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
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
|
/* Copyright (C) 1996-2025 Free Software Foundation, Inc.
This file is part of the GNU C Library.
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/>. */
/* Copy a null-terminated string from SRC to DST.
This is an internal routine used by strcpy, stpcpy, and strcat.
As such, it uses special linkage conventions to make implementation
of these public functions more efficient.
On input:
t9 = return address
a0 = DST
a1 = SRC
On output:
t8 = bitmask (with one bit set) indicating the last byte written
a0 = unaligned address of the last *word* written
Furthermore, v0, a3-a5, t11, and t12 are untouched.
*/
/* This is generally scheduled for the EV5, but should still be pretty
good for the EV4 too. */
#include <sysdep.h>
.set noat
.set noreorder
.text
.type __stxcpy, @function
.globl __stxcpy
.usepv __stxcpy, no
cfi_startproc
cfi_return_column (t9)
/* On entry to this basic block:
t0 == the first destination word for masking back in
t1 == the first source word. */
.align 3
stxcpy_aligned:
/* Create the 1st output word and detect 0's in the 1st input word. */
lda t2, -1 # e1 : build a mask against false zero
mskqh t2, a1, t2 # e0 : detection in the src word
mskqh t1, a1, t3 # e0 :
ornot t1, t2, t2 # .. e1 :
mskql t0, a1, t0 # e0 : assemble the first output word
cmpbge zero, t2, t7 # .. e1 : bits set iff null found
or t0, t3, t1 # e0 :
bne t7, $a_eos # .. e1 :
/* On entry to this basic block:
t0 == the first destination word for masking back in
t1 == a source word not containing a null. */
$a_loop:
stq_u t1, 0(a0) # e0 :
addq a0, 8, a0 # .. e1 :
ldq_u t1, 0(a1) # e0 :
addq a1, 8, a1 # .. e1 :
cmpbge zero, t1, t7 # e0 (stall)
beq t7, $a_loop # .. e1 (zdb)
/* Take care of the final (partial) word store.
On entry to this basic block we have:
t1 == the source word containing the null
t7 == the cmpbge mask that found it. */
$a_eos:
negq t7, t6 # e0 : find low bit set
and t7, t6, t8 # e1 (stall)
/* For the sake of the cache, don't read a destination word
if we're not going to need it. */
and t8, 0x80, t6 # e0 :
bne t6, 1f # .. e1 (zdb)
/* We're doing a partial word store and so need to combine
our source and original destination words. */
ldq_u t0, 0(a0) # e0 :
subq t8, 1, t6 # .. e1 :
zapnot t1, t6, t1 # e0 : clear src bytes >= null
or t8, t6, t7 # .. e1 :
zap t0, t7, t0 # e0 : clear dst bytes <= null
or t0, t1, t1 # e1 :
1: stq_u t1, 0(a0) # e0 :
ret (t9) # .. e1 :
.align 3
__stxcpy:
/* Are source and destination co-aligned? */
xor a0, a1, t0 # e0 :
unop # :
and t0, 7, t0 # e0 :
bne t0, $unaligned # .. e1 :
/* We are co-aligned; take care of a partial first word. */
ldq_u t1, 0(a1) # e0 : load first src word
and a0, 7, t0 # .. e1 : take care not to load a word ...
addq a1, 8, a1 # e0 :
beq t0, stxcpy_aligned # .. e1 : ... if we wont need it
ldq_u t0, 0(a0) # e0 :
br stxcpy_aligned # .. e1 :
/* The source and destination are not co-aligned. Align the destination
and cope. We have to be very careful about not reading too much and
causing a SEGV. */
.align 3
$u_head:
/* We know just enough now to be able to assemble the first
full source word. We can still find a zero at the end of it
|
