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d614a753 | 1 | /* Copyright (C) 1996-2020 Free Software Foundation, Inc. |
cf182b58 | 2 | Contributed by Richard Henderson (rth@tamu.edu) |
db31c863 UD |
3 | This file is part of the GNU C Library. |
4 | ||
5 | The GNU C Library is free software; you can redistribute it and/or | |
3214b89b AJ |
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. | |
db31c863 UD |
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 | |
3214b89b | 13 | Lesser General Public License for more details. |
db31c863 | 14 | |
3214b89b | 15 | You should have received a copy of the GNU Lesser General Public |
ab84e3ff | 16 | License along with the GNU C Library. If not, see |
5a82c748 | 17 | <https://www.gnu.org/licenses/>. */ |
cf182b58 UD |
18 | |
19 | /* Copy no more than COUNT bytes of the null-terminated string from | |
20 | SRC to DST. | |
21 | ||
22 | This is an internal routine used by strncpy, stpncpy, and strncat. | |
23 | As such, it uses special linkage conventions to make implementation | |
24 | of these public functions more efficient. | |
25 | ||
26 | On input: | |
27 | t9 = return address | |
28 | a0 = DST | |
29 | a1 = SRC | |
30 | a2 = COUNT | |
31 | ||
32 | Furthermore, COUNT may not be zero. | |
33 | ||
34 | On output: | |
35 | t0 = last word written | |
36 | t8 = bitmask (with one bit set) indicating the last byte written | |
37 | t10 = bitmask (with one bit set) indicating the byte position of | |
38 | the end of the range specified by COUNT | |
39 | a0 = unaligned address of the last *word* written | |
40 | a2 = the number of full words left in COUNT | |
41 | ||
42 | Furthermore, v0, a3-a5, t11, and t12 are untouched. | |
43 | */ | |
44 | ||
45 | ||
46 | /* This is generally scheduled for the EV5, but should still be pretty | |
47 | good for the EV4 too. */ | |
48 | ||
49 | #include <sysdep.h> | |
50 | ||
51 | .set noat | |
52 | .set noreorder | |
53 | ||
54 | .text | |
b2afe910 RH |
55 | .type __stxncpy, @function |
56 | .globl __stxncpy | |
57 | .usepv __stxncpy, no | |
cf182b58 | 58 | |
b2afe910 RH |
59 | cfi_startproc |
60 | cfi_return_column (t9) | |
cf182b58 UD |
61 | |
62 | /* On entry to this basic block: | |
63 | t0 == the first destination word for masking back in | |
64 | t1 == the first source word. */ | |
b2afe910 RH |
65 | .align 3 |
66 | stxncpy_aligned: | |
cf182b58 UD |
67 | /* Create the 1st output word and detect 0's in the 1st input word. */ |
68 | lda t2, -1 # e1 : build a mask against false zero | |
69 | mskqh t2, a1, t2 # e0 : detection in the src word | |
70 | mskqh t1, a1, t3 # e0 : | |
71 | ornot t1, t2, t2 # .. e1 : | |
72 | mskql t0, a1, t0 # e0 : assemble the first output word | |
73 | cmpbge zero, t2, t7 # .. e1 : bits set iff null found | |
74 | or t0, t3, t0 # e0 : | |
75 | beq a2, $a_eoc # .. e1 : | |
76 | bne t7, $a_eos # .. e1 : | |
77 | ||
78 | /* On entry to this basic block: | |
79 | t0 == a source word not containing a null. */ | |
cf182b58 UD |
80 | $a_loop: |
81 | stq_u t0, 0(a0) # e0 : | |
82 | addq a0, 8, a0 # .. e1 : | |
83 | ldq_u t0, 0(a1) # e0 : | |
84 | addq a1, 8, a1 # .. e1 : | |
85 | subq a2, 1, a2 # e0 : | |
86 | cmpbge zero, t0, t7 # .. e1 (stall) | |
87 | beq a2, $a_eoc # e1 : | |
88 | beq t7, $a_loop # e1 : | |
89 | ||
90 | /* Take care of the final (partial) word store. At this point | |
91 | the end-of-count bit is set in t7 iff it applies. | |
92 | ||
93 | On entry to this basic block we have: | |
94 | t0 == the source word containing the null | |
