« back to all changes in this revision
Viewing changes to reference/bionic/strcmp.S
- browse files at revision 103
- compare with another revision
- download diff
- download tarball
- view history from revision 103
- Committer: Will Newton
- Date: 2013-04-30 14:31:08 UTC
- Revision ID: will.newton@linaro.org-20130430143108-ww31c741wek8dnus
Split bionic reference code into A15 and A9 versions.
- files added:
- reference/bionic-a15
- reference/bionic-a9
- files removed:
- reference/bionic
- files modified:
- Makefile.am
added
removed
reference/bionic/strcmp.S
1
/*
2
* Copyright (c) 2011 The Android Open Source Project
3
* Copyright (c) 2008 ARM Ltd
4
* All rights reserved.
5
*
6
* Redistribution and use in source and binary forms, with or without
7
* modification, are permitted provided that the following conditions
8
* are met:
9
* 1. Redistributions of source code must retain the above copyright
10
* notice, this list of conditions and the following disclaimer.
11
* 2. Redistributions in binary form must reproduce the above copyright
12
* notice, this list of conditions and the following disclaimer in the
13
* documentation and/or other materials provided with the distribution.
14
* 3. The name of the company may not be used to endorse or promote
15
* products derived from this software without specific prior written
16
* permission.
17
*
18
* THIS SOFTWARE IS PROVIDED BY ARM LTD ``AS IS'' AND ANY EXPRESS OR IMPLIED
19
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
20
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21
* IN NO EVENT SHALL ARM LTD BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
22
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
23
* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
24
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
25
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
26
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
27
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28
*/
29
30
.text
31
.globl strcmp
32
.type strcmp, %function
33
34
#ifdef __ARMEB__
35
#define SHFT2LSB lsl
36
#define SHFT2LSBEQ lsleq
37
#define SHFT2MSB lsr
38
#define SHFT2MSBEQ lsreq
39
#define MSB 0x000000ff
40
#define LSB 0xff000000
41
#else
42
#define SHFT2LSB lsr
43
#define SHFT2LSBEQ lsreq
44
#define SHFT2MSB lsl
45
#define SHFT2MSBEQ lsleq
46
#define MSB 0xff000000
47
#define LSB 0x000000ff
48
#endif
49
50
#define magic1(REG) REG
51
#define magic2(REG) REG, lsl #7
52
53
strcmp:
54
.fnstart
55
PLD [r0, #0]
56
PLD [r1, #0]
57
eor r2, r0, r1
58
tst r2, #3
59
60
/* Strings not at same byte offset from a word boundary. */
61
bne .Lstrcmp_unaligned
62
ands r2, r0, #3
63
bic r0, r0, #3
64
bic r1, r1, #3
65
ldr ip, [r0], #4
66
it eq
67
ldreq r3, [r1], #4
68
beq 1f
69
70
/* Although s1 and s2 have identical initial alignment, they are
71
* not currently word aligned. Rather than comparing bytes,
72
* make sure that any bytes fetched from before the addressed
73
* bytes are forced to 0xff. Then they will always compare
74
* equal.
75
*/
76
eor r2, r2, #3
77
lsl r2, r2, #3
78
mvn r3, #MSB
79
SHFT2LSB r2, r3, r2
80
ldr r3, [r1], #4
81
orr ip, ip, r2
82
orr r3, r3, r2
83
1:
84
/* Load the 'magic' constant 0x01010101. */
85
str r4, [sp, #-4]!
86
mov r4, #1
87
orr r4, r4, r4, lsl #8
88
orr r4, r4, r4, lsl #16
89
.p2align 2
90
4:
91
PLD [r0, #8]
92
PLD [r1, #8]
93
sub r2, ip, magic1(r4)
94
cmp ip, r3
95
itttt eq
96
97
/* check for any zero bytes in first word */
98
biceq r2, r2, ip
99
tsteq r2, magic2(r4)
100
ldreq ip, [r0], #4
101
ldreq r3, [r1], #4
102
beq 4b
103
2:
104
/* There's a zero or a different byte in the word */
105
SHFT2MSB r0, ip, #24
106
SHFT2LSB ip, ip, #8
107
cmp r0, #1
108
it cs
109
cmpcs r0, r3, SHFT2MSB #24
110
it eq
111
SHFT2LSBEQ r3, r3, #8
112
beq 2b
113
/* On a big-endian machine, r0 contains the desired byte in bits
114
* 0-7; on a little-endian machine they are in bits 24-31. In
115
* both cases the other bits in r0 are all zero. For r3 the
116
* interesting byte is at the other end of the word, but the
117
* other bits are not necessarily zero. We need a signed result
118
* representing the differnece in the unsigned bytes, so for the
119
* little-endian case we can't just shift the interesting bits up.
120
*/
121
#ifdef __ARMEB__
122
sub r0, r0, r3, lsr #24
123
#else
124
and r3, r3, #255
125
/* No RSB instruction in Thumb2 */
126
#ifdef __thumb2__
127
lsr r0, r0, #24
128
sub r0, r0, r3
129
#else
130
rsb r0, r3, r0, lsr #24
131
#endif
132
#endif
133
ldr r4, [sp], #4
134
bx lr
135
136
.Lstrcmp_unaligned:
137
wp1 .req r0
138
wp2 .req r1
139
b1 .req r2
140
w1 .req r4
141
w2 .req r5
142
t1 .req ip
143
@ r3 is scratch
144
145
/* First of all, compare bytes until wp1(sp1) is word-aligned. */
146
1:
147
tst wp1, #3
148
beq 2f
149
ldrb r2, [wp1], #1
150
ldrb r3, [wp2], #1
151
cmp r2, #1
152
it cs
153
cmpcs r2, r3
154
beq 1b
155
sub r0, r2, r3
156
bx lr
157
158
2:
159
str r5, [sp, #-4]!
