1 /* SPDX-License-Identifier: GPL-2.0 */ 1 /* SPDX-License-Identifier: GPL-2.0 */
2 /* 2 /*
3 * arch/alpha/lib/stxncpy.S 3 * arch/alpha/lib/stxncpy.S
4 * Contributed by Richard Henderson (rth@tamu. 4 * Contributed by Richard Henderson (rth@tamu.edu)
5 * 5 *
6 * Copy no more than COUNT bytes of the null-t 6 * Copy no more than COUNT bytes of the null-terminated string from
7 * SRC to DST. 7 * SRC to DST.
8 * 8 *
9 * This is an internal routine used by strncpy 9 * This is an internal routine used by strncpy, stpncpy, and strncat.
10 * As such, it uses special linkage convention 10 * As such, it uses special linkage conventions to make implementation
11 * of these public functions more efficient. 11 * of these public functions more efficient.
12 * 12 *
13 * On input: 13 * On input:
14 * t9 = return address 14 * t9 = return address
15 * a0 = DST 15 * a0 = DST
16 * a1 = SRC 16 * a1 = SRC
17 * a2 = COUNT 17 * a2 = COUNT
18 * 18 *
19 * Furthermore, COUNT may not be zero. 19 * Furthermore, COUNT may not be zero.
20 * 20 *
21 * On output: 21 * On output:
22 * t0 = last word written 22 * t0 = last word written
23 * t10 = bitmask (with one bit set) indic 23 * t10 = bitmask (with one bit set) indicating the byte position of
24 * the end of the range specified b 24 * the end of the range specified by COUNT
25 * t12 = bitmask (with one bit set) indic 25 * t12 = bitmask (with one bit set) indicating the last byte written
26 * a0 = unaligned address of the last *w 26 * a0 = unaligned address of the last *word* written
27 * a2 = the number of full words left in 27 * a2 = the number of full words left in COUNT
28 * 28 *
29 * Furthermore, v0, a3-a5, t11, and $at are un 29 * Furthermore, v0, a3-a5, t11, and $at are untouched.
30 */ 30 */
31 31
32 #include <asm/regdef.h> 32 #include <asm/regdef.h>
33 33
34 .set noat 34 .set noat
35 .set noreorder 35 .set noreorder
36 36
37 .text 37 .text
38 38
39 /* There is a problem with either gdb (as of 4 39 /* There is a problem with either gdb (as of 4.16) or gas (as of 2.7) that
40 doesn't like putting the entry point for a 40 doesn't like putting the entry point for a procedure somewhere in the
41 middle of the procedure descriptor. Work a 41 middle of the procedure descriptor. Work around this by putting the
42 aligned copy in its own procedure descripto 42 aligned copy in its own procedure descriptor */
43 43
44 .ent stxncpy_aligned 44 .ent stxncpy_aligned
45 .align 3 45 .align 3
46 stxncpy_aligned: 46 stxncpy_aligned:
47 .frame sp, 0, t9, 0 47 .frame sp, 0, t9, 0
48 .prologue 0 48 .prologue 0
49 49
50 /* On entry to this basic block: 50 /* On entry to this basic block:
51 t0 == the first destination word fo 51 t0 == the first destination word for masking back in
52 t1 == the first source word. */ 52 t1 == the first source word. */
53 53
54 /* Create the 1st output word and dete 54 /* Create the 1st output word and detect 0's in the 1st input word. */
55 lda t2, -1 # e1 : buil 55 lda t2, -1 # e1 : build a mask against false zero
56 mskqh t2, a1, t2 # e0 : de 56 mskqh t2, a1, t2 # e0 : detection in the src word
57 mskqh t1, a1, t3 # e0 : 57 mskqh t1, a1, t3 # e0 :
58 ornot t1, t2, t2 # .. e1 : 58 ornot t1, t2, t2 # .. e1 :
59 mskql t0, a1, t0 # e0 : asse 59 mskql t0, a1, t0 # e0 : assemble the first output word
60 cmpbge zero, t2, t8 # .. e1 : bits 60 cmpbge zero, t2, t8 # .. e1 : bits set iff null found
61 or t0, t3, t0 # e0 : 61 or t0, t3, t0 # e0 :
62 beq a2, $a_eoc # .. e1 : 62 beq a2, $a_eoc # .. e1 :
63 bne t8, $a_eos # .. e1 : 63 bne t8, $a_eos # .. e1 :
64 64
65 /* On entry to this basic block: 65 /* On entry to this basic block:
66 t0 == a source word not containing 66 t0 == a source word not containing a null. */
67 67
68 $a_loop: 68 $a_loop:
69 stq_u t0, 0(a0) # e0 : 69 stq_u t0, 0(a0) # e0 :
70 addq a0, 8, a0 # .. e1 : 70 addq a0, 8, a0 # .. e1 :
71 ldq_u t0, 0(a1) # e0 : 71 ldq_u t0, 0(a1) # e0 :
72 addq a1, 8, a1 # .. e1 : 72 addq a1, 8, a1 # .. e1 :
73 subq a2, 1, a2 # e0 : 73 subq a2, 1, a2 # e0 :
74 cmpbge zero, t0, t8 # .. e1 (stall 74 cmpbge zero, t0, t8 # .. e1 (stall)
75 beq a2, $a_eoc # e1 : 75 beq a2, $a_eoc # e1 :
76 beq t8, $a_loop # e1 : 76 beq t8, $a_loop # e1 :
77 77
78 /* Take care of the final (partial) wo 78 /* Take care of the final (partial) word store. At this point
79 the end-of-count bit is set in t8 i 79 the end-of-count bit is set in t8 iff it applies.
