1/* Optimized version of the standard strncmp() function.
2   This file is part of the GNU C Library.
3   Copyright (C) 2000-2022 Free Software Foundation, Inc.
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
16   License along with the GNU C Library; if not, see
17   <https://www.gnu.org/licenses/>.  */
18
19/* Return: the result of the comparison
20
21   Inputs:
22        in0:    s1
23        in1:    s2
24        in2:    n
25
26   Unlike memcmp(), this function is optimized for mismatches within the
27   first few characters.  */
28
29#include <sysdep.h>
30#undef ret
31
32#define s1		in0
33#define s2		in1
34#define n		in2
35
36#define val1		r15
37#define val2		r16
38
39
40ENTRY(strncmp)
41	alloc	r2 = ar.pfs, 3, 0, 0, 0
42	mov	ret0 = r0
43	cmp.eq  p6, p0 = r0, r0		// set p6
44	cmp.eq	p7, p0 = n, r0		// return immediately if n == 0
45(p7)	br.cond.spnt .restore_and_exit ;;
46.loop:
47	ld1	val1 = [s1], 1
48	ld1	val2 = [s2], 1
49	adds	n = -1, n		// n--
50	;;
51	cmp.ne.and p6, p0 = val1, r0
52	cmp.ne.and p6, p0 = val2, r0
53	cmp.ne.and p6, p0 = n, r0
54	cmp.eq.and p6, p0 = val1, val2
55(p6)	br.cond.sptk .loop
56	sub	ret0 = val1, val2
57.restore_and_exit:
58	br.ret.sptk.many b0
59END(strncmp)
60libc_hidden_builtin_def (strncmp)
61