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1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * arch/alpha/lib/stxncpy.S
4 * Contributed by Richard Henderson (rth@tamu.edu)
5 *
6 * Copy no more than COUNT bytes of the null-terminated string from
7 * SRC to DST.
8 *
9 * This is an internal routine used by strncpy, stpncpy, and strncat.
10 * As such, it uses special linkage conventions to make implementation
11 * of these public functions more efficient.
12 *
13 * On input:
14 * t9 = return address
15 * a0 = DST
16 * a1 = SRC
17 * a2 = COUNT
18 *
19 * Furthermore, COUNT may not be zero.
20 *
21 * On output:
22 * t0 = last word written
23 * t10 = bitmask (with one bit set) indicating the byte position of
24 * the end of the range specified by COUNT
25 * t12 = bitmask (with one bit set) indicating the last byte written
26 * a0 = unaligned address of the last *word* written
27 * a2 = the number of full words left in COUNT
28 *
29 * Furthermore, v0, a3-a5, t11, and $at are untouched.
30 */
31
32#include <asm/regdef.h>
33
34 .set noat
35 .set noreorder
36
37 .text
38
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 procedure somewhere in the
41 middle of the procedure descriptor. Work around this by putting the
42 aligned copy in its own procedure descriptor */
43
44 .ent stxncpy_aligned
45 .align 3
46stxncpy_aligned:
47 .frame sp, 0, t9, 0
48 .prologue 0
49
50 /* On entry to this basic block:
51 t0 == the first destination word for masking back in
52 t1 == the first source word. */
53
54 /* Create the 1st output word and detect 0's in the 1st input word. */
55 lda t2, -1 # e1 : build a mask against false zero
56 mskqh t2, a1, t2 # e0 : detection in the src word
57 mskqh t1, a1, t3 # e0 :
58 ornot t1, t2, t2 # .. e1 :
59 mskql t0, a1, t0 # e0 : assemble the first output word
60 cmpbge zero, t2, t8 # .. e1 : bits set iff null found
61 or t0, t3, t0 # e0 :
62 beq a2, $a_eoc # .. e1 :
63 bne t8, $a_eos # .. e1 :
64
65 /* On entry to this basic block:
66 t0 == a source word not containing a null. */
67
68$a_loop:
69 stq_u t0, 0(a0) # e0 :
70 addq a0, 8, a0 # .. e1 :
71 ldq_u t0, 0(a1) # e0 :
72 addq a1, 8, a1 # .. e1 :
73 subq a2, 1, a2 # e0 :
74 cmpbge zero, t0, t8 # .. e1 (stall)
75 beq a2, $a_eoc # e1 :
76 beq t8, $a_loop # e1 :
77
78 /* Take care of the final (partial) word store. At this point
79 the end-of-count bit is set in t8 iff it applies.
80
81 On entry to this basic block we have:
82 t0 == the source word containing the null
83 t8 == the cmpbge mask that found it. */
84
85$a_eos:
86 negq t8, t12 # e0 : find low bit set
87 and t8, t12, t12 # e1 (stall)
88
89 /* For the sake of the cache, don't read a destination word
90 if we're not going to need it. */
91 and t12, 0x80, t6 # e0 :
92 bne t6, 1f # .. e1 (zdb)
93
94 /* We're doing a partial word store and so need to combine
95 our source and original destination words. */
96 ldq_u t1, 0(a0) # e0 :
97 subq t12, 1, t6 # .. e1 :
98 or t12, t6, t8 # e0 :
99 unop #
100 zapnot t0, t8, t0 # e0 : clear src bytes > null
101 zap t1, t8, t1 # .. e1 : clear dst bytes <= null
102 or t0, t1, t0 # e1 :
103
1041: stq_u t0, 0(a0) # e0 :
105 ret (t9) # e1 :
106
