1/* Vector optimized 32/64 bit S/390 version of strncat.
2 Copyright (C) 2015-2024 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-strncat.h>
20#if HAVE_STRNCAT_Z13
21
22# include "sysdep.h"
23# include "asm-syntax.h"
24
25 .text
26
27/* char * strncat (const char *dest, const char *src, size_t n)
28 Concatenate two strings - at most n characters of src.
29
30 Register usage:
31 -r0=saved dest pointer for return
32 -r1=tmp
33 -r2=dest
34 -r3=src
35 -r4=n
36 -r5=current_len
37 -r6=tmp
38 -r7=tmp
39 -v16=part of src
40 -v17=index of zero
41 -v18=part of src
42 -v31=register save area for r6, r7
43*/
44ENTRY(STRNCAT_Z13)
45 .machine "z13"
46 .machinemode "zarch_nohighgprs"
47
48# if !defined __s390x__
49 llgfr %r4,%r4
50# endif /* !defined __s390x__ */
51
52 clgfi %r4,0
53 ber %r14 /* Nothing to do, if n == 0. */
54 lgr %r0,%r2 /* Save destination pointer for return. */
55 vlvgp %v31,%r6,%r7 /* Save registers. */
56
57 /* STRLEN
58 %r1 = loaded bytes (tmp)
59 %r6 = zero byte index (tmp)
60 %r2 = dst
61 */
62 vlbb %v16,0(%r2),6 /* Load s until next 4k-byte boundary. */
63 lcbb %r1,0(%r2),6 /* Get bytes to 4k-byte boundary or 16. */
64
65 vfenezb %v16,%v16,%v16 /* Find element not equal with zero search. */
66 vlgvb %r5,%v16,7 /* Load zero index or 16 if not found. */
67 clrjl %r5,%r1,.Llen_end /* Found zero within loaded bytes, end. */
68
69 /* Align s to 16 byte. */
70 risbgn %r1,%r2,60,128+63,0 /* %r3 = bits 60-63 of %r2 'and' 15. */
71 lghi %r5,16 /* current_len = 16. */
72 slr %r5,%r1 /* Compute bytes to 16bytes boundary. */
73
74 /* Find zero in 16byte aligned loop. */
75.Llen_loop:
76 vl %v16,0(%r5,%r2) /* Load s. */
77 vfenezbs %v16,%v16,%v16 /* Find element not equal with zero search. */
78 je .Llen_found /* Jump away if zero was found. */
79 vl %v16,16(%r5,%r2)
80 vfenezbs %v16,%v16,%v16
81 je .Llen_found16
82 vl %v16,32(%r5,%r2)
83 vfenezbs %v16,%v16,%v16
84 je .Llen_found32
85 vl %v16,48(%r5,%r2)
86 vfenezbs %v16,%v16,%v16
87 je .Llen_found48
88
89 aghi %r5,64
90 j .Llen_loop /* No zero -> loop. */
91
92.Llen_found48:
93 aghi %r5,16
94.Llen_found32:
95 aghi %r5,16
96.Llen_found16:
97 aghi %r5,16
98.Llen_found:
99 vlgvb %r1,%v16,7 /* Load byte index of zero. */
100 algr %r5,%r1
101
102.Llen_end:
103 /* STRCPY
104 %r1 = zero byte index (tmp)
105 %r6 = loaded bytes (tmp)
106 %r3 = curr src pointer
107 %r2 = curr dst pointer
108 %r7 = border, tmp
109 */
110 la %r2,0(%r5,%r2) /* strcpy at end of dst-string. */
111
112 vlbb %v16,0(%r3),6 /* Load s until next 4k-byte boundary. */
113 lcbb %r6,0(%r3),6 /* Get bytes to 4k-byte boundary or 16. */
114 llgfr %r6,%r6 /* Convert 32bit to 64bit. */
115
116 lghi %r5,0 /* current_len = 0. */
117
118 clgrjle %r4,%r6,.Lcpy_remaining_v16 /* If n <= loaded-bytes
119 -> process remaining. */
120
121 /* n > loaded-byte-count. */
122 vfenezb %v17,%v16,%v16 /* Find element not equal with zero search. */
123 vlgvb %r1,%v17,7 /* Load zero index or 16 if not found. */
124 clrjl %r1,%r6,.Lcpy_found_v16_store /* Found zero within loaded
125 bytes, copy and return. */
126
127 /* Align s to 16 byte. */
128 risbgn %r7,%r3,60,128+63,0 /* %r3 = bits 60-63 of %r2 'and' 15. */
129 lghi %r5,15 /* current_len = 15. */
130 slr %r5,%r7 /* Compute highest index to 16byte boundary. */
131
132 /* Zero not found and n > loaded-byte-count. */
133 vstl %v16,%r5,0(%r2) /* Copy loaded characters - no zero. */
134 ahi %r5,1 /* Start loop at next character. */
135
136 /*
137 Now we are 16byte aligned, so we can load a full vreg
138 without page fault.
