1/* Copyright (C) 1996-2022 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
8
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library. If not, see
16 <https://www.gnu.org/licenses/>. */
17
18/* Return the address of a given character within a null-terminated
19 string, or null if it is not found.
20
21 This is generally scheduled for the EV5 (got to look out for my own
22 interests :-), but with EV4 needs in mind. There *should* be no more
23 stalls for the EV4 than there are for the EV5.
24*/
25
26#include <sysdep.h>
27
28 .set noreorder
29 .set noat
30
31ENTRY(strchr)
32#ifdef PROF
33 ldgp gp, 0(pv)
34 lda AT, _mcount
35 jsr AT, (AT), _mcount
36 .prologue 1
37#else
38 .prologue 0
39#endif
40
41 zapnot a1, 1, a1 # e0 : zero extend the search character
42 ldq_u t0, 0(a0) # .. e1 : load first quadword
43 sll a1, 8, t5 # e0 : replicate the search character
44 andnot a0, 7, v0 # .. e1 : align our loop pointer
45 or t5, a1, a1 # e0 :
46 lda t4, -1 # .. e1 : build garbage mask
47 sll a1, 16, t5 # e0 :
48 cmpbge zero, t0, t2 # .. e1 : bits set iff byte == zero
49 mskqh t4, a0, t4 # e0 :
50 or t5, a1, a1 # .. e1 :
51 sll a1, 32, t5 # e0 :
52 cmpbge zero, t4, t4 # .. e1 : bits set iff byte is garbage
53 or t5, a1, a1 # e0 :
54 xor t0, a1, t1 # .. e1 : make bytes == c zero
55 cmpbge zero, t1, t3 # e0 : bits set iff byte == c
56 or t2, t3, t0 # e1 : bits set iff char match or zero match
57 andnot t0, t4, t0 # e0 : clear garbage bits
58 bne t0, $found # .. e1 (zdb)
59
60$loop: ldq t0, 8(v0) # e0 :
61 addq v0, 8, v0 # .. e1 :
62 nop # e0 :
63 xor t0, a1, t1 # .. e1 (ev5 data stall)
64 cmpbge zero, t0, t2 # e0 : bits set iff byte == 0
65 cmpbge zero, t1, t3 # .. e1 : bits set iff byte == c
66 or t2, t3, t0 # e0 :
67 beq t0, $loop # .. e1 (zdb)
68
69$found: negq t0, t1 # e0 : clear all but least set bit
70 and t0, t1, t0 # e1 (stall)
71
72 and t0, t3, t1 # e0 : bit set iff byte was the char
73 beq t1, $retnull # .. e1 (zdb)
74
75 and t0, 0xf0, t2 # e0 : binary search for that set bit
76 and t0, 0xcc, t3 # .. e1 :
77 and t0, 0xaa, t4 # e0 :
78 cmovne t2, 4, t2 # .. e1 :
79 cmovne t3, 2, t3 # e0 :
80 cmovne t4, 1, t4 # .. e1 :
81 addq t2, t3, t2 # e0 :
82 addq v0, t4, v0 # .. e1 :
83 addq v0, t2, v0 # e0 :
84 ret # .. e1 :
85
86$retnull:
87 mov zero, v0 # e0 :
88 ret # .. e1 :
89
90 END(strchr)
91
92weak_alias (strchr, index)
93libc_hidden_builtin_def (strchr)
94

source code of glibc/sysdeps/alpha/strchr.S