1/* Vector optimized 32/64 bit S/390 version of stpncpy.
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-stpncpy.h>
20
21#if HAVE_STPNCPY_Z13
22
23# include "sysdep.h"
24# include "asm-syntax.h"
25
26 .text
27
28/* char * stpncpy (char *dest, const char *src, size_t n)
29 Copies at most n characters of string src to dest
30 returning a pointer to its end or dest+n
31 if src is smaller than n.
32
33 Register usage:
34 -%r0 = return value
35 -%r1 = zero byte index
36 -%r2 = curr dst pointer
37 -%r3 = curr src pointer
38 -%r4 = n
39 -%r5 = current_len
40 -%r6 = loaded bytes
41 -%r7 = border, tmp
42*/
43ENTRY(STPNCPY_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
54 la %r0,0(%r4,%r2) /* Save destination pointer + n for return. */
55 vlvgp %v31,%r6,%r7 /* Save registers. */
56
57 vlbb %v16,0(%r3),6 /* Load s until next 4k-byte boundary. */
58 lcbb %r6,0(%r3),6 /* Get bytes to 4k-byte boundary or 16. */
59 llgfr %r6,%r6 /* Convert 32bit to 64bit. */
60
61 lghi %r5,0 /* current_len = 0. */
62
63 clgrjle %r4,%r6,.Lremaining_v16 /* If n <= loaded-bytes
64 -> process remaining. */
65
66 /* n > loaded-byte-count */
67 vfenezb %v17,%v16,%v16 /* Find element not equal with zero search. */
68 vlgvb %r1,%v17,7 /* Load zero index or 16 if not found. */
69 clrjl %r1,%r6,.Lfound_v16_store /* Found zero within loaded bytes,
70 copy and return. */
71
72 /* Align s to 16 byte. */
73 risbgn %r7,%r3,60,128+63,0 /* %r3 = bits 60-63 of %r2 'and' 15. */
74 lghi %r5,15 /* current_len = 15. */
75 slr %r5,%r7 /* Compute highest index to 16byte boundary. */
76
77 /* Zero not found and n > loaded-byte-count. */
78 vstl %v16,%r5,0(%r2) /* Copy loaded characters - no zero. */
79 ahi %r5,1 /* Start loop at next character. */
80
81 /* Now we are 16byte aligned, so we can load a full vreg
82 without page fault. */
83 lgr %r1,%r5 /* If %r5 + 64 < maxlen? -> loop64. */
84 aghi %r1,64
85 clgrjl %r1,%r4,.Lloop64
86
87 vl %v16,0(%r5,%r3) /* Load s. */
88 clgijl %r4,17,.Lremaining_v16 /* If n <= 16, process remaining
89 bytes. */
90.Llt64:
91 lgr %r7,%r4
92 slgfi %r7,16 /* border_len = n - 16. */
93
94 clgrjhe %r5,%r7,.Lremaining_v16 /* If current_len >= border
95 then process remaining bytes. */
96 vfenezbs %v17,%v16,%v16 /* Find element not equal with zero search. */
97 je .Lfound_v16 /* Jump away if zero was found. */
98 vl %v18,16(%r5,%r3) /* Load next part of s. */
99 vst %v16,0(%r5,%r2) /* Save previous part without zero to dst. */
100 aghi %r5,16
101
102 clgrjhe %r5,%r7,.Lremaining_v18
103 vfenezbs %v17,%v18,%v18
104 je .Lfound_v18
105 vl %v16,16(%r5,%r3)
106 vst %v18,0(%r5,%r2)
107 aghi %r5,16
108
109 clgrjhe %r5,%r7,.Lremaining_v16
110 vfenezbs %v17,%v16,%v16
111 je .Lfound_v16
112 vl %v18,16(%r5,%r3)
113 vst %v16,0(%r5,%r2)
114 aghi %r5,16
115
116.Lremaining_v18:
117 vlr %v16,%v18
118.Lremaining_v16:
119 /* v16 contains the remaining bytes [1...16].
