diff options
author | Jonathan Herman <hermanjl@cs.unc.edu> | 2013-01-22 10:38:37 -0500 |
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committer | Jonathan Herman <hermanjl@cs.unc.edu> | 2013-01-22 10:38:37 -0500 |
commit | fcc9d2e5a6c89d22b8b773a64fb4ad21ac318446 (patch) | |
tree | a57612d1888735a2ec7972891b68c1ac5ec8faea /arch/sparc/lib/udiv.S | |
parent | 8dea78da5cee153b8af9c07a2745f6c55057fe12 (diff) |
Diffstat (limited to 'arch/sparc/lib/udiv.S')
-rw-r--r-- | arch/sparc/lib/udiv.S | 357 |
1 files changed, 357 insertions, 0 deletions
diff --git a/arch/sparc/lib/udiv.S b/arch/sparc/lib/udiv.S new file mode 100644 index 00000000000..2101405bdfc --- /dev/null +++ b/arch/sparc/lib/udiv.S | |||
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1 | /* | ||
2 | * udiv.S: This routine was taken from glibc-1.09 and is covered | ||
3 | * by the GNU Library General Public License Version 2. | ||
4 | */ | ||
5 | |||
6 | |||
7 | /* This file is generated from divrem.m4; DO NOT EDIT! */ | ||
8 | /* | ||
9 | * Division and remainder, from Appendix E of the Sparc Version 8 | ||
10 | * Architecture Manual, with fixes from Gordon Irlam. | ||
11 | */ | ||
12 | |||
13 | /* | ||
14 | * Input: dividend and divisor in %o0 and %o1 respectively. | ||
15 | * | ||
16 | * m4 parameters: | ||
17 | * .udiv name of function to generate | ||
18 | * div div=div => %o0 / %o1; div=rem => %o0 % %o1 | ||
19 | * false false=true => signed; false=false => unsigned | ||
20 | * | ||
21 | * Algorithm parameters: | ||
22 | * N how many bits per iteration we try to get (4) | ||
23 | * WORDSIZE total number of bits (32) | ||
24 | * | ||
25 | * Derived constants: | ||
26 | * TOPBITS number of bits in the top decade of a number | ||
27 | * | ||
28 | * Important variables: | ||
29 | * Q the partial quotient under development (initially 0) | ||
30 | * R the remainder so far, initially the dividend | ||
31 | * ITER number of main division loop iterations required; | ||
32 | * equal to ceil(log2(quotient) / N). Note that this | ||
33 | * is the log base (2^N) of the quotient. | ||
34 | * V the current comparand, initially divisor*2^(ITER*N-1) | ||
35 | * | ||
36 | * Cost: | ||
37 | * Current estimate for non-large dividend is | ||
38 | * ceil(log2(quotient) / N) * (10 + 7N/2) + C | ||
39 | * A large dividend is one greater than 2^(31-TOPBITS) and takes a | ||
40 | * different path, as the upper bits of the quotient must be developed | ||
41 | * one bit at a time. | ||
42 | */ | ||
43 | |||
44 | |||
45 | .globl .udiv | ||
46 | .globl _Udiv | ||
47 | .udiv: | ||
48 | _Udiv: /* needed for export */ | ||
49 | |||
50 | ! Ready to divide. Compute size of quotient; scale comparand. | ||
51 | orcc %o1, %g0, %o5 | ||
52 | bne 1f | ||
53 | mov %o0, %o3 | ||
54 | |||