107 /* Add the end-of-count bit to the eos detection bitmask. */
108$a_eoc:
109 or t10, t8, t8
110 br $a_eos
111
112 .end stxncpy_aligned
113
114 .align 3
115 .ent __stxncpy
116 .globl __stxncpy
117__stxncpy:
118 .frame sp, 0, t9, 0
119 .prologue 0
120
121 /* Are source and destination co-aligned? */
122 xor a0, a1, t1 # e0 :
123 and a0, 7, t0 # .. e1 : find dest misalignment
124 and t1, 7, t1 # e0 :
125 addq a2, t0, a2 # .. e1 : bias count by dest misalignment
126 subq a2, 1, a2 # e0 :
127 and a2, 7, t2 # e1 :
128 srl a2, 3, a2 # e0 : a2 = loop counter = (count - 1)/8
129 addq zero, 1, t10 # .. e1 :
130 sll t10, t2, t10 # e0 : t10 = bitmask of last count byte
131 bne t1, $unaligned # .. e1 :
132
133 /* We are co-aligned; take care of a partial first word. */
134
135 ldq_u t1, 0(a1) # e0 : load first src word
136 addq a1, 8, a1 # .. e1 :
137
138 beq t0, stxncpy_aligned # avoid loading dest word if not needed
139 ldq_u t0, 0(a0) # e0 :
140 br stxncpy_aligned # .. e1 :
141
142
143/* The source and destination are not co-aligned. Align the destination
144 and cope. We have to be very careful about not reading too much and
145 causing a SEGV. */
146
147 .align 3
148$u_head:
149 /* We know just enough now to be able to assemble the first
150 full source word. We can still find a zero at the end of it
151 that prevents us from outputting the whole thing.
152
153 On entry to this basic block:
154 t0 == the first dest word, unmasked
155 t1 == the shifted low bits of the first source word
156 t6 == bytemask that is -1 in dest word bytes */
157
158 ldq_u t2, 8(a1) # e0 : load second src word
159 addq a1, 8, a1 # .. e1 :
160 mskql t0, a0, t0 # e0 : mask trailing garbage in dst
161 extqh t2, a1, t4 # e0 :
162 or t1, t4, t1 # e1 : first aligned src word complete
163 mskqh t1, a0, t1 # e0 : mask leading garbage in src
164 or t0, t1, t0 # e0 : first output word complete
165 or t0, t6, t6 # e1 : mask original data for zero test
166 cmpbge zero, t6, t8 # e0 :
167 beq a2, $u_eocfin # .. e1 :
168 lda t6, -1 # e0 :
169 bne t8, $u_final # .. e1 :
170
171 mskql t6, a1, t6 # e0 : mask out bits already seen
172 nop # .. e1 :
173 stq_u t0, 0(a0) # e0 : store first output word
174 or t6, t2, t2 # .. e1 :
175 cmpbge zero, t2, t8 # e0 : find nulls in second partial
176 addq a0, 8, a0 # .. e1 :
177 subq a2, 1, a2 # e0 :
178 bne t8, $u_late_head_exit # .. e1 :
179
180 /* Finally, we've got all the stupid leading edge cases taken care
181 of and we can set up to enter the main loop. */
182
183 extql t2, a1, t1 # e0 : position hi-bits of lo word
184 beq a2, $u_eoc # .. e1 :
185 ldq_u t2, 8(a1) # e0 : read next high-order source word
186 addq a1, 8, a1 # .. e1 :
187 extqh t2, a1, t0 # e0 : position lo-bits of hi word (stall)
188 cmpbge zero, t2, t8 # .. e1 :
189 nop # e0 :
190 bne t8, $u_eos # .. e1 :
191
192 /* Unaligned copy main loop. In order to avoid reading too much,
193 the loop is structured to detect zeros in aligned source words.
194 This has, unfortunately, effectively pulled half of a loop
195 iteration out into the head and half into the tail, but it does
196 prevent nastiness from accumulating in the very thing we want
197 to run as fast as possible.