80 80
81 On entry to this basic block we hav 81 On entry to this basic block we have:
82 t0 == the source word containing th 82 t0 == the source word containing the null
83 t8 == the cmpbge mask that found it 83 t8 == the cmpbge mask that found it. */
84 84
85 $a_eos: 85 $a_eos:
86 negq t8, t12 # e0 : find 86 negq t8, t12 # e0 : find low bit set
87 and t8, t12, t12 # e1 (stall) 87 and t8, t12, t12 # e1 (stall)
88 88
89 /* For the sake of the cache, don't re 89 /* For the sake of the cache, don't read a destination word
90 if we're not going to need it. */ 90 if we're not going to need it. */
91 and t12, 0x80, t6 # e0 : 91 and t12, 0x80, t6 # e0 :
92 bne t6, 1f # .. e1 (zdb) 92 bne t6, 1f # .. e1 (zdb)
93 93
94 /* We're doing a partial word store an 94 /* We're doing a partial word store and so need to combine
95 our source and original destination 95 our source and original destination words. */
96 ldq_u t1, 0(a0) # e0 : 96 ldq_u t1, 0(a0) # e0 :
97 subq t12, 1, t6 # .. e1 : 97 subq t12, 1, t6 # .. e1 :
98 or t12, t6, t8 # e0 : 98 or t12, t6, t8 # e0 :
99 unop # 99 unop #
100 zapnot t0, t8, t0 # e0 : clea 100 zapnot t0, t8, t0 # e0 : clear src bytes > null
101 zap t1, t8, t1 # .. e1 : clea 101 zap t1, t8, t1 # .. e1 : clear dst bytes <= null
102 or t0, t1, t0 # e1 : 102 or t0, t1, t0 # e1 :
103 103
104 1: stq_u t0, 0(a0) # e0 : 104 1: stq_u t0, 0(a0) # e0 :
105 ret (t9) # e1 : 105 ret (t9) # e1 :
106 106
107 /* Add the end-of-count bit to the eos 107 /* Add the end-of-count bit to the eos detection bitmask. */
108 $a_eoc: 108 $a_eoc:
109 or t10, t8, t8 109 or t10, t8, t8
110 br $a_eos 110 br $a_eos
111 111
112 .end stxncpy_aligned 112 .end stxncpy_aligned
113 113
114 .align 3 114 .align 3
115 .ent __stxncpy 115 .ent __stxncpy
116 .globl __stxncpy 116 .globl __stxncpy
117 __stxncpy: 117 __stxncpy:
118 .frame sp, 0, t9, 0 118 .frame sp, 0, t9, 0
119 .prologue 0 119 .prologue 0
120 120
121 /* Are source and destination co-align 121 /* Are source and destination co-aligned? */
122 xor a0, a1, t1 # e0 : 122 xor a0, a1, t1 # e0 :
123 and a0, 7, t0 # .. e1 : find 123 and a0, 7, t0 # .. e1 : find dest misalignment
124 and t1, 7, t1 # e0 : 124 and t1, 7, t1 # e0 :
125 addq a2, t0, a2 # .. e1 : bias 125 addq a2, t0, a2 # .. e1 : bias count by dest misalignment
126 subq a2, 1, a2 # e0 : 126 subq a2, 1, a2 # e0 :
127 and a2, 7, t2 # e1 : 127 and a2, 7, t2 # e1 :
128 srl a2, 3, a2 # e0 : a2 = 128 srl a2, 3, a2 # e0 : a2 = loop counter = (count - 1)/8
129 addq zero, 1, t10 # .. e1 : 129 addq zero, 1, t10 # .. e1 :
130 sll t10, t2, t10 # e0 : t10 130 sll t10, t2, t10 # e0 : t10 = bitmask of last count byte
131 bne t1, $unaligned # .. e1 : 131 bne t1, $unaligned # .. e1 :
132 132
133 /* We are co-aligned; take care of a p 133 /* We are co-aligned; take care of a partial first word. */
134 134
135 ldq_u t1, 0(a1) # e0 : load 135 ldq_u t1, 0(a1) # e0 : load first src word
136 addq a1, 8, a1 # .. e1 : 136 addq a1, 8, a1 # .. e1 :
137 137
138 beq t0, stxncpy_aligned # avoi 138 beq t0, stxncpy_aligned # avoid loading dest word if not needed
139 ldq_u t0, 0(a0) # e0 : 139 ldq_u t0, 0(a0) # e0 :
140 br stxncpy_aligned # .. e1 : 140 br stxncpy_aligned # .. e1 :
141 141
142 142
143 /* The source and destination are not co-align 143 /* The source and destination are not co-aligned. Align the destination
