1 /*
2 * linux/arch/arm/lib/lib1funcs.S: Optimized A
3 *
4 * Author: Nicolas Pitre <nico@fluxnic.net>
5 * - contributed to gcc-3.4 on Sep 30, 2003
6 * - adapted for the Linux kernel on Oct 2,
7 */
8
9 /* Copyright 1995, 1996, 1998, 1999, 2000, 200
10
11 This file is free software; you can redistribu
12 under the terms of the GNU General Public Lice
13 Free Software Foundation; either version 2, or
14 later version.
15
16 In addition to the permissions in the GNU Gene
17 Free Software Foundation gives you unlimited p
18 compiled version of this file into combination
19 and to distribute those combinations without a
20 from the use of this file. (The General Publi
21 do apply in other respects; for example, they
22 the file, and distribution when not linked int
23 executable.)
24
25 This file is distributed in the hope that it w
26 WITHOUT ANY WARRANTY; without even the implied
27 MERCHANTABILITY or FITNESS FOR A PARTICULAR PU
28 General Public License for more details.
29
30 You should have received a copy of the GNU Gen
31 along with this program; see the file COPYING.
32 the Free Software Foundation, 59 Temple Place
33 Boston, MA 02111-1307, USA. */
34
35
36 #include <linux/linkage.h>
37 #include <asm/assembler.h>
38 #include <asm/unwind.h>
39
40 .macro ARM_DIV_BODY dividend, divisor, result,
41
42 #if __LINUX_ARM_ARCH__ >= 5
43
44 clz \curbit, \divisor
45 clz \result, \dividend
46 sub \result, \curbit, \result
47 mov \curbit, #1
48 mov \divisor, \divisor, lsl \resul
49 mov \curbit, \curbit, lsl \result
50 mov \result, #0
51
52 #else
53
54 @ Initially shift the divisor left 3 b
55 @ set curbit accordingly. This allows
56 @ at the left end of each 4 bit nibble
57 @ to save one loop in most cases.
58 tst \divisor, #0xe0000000
59 moveq \divisor, \divisor, lsl #3
60 moveq \curbit, #8
61 movne \curbit, #1
62
63 @ Unless the divisor is very big, shif
64 @ four bits, since this is the amount
65 @ division loop. Continue shifting un
66 @ larger than the dividend.
67 1: cmp \divisor, #0x10000000
68 cmplo \divisor, \dividend
69 movlo \divisor, \divisor, lsl #4
70 movlo \curbit, \curbit, lsl #4
71 blo 1b
72
73 @ For very big divisors, we must shift
74 @ we will be in danger of overflowing.
75 1: cmp \divisor, #0x80000000
76 cmplo \divisor, \dividend
77 movlo \divisor, \divisor, lsl #1
78 movlo \curbit, \curbit, lsl #1
79 blo 1b
80
81 mov \result, #0
82
83 #endif
84
85 @ Division loop
86 1: cmp \dividend, \divisor
87 subhs \dividend, \dividend, \divisor
88 orrhs \result, \result, \curbit
89 cmp \dividend, \divisor, lsr #1
90 subhs \dividend, \dividend, \divisor
91 orrhs \result, \result, \curbit,
92 cmp \dividend, \divisor, lsr #2
93 subhs \dividend, \dividend, \divisor
94 orrhs \result, \result, \curbit,
95 cmp \dividend, \divisor, lsr #3
96 subhs \dividend, \dividend, \divisor
97 orrhs \result, \result, \curbit,
98 cmp \dividend, #0
99 movsne \curbit, \curbit, lsr #4
100 movne \divisor, \divisor, lsr #4
101 bne 1b
102
103 .endm
104
105
106 .macro ARM_DIV2_ORDER divisor, order
107
108 #if __LINUX_ARM_ARCH__ >= 5
109
110 clz \order, \divisor
111 rsb \order, \order, #31
112
113 #else
114
115 cmp \divisor, #(1 << 16)
116 movhs \divisor, \divisor, lsr #16
117 movhs \order, #16
118 movlo \order, #0
119
120 cmp \divisor, #(1 << 8)
121 movhs \divisor, \divisor, lsr #8
122 addhs \order, \order, #8
123
124 cmp \divisor, #(1 << 4)
125 movhs \divisor, \divisor, lsr #4
126 addhs \order, \order, #4
127
128 cmp \divisor, #(1 << 2)
129 addhi \order, \order, #3
130 addls \order, \order, \divisor, lsr
131
132 #endif
133
134 .endm
135
136
137 .macro ARM_MOD_BODY dividend, divisor, order,
138
139 #if __LINUX_ARM_ARCH__ >= 5
140
141 clz \order, \divisor
142 clz \spare, \dividend
143 sub \order, \order, \spare
144 mov \divisor, \divisor, lsl \order
145
146 #else
147
148 mov \order, #0
149
150 @ Unless the divisor is very big, shif
151 @ four bits, since this is the amount
152 @ division loop. Continue shifting un
153 @ larger than the dividend.
154 1: cmp \divisor, #0x10000000
155 cmplo \divisor, \dividend
156 movlo \divisor, \divisor, lsl #4
157 addlo \order, \order, #4
158 blo 1b
159
160 @ For very big divisors, we must shift
161 @ we will be in danger of overflowing.
162 1: cmp \divisor, #0x80000000
163 cmplo \divisor, \dividend
164 movlo \divisor, \divisor, lsl #1
165 addlo \order, \order, #1
166 blo 1b
167
168 #endif
169
170 @ Perform all needed subtractions to k
171 @ Do comparisons in batch of 4 first.