198
199 On entry to this basic block:
200 t0 == the shifted low-order bits from the current source word
201 t1 == the shifted high-order bits from the previous source word
202 t2 == the unshifted current source word
203
204 We further know that t2 does not contain a null terminator. */
205
206 .align 3
207$u_loop:
208 or t0, t1, t0 # e0 : current dst word now complete
209 subq a2, 1, a2 # .. e1 : decrement word count
210 stq_u t0, 0(a0) # e0 : save the current word
211 addq a0, 8, a0 # .. e1 :
212 extql t2, a1, t1 # e0 : extract high bits for next time
213 beq a2, $u_eoc # .. e1 :
214 ldq_u t2, 8(a1) # e0 : load high word for next time
215 addq a1, 8, a1 # .. e1 :
216 nop # e0 :
217 cmpbge zero, t2, t8 # e1 : test new word for eos (stall)
218 extqh t2, a1, t0 # e0 : extract low bits for current word
219 beq t8, $u_loop # .. e1 :
220
221 /* We've found a zero somewhere in the source word we just read.
222 If it resides in the lower half, we have one (probably partial)
223 word to write out, and if it resides in the upper half, we
224 have one full and one partial word left to write out.
225
226 On entry to this basic block:
227 t0 == the shifted low-order bits from the current source word
228 t1 == the shifted high-order bits from the previous source word
229 t2 == the unshifted current source word. */
230$u_eos:
231 or t0, t1, t0 # e0 : first (partial) source word complete
232 nop # .. e1 :
233 cmpbge zero, t0, t8 # e0 : is the null in this first bit?
234 bne t8, $u_final # .. e1 (zdb)
235
236 stq_u t0, 0(a0) # e0 : the null was in the high-order bits
237 addq a0, 8, a0 # .. e1 :
238 subq a2, 1, a2 # e1 :
239
240$u_late_head_exit:
241 extql t2, a1, t0 # .. e0 :
242 cmpbge zero, t0, t8 # e0 :
243 or t8, t10, t6 # e1 :
244 cmoveq a2, t6, t8 # e0 :
245 nop # .. e1 :
246
247 /* Take care of a final (probably partial) result word.
248 On entry to this basic block:
249 t0 == assembled source word
250 t8 == cmpbge mask that found the null. */
251$u_final:
252 negq t8, t6 # e0 : isolate low bit set
253 and t6, t8, t12 # e1 :
254
255 and t12, 0x80, t6 # e0 : avoid dest word load if we can
256 bne t6, 1f # .. e1 (zdb)
257
258 ldq_u t1, 0(a0) # e0 :
259 subq t12, 1, t6 # .. e1 :
260 or t6, t12, t8 # e0 :
261 zapnot t0, t8, t0 # .. e1 : kill source bytes > null
262 zap t1, t8, t1 # e0 : kill dest bytes <= null
263 or t0, t1, t0 # e1 :
264
2651: stq_u t0, 0(a0) # e0 :
266 ret (t9) # .. e1 :
267
268 /* Got to end-of-count before end of string.
269 On entry to this basic block:
270 t1 == the shifted high-order bits from the previous source word */
271$u_eoc:
272 and a1, 7, t6 # e1 :
273 sll t10, t6, t6 # e0 :
274 and t6, 0xff, t6 # e0 :
275 bne t6, 1f # .. e1 :
276
277 ldq_u t2, 8(a1) # e0 : load final src word
278 nop # .. e1 :
279 extqh t2, a1, t0 # e0 : extract low bits for last word
280 or t1, t0, t1 # e1 :
281
2821: cmpbge zero, t1, t8
283 mov t1, t0
284
285$u_eocfin: # end-of-count, final word
286 or t10, t8, t8
287 br $u_final
288
289 /* Unaligned copy entry point. */
290 .align 3
291$unaligned:
292
293 ldq_u t1, 0(a1) # e0 : load first source word
294
295 and a0, 7, t4 # .. e1 : find dest misalignment
296 and a1, 7, t5 # e0 : find src misalignment
297
298 /* Conditionally load the first destination word and a bytemask
299 with 0xff indicating that the destination byte is sacrosanct. */
300
301 mov zero, t0 # .. e1 :
302 mov zero, t6 # e0 :
303 beq t4, 1f # .. e1 :
304 ldq_u t0, 0(a0) # e0 :
305 lda t6, -1 # .. e1 :
306 mskql t6, a0, t6 # e0 :
307 subq a1, t4, a1 # .. e1 : sub dest misalignment from src addr
308
309 /* If source misalignment is larger than dest misalignment, we need
310 extra startup checks to avoid SEGV. */
311
3121: cmplt t4, t5, t12 # e1 :
313 extql t1, a1, t1 # .. e0 : shift src into place
314 lda t2, -1 # e0 : for creating masks later
315 beq t12, $u_head # .. e1 :
316
317 extql t2, a1, t2 # e0 :
318 cmpbge zero, t1, t8 # .. e1 : is there a zero?
