1/* Vector optimized 32/64 bit S/390 version of strncpy.
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-strncpy.h>
20#include "sysdep.h"
21#include "asm-syntax.h"
22
23 .text
24
25#if HAVE_STRNCPY_Z13
26/* char * strncpy (const char *dest, const char *src, size_t n)
27 Copy at most n characters of string src to dest.
28
29 Register usage:
30 -r0=dest pointer for return
31 -r1=tmp, zero byte index
32 -r2=dest
33 -r3=src
34 -r4=n
35 -r5=current_len
36 -r6=tmp, loaded bytes
37 -r7=tmp, border
38 -v16=part of src
39 -v17=index of zero
40 -v18=part of src
41 -v31=register save area for r6, r7
42*/
43ENTRY(STRNCPY_Z13)
44 .machine "z13"
45 .machinemode "zarch_nohighgprs"
46
47# if !defined __s390x__
48 llgfr %r4,%r4
49# endif /* !defined __s390x__ */
50
51 clgfi %r4,0
52 ber %r14 /* Nothing to do, if n == 0. */
53 lgr %r0,%r2 /* Save destination pointer for return. */
54 vlvgp %v31,%r6,%r7 /* Save registers. */
55
56 vlbb %v16,0(%r3),6 /* Load s until next 4k-byte boundary. */
57 lcbb %r6,0(%r3),6 /* Get bytes to 4k-byte boundary or 16. */
58 llgfr %r6,%r6 /* Convert 32bit to 64bit. */
59
60 lghi %r5,0 /* current_len = 0. */
61
62 clgrjle %r4,%r6,.Lremaining_v16 /* If n <= loaded-bytes
63 -> process remaining. */
64
65 /* n > loaded-byte-count. */
66 vfenezb %v17,%v16,%v16 /* Find element not equal with zero search. */
67 vlgvb %r1,%v17,7 /* Load zero index or 16 if not found. */
68 clrjl %r1,%r6,.Lfound_v16_store /* Found zero within loaded bytes,
69 copy and return. */
70
71 /* Align s to 16 byte. */
72 risbgn %r7,%r3,60,128+63,0 /* %r3 = bits 60-63 of %r2 'and' 15. */
73 lghi %r5,15 /* current_len = 15. */
74 slr %r5,%r7 /* Compute highest index to 16byte boundary. */
75
76 /* Zero not found and n > loaded-byte-count. */
77 vstl %v16,%r5,0(%r2) /* Copy loaded characters - no zero. */
78 ahi %r5,1 /* Start loop at next character. */
79
80 /* Now we are 16byte aligned, so we can load
81 a full vreg without page fault. */
82 lgr %r1,%r5 /* If %r5 + 64 < maxlen? -> loop64. */
83 aghi %r1,64
84 clgrjl %r1,%r4,.Lloop64
85
86 vl %v16,0(%r5,%r3) /* Load s. */
87 clgijl %r4,17,.Lremaining_v16 /* If n <= 16, process remaining
88 bytes. */
89.Llt64:
90 lgr %r7,%r4
91 slgfi %r7,16 /* border_len = n - 16. */
92
93 clgrjhe %r5,%r7,.Lremaining_v16 /* If current_len >= border
94 then process remaining bytes. */
95 vfenezbs %v17,%v16,%v16 /* Find element not equal with zero search. */
96 je .Lfound_v16 /* Jump away if zero was found. */
97 vl %v18,16(%r5,%r3) /* Load next part of s. */
98 vst %v16,0(%r5,%r2) /* Store previous part without zero to dst. */
99 aghi %r5,16
100
101 clgrjhe %r5,%r7,.Lremaining_v18
102 vfenezbs %v17,%v18,%v18
103 je .Lfound_v18
104 vl %v16,16(%r5,%r3)
105 vst %v18,0(%r5,%r2)
106 aghi %r5,16
107
108 clgrjhe %r5,%r7,.Lremaining_v16
109 vfenezbs %v17,%v16,%v16
110 je .Lfound_v16
111 vl %v18,16(%r5,%r3)
112 vst %v16,0(%r5,%r2)
113 aghi %r5,16
114
115.Lremaining_v18:
116 vlr %v16,%v18
117.Lremaining_v16:
118 /* v16 contains the remaining bytes [1...16].
