1/* Vector optimized 32/64 bit S/390 version of strncmp.
2 Copyright (C) 2015-2022 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
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#include <ifunc-strncmp.h>
20
21#if HAVE_STRNCMP_Z13
22
23# include "sysdep.h"
24# include "asm-syntax.h"
25
26 .text
27
28/* int strncmp (const char *s1, const char *s2, size_t n)
29 Compare at most n characters of two strings.
30
31 Register usage:
32 -r0=tmp
33 -r1=tmp
34 -r2=s1
35 -r3=s2
36 -r4=n
37 -r5=current_len
38 -v16=part of s1
39 -v17=part of s2
40 -v18=index of unequal
41*/
42ENTRY(STRNCMP_Z13)
43 .machine "z13"
44 .machinemode "zarch_nohighgprs"
45
46# if !defined __s390x__
47 llgfr %r4,%r4
48# endif /* !defined __s390x__ */
49
50 clgije %r4,0,.Lend_equal /* Nothing to do if n == 0, */
51 lghi %r5,0 /* current_len = 0. */
52
53.Lloop:
54 vlbb %v16,0(%r5,%r2),6 /* Load s1 to block boundary. */
55 vlbb %v17,0(%r5,%r3),6 /* Load s2 to block boundary. */
56 lcbb %r0,0(%r5,%r2),6 /* Get loaded byte count of s1. */
57 jo .Llt16_1 /* Jump away if vr is not fully loaded. */
58 lcbb %r1,0(%r5,%r3),6 /* Get loaded byte count of s2. */
59 jo .Llt16_2 /* Jump away if vr is not fully loaded. */
60 aghi %r5,16 /* Both vrs are fully loaded. */
61 clgrjhe %r5,%r4,.Llastcmp /* If current_len >= n ->last compare. */
62 vfenezbs %v18,%v16,%v17 /* Compare not equal with zero search. */
63 jno .Lfound
64
65 vlbb %v16,0(%r5,%r2),6
66 vlbb %v17,0(%r5,%r3),6
67 lcbb %r0,0(%r5,%r2),6
68 jo .Llt16_1
69 lcbb %r1,0(%r5,%r3),6
70 jo .Llt16_2
71 aghi %r5,16
72 clgrjhe %r5,%r4,.Llastcmp
73 vfenezbs %v18,%v16,%v17
74 jno .Lfound
75
76 vlbb %v16,0(%r5,%r2),6
77 vlbb %v17,0(%r5,%r3),6
78 lcbb %r0,0(%r5,%r2),6
79 jo .Llt16_1
80 lcbb %r1,0(%r5,%r3),6
81 jo .Llt16_2
82 aghi %r5,16
83 clgrjhe %r5,%r4,.Llastcmp
84 vfenezbs %v18,%v16,%v17
85 jno .Lfound
86
87 vlbb %v16,0(%r5,%r2),6
88 vlbb %v17,0(%r5,%r3),6
89 lcbb %r0,0(%r5,%r2),6
90 jo .Llt16_1
91 lcbb %r1,0(%r5,%r3),6
92 jo .Llt16_2
93 aghi %r5,16
94 clgrjhe %r5,%r4,.Llastcmp
95 vfenezbs %v18,%v16,%v17
96 jno .Lfound
97 j .Lloop
98
99.Llt16_1:
100 lcbb %r1,0(%r5,%r3),6 /* Get loaded byte count ofs2. */
101.Llt16_2:
102 clr %r0,%r1 /* Compare logical. */
103 locrh %r0,%r1 /* Compute minimum of bytes loaded. */
104 algfr %r5,%r0 /* Add smallest loaded bytes to current_len. */
105 clgrj %r5,%r4,10,.Llastcmp /* If current_len >= n ->last compare. */
106 vfenezbs %v18,%v16,%v17 /* Compare not equal with zero search. */
107 vlgvb %r1,%v18,7 /* Get not equal index or 16 if all equal. */
108 clrjl %r1,%r0,.Lfound /* Jump away if miscompare is within
109 loaded bytes (index < loaded-bytes) */
110 j .Lloop
111
112.Llastcmp:
113 /* Use comparision result only if located within first n characters.
114 %r0: loaded byte count in vreg;
115 %r5: current_len;
116 %r4: n;
117 (current_len - n): [0...16[
118 First ignored match index: loaded bytes - (current_len-n): ]0...16]
119 */
120 slgr %r5,%r4 /* %r5 = current_len - n. */
121 slr %r0,%r5 /* %r0 = first ignored match index. */
122 vfenezbs %v18,%v16,%v17 /* Compare not equal with zero search. */
123 vlgvb %r1,%v18,7 /* Get not equal index or 16 if all equal. */
124 clrjl %r1,%r0,.Lfound /* Jump away if miscompare is within
125 loaded bytes and below n bytes. */
126 j .Lend_equal /* Miscompare after n-bytes -> end equal. */
127
128.Lfound:
129 /* Difference or end of string. */
130 je .Lend_equal
131 lghi %r2,1
132 lghi %r1,-1
133 locgrl %r2,%r1
134 br %r14
135.Lend_equal:
136 lghi %r2,0
137 br %r14
138END(STRNCMP_Z13)
139
140# if ! HAVE_STRNCMP_IFUNC
141strong_alias (STRNCMP_Z13, strncmp)
142# endif
143
144# if ! HAVE_STRNCMP_C && defined SHARED && IS_IN (libc)
145strong_alias (STRNCMP_Z13, __GI_strncmp)
146# endif
147
148#endif /* HAVE_STRNCMP_Z13 */
149

source code of glibc/sysdeps/s390/strncmp-vx.S