319 andnot t2, t6, t2 # e0 : dest mask for a single word copy
320 or t8, t10, t5 # .. e1 : test for end-of-count too
321 cmpbge zero, t2, t3 # e0 :
322 cmoveq a2, t5, t8 # .. e1 :
323 andnot t8, t3, t8 # e0 :
324 beq t8, $u_head # .. e1 (zdb)
325
326 /* At this point we've found a zero in the first partial word of
327 the source. We need to isolate the valid source data and mask
328 it into the original destination data. (Incidentally, we know
329 that we'll need at least one byte of that original dest word.) */
330
331 ldq_u t0, 0(a0) # e0 :
332 negq t8, t6 # .. e1 : build bitmask of bytes <= zero
333 mskqh t1, t4, t1 # e0 :
334 and t6, t8, t12 # .. e1 :
335 subq t12, 1, t6 # e0 :
336 or t6, t12, t8 # e1 :
337
338 zapnot t2, t8, t2 # e0 : prepare source word; mirror changes
339 zapnot t1, t8, t1 # .. e1 : to source validity mask
340
341 andnot t0, t2, t0 # e0 : zero place for source to reside
342 or t0, t1, t0 # e1 : and put it there
343 stq_u t0, 0(a0) # e0 :
344 ret (t9) # .. e1 :
345
346 .end __stxncpy
1/*
2 * arch/alpha/lib/stxncpy.S
3 * Contributed by Richard Henderson (rth@tamu.edu)
4 *
5 * Copy no more than COUNT bytes of the null-terminated string from
6 * SRC to DST.
7 *
8 * This is an internal routine used by strncpy, stpncpy, and strncat.
9 * As such, it uses special linkage conventions to make implementation
10 * of these public functions more efficient.
11 *
12 * On input:
13 * t9 = return address
14 * a0 = DST
15 * a1 = SRC
16 * a2 = COUNT
17 *
18 * Furthermore, COUNT may not be zero.
19 *
20 * On output:
21 * t0 = last word written
22 * t10 = bitmask (with one bit set) indicating the byte position of
23 * the end of the range specified by COUNT
24 * t12 = bitmask (with one bit set) indicating the last byte written
25 * a0 = unaligned address of the last *word* written
26 * a2 = the number of full words left in COUNT
27 *
28 * Furthermore, v0, a3-a5, t11, and $at are untouched.
29 */
30
31#include <asm/regdef.h>
32
33 .set noat
34 .set noreorder
35
36 .text
37
38/* There is a problem with either gdb (as of 4.16) or gas (as of 2.7) that
39 doesn't like putting the entry point for a procedure somewhere in the
40 middle of the procedure descriptor. Work around this by putting the
41 aligned copy in its own procedure descriptor */
42
43 .ent stxncpy_aligned
44 .align 3
45stxncpy_aligned:
46 .frame sp, 0, t9, 0
47 .prologue 0
48
49 /* On entry to this basic block:
50 t0 == the first destination word for masking back in
51 t1 == the first source word. */
52
53 /* Create the 1st output word and detect 0's in the 1st input word. */
54 lda t2, -1 # e1 : build a mask against false zero
55 mskqh t2, a1, t2 # e0 : detection in the src word
56 mskqh t1, a1, t3 # e0 :
57 ornot t1, t2, t2 # .. e1 :
58 mskql t0, a1, t0 # e0 : assemble the first output word
59 cmpbge zero, t2, t8 # .. e1 : bits set iff null found
60 or t0, t3, t0 # e0 :
61 beq a2, $a_eoc # .. e1 :
62 bne t8, $a_eos # .. e1 :
63
64 /* On entry to this basic block:
65 t0 == a source word not containing a null. */
66
67$a_loop:
68 stq_u t0, 0(a0) # e0 :
69 addq a0, 8, a0 # .. e1 :
70 ldq_u t0, 0(a1) # e0 :
71 addq a1, 8, a1 # .. e1 :
72 subq a2, 1, a2 # e0 :
73 cmpbge zero, t0, t8 # .. e1 (stall)
74 beq a2, $a_eoc # e1 :
75 beq t8, $a_loop # e1 :
76
77 /* Take care of the final (partial) word store. At this point
78 the end-of-count bit is set in t8 iff it applies.
