1/* Copyright (C) 2000-2022 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#include <sysdep.h>
22
23 .arch ev6
24 .set noreorder
25 .set noat
26
27ENTRY(strchr)
28#ifdef PROF
29 ldgp gp, 0(pv)
30 lda AT, _mcount
31 jsr AT, (AT), _mcount
32 .prologue 1
33#else
34 .prologue 0
35#endif
36
37 ldq_u t0, 0(a0) # L : load first quadword Latency=3
38 and a1, 0xff, t3 # E : 00000000000000ch
39 insbl a1, 1, t5 # U : 000000000000ch00
40 insbl a1, 7, a2 # U : ch00000000000000
41
42 insbl t3, 6, a3 # U : 00ch000000000000
43 or t5, t3, a1 # E : 000000000000chch
44 andnot a0, 7, v0 # E : align our loop pointer
45 lda t4, -1 # E : build garbage mask
46
47 mskqh t4, a0, t4 # U : only want relevant part of first quad
48 or a2, a3, a2 # E : chch000000000000
49 inswl a1, 2, t5 # E : 00000000chch0000
50 inswl a1, 4, a3 # E : 0000chch00000000
51
52 or a1, a2, a1 # E : chch00000000chch
53 or a3, t5, t5 # E : 0000chchchch0000
54 cmpbge zero, t0, t2 # E : bits set iff byte == zero
55 cmpbge zero, t4, t4 # E : bits set iff byte is garbage
56
57 /* This quad is _very_ serialized. Lots of stalling happens */
58 or t5, a1, a1 # E : chchchchchchchch
59 xor t0, a1, t1 # E : make bytes == c zero
60 cmpbge zero, t1, t3 # E : bits set iff byte == c
61 or t2, t3, t0 # E : bits set iff char match or zero match
62
63 andnot t0, t4, t0 # E : clear garbage bits
64 cttz t0, a2 # U0 : speculative (in case we get a match)
65 nop # E :
66 bne t0, $found # U :
67
68 /*
69 * Yuk. This loop is going to stall like crazy waiting for the
70 * data to be loaded. Not much can be done about it unless it's
71 * unrolled multiple times, which is generally unsafe.
72 */
73$loop:
74 ldq t0, 8(v0) # L : Latency=3
75 addq v0, 8, v0 # E :
76 xor t0, a1, t1 # E :
77 cmpbge zero, t0, t2 # E : bits set iff byte == 0
78
79 cmpbge zero, t1, t3 # E : bits set iff byte == c
80 or t2, t3, t0 # E :
81 cttz t3, a2 # U0 : speculative (in case we get a match)
82 beq t0, $loop # U :
83
84$found:
85 negq t0, t1 # E : clear all but least set bit
86 and t0, t1, t0 # E :
87 and t0, t3, t1 # E : bit set iff byte was the char
88 addq v0, a2, v0 # E : Add in the bit number from above
89
90 cmoveq t1, $31, v0 # E : Two mapping slots, latency = 2
91 nop
92 nop
93 ret # L0 :
94
95 END(strchr)
96
97weak_alias (strchr, index)
98libc_hidden_builtin_def (strchr)
99

source code of glibc/sysdeps/alpha/alphaev67/strchr.S