1/*
2 * strchr/strchrnul - find a character in a string
3 *
4 * Copyright (c) 2018-2022, Arm Limited.
5 * SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception
6 */
7
8#include "asmdefs.h"
9
10#if __ARM_FEATURE_SVE
11/* Assumptions:
12 *
13 * ARMv8-a, AArch64
14 * SVE Available.
15 */
16
17/* To build as strchrnul, define BUILD_STRCHRNUL before compiling this file.  */
18#ifdef BUILD_STRCHRNUL
19#define FUNC  __strchrnul_aarch64_sve
20#else
21#define FUNC  __strchr_aarch64_sve
22#endif
23
24ENTRY (FUNC)
25	PTR_ARG (0)
26	dup	z1.b, w1		/* replicate byte across vector */
27	setffr				/* initialize FFR */
28	ptrue	p1.b			/* all ones; loop invariant */
29
30	.p2align 4
31	/* Read a vector's worth of bytes, stopping on first fault.  */
320:	ldff1b	z0.b, p1/z, [x0, xzr]
33	rdffrs	p0.b, p1/z
34	b.nlast	2f
35
36	/* First fault did not fail: the whole vector is valid.
37	   Avoid depending on the contents of FFR beyond the branch.  */
38	incb	x0				/* speculate increment */
39	cmpeq	p2.b, p1/z, z0.b, z1.b		/* search for c */
40	cmpeq	p3.b, p1/z, z0.b, 0		/* search for 0 */
41	orrs	p4.b, p1/z, p2.b, p3.b		/* c | 0 */
42	b.none	0b
43	decb	x0				/* undo speculate */
44
45	/* Found C or 0.  */
461:	brka	p4.b, p1/z, p4.b	/* find first such */
47	sub	x0, x0, 1		/* adjust pointer for that byte */
48	incp	x0, p4.b
49#ifndef BUILD_STRCHRNUL
50	ptest	p4, p2.b		/* was first in c? */
51	csel	x0, xzr, x0, none	/* if there was no c, return null */
52#endif
53	ret
54
55	/* First fault failed: only some of the vector is valid.
56	   Perform the comparision only on the valid bytes.  */
572:	cmpeq	p2.b, p0/z, z0.b, z1.b		/* search for c */
58	cmpeq	p3.b, p0/z, z0.b, 0		/* search for 0 */
59	orrs	p4.b, p0/z, p2.b, p3.b		/* c | 0 */
60	b.any	1b
61
62	/* No C or 0 found.  Re-init FFR, increment, and loop.  */
63	setffr
64	incp	x0, p0.b
65	b	0b
66
67END (FUNC)
68
69#endif
70
71