1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
|
/* Optimized version of the standard strncpy() function.
This file is part of the GNU C Library.
Copyright (C) 2000-2024 Free Software Foundation, Inc.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
/* Return: dest
Inputs:
in0: dest
in1: src
in2: len
In this form, it assumes little endian mode.
*/
#include <sysdep.h>
#undef ret
#define saved_lc r15
#define saved_pr r16
#define thresh r17
#define dest r18
#define dest2 r19
#define src r20
#define len r21
#define asrc r22
#define tmp r23
#define pos r24
#define w0 r25
#define w1 r26
#define c r27
#define sh2 r28
#define sh1 r29
#define loopcnt r30
#define value r31
ENTRY(strncpy)
.prologue
alloc r2 = ar.pfs, 3, 0, 29, 32
#define MEMLAT 2
.rotr r[MEMLAT + 2]
.rotp p[MEMLAT + 1]
mov ret0 = in0 // return value = dest
.save pr, saved_pr
mov saved_pr = pr // save the predicate registers
.save ar.lc, saved_lc
mov saved_lc = ar.lc // save the loop counter
mov ar.ec = 0 // ec is not guaranteed to
// be zero upon function entry
.body
cmp.geu p6, p5 = 24, in2
(p6) br.cond.spnt .short_len
sub tmp = r0, in0 ;; // tmp = -dest
mov len = in2 // len
mov dest = in0 // dest
mov src = in1 // src
and tmp = 7, tmp ;; // loopcnt = -dest % 8
cmp.eq p6, p7 = tmp, r0
adds loopcnt = -1, tmp // --loopcnt
(p6) br.cond.sptk .dest_aligned ;;
sub len = len, tmp // len -= -dest % 8
mov ar.lc = loopcnt
.l1: // copy -dest % 8 bytes
(p5) ld1 c = [src], 1 // c = *src++
;;
st1 [dest] = c, 1 // *dest++ = c
cmp.ne p5, p7 = c, r0
br.cloop.dptk .l1 ;;
(p7) br.cond.dpnt .found0_align
.dest_aligned: // p7 should be cleared here
shr.u c = len, 3 // c = len / 8
and sh1 = 7, src // sh1 = src % 8
and asrc = -8, src ;; // asrc = src & -OPSIZ -- align src
adds c = (MEMLAT-1), c // c = (len / 8) + MEMLAT - 1
sub thresh = 8, sh1
mov pr.rot = 1 << 16 // set rotating predicates
shl sh1 = sh1, 3 ;; // sh1 = 8 * (src % 8)
mov ar.lc = c // "infinite" loop
sub sh2 = 64, sh1 // sh2 = 64 - sh1
cmp.eq p6, p0 = sh1, r0 // is the src aligned?
(p6) br.cond.sptk .src_aligned
adds c = -(MEMLAT-1), c ;; // c = (len / 8)
ld8 r[1] = [asrc],8
mov ar.lc = c ;;
.align 32
.l2:
(p6) st8 [dest] = value, 8 // store val to dest
ld8.s r[0] = [asrc], 8
shr.u value = r[1], sh1 ;; // value = w0 >> sh1
czx1.r pos = value ;; // do we have an "early" zero
cmp.lt p7, p0 = pos, thresh // in w0 >> sh1?