95 | t7 == the cmpbge mask that found it. */ | |
cf182b58 UD |
96 | $a_eos: |
97 | negq t7, t8 # e0 : find low bit set | |
98 | and t7, t8, t8 # e1 (stall) | |
99 | ||
100 | /* For the sake of the cache, don't read a destination word | |
101 | if we're not going to need it. */ | |
102 | and t8, 0x80, t6 # e0 : | |
103 | bne t6, 1f # .. e1 (zdb) | |
104 | ||
105 | /* We're doing a partial word store and so need to combine | |
106 | our source and original destination words. */ | |
107 | ldq_u t1, 0(a0) # e0 : | |
108 | subq t8, 1, t6 # .. e1 : | |
109 | or t8, t6, t7 # e0 : | |
110 | unop # | |
111 | zapnot t0, t7, t0 # e0 : clear src bytes > null | |
112 | zap t1, t7, t1 # .. e1 : clear dst bytes <= null | |
113 | or t0, t1, t0 # e1 : | |
114 | ||
115 | 1: stq_u t0, 0(a0) # e0 : | |
116 | ret (t9) # e1 : | |
117 | ||
118 | /* Add the end-of-count bit to the eos detection bitmask. */ | |
119 | $a_eoc: | |
120 | or t10, t7, t7 | |
121 | br $a_eos | |
122 | ||
cf182b58 | 123 | .align 3 |
cf182b58 | 124 | __stxncpy: |
cf182b58 | 125 | /* Are source and destination co-aligned? */ |
8e2f4e97 RH |
126 | lda t2, -1 |
127 | xor a0, a1, t1 | |
128 | srl t2, 1, t2 | |
129 | and a0, 7, t0 # find dest misalignment | |
130 | cmovlt a2, t2, a2 # bound neg count to LONG_MAX | |
131 | and t1, 7, t1 | |
132 | addq a2, t0, a2 # bias count by dest misalignment | |
133 | subq a2, 1, a2 | |
134 | and a2, 7, t2 | |
135 | srl a2, 3, a2 # a2 = loop counter = (count - 1)/8 | |
136 | addq zero, 1, t10 | |
137 | sll t10, t2, t10 # t10 = bitmask of last count byte | |
138 | bne t1, $unaligned | |
cf182b58 UD |
139 | |
140 | /* We are co-aligned; take care of a partial first word. */ | |
141 | ||
142 | ldq_u t1, 0(a1) # e0 : load first src word | |
143 | addq a1, 8, a1 # .. e1 : | |
144 | ||
145 | beq t0, stxncpy_aligned # avoid loading dest word if not needed | |
146 | ldq_u t0, 0(a0) # e0 : | |
147 | br stxncpy_aligned # .. e1 : | |
148 | ||
149 | ||
150 | /* The source and destination are not co-aligned. Align the destination | |
151 | and cope. We have to be very careful about not reading too much and | |
152 | causing a SEGV. */ | |
153 | ||
154 | .align 3 | |
155 | $u_head: | |
156 | /* We know just enough now to be able to assemble the first | |
157 | full source word. We can still find a zero at the end of it | |
158 | that prevents us from outputting the whole thing. | |
159 | ||
160 | On entry to this basic block: | |
161 | t0 == the first dest word, unmasked | |
162 | t1 == the shifted low bits of the first source word | |
163 | t6 == bytemask that is -1 in dest word bytes */ | |
164 | ||
165 | ldq_u t2, 8(a1) # e0 : load second src word | |
166 | addq a1, 8, a1 # .. e1 : | |
167 | mskql t0, a0, t0 # e0 : mask trailing garbage in dst | |
168 | extqh t2, a1, t4 # e0 : | |
169 | or t1, t4, t1 # e1 : first aligned src word complete | |
170 | mskqh t1, a0, t1 # e0 : mask leading garbage in src | |
171 | or t0, t1, t0 # e0 : first output word complete | |
172 | or t0, t6, t6 # e1 : mask original data for zero test | |
173 | cmpbge zero, t6, t7 # e0 : | |
174 | beq a2, $u_eocfin # .. e1 : | |
5556231d | 175 | lda t6, -1 # e0 : |
d78045b1 | 176 | bne t7, $u_final # .. e1 : |
cf182b58 | 177 | |
d78045b1 UD |
178 | mskql t6, a1, t6 # e0 : mask out bits already seen |
179 | nop # .. e1 : | |
cf182b58 UD |
180 | stq_u t0, 0(a0) # e0 : store first output word |
181 | or t6, t2, t2 # .. e1 : | |
182 | cmpbge zero, t2, t7 # e0 : find nulls in second partial | |
183 | addq a0, 8, a0 # .. e1 : | |
184 | subq a2, 1, a2 # e0 : | |
