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04277e02 | 1 | /* Copyright (C) 2000-2019 Free Software Foundation, Inc. |
6e6bafa8 UD |
2 | Contributed by Richard Henderson (rth@tamu.edu) |
3 | EV6 optimized by Rick Gorton <rick.gorton@alpha-processor.com>. | |
6e6bafa8 UD |
4 | This file is part of the GNU C Library. |
5 | ||
6 | The GNU C Library is free software; you can redistribute it and/or | |
3214b89b AJ |
7 | modify it under the terms of the GNU Lesser General Public |
8 | License as published by the Free Software Foundation; either | |
9 | version 2.1 of the License, or (at your option) any later version. | |
6e6bafa8 UD |
10 | |
11 | The GNU C Library is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
3214b89b | 14 | Lesser General Public License for more details. |
6e6bafa8 | 15 | |
3214b89b | 16 | You should have received a copy of the GNU Lesser General Public |
ab84e3ff | 17 | License along with the GNU C Library. If not, see |
5a82c748 | 18 | <https://www.gnu.org/licenses/>. */ |
6e6bafa8 UD |
19 | |
20 | /* Copy no more than COUNT bytes of the null-terminated string from | |
21 | SRC to DST. | |
22 | ||
23 | This is an internal routine used by strncpy, stpncpy, and strncat. | |
24 | As such, it uses special linkage conventions to make implementation | |
25 | of these public functions more efficient. | |
26 | ||
27 | On input: | |
28 | t9 = return address | |
29 | a0 = DST | |
30 | a1 = SRC | |
31 | a2 = COUNT | |
32 | ||
33 | Furthermore, COUNT may not be zero. | |
34 | ||
35 | On output: | |
36 | t0 = last word written | |
37 | t8 = bitmask (with one bit set) indicating the last byte written | |
38 | t10 = bitmask (with one bit set) indicating the byte position of | |
39 | the end of the range specified by COUNT | |
40 | a0 = unaligned address of the last *word* written | |
41 | a2 = the number of full words left in COUNT | |
42 | ||
43 | Furthermore, v0, a3-a5, t11, and t12 are untouched. | |
44 | */ | |
45 | ||
46 | #include <sysdep.h> | |
47 | ||
48 | .arch ev6 | |
49 | .set noat | |
50 | .set noreorder | |
51 | ||
b2afe910 RH |
52 | .text |
53 | .type __stxncpy, @function | |
54 | .globl __stxncpy | |
55 | .usepv __stxncpy, no | |
6e6bafa8 | 56 | |
b2afe910 RH |
57 | cfi_startproc |
58 | cfi_return_column (t9) | |
6e6bafa8 UD |
59 | |
60 | /* On entry to this basic block: | |
61 | t0 == the first destination word for masking back in | |
62 | t1 == the first source word. */ | |
b2afe910 RH |
63 | .align 4 |
64 | stxncpy_aligned: | |
6e6bafa8 UD |
65 | /* Create the 1st output word and detect 0's in the 1st input word. */ |
66 | lda t2, -1 # E : build a mask against false zero | |
67 | mskqh t2, a1, t2 # U : detection in the src word (stall) | |
68 | mskqh t1, a1, t3 # U : | |
69 | ornot t1, t2, t2 # E : (stall) | |
70 | ||
71 | mskql t0, a1, t0 # U : assemble the first output word | |
72 | cmpbge zero, t2, t7 # E : bits set iff null found | |
73 | or t0, t3, t0 # E : (stall) | |
74 | beq a2, $a_eoc # U : | |
75 | ||
76 | bne t7, $a_eos # U : | |
77 | nop | |
78 | nop | |
79 | nop | |