144 and cope. We have to be very careful about 144 and cope. We have to be very careful about not reading too much and
145 causing a SEGV. */ 145 causing a SEGV. */
146 146
147 .align 3 147 .align 3
148 $u_head: 148 $u_head:
149 /* We know just enough now to be able 149 /* We know just enough now to be able to assemble the first
150 full source word. We can still fin 150 full source word. We can still find a zero at the end of it
151 that prevents us from outputting th 151 that prevents us from outputting the whole thing.
152 152
153 On entry to this basic block: 153 On entry to this basic block:
154 t0 == the first dest word, unmasked 154 t0 == the first dest word, unmasked
155 t1 == the shifted low bits of the f 155 t1 == the shifted low bits of the first source word
156 t6 == bytemask that is -1 in dest w 156 t6 == bytemask that is -1 in dest word bytes */
157 157
158 ldq_u t2, 8(a1) # e0 : load 158 ldq_u t2, 8(a1) # e0 : load second src word
159 addq a1, 8, a1 # .. e1 : 159 addq a1, 8, a1 # .. e1 :
160 mskql t0, a0, t0 # e0 : mask 160 mskql t0, a0, t0 # e0 : mask trailing garbage in dst
161 extqh t2, a1, t4 # e0 : 161 extqh t2, a1, t4 # e0 :
162 or t1, t4, t1 # e1 : firs 162 or t1, t4, t1 # e1 : first aligned src word complete
163 mskqh t1, a0, t1 # e0 : mask 163 mskqh t1, a0, t1 # e0 : mask leading garbage in src
164 or t0, t1, t0 # e0 : firs 164 or t0, t1, t0 # e0 : first output word complete
165 or t0, t6, t6 # e1 : mask 165 or t0, t6, t6 # e1 : mask original data for zero test
166 cmpbge zero, t6, t8 # e0 : 166 cmpbge zero, t6, t8 # e0 :
167 beq a2, $u_eocfin # .. e1 : 167 beq a2, $u_eocfin # .. e1 :
168 lda t6, -1 # e0 : 168 lda t6, -1 # e0 :
169 bne t8, $u_final # .. e1 : 169 bne t8, $u_final # .. e1 :
170 170
171 mskql t6, a1, t6 # e0 : mask 171 mskql t6, a1, t6 # e0 : mask out bits already seen
172 nop # .. e1 : 172 nop # .. e1 :
173 stq_u t0, 0(a0) # e0 : stor 173 stq_u t0, 0(a0) # e0 : store first output word
174 or t6, t2, t2 # .. e1 : 174 or t6, t2, t2 # .. e1 :
175 cmpbge zero, t2, t8 # e0 : find 175 cmpbge zero, t2, t8 # e0 : find nulls in second partial
176 addq a0, 8, a0 # .. e1 : 176 addq a0, 8, a0 # .. e1 :
177 subq a2, 1, a2 # e0 : 177 subq a2, 1, a2 # e0 :
178 bne t8, $u_late_head_exit # .. e 178 bne t8, $u_late_head_exit # .. e1 :
179 179
180 /* Finally, we've got all the stupid l 180 /* Finally, we've got all the stupid leading edge cases taken care
181 of and we can set up to enter the m 181 of and we can set up to enter the main loop. */
182 182
183 extql t2, a1, t1 # e0 : posi 183 extql t2, a1, t1 # e0 : position hi-bits of lo word
184 beq a2, $u_eoc # .. e1 : 184 beq a2, $u_eoc # .. e1 :
185 ldq_u t2, 8(a1) # e0 : read 185 ldq_u t2, 8(a1) # e0 : read next high-order source word
186 addq a1, 8, a1 # .. e1 : 186 addq a1, 8, a1 # .. e1 :
187 extqh t2, a1, t0 # e0 : posi 187 extqh t2, a1, t0 # e0 : position lo-bits of hi word (stall)
188 cmpbge zero, t2, t8 # .. e1 : 188 cmpbge zero, t2, t8 # .. e1 :
189 nop # e0 : 189 nop # e0 :
190 bne t8, $u_eos # .. e1 : 190 bne t8, $u_eos # .. e1 :
191 191
192 /* Unaligned copy main loop. In order 192 /* Unaligned copy main loop. In order to avoid reading too much,
193 the loop is structured to detect ze 193 the loop is structured to detect zeros in aligned source words.