55 | ! Divide by zero trap. If it returns, return 0 (about as | ||
56 | ! wrong as possible, but that is what SunOS does...). | ||
57 | ta ST_DIV0 | ||
58 | retl | ||
59 | clr %o0 | ||
60 | |||
61 | 1: | ||
62 | cmp %o3, %o5 ! if %o1 exceeds %o0, done | ||
63 | blu Lgot_result ! (and algorithm fails otherwise) | ||
64 | clr %o2 | ||
65 | |||
66 | sethi %hi(1 << (32 - 4 - 1)), %g1 | ||
67 | |||
68 | cmp %o3, %g1 | ||
69 | blu Lnot_really_big | ||
70 | clr %o4 | ||
71 | |||
72 | ! Here the dividend is >= 2**(31-N) or so. We must be careful here, | ||
73 | ! as our usual N-at-a-shot divide step will cause overflow and havoc. | ||
74 | ! The number of bits in the result here is N*ITER+SC, where SC <= N. | ||
75 | ! Compute ITER in an unorthodox manner: know we need to shift V into | ||
76 | ! the top decade: so do not even bother to compare to R. | ||
77 | 1: | ||
78 | cmp %o5, %g1 | ||
79 | bgeu 3f | ||
80 | mov 1, %g7 | ||
81 | |||
82 | sll %o5, 4, %o5 | ||
83 | |||
84 | b 1b | ||
85 | add %o4, 1, %o4 | ||
86 | |||
87 | ! Now compute %g7. | ||
88 | 2: | ||
89 | addcc %o5, %o5, %o5 | ||
90 | bcc Lnot_too_big | ||
91 | add %g7, 1, %g7 | ||
92 | |||
93 | ! We get here if the %o1 overflowed while shifting. | ||
94 | ! This means that %o3 has the high-order bit set. | ||
95 | ! Restore %o5 and subtract from %o3. | ||
96 | sll %g1, 4, %g1 ! high order bit | ||
97 | srl %o5, 1, %o5 ! rest of %o5 | ||
98 | add %o5, %g1, %o5 | ||
99 | |||
100 | b Ldo_single_div | ||
101 | sub %g7, 1, %g7 | ||
102 | |||
103 | Lnot_too_big: | ||
104 | 3: | ||
105 | cmp %o5, %o3 | ||
106 | blu 2b | ||
107 | nop | ||
108 | |||
109 | be Ldo_single_div | ||
110 | nop | ||
111 | /* NB: these are commented out in the V8-Sparc manual as well */ | ||
112 | /* (I do not understand this) */ | ||
113 | ! %o5 > %o3: went too far: back up 1 step | ||
114 | ! srl %o5, 1, %o5 | ||
115 | ! dec %g7 | ||
116 | ! do single-bit divide steps | ||
117 | ! | ||
118 | ! We have to be careful here. We know that %o3 >= %o5, so we can do the | ||
119 | ! first divide step without thinking. BUT, the others are conditional, | ||
120 | ! and are only done if %o3 >= 0. Because both %o3 and %o5 may have the high- | ||
121 | ! order bit set in the first step, just falling into the regular | ||
122 | ! division loop will mess up the first time around. | ||
123 | ! So we unroll slightly... | ||
124 | Ldo_single_div: | ||
125 | subcc %g7, 1, %g7 | ||
126 | bl Lend_regular_divide | ||
127 | nop | ||
128 | |||
129 | sub %o3, %o5, %o3 | ||
130 | mov 1, %o2 | ||
131 | |||
132 | b Lend_single_divloop | ||
133 | nop | ||
134 | Lsingle_divloop: | ||
135 | sll %o2, 1, %o2 | ||
136 | bl 1f | ||
137 | srl %o5, 1, %o5 | ||
138 | ! %o3 >= 0 | ||
139 | sub %o3, %o5, %o3 | ||
140 | b 2f | ||
141 | add %o2, 1, %o2 | ||