160
str r4, [sp, #-4]!
161
mov b1, #1
162
orr b1, b1, b1, lsl #8
163
orr b1, b1, b1, lsl #16
164
165
and t1, wp2, #3
166
bic wp2, wp2, #3
167
ldr w1, [wp1], #4
168
ldr w2, [wp2], #4
169
cmp t1, #2
170
beq 2f
171
bhi 3f
172
173
/* Critical inner Loop: Block with 3 bytes initial overlap */
174
.p2align 2
175
1:
176
bic t1, w1, #MSB
177
cmp t1, w2, SHFT2LSB #8
178
sub r3, w1, b1
179
bic r3, r3, w1
180
bne 4f
181
ands r3, r3, b1, lsl #7
182
it eq
183
ldreq w2, [wp2], #4
184
bne 5f
185
eor t1, t1, w1
186
cmp t1, w2, SHFT2MSB #24
187
bne 6f
188
ldr w1, [wp1], #4
189
b 1b
190
4:
191
SHFT2LSB w2, w2, #8
192
b 8f
193
194
5:
195
#ifdef __ARMEB__
196
/* The syndrome value may contain false ones if the string ends
197
* with the bytes 0x01 0x00
198
*/
199
tst w1, #0xff000000
200
itt ne
201
tstne w1, #0x00ff0000
202
tstne w1, #0x0000ff00
203
beq 7f
204
#else
205
bics r3, r3, #0xff000000
206
bne 7f
207
#endif
208
ldrb w2, [wp2]
209
SHFT2LSB t1, w1, #24
210
#ifdef __ARMEB__
211
lsl w2, w2, #24
212
#endif
213
b 8f
214
215
6:
216
SHFT2LSB t1, w1, #24
217
and w2, w2, #LSB
218
b 8f
219
220
/* Critical inner Loop: Block with 2 bytes initial overlap */
221
.p2align 2
222
2:
223
SHFT2MSB t1, w1, #16
224
sub r3, w1, b1
225
SHFT2LSB t1, t1, #16
226
bic r3, r3, w1
227
cmp t1, w2, SHFT2LSB #16
228
bne 4f
229
ands r3, r3, b1, lsl #7
230
it eq
231
ldreq w2, [wp2], #4
232
bne 5f
233
eor t1, t1, w1
234
cmp t1, w2, SHFT2MSB #16
235
bne 6f
236
ldr w1, [wp1], #4
237
b 2b
238
239
5:
240
#ifdef __ARMEB__
241
/* The syndrome value may contain false ones if the string ends
242
* with the bytes 0x01 0x00
243
*/
244
tst w1, #0xff000000
245
it ne
246
tstne w1, #0x00ff0000
247
beq 7f
248
#else
249
lsls r3, r3, #16
250
bne 7f
251
#endif
252
ldrh w2, [wp2]
253
SHFT2LSB t1, w1, #16
254
#ifdef __ARMEB__
255
lsl w2, w2, #16
256
#endif
257
b 8f
258
259
6:
260
SHFT2MSB w2, w2, #16
261
SHFT2LSB t1, w1, #16
262
4:
263
SHFT2LSB w2, w2, #16
264
b 8f
265
266
/* Critical inner Loop: Block with 1 byte initial overlap */
267
.p2align 2
268
3:
269
and t1, w1, #LSB
270
cmp t1, w2, SHFT2LSB #24
271
sub r3, w1, b1
272
bic r3, r3, w1
273
bne 4f
274
ands r3, r3, b1, lsl #7
275
it eq
276
ldreq w2, [wp2], #4
277
bne 5f
278
eor t1, t1, w1
279
cmp t1, w2, SHFT2MSB #8
280
bne 6f
281
ldr w1, [wp1], #4
282
b 3b
283
4:
284
SHFT2LSB w2, w2, #24
285
b 8f
286
5:
287
/* The syndrome value may contain false ones if the string ends
288
* with the bytes 0x01 0x00
289
*/
290
tst w1, #LSB
291
beq 7f
292
ldr w2, [wp2], #4
293
6:
294
SHFT2LSB t1, w1, #8
295
bic w2, w2, #MSB
296
b 8f
297
7:
298
mov r0, #0
299
ldr r4, [sp], #4
300
ldr r5, [sp], #4
301
bx lr
302
303
8:
304
and r2, t1, #LSB
305
and r0, w2, #LSB
306
cmp r0, #1
307
it cs
308
cmpcs r0, r2
309
itt eq
310
SHFT2LSBEQ t1, t1, #8
311
SHFT2LSBEQ w2, w2, #8
312
beq 8b
313
sub r0, r2, r0
314
ldr r4, [sp], #4
315
ldr r5, [sp], #4
316
bx lr
317
318
.fnend
Loggerhead is a web-based interface for Breezy
Version: 2.0.1