80 | ||
81 | /* On entry to this basic block: | |
82 | t0 == a source word not containing a null. */ | |
83 | ||
84 | /* | |
85 | * nops here to: | |
86 | * separate store quads from load quads | |
87 | * limit of 1 bcond/quad to permit training | |
88 | */ | |
89 | $a_loop: | |
90 | stq_u t0, 0(a0) # L : | |
91 | addq a0, 8, a0 # E : | |
92 | subq a2, 1, a2 # E : | |
93 | nop | |
94 | ||
95 | ldq_u t0, 0(a1) # L : | |
96 | addq a1, 8, a1 # E : | |
97 | cmpbge zero, t0, t7 # E : | |
98 | beq a2, $a_eoc # U : | |
99 | ||
100 | beq t7, $a_loop # U : | |
101 | nop | |
102 | nop | |
103 | nop | |
104 | ||
105 | /* Take care of the final (partial) word store. At this point | |
106 | the end-of-count bit is set in t7 iff it applies. | |
107 | ||
108 | On entry to this basic block we have: | |
109 | t0 == the source word containing the null | |
110 | t7 == the cmpbge mask that found it. */ | |
6e6bafa8 UD |
111 | $a_eos: |
112 | negq t7, t8 # E : find low bit set | |
113 | and t7, t8, t8 # E : (stall) | |
114 | /* For the sake of the cache, don't read a destination word | |
115 | if we're not going to need it. */ | |
116 | and t8, 0x80, t6 # E : (stall) | |
117 | bne t6, 1f # U : (stall) | |
118 | ||
119 | /* We're doing a partial word store and so need to combine | |
120 | our source and original destination words. */ | |
121 | ldq_u t1, 0(a0) # L : | |
122 | subq t8, 1, t6 # E : | |
123 | or t8, t6, t7 # E : (stall) | |
124 | zapnot t0, t7, t0 # U : clear src bytes > null (stall) | |
125 | ||
126 | zap t1, t7, t1 # .. e1 : clear dst bytes <= null | |
127 | or t0, t1, t0 # e1 : (stall) | |
128 | nop | |
129 | nop | |
130 | ||
131 | 1: stq_u t0, 0(a0) # L : | |
132 | ret (t9) # L0 : Latency=3 | |
133 | nop | |
134 | nop | |
135 | ||
136 | /* Add the end-of-count bit to the eos detection bitmask. */ | |
137 | $a_eoc: | |
138 | or t10, t7, t7 # E : | |
139 | br $a_eos # L0 : Latency=3 | |
140 | nop | |
141 | nop | |
142 | ||
6e6bafa8 | 143 | .align 4 |
6e6bafa8 | 144 | __stxncpy: |
6e6bafa8 | 145 | /* Are source and destination co-aligned? */ |
8e2f4e97 | 146 | lda t2, -1 # E : |
6e6bafa8 UD |
147 | xor a0, a1, t1 # E : |
148 | and a0, 7, t0 # E : find dest misalignment | |
8e2f4e97 | 149 | nop # E : |
6e6bafa8 | 150 | |
8e2f4e97 RH |
151 | srl t2, 1, t2 # U : |
152 | and t1, 7, t1 # E : | |
153 | cmovlt a2, t2, a2 # E : bound count to LONG_MAX (stall) | |
154 | nop # E : | |
155 | ||
156 | addq a2, t0, a2 # E : bias count by dest misalignment | |
157 | subq a2, 1, a2 # E : (stall) | |
6e6bafa8 | 158 | and a2, 7, t2 # E : (stall) |
8e2f4e97 | 159 | lda t10, 1 # E : |
6e6bafa8 | 160 | |
8e2f4e97 | 161 | srl a2, 3, a2 # U : a2 = loop counter = (count - 1)/8 |
6e6bafa8 | 162 | sll t10, t2, t10 # U : t10 = bitmask of last count byte |
8e2f4e97 RH |
163 | nop # E : |
164 | bne t1, $unaligned # U : (stall) | |
b2afe910 | 165 | |
6e6bafa8 UD |
166 | /* We are co-aligned; take care of a partial first word. */ |
167 | ldq_u t1, 0(a1) # L : load first src word | |
168 | addq a1, 8, a1 # E : | |