194 This has, unfortunately, effectivel 194 This has, unfortunately, effectively pulled half of a loop
195 iteration out into the head and hal 195 iteration out into the head and half into the tail, but it does
196 prevent nastiness from accumulating 196 prevent nastiness from accumulating in the very thing we want
197 to run as fast as possible. 197 to run as fast as possible.
198 198
199 On entry to this basic block: 199 On entry to this basic block:
200 t0 == the shifted low-order bits fr 200 t0 == the shifted low-order bits from the current source word
201 t1 == the shifted high-order bits f 201 t1 == the shifted high-order bits from the previous source word
202 t2 == the unshifted current source 202 t2 == the unshifted current source word
203 203
204 We further know that t2 does not co 204 We further know that t2 does not contain a null terminator. */
205 205
206 .align 3 206 .align 3
207 $u_loop: 207 $u_loop:
208 or t0, t1, t0 # e0 : curr 208 or t0, t1, t0 # e0 : current dst word now complete
209 subq a2, 1, a2 # .. e1 : decr 209 subq a2, 1, a2 # .. e1 : decrement word count
210 stq_u t0, 0(a0) # e0 : save 210 stq_u t0, 0(a0) # e0 : save the current word
211 addq a0, 8, a0 # .. e1 : 211 addq a0, 8, a0 # .. e1 :
212 extql t2, a1, t1 # e0 : extr 212 extql t2, a1, t1 # e0 : extract high bits for next time
213 beq a2, $u_eoc # .. e1 : 213 beq a2, $u_eoc # .. e1 :
214 ldq_u t2, 8(a1) # e0 : load 214 ldq_u t2, 8(a1) # e0 : load high word for next time
215 addq a1, 8, a1 # .. e1 : 215 addq a1, 8, a1 # .. e1 :
216 nop # e0 : 216 nop # e0 :
217 cmpbge zero, t2, t8 # e1 : test 217 cmpbge zero, t2, t8 # e1 : test new word for eos (stall)
218 extqh t2, a1, t0 # e0 : extr 218 extqh t2, a1, t0 # e0 : extract low bits for current word
219 beq t8, $u_loop # .. e1 : 219 beq t8, $u_loop # .. e1 :
220 220
221 /* We've found a zero somewhere in the 221 /* We've found a zero somewhere in the source word we just read.
222 If it resides in the lower half, we 222 If it resides in the lower half, we have one (probably partial)
223 word to write out, and if it reside 223 word to write out, and if it resides in the upper half, we
224 have one full and one partial word 224 have one full and one partial word left to write out.
225 225
226 On entry to this basic block: 226 On entry to this basic block:
227 t0 == the shifted low-order bits fr 227 t0 == the shifted low-order bits from the current source word
228 t1 == the shifted high-order bits f 228 t1 == the shifted high-order bits from the previous source word
229 t2 == the unshifted current source 229 t2 == the unshifted current source word. */
230 $u_eos: 230 $u_eos:
231 or t0, t1, t0 # e0 : firs 231 or t0, t1, t0 # e0 : first (partial) source word complete
232 nop # .. e1 : 232 nop # .. e1 :
233 cmpbge zero, t0, t8 # e0 : is t 233 cmpbge zero, t0, t8 # e0 : is the null in this first bit?
