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d5efd131 MF |
1 | /* Optimized version of the standard strchr() function. |
2 | This file is part of the GNU C Library. | |
dff8da6b | 3 | Copyright (C) 2000-2024 Free Software Foundation, Inc. |
d5efd131 MF |
4 | |
5 | The GNU C Library is free software; you can redistribute it and/or | |
6 | modify it under the terms of the GNU Lesser General Public | |
7 | License as published by the Free Software Foundation; either | |
8 | version 2.1 of the License, or (at your option) any later version. | |
9 | ||
10 | The GNU C Library is distributed in the hope that it will be useful, | |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
13 | Lesser General Public License for more details. | |
14 | ||
15 | You should have received a copy of the GNU Lesser General Public | |
75efb018 | 16 | License along with the GNU C Library; if not, see |
5a82c748 | 17 | <https://www.gnu.org/licenses/>. */ |
d5efd131 | 18 | |
65cc53fe | 19 | /* Return: the address of the first occurrence of chr in str or NULL |
d5efd131 MF |
20 | |
21 | Inputs: | |
22 | in0: str | |
23 | in1: chr | |
24 | ||
25 | A modified version of memchr.S, the search ends when the character is | |
26 | found or the terminating null character is encountered. | |
27 | ||
28 | This implementation assumes little endian mode. For big endian mode, | |
29 | the instruction czx1.r should be replaced by czx1.l. */ | |
30 | ||
31 | #include <sysdep.h> | |
32 | #undef ret | |
33 | ||
34 | #define saved_lc r18 | |
35 | #define poschr r19 | |
36 | #define pos0 r20 | |
37 | #define val1 r21 | |
38 | #define val2 r22 | |
39 | #define tmp r24 | |
40 | #define chrx8 r25 | |
41 | #define loopcnt r30 | |
42 | ||
43 | #define str in0 | |
44 | #define chr in1 | |
45 | ||
46 | ENTRY(strchr) | |
47 | .prologue | |
48 | alloc r2 = ar.pfs, 2, 0, 0, 0 | |
49 | .save ar.lc, saved_lc | |
50 | mov saved_lc = ar.lc // save the loop counter | |
51 | .body | |
0347518d | 52 | mov ret0 = str |
d5efd131 MF |
53 | and tmp = 7, str // tmp = str % 8 |
54 | mux1 chrx8 = chr, @brcst | |
55 | extr.u chr = chr, 0, 8 // retain only the last byte | |
56 | cmp.ne p8, p0 = r0, r0 // clear p8 | |
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 = [ret0], 1 | |
65 | ;; | |
66 | cmp.eq p6, p0 = val2, chr | |
67 | cmp.eq p7, p0 = val2, r0 | |
68 | (p6) br.cond.spnt .restore_and_exit | |
69 | (p7) br.cond.spnt .notfound | |
70 | br.cloop.sptk .l1 | |
71 | .str_aligned: | |
72 | ld8 val1 = [ret0], 8;; | |
73 | nop.b 0 | |
74 | nop.b 0 | |
0347518d | 75 | .l2: |
d5efd131 | 76 | ld8.s val2 = [ret0], 8 // don't bomb out here |
0347518d | 77 | czx1.r pos0 = val1 |
d5efd131 MF |
78 | xor tmp = val1, chrx8 // if val1 contains chr, tmp will |
79 | ;; // contain a zero in its position | |
80 | czx1.r poschr = tmp | |
81 | cmp.ne p6, p0 = 8, pos0 | |
82 | ;; | |
83 | cmp.ne p7, p0 = 8, poschr | |
84 | (p7) br.cond.spnt .foundit | |
85 | (p6) br.cond.spnt .notfound | |
86 | chk.s val2, .recovery | |
87 | .back: | |
0347518d | 88 | mov val1 = val2 |
d5efd131 MF |
89 | br.cond.dptk .l2 |
90 | .foundit: | |
91 | (p6) cmp.lt p8, p0 = pos0, poschr // we found chr and null in the word | |
92 | (p8) br.cond.spnt .notfound // null was found before chr | |
93 | add ret0 = ret0, poschr ;; | |
94 | adds ret0 = -15, ret0 ;; // should be -16, but we decrement | |
95 | .restore_and_exit: // ret0 in the next instruction | |
96 | adds ret0 = -1, ret0 // ret0 was pointing 1 char too far | |
97 | mov ar.lc = saved_lc // restore the loop counter | |
98 | br.ret.sptk.many b0 | |
99 | .notfound: | |
100 | mov ret0 = r0 // return NULL if null was found | |
101 | mov ar.lc = saved_lc | |
102 | br.ret.sptk.many b0 | |
103 | .recovery: | |
104 | adds ret0 = -8, ret0;; | |
105 | ld8 val2 = [ret0], 8 // bomb out here | |
106 | br.cond.sptk .back | |
107 | END(strchr) | |
108 | ||
109 | weak_alias (strchr, index) | |
110 | libc_hidden_builtin_def (strchr) |