79
80 On entry to this basic block we have:
81 t0 == the source word containing the null
82 t8 == the cmpbge mask that found it. */
83
84$a_eos:
85 negq t8, t12 # e0 : find low bit set
86 and t8, t12, t12 # e1 (stall)
87
88 /* For the sake of the cache, don't read a destination word
89 if we're not going to need it. */
90 and t12, 0x80, t6 # e0 :
91 bne t6, 1f # .. e1 (zdb)
92
93 /* We're doing a partial word store and so need to combine
94 our source and original destination words. */
95 ldq_u t1, 0(a0) # e0 :
96 subq t12, 1, t6 # .. e1 :
97 or t12, t6, t8 # e0 :
98 unop #
99 zapnot t0, t8, t0 # e0 : clear src bytes > null
100 zap t1, t8, t1 # .. e1 : clear dst bytes <= null
101 or t0, t1, t0 # e1 :
102
1031: stq_u t0, 0(a0) # e0 :
104 ret (t9) # e1 :
105
106 /* Add the end-of-count bit to the eos detection bitmask. */
107$a_eoc:
108 or t10, t8, t8
109 br $a_eos
110
111 .end stxncpy_aligned
112
113 .align 3
114 .ent __stxncpy
115 .globl __stxncpy
116__stxncpy:
117 .frame sp, 0, t9, 0
118 .prologue 0
119
120 /* Are source and destination co-aligned? */
121 xor a0, a1, t1 # e0 :
122 and a0, 7, t0 # .. e1 : find dest misalignment
123 and t1, 7, t1 # e0 :
124 addq a2, t0, a2 # .. e1 : bias count by dest misalignment
125 subq a2, 1, a2 # e0 :
126 and a2, 7, t2 # e1 :
127 srl a2, 3, a2 # e0 : a2 = loop counter = (count - 1)/8
128 addq zero, 1, t10 # .. e1 :
129 sll t10, t2, t10 # e0 : t10 = bitmask of last count byte
130 bne t1, $unaligned # .. e1 :
131
132 /* We are co-aligned; take care of a partial first word. */
133
134 ldq_u t1, 0(a1) # e0 : load first src word
135 addq a1, 8, a1 # .. e1 :
136
137 beq t0, stxncpy_aligned # avoid loading dest word if not needed
138 ldq_u t0, 0(a0) # e0 :
139 br stxncpy_aligned # .. e1 :
140
141
142/* The source and destination are not co-aligned. Align the destination
143 and cope. We have to be very careful about not reading too much and
144 causing a SEGV. */
145
146 .align 3
147$u_head:
148 /* We know just enough now to be able to assemble the first
149 full source word. We can still find a zero at the end of it
150 that prevents us from outputting the whole thing.
