1/* Optimized version of the standard strncpy() function.
2 This file is part of the GNU C Library.
3 Copyright (C) 2000-2022 Free Software Foundation, Inc.
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/* Return: dest
20
21 Inputs:
22 in0: dest
23 in1: src
24 in2: len
25
26 In this form, it assumes little endian mode.
27 */
28
29#include <sysdep.h>
30#undef ret
31
32#define saved_lc r15
33#define saved_pr r16
34#define thresh r17
35#define dest r18
36#define dest2 r19
37#define src r20
38#define len r21
39#define asrc r22
40#define tmp r23
41#define pos r24
42#define w0 r25
43#define w1 r26
44#define c r27
45#define sh2 r28
46#define sh1 r29
47#define loopcnt r30
48#define value r31
49
50ENTRY(strncpy)
51 .prologue
52 alloc r2 = ar.pfs, 3, 0, 29, 32
53
54#define MEMLAT 2
55 .rotr r[MEMLAT + 2]
56 .rotp p[MEMLAT + 1]
57
58 mov ret0 = in0 // return value = dest
59 .save pr, saved_pr
60 mov saved_pr = pr // save the predicate registers
61 .save ar.lc, saved_lc
62 mov saved_lc = ar.lc // save the loop counter
63 mov ar.ec = 0 // ec is not guaranteed to
64 // be zero upon function entry
65 .body
66 cmp.geu p6, p5 = 24, in2
67(p6) br.cond.spnt .short_len
68 sub tmp = r0, in0 ;; // tmp = -dest
69 mov len = in2 // len
70 mov dest = in0 // dest
71 mov src = in1 // src
72 and tmp = 7, tmp ;; // loopcnt = -dest % 8
73 cmp.eq p6, p7 = tmp, r0
74 adds loopcnt = -1, tmp // --loopcnt
75(p6) br.cond.sptk .dest_aligned ;;
76 sub len = len, tmp // len -= -dest % 8
77 mov ar.lc = loopcnt
78.l1: // copy -dest % 8 bytes
79(p5) ld1 c = [src], 1 // c = *src++
80 ;;
81 st1 [dest] = c, 1 // *dest++ = c
82 cmp.ne p5, p7 = c, r0
83 br.cloop.dptk .l1 ;;
84(p7) br.cond.dpnt .found0_align
85
86.dest_aligned: // p7 should be cleared here
87 shr.u c = len, 3 // c = len / 8
88 and sh1 = 7, src // sh1 = src % 8
89 and asrc = -8, src ;; // asrc = src & -OPSIZ -- align src
90 adds c = (MEMLAT-1), c // c = (len / 8) + MEMLAT - 1
91 sub thresh = 8, sh1
92 mov pr.rot = 1 << 16 // set rotating predicates
93 shl sh1 = sh1, 3 ;; // sh1 = 8 * (src % 8)
94 mov ar.lc = c // "infinite" loop
95 sub sh2 = 64, sh1 // sh2 = 64 - sh1
96 cmp.eq p6, p0 = sh1, r0 // is the src aligned?
97(p6) br.cond.sptk .src_aligned
98 adds c = -(MEMLAT-1), c ;; // c = (len / 8)
99 ld8 r[1] = [asrc],8
100 mov ar.lc = c ;;
101
102 .align 32
103.l2:
104(p6) st8 [dest] = value, 8 // store val to dest
105 ld8.s r[0] = [asrc], 8
106 shr.u value = r[1], sh1 ;; // value = w0 >> sh1
107 czx1.r pos = value ;; // do we have an "early" zero
108 cmp.lt p7, p0 = pos, thresh // in w0 >> sh1?