139 */
140 lgr %r1,%r5 /* If %r5 + 64 < maxlen? -> loop64. */
141 aghi %r1,64
142 clgrjl %r1,%r4,.Lcpy_loop64
143
144 vl %v16,0(%r5,%r3) /* Load s. */
145 clgijl %r4,17,.Lcpy_remaining_v16 /* If n <=16,
146 process remaining bytes. */
147.Lcpy_lt64:
148 lgr %r7,%r4
149 slgfi %r7,16 /* border_len = n - 16. */
150
151 /* If current_len >= border then process remaining bytes. */
152 clgrjhe %r5,%r7,.Lcpy_remaining_v16
153 vfenezbs %v17,%v16,%v16 /* Find element not equal with zero search. */
154 je .Lcpy_found_v16 /* Jump away if zero was found. */
155 vl %v18,16(%r5,%r3) /* Load next part of s. */
156 vst %v16,0(%r5,%r2) /* Store previous part without zero to dst. */
157 aghi %r5,16
158
159 clgrjhe %r5,%r7,.Lcpy_remaining_v18
160 vfenezbs %v17,%v18,%v18
161 je .Lcpy_found_v18
162 vl %v16,16(%r5,%r3)
163 vst %v18,0(%r5,%r2)
164 aghi %r5,16
165
166 clgrjhe %r5,%r7,.Lcpy_remaining_v16
167 vfenezbs %v17,%v16,%v16
168 je .Lcpy_found_v16
169 vl %v18,16(%r5,%r3)
170 vst %v16,0(%r5,%r2)
171 aghi %r5,16
172
173.Lcpy_remaining_v18:
174 vlr %v16,%v18
175.Lcpy_remaining_v16:
176 /* v16 contains the remaining bytes [1...16].
177 Store remaining bytes and append string-termination. */
178 vfenezb %v17,%v16,%v16 /* Find element not equal with zero search. */
179 slgrk %r7,%r4,%r5 /* Remaining bytes = maxlen - current_len. */
180 aghi %r7,-1 /* vstl needs highest index. */
181 vlgvb %r1,%v17,7 /* Load zero index or 16 if not found. */
182 la %r2,0(%r5,%r2) /* vstl has no index register. */
183 /* Zero-index within remaining-bytes, store up to zero and end. */
184 clgrjle %r1,%r7,.Lcpy_found_v16_store
185 vstl %v16,%r7,0(%r2) /* Store remaining bytes. */
186 lghi %r1,0
187 stc %r1,1(%r7,%r2) /* Store string-null-termination beyond n. */
188.Lcpy_end:
189 /* Restore saved registers. */
190 vlgvg %r6,%v31,0
191 vlgvg %r7,%v31,1
192 lgr %r2,%r0 /* Load saved dest-ptr. */
193 br %r14
194
195.Lcpy_found_v16_32:
196 aghi %r5,32
197 j .Lcpy_found_v16
198.Lcpy_found_v18_48:
199 aghi %r5,32
200.Lcpy_found_v18_16:
201 aghi %r5,16
202.Lcpy_found_v18:
203 vlr %v16,%v18
204.Lcpy_found_v16:
205 /* v16 contains a zero. Store remaining bytes to zero. current_len
206 has not reached border, thus checking for n is not needed! */
207 vlgvb %r1,%v17,7 /* Load byte index of zero. */
208 la %r2,0(%r5,%r2)
209.Lcpy_found_v16_store:
210 vstl %v16,%r1,0(%r2) /* Copy characters including zero. */
211 j .Lcpy_end
212
213 /* Find zero in 16byte aligned loop. */
214.Lcpy_loop64:
215 vl %v16,0(%r5,%r3) /* Load s. */
216 vfenezbs %v17,%v16,%v16 /* Find element not equal with zero search. */
217 je .Lcpy_found_v16 /* Jump away if zero was found. */
218 vl %v18,16(%r5,%r3) /* Load next part of s. */
219 vst %v16,0(%r5,%r2) /* Store previous part without zero to dst. */
220 vfenezbs %v17,%v18,%v18
221 je .Lcpy_found_v18_16
222 vl %v16,32(%r5,%r3)
223 vst %v18,16(%r5,%r2)
224 vfenezbs %v17,%v16,%v16
225 je .Lcpy_found_v16_32
226 vl %v18,48(%r5,%r3)
227 vst %v16,32(%r5,%r2)
228 vfenezbs %v17,%v18,%v18
229 je .Lcpy_found_v18_48
230 vst %v18,48(%r5,%r2)
231
232 aghi %r5,64
233 lgr %r1,%r5 /* If %r5 + 64 < maxlen? -> loop64. */
234 aghi %r1,64
235 clgrjl %r1,%r4,.Lcpy_loop64
236
237 vl %v16,0(%r5,%r3) /* Load s. */
238 j .Lcpy_lt64
239END(STRNCAT_Z13)
240
241# if ! HAVE_STRNCAT_IFUNC
242strong_alias (STRNCAT_Z13, strncat)
243# endif
244
245# if ! HAVE_STRNCAT_C
246/* See string/strncat.c and define STRNCAT_PRIMARY. */
247strong_alias (STRNCAT_Z13, __strncat)
248# if defined SHARED && IS_IN (libc)
249strong_alias (__strncat, __GI___strncat)
250# endif
251# endif
252#endif
253

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