119 Store remaining bytes and append string-termination. */
120 vfenezb %v17,%v16,%v16 /* Find element not equal with zero search. */
121 slgrk %r7,%r4,%r5 /* Remaining bytes = maxlen - current_len. */
122 aghi %r7,-1 /* vstl needs highest index. */
123 la %r2,0(%r5,%r2) /* vstl has no index register. */
124 vlgvb %r1,%v17,7 /* Load zero index or 16 if not found. */
125 /* Zero in remaining bytes? -> jump away (zero-index < max-index)
126 Do not jump away if zero-index == max-index,
127 but simply copy zero with vstl below. */
128 clrjl %r1,%r7,.Lfound_v16_store
129 vstl %v16,%r7,0(%r2) /* Store remaining bytes without null
130 termination!. */
131.Lend:
132 /* Restore saved registers. */
133 vlgvg %r6,%v31,0
134 vlgvg %r7,%v31,1
135 lgr %r2,%r0 /* Load saved dest-ptr. */
136 br %r14
137
138
139.Lfound_v16_32:
140 aghi %r5,32
141 j .Lfound_v16
142.Lfound_v18_48:
143 aghi %r5,32
144.Lfound_v18_16:
145 aghi %r5,16
146.Lfound_v18:
147 vlr %v16,%v18
148.Lfound_v16:
149 /* v16 contains a zero. Store remaining bytes to zero. current_len
150 has not reached border, thus checking for n is not needed! */
151 vlgvb %r1,%v17,7 /* Load byte index of zero. */
152 la %r2,0(%r5,%r2) /* vstl has no support for index-register. */
153.Lfound_v16_store:
154 vstl %v16,%r1,0(%r2) /* Copy characters including zero. */
155 /* Fill remaining bytes with zero - remaining count always > 0. */
156 algr %r5,%r1 /* Remaining bytes (=%r4) = ... */
157 slgr %r4,%r5 /* = n - (current_len + zero_index + 1). */
158 la %r2,0(%r1,%r2) /* Pointer to zero. start filling beyond. */
159 aghi %r4,-2 /* mvc with exrl needs count - 1.
160 (additional -1, see remaining bytes above) */
161 srlg %r6,%r4,8 /* Split into 256 byte blocks. */
162 ltgr %r6,%r6
163 je .Lzero_lt256
164.Lzero_loop256:
165 mvc 1(256,%r2),0(%r2) /* Fill 256 zeros at once. */
166 la %r2,256(%r2)
167 brctg %r6,.Lzero_loop256 /* Loop until all blocks are processed. */
168.Lzero_lt256:
169 exrl %r4,.Lmvc_lt256
170 j .Lend
171.Lmvc_lt256:
172 mvc 1(1,%r2),0(%r2)
173
174.Lloop64:
175 vl %v16,0(%r5,%r3) /* Load s. */
176 vfenezbs %v17,%v16,%v16 /* Find element not equal with zero search. */
177 je .Lfound_v16 /* Jump away if zero was found. */
178 vl %v18,16(%r5,%r3) /* Load next part of s. */
179 vst %v16,0(%r5,%r2) /* Store previous part without zero to dst. */
180 vfenezbs %v17,%v18,%v18
181 je .Lfound_v18_16
182 vl %v16,32(%r5,%r3)
183 vst %v18,16(%r5,%r2)
184 vfenezbs %v17,%v16,%v16
185 je .Lfound_v16_32
186 vl %v18,48(%r5,%r3)
187 vst %v16,32(%r5,%r2)
188 vfenezbs %v17,%v18,%v18
189 je .Lfound_v18_48
190 vst %v18,48(%r5,%r2)
191
192 aghi %r5,64
193 lgr %r1,%r5 /* If %r5 + 64 < maxlen? -> loop64. */
194 aghi %r1,64
195 clgrjl %r1,%r4,.Lloop64
196
197 vl %v16,0(%r5,%r3) /* Load s. */
198 j .Llt64
199END(STRNCPY_Z13)
200
201# if ! HAVE_STRNCPY_IFUNC
202strong_alias (STRNCPY_Z13, strncpy)
203# endif
204
205# if ! HAVE_STRNCPY_Z900_G5 && defined SHARED && IS_IN (libc)
206strong_alias (STRNCPY_Z13, __GI_strncpy)
207# endif
208#endif
209

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