b2afe910 | 169 | beq t0, stxncpy_aligned # U : avoid loading dest word if not needed |
6e6bafa8 | 170 | ldq_u t0, 0(a0) # L : |
6e6bafa8 | 171 | |
b2afe910 | 172 | br stxncpy_aligned # U : |
6e6bafa8 UD |
173 | nop |
174 | nop | |
175 | nop | |
176 | ||
177 | ||
178 | ||
179 | /* The source and destination are not co-aligned. Align the destination | |
180 | and cope. We have to be very careful about not reading too much and | |
181 | causing a SEGV. */ | |
182 | ||
183 | .align 4 | |
184 | $u_head: | |
185 | /* We know just enough now to be able to assemble the first | |
186 | full source word. We can still find a zero at the end of it | |
187 | that prevents us from outputting the whole thing. | |
188 | ||
189 | On entry to this basic block: | |
190 | t0 == the first dest word, unmasked | |
191 | t1 == the shifted low bits of the first source word | |
192 | t6 == bytemask that is -1 in dest word bytes */ | |
193 | ||
194 | ldq_u t2, 8(a1) # L : Latency=3 load second src word | |
195 | addq a1, 8, a1 # E : | |
196 | mskql t0, a0, t0 # U : mask trailing garbage in dst | |
197 | extqh t2, a1, t4 # U : (3 cycle stall on t2) | |
198 | ||
199 | or t1, t4, t1 # E : first aligned src word complete (stall) | |
200 | mskqh t1, a0, t1 # U : mask leading garbage in src (stall) | |
201 | or t0, t1, t0 # E : first output word complete (stall) | |
202 | or t0, t6, t6 # E : mask original data for zero test (stall) | |
203 | ||
204 | cmpbge zero, t6, t7 # E : | |
205 | beq a2, $u_eocfin # U : | |
d78045b1 | 206 | lda t6, -1 # E : |
6e6bafa8 UD |
207 | nop |
208 | ||
209 | bne t7, $u_final # U : | |
d78045b1 | 210 | mskql t6, a1, t6 # U : mask out bits already seen |
6e6bafa8 | 211 | stq_u t0, 0(a0) # L : store first output word |
d78045b1 | 212 | or t6, t2, t2 # E : |
6e6bafa8 | 213 | |
d78045b1 UD |
214 | cmpbge zero, t2, t7 # E : find nulls in second partial |
215 | addq a0, 8, a0 # E : | |
216 | subq a2, 1, a2 # E : | |
6e6bafa8 | 217 | bne t7, $u_late_head_exit # U : |
d78045b1 | 218 | |
6e6bafa8 UD |
219 | /* Finally, we've got all the stupid leading edge cases taken care |
220 | of and we can set up to enter the main loop. */ | |
221 | extql t2, a1, t1 # U : position hi-bits of lo word | |
d78045b1 | 222 | beq a2, $u_eoc # U : |
6e6bafa8 UD |
223 | ldq_u t2, 8(a1) # L : read next high-order source word |
224 | addq a1, 8, a1 # E : | |
225 | ||
d78045b1 UD |
226 | extqh t2, a1, t0 # U : position lo-bits of hi word (stall) |
227 | cmpbge zero, t2, t7 # E : | |
b2afe910 | 228 | nop |
d78045b1 | 229 | bne t7, $u_eos # U : |
6e6bafa8 UD |
230 | |
231 | /* Unaligned copy main loop. In order to avoid reading too much, | |
232 | the loop is structured to detect zeros in aligned source words. | |
233 | This has, unfortunately, effectively pulled half of a loop | |
234 | iteration out into the head and half into the tail, but it does | |
235 | prevent nastiness from accumulating in the very thing we want | |
236 | to run as fast as possible. | |
237 | ||
238 | On entry to this basic block: | |
d78045b1 | 239 | t0 == the shifted low-order bits from the current source word |