234 bne t8, $u_final # .. e1 (zdb) 234 bne t8, $u_final # .. e1 (zdb)
235 235
236 stq_u t0, 0(a0) # e0 : the 236 stq_u t0, 0(a0) # e0 : the null was in the high-order bits
237 addq a0, 8, a0 # .. e1 : 237 addq a0, 8, a0 # .. e1 :
238 subq a2, 1, a2 # e1 : 238 subq a2, 1, a2 # e1 :
239 239
240 $u_late_head_exit: 240 $u_late_head_exit:
241 extql t2, a1, t0 # .. e0 : 241 extql t2, a1, t0 # .. e0 :
242 cmpbge zero, t0, t8 # e0 : 242 cmpbge zero, t0, t8 # e0 :
243 or t8, t10, t6 # e1 : 243 or t8, t10, t6 # e1 :
244 cmoveq a2, t6, t8 # e0 : 244 cmoveq a2, t6, t8 # e0 :
245 nop # .. e1 : 245 nop # .. e1 :
246 246
247 /* Take care of a final (probably part 247 /* Take care of a final (probably partial) result word.
248 On entry to this basic block: 248 On entry to this basic block:
249 t0 == assembled source word 249 t0 == assembled source word
250 t8 == cmpbge mask that found the nu 250 t8 == cmpbge mask that found the null. */
251 $u_final: 251 $u_final:
252 negq t8, t6 # e0 : isol 252 negq t8, t6 # e0 : isolate low bit set
253 and t6, t8, t12 # e1 : 253 and t6, t8, t12 # e1 :
254 254
255 and t12, 0x80, t6 # e0 : avoi 255 and t12, 0x80, t6 # e0 : avoid dest word load if we can
256 bne t6, 1f # .. e1 (zdb) 256 bne t6, 1f # .. e1 (zdb)
257 257
258 ldq_u t1, 0(a0) # e0 : 258 ldq_u t1, 0(a0) # e0 :
259 subq t12, 1, t6 # .. e1 : 259 subq t12, 1, t6 # .. e1 :
260 or t6, t12, t8 # e0 : 260 or t6, t12, t8 # e0 :
261 zapnot t0, t8, t0 # .. e1 : kill 261 zapnot t0, t8, t0 # .. e1 : kill source bytes > null
262 zap t1, t8, t1 # e0 : kill 262 zap t1, t8, t1 # e0 : kill dest bytes <= null
263 or t0, t1, t0 # e1 : 263 or t0, t1, t0 # e1 :
264 264
265 1: stq_u t0, 0(a0) # e0 : 265 1: stq_u t0, 0(a0) # e0 :
266 ret (t9) # .. e1 : 266 ret (t9) # .. e1 :
267 267
268 /* Got to end-of-count before end of s 268 /* Got to end-of-count before end of string.
269 On entry to this basic block: 269 On entry to this basic block:
270 t1 == the shifted high-order bits f 270 t1 == the shifted high-order bits from the previous source word */
271 $u_eoc: 271 $u_eoc:
272 and a1, 7, t6 # e1 : 272 and a1, 7, t6 # e1 :
273 sll t10, t6, t6 # e0 : 273 sll t10, t6, t6 # e0 :
274 and t6, 0xff, t6 # e0 : 274 and t6, 0xff, t6 # e0 :
275 bne t6, 1f # .. e1 : 275 bne t6, 1f # .. e1 :
276 276
277 ldq_u t2, 8(a1) # e0 : load 277 ldq_u t2, 8(a1) # e0 : load final src word
278 nop # .. e1 : 278 nop # .. e1 :
279 extqh t2, a1, t0 # e0 : extr 279 extqh t2, a1, t0 # e0 : extract low bits for last word
280 or t1, t0, t1 # e1 : 280 or t1, t0, t1 # e1 :
281 281
282 1: cmpbge zero, t1, t8 282 1: cmpbge zero, t1, t8
283 mov t1, t0 283 mov t1, t0
284 284
285 $u_eocfin: # end-of-count 285 $u_eocfin: # end-of-count, final word
286 or t10, t8, t8 286 or t10, t8, t8
287 br $u_final 287 br $u_final
288 288
289 /* Unaligned copy entry point. */ 289 /* Unaligned copy entry point. */
290 .align 3 290 .align 3
291 $unaligned: 291 $unaligned:
292 292
293 ldq_u t1, 0(a1) # e0 : load 293 ldq_u t1, 0(a1) # e0 : load first source word
294 294
295 and a0, 7, t4 # .. e1 : find 295 and a0, 7, t4 # .. e1 : find dest misalignment
296 and a1, 7, t5 # e0 : find 296 and a1, 7, t5 # e0 : find src misalignment