142 | 1: ! %o3 < 0 | ||
143 | add %o3, %o5, %o3 | ||
144 | sub %o2, 1, %o2 | ||
145 | 2: | ||
146 | Lend_single_divloop: | ||
147 | subcc %g7, 1, %g7 | ||
148 | bge Lsingle_divloop | ||
149 | tst %o3 | ||
150 | |||
151 | b,a Lend_regular_divide | ||
152 | |||
153 | Lnot_really_big: | ||
154 | 1: | ||
155 | sll %o5, 4, %o5 | ||
156 | |||
157 | cmp %o5, %o3 | ||
158 | bleu 1b | ||
159 | addcc %o4, 1, %o4 | ||
160 | |||
161 | be Lgot_result | ||
162 | sub %o4, 1, %o4 | ||
163 | |||
164 | tst %o3 ! set up for initial iteration | ||
165 | Ldivloop: | ||
166 | sll %o2, 4, %o2 | ||
167 | ! depth 1, accumulated bits 0 | ||
168 | bl L.1.16 | ||
169 | srl %o5,1,%o5 | ||
170 | ! remainder is positive | ||
171 | subcc %o3,%o5,%o3 | ||
172 | ! depth 2, accumulated bits 1 | ||
173 | bl L.2.17 | ||
174 | srl %o5,1,%o5 | ||
175 | ! remainder is positive | ||
176 | subcc %o3,%o5,%o3 | ||
177 | ! depth 3, accumulated bits 3 | ||
178 | bl L.3.19 | ||
179 | srl %o5,1,%o5 | ||
180 | ! remainder is positive | ||
181 | subcc %o3,%o5,%o3 | ||
182 | ! depth 4, accumulated bits 7 | ||
183 | bl L.4.23 | ||
184 | srl %o5,1,%o5 | ||
185 | ! remainder is positive | ||
186 | subcc %o3,%o5,%o3 | ||
187 | b 9f | ||
188 | add %o2, (7*2+1), %o2 | ||
189 | |||
190 | L.4.23: | ||
191 | ! remainder is negative | ||
192 | addcc %o3,%o5,%o3 | ||
193 | b 9f | ||
194 | add %o2, (7*2-1), %o2 | ||
195 | |||
196 | L.3.19: | ||
197 | ! remainder is negative | ||
198 | addcc %o3,%o5,%o3 | ||
199 | ! depth 4, accumulated bits 5 | ||
200 | bl L.4.21 | ||
201 | srl %o5,1,%o5 | ||
202 | ! remainder is positive | ||
203 | subcc %o3,%o5,%o3 | ||
204 | b 9f | ||
205 | add %o2, (5*2+1), %o2 | ||
206 | |||
207 | L.4.21: | ||
208 | ! remainder is negative | ||
209 | addcc %o3,%o5,%o3 | ||
210 | b 9f | ||
211 | add %o2, (5*2-1), %o2 | ||
212 | |||
213 | L.2.17: | ||
214 | ! remainder is negative | ||
215 | addcc %o3,%o5,%o3 | ||
216 | ! depth 3, accumulated bits 1 | ||
217 | bl L.3.17 | ||
218 | srl %o5,1,%o5 | ||
219 | ! remainder is positive | ||
220 | subcc %o3,%o5,%o3 | ||
221 | ! depth 4, accumulated bits 3 | ||
222 | bl L.4.19 | ||
223 | srl %o5,1,%o5 | ||
224 | ! remainder is positive | ||
225 | subcc %o3,%o5,%o3 | ||
226 | b 9f | ||
227 | add %o2, (3*2+1), %o2 | ||
228 | |||
229 | L.4.19: | ||
230 | ! remainder is negative | ||
231 | addcc %o3,%o5,%o3 | ||
232 | b 9f | ||
233 | add %o2, (3*2-1), %o2 | ||
234 | |||
235 | L.3.17: | ||
236 | ! remainder is negative | ||
237 | addcc %o3,%o5,%o3 | ||
238 | ! depth 4, accumulated bits 1 | ||
239 | bl L.4.17 | ||
240 | srl %o5,1,%o5 | ||
241 | ! remainder is positive | ||
242 | subcc %o3,%o5,%o3 | ||
243 | b 9f | ||
244 | add %o2, (1*2+1), %o2 | ||
245 | |||
246 | L.4.17: | ||
247 | ! remainder is negative | ||
248 | addcc %o3,%o5,%o3 | ||