185 | bne t7, $u_late_head_exit # .. e1 : | |
186 | ||
187 | /* Finally, we've got all the stupid leading edge cases taken care | |
188 | of and we can set up to enter the main loop. */ | |
189 | ||
190 | extql t2, a1, t1 # e0 : position hi-bits of lo word | |
d78045b1 UD |
191 | beq a2, $u_eoc # .. e1 : |
192 | ldq_u t2, 8(a1) # e0 : read next high-order source word | |
193 | addq a1, 8, a1 # .. e1 : | |
194 | extqh t2, a1, t0 # e0 : position lo-bits of hi word | |
195 | cmpbge zero, t2, t7 # .. e1 : test new word for eos | |
196 | nop # e0 : | |
197 | bne t7, $u_eos # .. e1 : | |
cf182b58 UD |
198 | |
199 | /* Unaligned copy main loop. In order to avoid reading too much, | |
200 | the loop is structured to detect zeros in aligned source words. | |
201 | This has, unfortunately, effectively pulled half of a loop | |
202 | iteration out into the head and half into the tail, but it does | |
203 | prevent nastiness from accumulating in the very thing we want | |
204 | to run as fast as possible. | |
205 | ||
206 | On entry to this basic block: | |
d78045b1 | 207 | t0 == the shifted low-order bits from the current source word |
cf182b58 UD |
208 | t1 == the shifted high-order bits from the previous source word |
209 | t2 == the unshifted current source word | |
210 | ||
211 | We further know that t2 does not contain a null terminator. */ | |
212 | ||
213 | .align 3 | |
214 | $u_loop: | |
cf182b58 | 215 | or t0, t1, t0 # e0 : current dst word now complete |
d78045b1 UD |
216 | subq a2, 1, a2 # .. e1 : decrement word count |
217 | stq_u t0, 0(a0) # e0 : save the current word | |
218 | addq a0, 8, a0 # .. e1 : | |
219 | extql t2, a1, t1 # e0 : extract high bits for next time | |
220 | beq a2, $u_eoc # .. e1 : | |
221 | ldq_u t2, 8(a1) # e0 : load high word for next time | |
222 | addq a1, 8, a1 # .. e1 : | |
223 | nop # e0 : | |
cf182b58 | 224 | cmpbge zero, t2, t7 # .. e1 : test new word for eos |
d78045b1 UD |
225 | extqh t2, a1, t0 # e0 : extract low bits for current word |
226 | beq t7, $u_loop # .. e1 : | |
cf182b58 UD |
227 | |
228 | /* We've found a zero somewhere in the source word we just read. | |
229 | If it resides in the lower half, we have one (probably partial) | |
230 | word to write out, and if it resides in the upper half, we | |
231 | have one full and one partial word left to write out. | |
232 | ||
233 | On entry to this basic block: | |
d78045b1 | 234 | t0 == the shifted low-order bits from the current source word |
cf182b58 UD |
235 | t1 == the shifted high-order bits from the previous source word |
236 | t2 == the unshifted current source word. */ | |
237 | $u_eos: | |
d78045b1 | 238 | or t0, t1, t0 # e0 : first (partial) source word complete |
cf182b58 UD |
239 | cmpbge zero, t0, t7 # e0 : is the null in this first bit? |
240 | bne t7, $u_final # .. e1 (zdb) | |
241 | ||
242 | stq_u t0, 0(a0) # e0 : the null was in the high-order bits | |
243 | addq a0, 8, a0 # .. e1 : | |
d78045b1 | 244 | subq a2, 1, a2 # e0 : |
cf182b58 UD |
245 | |
246 | $u_late_head_exit: | |
d78045b1 | 247 | extql t2, a1, t0 # e0 : |
cf182b58 UD |
248 | cmpbge zero, t0, t7 # e0 : |
249 | or t7, t10, t6 # e1 : | |
250 | cmoveq a2, t6, t7 # e0 : | |
cf182b58 UD |
251 | |
252 | /* Take care of a final (probably partial) result word. | |
253 | On entry to this basic block: | |
254 | t0 == assembled source word | |
255 | t7 == cmpbge mask that found the null. */ | |
256 | $u_final: | |
257 | negq t7, t6 # e0 : isolate low bit set | |
258 | and t6, t7, t8 # e1 : | |
259 | ||