151
152 On entry to this basic block:
153 t0 == the first dest word, unmasked
154 t1 == the shifted low bits of the first source word
155 t6 == bytemask that is -1 in dest word bytes */
156
157 ldq_u t2, 8(a1) # e0 : load second src word
158 addq a1, 8, a1 # .. e1 :
159 mskql t0, a0, t0 # e0 : mask trailing garbage in dst
160 extqh t2, a1, t4 # e0 :
161 or t1, t4, t1 # e1 : first aligned src word complete
162 mskqh t1, a0, t1 # e0 : mask leading garbage in src
163 or t0, t1, t0 # e0 : first output word complete
164 or t0, t6, t6 # e1 : mask original data for zero test
165 cmpbge zero, t6, t8 # e0 :
166 beq a2, $u_eocfin # .. e1 :
167 lda t6, -1 # e0 :
168 bne t8, $u_final # .. e1 :
169
170 mskql t6, a1, t6 # e0 : mask out bits already seen
171 nop # .. e1 :
172 stq_u t0, 0(a0) # e0 : store first output word
173 or t6, t2, t2 # .. e1 :
174 cmpbge zero, t2, t8 # e0 : find nulls in second partial
175 addq a0, 8, a0 # .. e1 :
176 subq a2, 1, a2 # e0 :
177 bne t8, $u_late_head_exit # .. e1 :
178
179 /* Finally, we've got all the stupid leading edge cases taken care
180 of and we can set up to enter the main loop. */
181
182 extql t2, a1, t1 # e0 : position hi-bits of lo word
183 beq a2, $u_eoc # .. e1 :
184 ldq_u t2, 8(a1) # e0 : read next high-order source word
185 addq a1, 8, a1 # .. e1 :
186 extqh t2, a1, t0 # e0 : position lo-bits of hi word (stall)
187 cmpbge zero, t2, t8 # .. e1 :
188 nop # e0 :
189 bne t8, $u_eos # .. e1 :
190
191 /* Unaligned copy main loop. In order to avoid reading too much,
192 the loop is structured to detect zeros in aligned source words.
193 This has, unfortunately, effectively pulled half of a loop
194 iteration out into the head and half into the tail, but it does
195 prevent nastiness from accumulating in the very thing we want
196 to run as fast as possible.
197
198 On entry to this basic block:
199 t0 == the shifted low-order bits from the current source word
200 t1 == the shifted high-order bits from the previous source word
201 t2 == the unshifted current source word
202
203 We further know that t2 does not contain a null terminator. */
204
205 .align 3
206$u_loop:
207 or t0, t1, t0 # e0 : current dst word now complete
208 subq a2, 1, a2 # .. e1 : decrement word count
209 stq_u t0, 0(a0) # e0 : save the current word
210 addq a0, 8, a0 # .. e1 :
211 extql t2, a1, t1 # e0 : extract high bits for next time
212 beq a2, $u_eoc # .. e1 :
213 ldq_u t2, 8(a1) # e0 : load high word for next time
214 addq a1, 8, a1 # .. e1 :
215 nop # e0 :
216 cmpbge zero, t2, t8 # e1 : test new word for eos (stall)
217 extqh t2, a1, t0 # e0 : extract low bits for current word
218 beq t8, $u_loop # .. e1 :
219
220 /* We've found a zero somewhere in the source word we just read.
221 If it resides in the lower half, we have one (probably partial)
222 word to write out, and if it resides in the upper half, we
223 have one full and one partial word left to write out.
224
225 On entry to this basic block:
226 t0 == the shifted low-order bits from the current source word
227 t1 == the shifted high-order bits from the previous source word
228 t2 == the unshifted current source word. */
229$u_eos:
230 or t0, t1, t0 # e0 : first (partial) source word complete
231 nop # .. e1 :
232 cmpbge zero, t0, t8 # e0 : is the null in this first bit?
233 bne t8, $u_final # .. e1 (zdb)
234
235 stq_u t0, 0(a0) # e0 : the null was in the high-order bits
236 addq a0, 8, a0 # .. e1 :
237 subq a2, 1, a2 # e1 :
238
239$u_late_head_exit:
240 extql t2, a1, t0 # .. e0 :
241 cmpbge zero, t0, t8 # e0 :
242 or t8, t10, t6 # e1 :
243 cmoveq a2, t6, t8 # e0 :
244 nop # .. e1 :
245
246 /* Take care of a final (probably partial) result word.