172 subs \order, \order, #3
173 blt 2f
174
175 1: cmp \dividend, \divisor
176 subhs \dividend, \dividend, \divisor
177 cmp \dividend, \divisor, lsr #1
178 subhs \dividend, \dividend, \divisor
179 cmp \dividend, \divisor, lsr #2
180 subhs \dividend, \dividend, \divisor
181 cmp \dividend, \divisor, lsr #3
182 subhs \dividend, \dividend, \divisor
183 cmp \dividend, #1
184 mov \divisor, \divisor, lsr #4
185 subsge \order, \order, #4
186 bge 1b
187
188 tst \order, #3
189 teqne \dividend, #0
190 beq 5f
191
192 @ Either 1, 2 or 3 comparison/subtract
193 2: cmn \order, #2
194 blt 4f
195 beq 3f
196 cmp \dividend, \divisor
197 subhs \dividend, \dividend, \divisor
198 mov \divisor, \divisor, lsr #1
199 3: cmp \dividend, \divisor
200 subhs \dividend, \dividend, \divisor
201 mov \divisor, \divisor, lsr #1
202 4: cmp \dividend, \divisor
203 subhs \dividend, \dividend, \divisor
204 5:
205 .endm
206
207
208 #ifdef CONFIG_ARM_PATCH_IDIV
209 .align 3
210 #endif
211
212 ENTRY(__udivsi3)
213 ENTRY(__aeabi_uidiv)
214 UNWIND(.fnstart)
215
216 subs r2, r1, #1
217 reteq lr
218 bcc Ldiv0
219 cmp r0, r1
220 bls 11f
221 tst r1, r2
222 beq 12f
223
224 ARM_DIV_BODY r0, r1, r2, r3
225
226 mov r0, r2
227 ret lr
228
229 11: moveq r0, #1
230 movne r0, #0
231 ret lr
232
233 12: ARM_DIV2_ORDER r1, r2
234
235 mov r0, r0, lsr r2
236 ret lr
237
238 UNWIND(.fnend)
239 ENDPROC(__udivsi3)
240 ENDPROC(__aeabi_uidiv)
241
242 ENTRY(__umodsi3)
243 UNWIND(.fnstart)
244
245 subs r2, r1, #1
246 bcc Ldiv0
247 cmpne r0, r1
248 moveq r0, #0
249 tsthi r1, r2
250 andeq r0, r0, r2
251 retls lr
252
253 ARM_MOD_BODY r0, r1, r2, r3
254
255 ret lr
256
257 UNWIND(.fnend)
258 ENDPROC(__umodsi3)
259
260 #ifdef CONFIG_ARM_PATCH_IDIV
261 .align 3
262 #endif
263
264 ENTRY(__divsi3)
265 ENTRY(__aeabi_idiv)
266 UNWIND(.fnstart)
267
268 cmp r1, #0
269 eor ip, r0, r1
270 beq Ldiv0
271 rsbmi r1, r1, #0
272 subs r2, r1, #1
273 beq 10f
274 movs r3, r0
275 rsbmi r3, r0, #0
276 cmp r3, r1
277 bls 11f
278 tst r1, r2
279 beq 12f
280
281 ARM_DIV_BODY r3, r1, r0, r2
282
283 cmp ip, #0
284 rsbmi r0, r0, #0
285 ret lr
286
287 10: teq ip, r0
288 rsbmi r0, r0, #0
289 ret lr
290
291 11: movlo r0, #0
292 moveq r0, ip, asr #31
293 orreq r0, r0, #1
294 ret lr
295
296 12: ARM_DIV2_ORDER r1, r2
297
298 cmp ip, #0
299 mov r0, r3, lsr r2
300 rsbmi r0, r0, #0
301 ret lr
302
303 UNWIND(.fnend)
304 ENDPROC(__divsi3)
305 ENDPROC(__aeabi_idiv)
306
307 ENTRY(__modsi3)
308 UNWIND(.fnstart)
309
310 cmp r1, #0
311 beq Ldiv0
312 rsbmi r1, r1, #0
313 movs ip, r0
314 rsbmi r0, r0, #0
315 subs r2, r1, #1
316 cmpne r0, r1
317 moveq r0, #0
318 tsthi r1, r2
319 andeq r0, r0, r2
320 bls 10f
321
322 ARM_MOD_BODY r0, r1, r2, r3
323
324 10: cmp ip, #0
325 rsbmi r0, r0, #0
326 ret lr
327
328 UNWIND(.fnend)
329 ENDPROC(__modsi3)
330
331 #ifdef CONFIG_AEABI
332
333 ENTRY(__aeabi_uidivmod)
334 UNWIND(.fnstart)
335 UNWIND(.save {r0, r1, ip, lr} )
336
337 stmfd sp!, {r0, r1, ip, lr}
338 bl __aeabi_uidiv
339 ldmfd sp!, {r1, r2, ip, lr}
340 mul r3, r0, r2
341 sub r1, r1, r3
342 ret lr
343
344 UNWIND(.fnend)
345 ENDPROC(__aeabi_uidivmod)
346
347 ENTRY(__aeabi_idivmod)
348 UNWIND(.fnstart)
349 UNWIND(.save {r0, r1, ip, lr} )
350 stmfd sp!, {r0, r1, ip, lr}
351 bl __aeabi_idiv
352 ldmfd sp!, {r1, r2, ip, lr}
353 mul r3, r0, r2
354 sub r1, r1, r3
355 ret lr
356
357 UNWIND(.fnend)
358 ENDPROC(__aeabi_idivmod)
359
360 #endif
361
362 Ldiv0:
363 UNWIND(.fnstart)
364 UNWIND(.pad #4)
365 UNWIND(.save {lr})
366 str lr, [sp, #-8]!
367 bl __div0
368 mov r0, #0 @ Abou
369 ldr pc, [sp], #8
370 UNWIND(.fnend)
371 ENDPROC(Ldiv0)
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