297 297
298 /* Conditionally load the first destin 298 /* Conditionally load the first destination word and a bytemask
299 with 0xff indicating that the desti 299 with 0xff indicating that the destination byte is sacrosanct. */
300 300
301 mov zero, t0 # .. e1 : 301 mov zero, t0 # .. e1 :
302 mov zero, t6 # e0 : 302 mov zero, t6 # e0 :
303 beq t4, 1f # .. e1 : 303 beq t4, 1f # .. e1 :
304 ldq_u t0, 0(a0) # e0 : 304 ldq_u t0, 0(a0) # e0 :
305 lda t6, -1 # .. e1 : 305 lda t6, -1 # .. e1 :
306 mskql t6, a0, t6 # e0 : 306 mskql t6, a0, t6 # e0 :
307 subq a1, t4, a1 # .. e1 : sub 307 subq a1, t4, a1 # .. e1 : sub dest misalignment from src addr
308 308
309 /* If source misalignment is larger th 309 /* If source misalignment is larger than dest misalignment, we need
310 extra startup checks to avoid SEGV. 310 extra startup checks to avoid SEGV. */
311 311
312 1: cmplt t4, t5, t12 # e1 : 312 1: cmplt t4, t5, t12 # e1 :
313 extql t1, a1, t1 # .. e0 : shif 313 extql t1, a1, t1 # .. e0 : shift src into place
314 lda t2, -1 # e0 : for 314 lda t2, -1 # e0 : for creating masks later
315 beq t12, $u_head # .. e1 : 315 beq t12, $u_head # .. e1 :
316 316
317 extql t2, a1, t2 # e0 : 317 extql t2, a1, t2 # e0 :
318 cmpbge zero, t1, t8 # .. e1 : is t 318 cmpbge zero, t1, t8 # .. e1 : is there a zero?
319 andnot t2, t6, t2 # e0 : dest 319 andnot t2, t6, t2 # e0 : dest mask for a single word copy
320 or t8, t10, t5 # .. e1 : test 320 or t8, t10, t5 # .. e1 : test for end-of-count too
321 cmpbge zero, t2, t3 # e0 : 321 cmpbge zero, t2, t3 # e0 :
322 cmoveq a2, t5, t8 # .. e1 : 322 cmoveq a2, t5, t8 # .. e1 :
323 andnot t8, t3, t8 # e0 : 323 andnot t8, t3, t8 # e0 :
324 beq t8, $u_head # .. e1 (zdb) 324 beq t8, $u_head # .. e1 (zdb)
325 325
326 /* At this point we've found a zero in 326 /* At this point we've found a zero in the first partial word of
327 the source. We need to isolate the 327 the source. We need to isolate the valid source data and mask
328 it into the original destination da 328 it into the original destination data. (Incidentally, we know
329 that we'll need at least one byte o 329 that we'll need at least one byte of that original dest word.) */
330 330
331 ldq_u t0, 0(a0) # e0 : 331 ldq_u t0, 0(a0) # e0 :
332 negq t8, t6 # .. e1 : buil 332 negq t8, t6 # .. e1 : build bitmask of bytes <= zero
333 mskqh t1, t4, t1 # e0 : 333 mskqh t1, t4, t1 # e0 :
334 and t6, t8, t12 # .. e1 : 334 and t6, t8, t12 # .. e1 :
335 subq t12, 1, t6 # e0 : 335 subq t12, 1, t6 # e0 :
336 or t6, t12, t8 # e1 : 336 or t6, t12, t8 # e1 :
337 337
338 zapnot t2, t8, t2 # e0 : prep 338 zapnot t2, t8, t2 # e0 : prepare source word; mirror changes
339 zapnot t1, t8, t1 # .. e1 : to s 339 zapnot t1, t8, t1 # .. e1 : to source validity mask
340 340
341 andnot t0, t2, t0 # e0 : zero 341 andnot t0, t2, t0 # e0 : zero place for source to reside
342 or t0, t1, t0 # e1 : and 342 or t0, t1, t0 # e1 : and put it there
343 stq_u t0, 0(a0) # e0 : 343 stq_u t0, 0(a0) # e0 :
344 ret (t9) # .. e1 : 344 ret (t9) # .. e1 :
345 345
346 .end __stxncpy 346 .end __stxncpy
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