247 On entry to this basic block:
248 t0 == assembled source word
249 t8 == cmpbge mask that found the null. */
250$u_final:
251 negq t8, t6 # e0 : isolate low bit set
252 and t6, t8, t12 # e1 :
253
254 and t12, 0x80, t6 # e0 : avoid dest word load if we can
255 bne t6, 1f # .. e1 (zdb)
256
257 ldq_u t1, 0(a0) # e0 :
258 subq t12, 1, t6 # .. e1 :
259 or t6, t12, t8 # e0 :
260 zapnot t0, t8, t0 # .. e1 : kill source bytes > null
261 zap t1, t8, t1 # e0 : kill dest bytes <= null
262 or t0, t1, t0 # e1 :
263
2641: stq_u t0, 0(a0) # e0 :
265 ret (t9) # .. e1 :
266
267 /* Got to end-of-count before end of string.
268 On entry to this basic block:
269 t1 == the shifted high-order bits from the previous source word */
270$u_eoc:
271 and a1, 7, t6 # e1 :
272 sll t10, t6, t6 # e0 :
273 and t6, 0xff, t6 # e0 :
274 bne t6, 1f # .. e1 :
275
276 ldq_u t2, 8(a1) # e0 : load final src word
277 nop # .. e1 :
278 extqh t2, a1, t0 # e0 : extract low bits for last word
279 or t1, t0, t1 # e1 :
280
2811: cmpbge zero, t1, t8
282 mov t1, t0
283
284$u_eocfin: # end-of-count, final word
285 or t10, t8, t8
286 br $u_final
287
288 /* Unaligned copy entry point. */
289 .align 3
290$unaligned:
291
292 ldq_u t1, 0(a1) # e0 : load first source word
293
294 and a0, 7, t4 # .. e1 : find dest misalignment
295 and a1, 7, t5 # e0 : find src misalignment
296
297 /* Conditionally load the first destination word and a bytemask
298 with 0xff indicating that the destination byte is sacrosanct. */
299
300 mov zero, t0 # .. e1 :
301 mov zero, t6 # e0 :
302 beq t4, 1f # .. e1 :
303 ldq_u t0, 0(a0) # e0 :
304 lda t6, -1 # .. e1 :
305 mskql t6, a0, t6 # e0 :
306 subq a1, t4, a1 # .. e1 : sub dest misalignment from src addr
307
308 /* If source misalignment is larger than dest misalignment, we need
309 extra startup checks to avoid SEGV. */
310
3111: cmplt t4, t5, t12 # e1 :
312 extql t1, a1, t1 # .. e0 : shift src into place
313 lda t2, -1 # e0 : for creating masks later
314 beq t12, $u_head # .. e1 :
315
316 extql t2, a1, t2 # e0 :
317 cmpbge zero, t1, t8 # .. e1 : is there a zero?
318 andnot t2, t6, t2 # e0 : dest mask for a single word copy
319 or t8, t10, t5 # .. e1 : test for end-of-count too
320 cmpbge zero, t2, t3 # e0 :
321 cmoveq a2, t5, t8 # .. e1 :
322 andnot t8, t3, t8 # e0 :
323 beq t8, $u_head # .. e1 (zdb)
324
325 /* At this point we've found a zero in the first partial word of
326 the source. We need to isolate the valid source data and mask
327 it into the original destination data. (Incidentally, we know
328 that we'll need at least one byte of that original dest word.) */
329
330 ldq_u t0, 0(a0) # e0 :
331 negq t8, t6 # .. e1 : build bitmask of bytes <= zero
332 mskqh t1, t4, t1 # e0 :
333 and t6, t8, t12 # .. e1 :
334 subq t12, 1, t6 # e0 :
335 or t6, t12, t8 # e1 :
336
337 zapnot t2, t8, t2 # e0 : prepare source word; mirror changes
338 zapnot t1, t8, t1 # .. e1 : to source validity mask
339
340 andnot t0, t2, t0 # e0 : zero place for source to reside
341 or t0, t1, t0 # e1 : and put it there
342 stq_u t0, 0(a0) # e0 :
343 ret (t9) # .. e1 :
344
345 .end __stxncpy