6e6bafa8 UD |
240 | t1 == the shifted high-order bits from the previous source word |
241 | t2 == the unshifted current source word | |
242 | ||
243 | We further know that t2 does not contain a null terminator. */ | |
244 | ||
245 | .align 4 | |
246 | $u_loop: | |
d78045b1 UD |
247 | or t0, t1, t0 # E : current dst word now complete |
248 | subq a2, 1, a2 # E : decrement word count | |
249 | extql t2, a1, t1 # U : extract high bits for next time | |
6e6bafa8 UD |
250 | addq a0, 8, a0 # E : |
251 | ||
d78045b1 UD |
252 | stq_u t0, -8(a0) # L : save the current word |
253 | beq a2, $u_eoc # U : | |
254 | ldq_u t2, 8(a1) # L : Latency=3 load high word for next time | |
255 | addq a1, 8, a1 # E : | |
6e6bafa8 | 256 | |
d78045b1 UD |
257 | extqh t2, a1, t0 # U : extract low bits (2 cycle stall) |
258 | cmpbge zero, t2, t7 # E : test new word for eos | |
6e6bafa8 | 259 | nop |
6e6bafa8 | 260 | beq t7, $u_loop # U : |
6e6bafa8 UD |
261 | |
262 | /* We've found a zero somewhere in the source word we just read. | |
263 | If it resides in the lower half, we have one (probably partial) | |
264 | word to write out, and if it resides in the upper half, we | |
265 | have one full and one partial word left to write out. | |
266 | ||
267 | On entry to this basic block: | |
d78045b1 | 268 | t0 == the shifted low-order bits from the current source word |
6e6bafa8 UD |
269 | t1 == the shifted high-order bits from the previous source word |
270 | t2 == the unshifted current source word. */ | |
271 | $u_eos: | |
d78045b1 UD |
272 | or t0, t1, t0 # E : first (partial) source word complete |
273 | nop | |
6e6bafa8 UD |
274 | cmpbge zero, t0, t7 # E : is the null in this first bit? (stall) |
275 | bne t7, $u_final # U : (stall) | |
276 | ||
277 | stq_u t0, 0(a0) # L : the null was in the high-order bits | |
278 | addq a0, 8, a0 # E : | |
279 | subq a2, 1, a2 # E : | |
280 | nop | |
281 | ||
282 | $u_late_head_exit: | |
283 | extql t2, a1, t0 # U : | |
284 | cmpbge zero, t0, t7 # E : | |
285 | or t7, t10, t6 # E : (stall) | |
286 | cmoveq a2, t6, t7 # E : Latency=2, extra map slot (stall) | |
287 | ||
288 | /* Take care of a final (probably partial) result word. | |
289 | On entry to this basic block: | |
290 | t0 == assembled source word | |
291 | t7 == cmpbge mask that found the null. */ | |
292 | $u_final: | |
293 | negq t7, t6 # E : isolate low bit set | |
294 | and t6, t7, t8 # E : (stall) | |
295 | and t8, 0x80, t6 # E : avoid dest word load if we can (stall) | |
296 | bne t6, 1f # U : (stall) | |
297 | ||
298 | ldq_u t1, 0(a0) # L : | |
299 | subq t8, 1, t6 # E : | |
300 | or t6, t8, t7 # E : (stall) | |
301 | zapnot t0, t7, t0 # U : kill source bytes > null | |
302 | ||
303 | zap t1, t7, t1 # U : kill dest bytes <= null | |
304 | or t0, t1, t0 # E : (stall) | |
305 | nop | |
306 | nop | |
307 | ||
308 | 1: stq_u t0, 0(a0) # L : | |
309 | ret (t9) # L0 : Latency=3 | |
310 | ||
b2afe910 | 311 | /* Got to end-of-count before end of string. |
d78045b1 UD |
312 | On entry to this basic block: |
313 | t1 == the shifted high-order bits from the previous source word */ | |
