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
|