260 | and t8, 0x80, t6 # e0 : avoid dest word load if we can | |
261 | bne t6, 1f # .. e1 (zdb) | |
262 | ||
263 | ldq_u t1, 0(a0) # e0 : | |
264 | subq t8, 1, t6 # .. e1 : | |
265 | or t6, t8, t7 # e0 : | |
266 | zapnot t0, t7, t0 # .. e1 : kill source bytes > null | |
267 | zap t1, t7, t1 # e0 : kill dest bytes <= null | |
268 | or t0, t1, t0 # e1 : | |
269 | ||
270 | 1: stq_u t0, 0(a0) # e0 : | |
271 | ret (t9) # .. e1 : | |
272 | ||
5556231d | 273 | /* Got to end-of-count before end of string. |
d78045b1 UD |
274 | On entry to this basic block: |
275 | t1 == the shifted high-order bits from the previous source word */ | |
276 | $u_eoc: | |
277 | and a1, 7, t6 # e1 : | |
278 | sll t10, t6, t6 # e0 : | |
279 | and t6, 0xff, t6 # e0 : | |
280 | bne t6, 1f # e1 : avoid src word load if we can | |
281 | ||
282 | ldq_u t2, 8(a1) # e0 : load final src word | |
283 | nop # .. e1 : | |
284 | extqh t2, a1, t0 # e0 : extract high bits for last word | |
285 | or t1, t0, t1 # e1 : | |
286 | ||
287 | 1: cmpbge zero, t1, t7 | |
288 | mov t1, t0 | |
cf182b58 UD |
289 | |
290 | $u_eocfin: # end-of-count, final word | |
291 | or t10, t7, t7 | |
292 | br $u_final | |
293 | ||
294 | /* Unaligned copy entry point. */ | |
295 | .align 3 | |
296 | $unaligned: | |
297 | ||
298 | ldq_u t1, 0(a1) # e0 : load first source word | |
299 | ||
300 | and a0, 7, t4 # .. e1 : find dest misalignment | |
301 | and a1, 7, t5 # e0 : find src misalignment | |
302 | ||
303 | /* Conditionally load the first destination word and a bytemask | |
304 | with 0xff indicating that the destination byte is sacrosanct. */ | |
305 | ||
306 | mov zero, t0 # .. e1 : | |
307 | mov zero, t6 # e0 : | |
308 | beq t4, 1f # .. e1 : | |
309 | ldq_u t0, 0(a0) # e0 : | |
310 | lda t6, -1 # .. e1 : | |
311 | mskql t6, a0, t6 # e0 : | |
312 | 1: | |
313 | subq a1, t4, a1 # .. e1 : sub dest misalignment from src addr | |
314 | ||
315 | /* If source misalignment is larger than dest misalignment, we need | |
316 | extra startup checks to avoid SEGV. */ | |
317 | ||
318 | cmplt t4, t5, t8 # e1 : | |
319 | extql t1, a1, t1 # .. e0 : shift src into place | |
320 | lda t2, -1 # e0 : for creating masks later | |
321 | beq t8, $u_head # e1 : | |
322 | ||
323 | mskqh t2, t5, t2 # e0 : begin src byte validity mask | |
324 | cmpbge zero, t1, t7 # .. e1 : is there a zero? | |
325 | extql t2, a1, t2 # e0 : | |
f316a011 | 326 | or t7, t10, t5 # .. e1 : test for end-of-count too |
cf182b58 | 327 | cmpbge zero, t2, t3 # e0 : |
f316a011 | 328 | cmoveq a2, t5, t7 # .. e1 : |
cf182b58 UD |
329 | andnot t7, t3, t7 # e0 : |
330 | beq t7, $u_head # .. e1 (zdb) | |
331 | ||
332 | /* At this point we've found a zero in the first partial word of | |
333 | the source. We need to isolate the valid source data and mask | |
334 | it into the original destination data. (Incidentally, we know | |
335 | that we'll need at least one byte of that original dest word.) */ | |
336 | ||
337 | ldq_u t0, 0(a0) # e0 : | |
338 | negq t7, t6 # .. e1 : build bitmask of bytes <= zero | |
339 | mskqh t1, t4, t1 # e0 : | |
340 | and t6, t7, t8 # .. e1 : | |
341 | subq t8, 1, t6 # e0 : | |
342 | or t6, t8, t7 # e1 : | |
343 | ||
344 | zapnot t2, t7, t2 # e0 : prepare source word; mirror changes | |
345 | zapnot t1, t7, t1 # .. e1 : to source validity mask | |
346 | ||
347 | andnot t0, t2, t0 # e0 : zero place for source to reside | |
348 | or t0, t1, t0 # e1 : and put it there | |
349 | stq_u t0, 0(a0) # e0 : | |
350 | ret (t9) # .. e1 : | |
351 | ||
b2afe910 | 352 | cfi_endproc |