249 | b 9f | ||
250 | add %o2, (1*2-1), %o2 | ||
251 | |||
252 | L.1.16: | ||
253 | ! remainder is negative | ||
254 | addcc %o3,%o5,%o3 | ||
255 | ! depth 2, accumulated bits -1 | ||
256 | bl L.2.15 | ||
257 | srl %o5,1,%o5 | ||
258 | ! remainder is positive | ||
259 | subcc %o3,%o5,%o3 | ||
260 | ! depth 3, accumulated bits -1 | ||
261 | bl L.3.15 | ||
262 | srl %o5,1,%o5 | ||
263 | ! remainder is positive | ||
264 | subcc %o3,%o5,%o3 | ||
265 | ! depth 4, accumulated bits -1 | ||
266 | bl L.4.15 | ||
267 | srl %o5,1,%o5 | ||
268 | ! remainder is positive | ||
269 | subcc %o3,%o5,%o3 | ||
270 | b 9f | ||
271 | add %o2, (-1*2+1), %o2 | ||
272 | |||
273 | L.4.15: | ||
274 | ! remainder is negative | ||
275 | addcc %o3,%o5,%o3 | ||
276 | b 9f | ||
277 | add %o2, (-1*2-1), %o2 | ||
278 | |||
279 | L.3.15: | ||
280 | ! remainder is negative | ||
281 | addcc %o3,%o5,%o3 | ||
282 | ! depth 4, accumulated bits -3 | ||
283 | bl L.4.13 | ||
284 | srl %o5,1,%o5 | ||
285 | ! remainder is positive | ||
286 | subcc %o3,%o5,%o3 | ||
287 | b 9f | ||
288 | add %o2, (-3*2+1), %o2 | ||
289 | |||
290 | L.4.13: | ||
291 | ! remainder is negative | ||
292 | addcc %o3,%o5,%o3 | ||
293 | b 9f | ||
294 | add %o2, (-3*2-1), %o2 | ||
295 | |||
296 | L.2.15: | ||
297 | ! remainder is negative | ||
298 | addcc %o3,%o5,%o3 | ||
299 | ! depth 3, accumulated bits -3 | ||
300 | bl L.3.13 | ||
301 | srl %o5,1,%o5 | ||
302 | ! remainder is positive | ||
303 | subcc %o3,%o5,%o3 | ||
304 | ! depth 4, accumulated bits -5 | ||
305 | bl L.4.11 | ||
306 | srl %o5,1,%o5 | ||
307 | ! remainder is positive | ||
308 | subcc %o3,%o5,%o3 | ||
309 | b 9f | ||
310 | add %o2, (-5*2+1), %o2 | ||
311 | |||
312 | L.4.11: | ||
313 | ! remainder is negative | ||
314 | addcc %o3,%o5,%o3 | ||
315 | b 9f | ||
316 | add %o2, (-5*2-1), %o2 | ||
317 | |||
318 | L.3.13: | ||
319 | ! remainder is negative | ||
320 | addcc %o3,%o5,%o3 | ||
321 | ! depth 4, accumulated bits -7 | ||
322 | bl L.4.9 | ||
323 | srl %o5,1,%o5 | ||
324 | ! remainder is positive | ||
325 | subcc %o3,%o5,%o3 | ||
326 | b 9f | ||
327 | add %o2, (-7*2+1), %o2 | ||
328 | |||
329 | L.4.9: | ||
330 | ! remainder is negative | ||
331 | addcc %o3,%o5,%o3 | ||
332 | b 9f | ||
333 | add %o2, (-7*2-1), %o2 | ||
334 | |||
335 | 9: | ||
336 | Lend_regular_divide: | ||
337 | subcc %o4, 1, %o4 | ||
338 | bge Ldivloop | ||
339 | tst %o3 | ||
340 | |||
341 | bl,a Lgot_result | ||
342 | ! non-restoring fixup here (one instruction only!) | ||
343 | sub %o2, 1, %o2 | ||
344 | |||
345 | Lgot_result: | ||
346 | |||
347 | retl | ||
348 | mov %o2, %o0 | ||
349 | |||
350 | .globl .udiv_patch | ||
351 | .udiv_patch: | ||
352 | wr %g0, 0x0, %y | ||
353 | nop | ||
354 | nop | ||
355 | retl | ||
356 | udiv %o0, %o1, %o0 | ||
357 | nop | ||