109 adds len = -8, len // len -= 8
110(p7) br.cond.dpnt .nonalign_found0
111 chk.s r[0], .recovery2 // it is safe to do that only
112.back2: // after the previous test
113 shl tmp = r[0], sh2 // tmp = w1 << sh2
114 ;;
115 or value = value, tmp ;; // value |= tmp
116 czx1.r pos = value ;;
117 cmp.ne p7, p6 = 8, pos
118(p7) br.cond.dpnt .nonalign_found0
119 br.ctop.dptk .l2 ;;
120 adds len = 8, len
121 br.cond.sptk .not_found0 ;;
122.nonalign_found0:
123 cmp.gtu p6, p0 = -8, len
124(p6) br.cond.dptk .found0
125 adds len = 8, len
126 br.cond.sptk .not_found0 ;;
127
128 .align 32
129.src_aligned:
130.l3:
131(p[0]) ld8.s r[0] = [src], 8
132(p[MEMLAT]) chk.s r[MEMLAT], .recovery3
133.back3:
134(p[MEMLAT]) mov value = r[MEMLAT]
135(p[MEMLAT]) czx1.r pos = r[MEMLAT] ;;
136(p[MEMLAT]) cmp.ne p7, p0 = 8, pos
137(p[MEMLAT]) adds len = -8, len // len -= 8
138(p7) br.cond.dpnt .found0
139(p[MEMLAT]) st8 [dest] = r[MEMLAT], 8
140 br.ctop.dptk .l3 ;;
141
142 chk.s r[MEMLAT-1], .recovery4
143.back4:
144 mov value = r[MEMLAT-1]
145
146.not_found0:
147 cmp.eq p5, p6 = len, r0
148 adds len = -1, len
149(p5) br.cond.dptk .restore_and_exit ;;
150 mov ar.lc = len
151.l4:
152(p6) extr.u c = value, 0, 8 // c = value & 0xff
153(p6) shr.u value = value, 8 ;;
154 st1 [dest] = c, 1
155 cmp.ne p6, p0 = c, r0
156 br.cloop.dptk .l4
157 br.cond.sptk .restore_and_exit
158
159.found0_align:
160 mov pos = 0
161 adds len = -8, len
162 mov value = 0 ;;
163.found0:
164 shl tmp = pos, 3
165 shr.u loopcnt = len, 4 // loopcnt = len / 16
166 mov c = -1 ;;
167 cmp.eq p6, p0 = loopcnt, r0
168 adds loopcnt = -1, loopcnt
169 shl c = c, tmp ;;
170 and len = 0xf, len
171 andcm value = value, c
172 mov ar.lc = loopcnt ;;
173 cmp.le p7, p0 = 8, len
174 adds dest2 = 16, dest
175 st8 [dest] = value, 8
176 and len = 0x7, len
177(p6) br.cond.dpnt .l6 ;;
178.l5:
179 st8 [dest] = r0, 16
180 st8 [dest2] = r0, 16
181 br.cloop.dptk .l5 ;;
182.l6:
183(p7) st8 [dest] = r0, 8
184 cmp.eq p5, p0 = len, r0
185 adds len = -1, len
186(p5) br.cond.dptk .restore_and_exit ;;
187 mov ar.lc = len ;;
188.l7:
189 st1 [dest] = r0, 1
190 br.cloop.dptk .l7 ;;
191.restore_and_exit:
192 mov ar.lc = saved_lc // restore the loop counter
193 mov pr = saved_pr, -1 // restore the predicate registers
194 br.ret.sptk.many b0
195
196.short_len:
197 cmp.eq p5, p0 = in2, r0
198 adds loopcnt = -1, in2
199(p5) br.cond.spnt .restore_and_exit ;;
200 mov ar.lc = loopcnt // p6 should be set when we get here
201.l8:
202(p6) ld1 c = [in1], 1 // c = *src++
203 ;;
204 st1 [in0] = c, 1 // *dest++ = c
205(p6) cmp.ne p6, p0 = c, r0
206 br.cloop.dptk .l8
207 ;;
208 mov ar.lc = saved_lc // restore the loop counter
209 mov pr = saved_pr, -1 // restore the predicate registers
210 br.ret.sptk.many b0
211.recovery2:
212 add c = 8, len
213 add tmp = -8, asrc ;;
214 cmp.gtu p8, p5 = c, thresh ;;
215(p8) ld8 r[0] = [tmp]
216(p5) mov r[0] = r0
217 br.cond.sptk .back2
218.recovery3:
219 add tmp = -(MEMLAT + 1) * 8, src ;;
220 ld8 r[MEMLAT] = [tmp]
221 br.cond.sptk .back3
222.recovery4:
223 cmp.eq p5, p6 = len, r0
224 add tmp = -MEMLAT * 8, src ;;
225(p6) ld8 r[MEMLAT - 1] = [tmp]
226(p5) mov r[MEMLAT - 1] = r0
227 br.cond.sptk .back4
228END(strncpy)
229libc_hidden_builtin_def (strncpy)
230

source code of glibc/sysdeps/ia64/strncpy.S