1 /* strchrnul - find a character or nul in a string
3 Copyright (C) 2014-2024 Free Software Foundation, Inc.
5 This file is part of the GNU C Library.
7 The GNU C Library is free software; you can redistribute it and/or
8 modify it under the terms of the GNU Lesser General Public
9 License as published by the Free Software Foundation; either
10 version 2.1 of the License, or (at your option) any later version.
12 The GNU C Library is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 Lesser General Public License for more details.
17 You should have received a copy of the GNU Lesser General Public
18 License along with the GNU C Library. If not, see
19 <https://www.gnu.org/licenses/>. */
25 * ARMv8-a, AArch64, Advanced SIMD.
47 For each 16-byte chunk we calculate a 64-bit nibble mask value with four bits
48 per byte. We take 4 bits of every comparison byte with shift right and narrow
49 by 4 instruction. Since the bits in the nibble mask reflect the order in
50 which things occur in the original string, counting leading zeros identifies
51 exactly which byte matched. */
56 dup vrepchr.16b, chrin
57 ld1 {vdata.16b}, [src]
58 cmeq vhas_chr.16b, vdata.16b, vrepchr.16b
59 cmhs vhas_chr.16b, vhas_chr.16b, vdata.16b
61 shrn vend.8b, vhas_chr.8h, 4 /* 128->64 */
63 lsr tmp1, tmp1, tmp2 /* Mask padding bits. */
68 add result, srcin, tmp1, lsr 2
74 cmeq vhas_chr.16b, vdata.16b, vrepchr.16b
75 cmhs vhas_chr.16b, vhas_chr.16b, vdata.16b
76 umaxp vend.16b, vhas_chr.16b, vhas_chr.16b
80 cmeq vhas_chr.16b, vdata.16b, vrepchr.16b
81 cmhs vhas_chr.16b, vhas_chr.16b, vdata.16b
82 umaxp vend.16b, vhas_chr.16b, vhas_chr.16b
87 shrn vend.8b, vhas_chr.8h, 4 /* 128->64 */
94 add result, src, tmp1, lsr 2
98 libc_hidden_def (__strchrnul)
99 weak_alias (__strchrnul, strchrnul)