loopcnt
.l1:
	ld1	val = [ret0], 1
	;;
	cmp.eq	p6, p0 = val, chr
(p6)	br.cond.spnt	.foundit
	br.cloop.sptk	.l1 ;;
.str_aligned:
	cmp.ne	p6, p0 = r0, r0		// clear p6
	shr.u	loopcnt = len, 3	// loopcnt = len / 8
	and 	len = 7, len ;;		// remaining len = len & 7
	adds	loopcnt = -1, loopcnt
	mov	ar.ec = MEMLAT + 3
	mux1	chrx8 = chr, @brcst ;;	// get a word full of chr
	mov	ar.lc = loopcnt
	mov	pr.rot = 1 << 16 ;;
.l2:
(p[0])		mov	addr[0] = ret0
(p[0])		ld8	value[0] = [ret0], 8
(p[MEMLAT])	xor	aux[0] = value[MEMLAT], chrx8
(p[MEMLAT+1])	czx1.r	poschr[0] = aux[1]
(p[MEMLAT+2])	cmp.ne	p7, p0 = 8, poschr[1]
(p7)		br.cond.dpnt .foundit
		br.ctop.dptk .l2
.srchfew:
	adds	loopcnt = -1, len
	cmp.eq	p6, p0 = len, r0
(p6)	br.cond.spnt .notfound ;;
	mov	ar.lc = loopcnt
.l3:
	ld1	val = [ret0], 1
	;;
	cmp.eq	p6, p0 = val, chr
(p6)	br.cond.dpnt	.foundit
	br.cloop.sptk	.l3 ;;
.notfound:
	cmp.ne	p6, p0 = r0, r0	// clear p6 (p7 was already 0 when we got here)
	mov	ret0 = r0 ;;	// return NULL
.foundit:
	.pred.rel "mutex" p6, p7
(p6)	adds	ret0 = -1, ret0 		   // if we got here from l1 or l3
(p7)	add	ret0 = addr[MEMLAT+2], poschr[1]   // if we got here from l2
	mov	pr = saved_pr, -1
	mov	ar.pfs = saved_pfs
	mov	ar.lc = saved_lc
	br.ret.sptk.many b0

END(__memchr)

weak_alias (__memchr, memchr)
#if !__BOUNDED_POINTERS__
weak_alias (__memchr, __ubp_memchr)
#endif