120 Store remaining bytes and append string-termination. */
121 vfenezb %v17,%v16,%v16 /* Find element not equal with zero search. */
122 slgrk %r7,%r4,%r5 /* Remaining bytes = maxlen - current_len */
123 aghi %r7,-1 /* vstl needs highest index. */
124 la %r2,0(%r5,%r2) /* vstl has no index register. */
125 vlgvb %r1,%v17,7 /* Load zero index or 16 if not found. */
126 /* Zero in remaining bytes? -> jump away (zero-index <= max-index). */
127 clrjle %r1,%r7,.Lfound_v16_store
128 vstl %v16,%r7,0(%r2) /* Store remaining bytes without null
129 termination! */
130.Lend:
131 /* Restore saved registers. */
132 vlgvg %r6,%v31,0
133 vlgvg %r7,%v31,1
134 lgr %r2,%r0 /* Load saved dest-ptr. */
135 br %r14
136
137.Lfound_v16_32:
138 aghi %r5,32
139 j .Lfound_v16
140.Lfound_v18_48:
141 aghi %r5,32
142.Lfound_v18_16:
143 aghi %r5,16
144.Lfound_v18:
145 vlr %v16,%v18
146.Lfound_v16:
147 /* v16 contains a zero. Store remaining bytes to zero. current_len
148 has not reached border, thus checking for n is not needed! */
149 vlgvb %r1,%v17,7 /* Load byte index of zero. */
150 la %r2,0(%r5,%r2) /* vstl has no support for index-register. */
151.Lfound_v16_store:
152 vstl %v16,%r1,0(%r2) /* Copy characters including zero. */
153 /* Fill remaining bytes with zero - remaining count always > 0. */
154 algr %r5,%r1 /* Remaining bytes (=%r4) = ... */
155 slgr %r4,%r5 /* = maxlen - (currlen + zero_index + 1) */
156 la %r2,0(%r1,%r2) /* Pointer to zero. start filling beyond. */
157 lgr %r0,%r2 /* Save return-pointer to found zero. */
158 clgije %r4,1,.Lend /* Skip zero-filling, if found zero is last
159 possible character.
160 (1 is substracted from r4 below!). */
161 aghi %r4,-2 /* mvc with exrl needs count - 1.
162 (additional -1, see remaining bytes above) */
163 srlg %r6,%r4,8 /* Split into 256 byte blocks. */
164 ltgr %r6,%r6
165 je .Lzero_lt256
166.Lzero_loop256:
167 mvc 1(256,%r2),0(%r2) /* Fill 256 zeros at once. */
168 la %r2,256(%r2)
169 brctg %r6,.Lzero_loop256 /* Loop until all blocks are processed. */
170.Lzero_lt256:
171 exrl %r4,.Lmvc_lt256
172 j .Lend
173.Lmvc_lt256:
174 mvc 1(1,%r2),0(%r2)
175
176.Lloop64:
177 vl %v16,0(%r5,%r3)
178 vfenezbs %v17,%v16,%v16 /* Find element not equal with zero search. */
179 je .Lfound_v16 /* Jump away if zero was found. */
180 vl %v18,16(%r5,%r3) /* Load next part of s. */
181 vst %v16,0(%r5,%r2) /* Save previous part without zero to dst. */
182 vfenezbs %v17,%v18,%v18
183 je .Lfound_v18_16
184 vl %v16,32(%r5,%r3)
185 vst %v18,16(%r5,%r2)
186 vfenezbs %v17,%v16,%v16
187 je .Lfound_v16_32
188 vl %v18,48(%r5,%r3)
189 vst %v16,32(%r5,%r2)
190 vfenezbs %v17,%v18,%v18
191 je .Lfound_v18_48
192 vst %v18,48(%r5,%r2)
193
194 aghi %r5,64
195 lgr %r1,%r5 /* If %r5 + 64 < maxlen? -> loop64. */
196 aghi %r1,64
197 clgrjl %r1,%r4,.Lloop64
198
199 vl %v16,0(%r5,%r3) /* Load s. */
200 j .Llt64
201END(STPNCPY_Z13)
202
203# if ! HAVE_STPNCPY_IFUNC
204strong_alias (STPNCPY_Z13, __stpncpy)
205weak_alias (__stpncpy, stpncpy)
206# endif
207
208# if ! HAVE_STPNCPY_C && defined SHARED && IS_IN (libc)
209strong_alias (STPNCPY_Z13, __GI___stpncpy)
210# endif
211#endif
212

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