adds len = -8, len // len -= 8
(p7) br.cond.dpnt .nonalign_found0
chk.s r[0], .recovery2 // it is safe to do that only
.back2: // after the previous test
shl tmp = r[0], sh2 // tmp = w1 << sh2
;;
or value = value, tmp ;; // value |= tmp
czx1.r pos = value ;;
cmp.ne p7, p6 = 8, pos
(p7) br.cond.dpnt .nonalign_found0
br.ctop.dptk .l2 ;;
adds len = 8, len
br.cond.sptk .not_found0 ;;
.nonalign_found0:
cmp.gtu p6, p0 = -8, len
(p6) br.cond.dptk .found0
adds len = 8, len
br.cond.sptk .not_found0 ;;
.align 32
.src_aligned:
.l3:
(p[0]) ld8.s r[0] = [src], 8
(p[MEMLAT]) chk.s r[MEMLAT], .recovery3
.back3:
(p[MEMLAT]) mov value = r[MEMLAT]
(p[MEMLAT]) czx1.r pos = r[MEMLAT] ;;
(p[MEMLAT]) cmp.ne p7, p0 = 8, pos
(p[MEMLAT]) adds len = -8, len // len -= 8
(p7) br.cond.dpnt .found0
(p[MEMLAT]) st8 [dest] = r[MEMLAT], 8
br.ctop.dptk .l3 ;;
chk.s r[MEMLAT-1], .recovery4
.back4:
mov value = r[MEMLAT-1]
.not_found0:
cmp.eq p5, p6 = len, r0
adds len = -1, len
(p5) br.cond.dptk .restore_and_exit ;;
mov ar.lc = len
.l4:
(p6) extr.u c = value, 0, 8 // c = value & 0xff
(p6) shr.u value = value, 8 ;;
st1 [dest] = c, 1
cmp.ne p6, p0 = c, r0
br.cloop.dptk .l4
br.cond.sptk .restore_and_exit
.found0_align:
mov pos = 0
adds len = -8, len
mov value = 0 ;;
.found0:
shl tmp = pos, 3
shr.u loopcnt = len, 4 // loopcnt = len / 16
mov c = -1 ;;
cmp.eq p6, p0 = loopcnt, r0
adds loopcnt = -1, loopcnt
shl c = c, tmp ;;
and len = 0xf, len
andcm value = value, c
mov ar.lc = loopcnt ;;
cmp.le p7, p0 = 8, len
adds dest2 = 16, dest
st8 [dest] = value, 8
and len = 0x7, len
(p6) br.cond.dpnt .l6 ;;
.l5:
st8 [dest] = r0, 16
st8 [dest2] = r0, 16
br.cloop.dptk .l5 ;;
.l6:
(p7) st8 [dest] = r0, 8
cmp.eq p5, p0 = len, r0
adds len = -1, len
(p5) br.cond.dptk .restore_and_exit ;;
mov ar.lc = len ;;
.l7:
st1 [dest] = r0, 1
br.cloop.dptk .l7 ;;
.restore_and_exit:
mov ar.lc = saved_lc // restore the loop counter
mov pr = saved_pr, -1 // restore the predicate registers
br.ret.sptk.many b0
.short_len:
cmp.eq p5, p0 = in2, r0
adds loopcnt = -1, in2
(p5) br.cond.spnt .restore_and_exit ;;
mov ar.lc = loopcnt // p6 should be set when we get here
.l8:
(p6) ld1 c = [in1], 1 // c = *src++
;;
st1 [in0] = c, 1 // *dest++ = c
(p6) cmp.ne p6, p0 = c, r0
br.cloop.dptk .l8
;;
mov ar.lc = saved_lc // restore the loop counter
mov pr = saved_pr, -1 // restore the predicate registers
br.ret.sptk.many b0
.recovery2:
add c = 8, len
add tmp = -8, asrc ;;
cmp.gtu p8, p5 = c, thresh ;;
(p8) ld8 r[0] = [tmp]
(p5) mov r[0] = r0
br.cond.sptk .back2
.recovery3:
add tmp = -(MEMLAT + 1) * 8, src ;;
ld8 r[MEMLAT] = [tmp]
br.cond.sptk .back3
.recovery4:
cmp.eq p5, p6 = len, r0
add tmp = -MEMLAT * 8, src ;;
(p6) ld8 r[MEMLAT - 1] = [tmp]
(p5) mov r[MEMLAT - 1] = r0
br.cond.sptk .back4
END(strncpy)
libc_hidden_builtin_def (strncpy)
|