314 | $u_eoc: | |
315 | and a1, 7, t6 # E : | |
316 | sll t10, t6, t6 # U : (stall) | |
317 | and t6, 0xff, t6 # E : (stall) | |
318 | bne t6, 1f # U : (stall) | |
319 | ||
320 | ldq_u t2, 8(a1) # L : load final src word | |
6e6bafa8 | 321 | nop |
b2afe910 | 322 | extqh t2, a1, t0 # U : extract low bits for last word (stall) |
d78045b1 UD |
323 | or t1, t0, t1 # E : (stall) |
324 | ||
325 | 1: cmpbge zero, t1, t7 # E : | |
326 | mov t1, t0 | |
6e6bafa8 UD |
327 | |
328 | $u_eocfin: # end-of-count, final word | |
329 | or t10, t7, t7 # E : | |
330 | br $u_final # L0 : Latency=3 | |
6e6bafa8 UD |
331 | |
332 | /* Unaligned copy entry point. */ | |
333 | .align 4 | |
334 | $unaligned: | |
335 | ||
336 | ldq_u t1, 0(a1) # L : load first source word | |
337 | and a0, 7, t4 # E : find dest misalignment | |
338 | and a1, 7, t5 # E : find src misalignment | |
339 | /* Conditionally load the first destination word and a bytemask | |
340 | with 0xff indicating that the destination byte is sacrosanct. */ | |
341 | mov zero, t0 # E : | |
342 | ||
343 | mov zero, t6 # E : | |
344 | beq t4, 1f # U : | |
345 | ldq_u t0, 0(a0) # L : | |
346 | lda t6, -1 # E : | |
347 | ||
348 | mskql t6, a0, t6 # U : | |
349 | nop | |
350 | nop | |
d78045b1 | 351 | 1: subq a1, t4, a1 # E : sub dest misalignment from src addr |
6e6bafa8 UD |
352 | |
353 | /* If source misalignment is larger than dest misalignment, we need | |
354 | extra startup checks to avoid SEGV. */ | |
355 | ||
356 | cmplt t4, t5, t8 # E : | |
357 | extql t1, a1, t1 # U : shift src into place | |
358 | lda t2, -1 # E : for creating masks later | |
359 | beq t8, $u_head # U : (stall) | |
360 | ||
361 | mskqh t2, t5, t2 # U : begin src byte validity mask | |
362 | cmpbge zero, t1, t7 # E : is there a zero? | |
363 | extql t2, a1, t2 # U : | |
364 | or t7, t10, t5 # E : test for end-of-count too | |
365 | ||
366 | cmpbge zero, t2, t3 # E : | |
367 | cmoveq a2, t5, t7 # E : Latency=2, extra map slot | |
368 | nop # E : keep with cmoveq | |
369 | andnot t7, t3, t7 # E : (stall) | |
370 | ||
371 | beq t7, $u_head # U : | |
372 | /* At this point we've found a zero in the first partial word of | |
373 | the source. We need to isolate the valid source data and mask | |
374 | it into the original destination data. (Incidentally, we know | |
375 | that we'll need at least one byte of that original dest word.) */ | |
376 | ldq_u t0, 0(a0) # L : | |
377 | negq t7, t6 # E : build bitmask of bytes <= zero | |
378 | mskqh t1, t4, t1 # U : | |
379 | ||
380 | and t6, t7, t8 # E : | |
381 | subq t8, 1, t6 # E : (stall) | |
382 | or t6, t8, t7 # E : (stall) | |
383 | zapnot t2, t7, t2 # U : prepare source word; mirror changes (stall) | |
384 | ||
385 | zapnot t1, t7, t1 # U : to source validity mask | |
386 | andnot t0, t2, t0 # E : zero place for source to reside | |
387 | or t0, t1, t0 # E : and put it there (stall both t0, t1) | |
388 | stq_u t0, 0(a0) # L : (stall) | |
389 | ||
390 | ret (t9) # L0 : Latency=3 | |
6e6bafa8 | 391 | |
b2afe910 | 392 | cfi_endproc |