about summary refs log tree commit diff
path: root/sysdeps/i386/i686/memcmp.S
blob: eacac8ee18207b5cba50c04ba5a659d2245d40ab (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
/* Compare two memory blocks for differences in the first COUNT bytes.
   Copyright (C) 2004-2013 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <http://www.gnu.org/licenses/>.  */

#include <sysdep.h>
#include "asm-syntax.h"
#include "bp-sym.h"
#include "bp-asm.h"

#define PARMS		LINKAGE+4	/* Preserve EBX.  */
#define BLK1		PARMS
#define BLK2		BLK1+PTR_SIZE
#define LEN		BLK2+PTR_SIZE
#define ENTRANCE	pushl %ebx; cfi_adjust_cfa_offset (4); \
			cfi_rel_offset (ebx, 0); ENTER
#define RETURN		popl %ebx; cfi_adjust_cfa_offset (-4); \
			cfi_restore (ebx); LEAVE; ret

/* Load an entry in a jump table into EBX.  TABLE is a jump table
   with relative offsets.  INDEX is a register contains the index
   into the jump table.  */
#define LOAD_JUMP_TABLE_ENTRY(TABLE, INDEX) \
  /* We first load PC into EBX.  */					      \
  SETUP_PIC_REG(bx);							      \
  /* Get the address of the jump table.  */				      \
  addl	$(TABLE - .), %ebx;						      \
  /* Get the entry and convert the relative offset to the		      \
     absolute address.  */						      \
  addl	(%ebx,INDEX,4), %ebx

        .text
	ALIGN (4)
ENTRY (BP_SYM (memcmp))
	ENTRANCE

	movl	BLK1(%esp), %eax
	movl	BLK2(%esp), %edx
	movl	LEN(%esp), %ecx

	cmpl 	$1, %ecx
	jne	L(not_1)
	movzbl	(%eax), %ecx		/* LEN == 1  */
	cmpb	(%edx), %cl
	jne	L(neq)
L(bye):
	xorl	%eax, %eax
	RETURN

	cfi_adjust_cfa_offset (4)
	cfi_rel_offset (ebx, 0)
L(neq):
	sbbl	%eax, %eax
	sbbl	$-1, %eax
	RETURN

	cfi_adjust_cfa_offset (4)
	cfi_rel_offset (ebx, 0)
L(not_1):
	jl	L(bye)			/* LEN == 0  */

	pushl	%esi
	cfi_adjust_cfa_offset (4)
	movl	%eax, %esi
	cfi_rel_offset (esi, 0)
	cmpl	$32, %ecx;
	jge	L(32bytesormore)	/* LEN => 32  */

	LOAD_JUMP_TABLE_ENTRY (L(table_32bytes), %ecx)
	addl	%ecx, %edx
	addl	%ecx, %esi
	jmp	*%ebx

	ALIGN (4)
L(28bytes):
	movl	-28(%esi), %eax
	movl	-28(%edx), %ecx
	cmpl	%ecx, %eax
	jne	L(find_diff)
L(24bytes):
	movl	-24(%esi), %eax
	movl	-24(%edx), %ecx
	cmpl	%ecx, %eax
	jne	L(find_diff)
L(20bytes):
	movl	-20(%esi), %eax
	movl	-20(%edx), %ecx
	cmpl	%ecx, %eax
	jne	L(find_diff)
L(16bytes):
	movl	-16(%esi), %eax
	movl	-16(%edx), %ecx
	cmpl	%ecx, %eax
	jne	L(find_diff)
L(12bytes):
	movl	-12(%esi), %eax
	movl	-12(%edx), %ecx
	cmpl	%ecx, %eax
	jne	L(find_diff)
L(8bytes):
	movl	-8(%esi), %eax
	movl	-8(%edx), %ecx
	cmpl	%ecx, %eax
	jne	L(find_diff)
L(4bytes):
	movl	-4(%esi), %eax
	movl	-4(%edx), %ecx
	cmpl	%ecx, %eax
	jne	L(find_diff)
L(0bytes):
	popl	%esi
	cfi_adjust_cfa_offset (-4)
	cfi_restore (esi)
	xorl	%eax, %eax
	RETURN

	cfi_adjust_cfa_offset (8)
	cfi_rel_offset (esi, 0)
	cfi_rel_offset (ebx, 4)
L(29bytes):
	movl	-29(%esi), %eax
	movl	-29(%edx), %ecx
	cmpl	%ecx, %eax
	jne	L(find_diff)
L(25bytes):
	movl	-25(%esi), %eax
	movl	-25(%edx), %ecx
	cmpl	%ecx, %eax
	jne	L(find_diff)
L(21bytes):
	movl	-21(%esi), %eax
	movl	-21(%edx), %ecx
	cmpl	%ecx, %eax
	jne	L(find_diff)
L(17bytes):
	movl	-17(%esi), %eax
	movl	-17(%edx), %ecx
	cmpl	%ecx, %eax
	jne	L(find_diff)
L(13bytes):
	movl	-13(%esi), %eax
	movl	-13(%edx), %ecx
	cmpl	%ecx, %eax
	jne	L(find_diff)
L(9bytes):
	movl	-9(%esi), %eax
	movl	-9(%edx), %ecx
	cmpl	%ecx, %eax
	jne	L(find_diff)
L(5bytes):
	movl	-5(%esi), %eax
	movl	-5(%edx), %ecx
	cmpl	%ecx, %eax
	jne	L(find_diff)
L(1bytes):
	movzbl	-1(%esi), %eax
	cmpb	-1(%edx), %al
	jne	L(set)
	popl	%esi
	cfi_adjust_cfa_offset (-4)
	cfi_restore (esi)
	xorl	%eax, %eax
	RETURN

	cfi_adjust_cfa_offset (8)
	cfi_rel_offset (esi, 0)
	cfi_rel_offset (ebx, 4)
L(30bytes):
	movl	-30(%esi), %eax
	movl	-30(%edx), %ecx
	cmpl	%ecx, %eax
	jne	L(find_diff)
L(26bytes):
	movl	-26(%esi), %eax
	movl	-26(%edx), %ecx
	cmpl	%ecx, %eax
	jne	L(find_diff)
L(22bytes):
	movl	-22(%esi), %eax
	movl	-22(%edx), %ecx
	cmpl	%ecx, %eax
	jne	L(find_diff)
L(18bytes):
	movl	-18(%esi), %eax
	movl	-18(%edx), %ecx
	cmpl	%ecx, %eax
	jne	L(find_diff)
L(14bytes):
	movl	-14(%esi), %eax
	movl	-14(%edx), %ecx
	cmpl	%ecx, %eax
	jne	L(find_diff)
L(10bytes):
	movl	-10(%esi), %eax
	movl	-10(%edx), %ecx
	cmpl	%ecx, %eax
	jne	L(find_diff)
L(6bytes):
	movl	-6(%esi), %eax
	movl	-6(%edx), %ecx
	cmpl	%ecx, %eax
	jne	L(find_diff)
L(2bytes):
	movzwl	-2(%esi), %eax
	movzwl	-2(%edx), %ecx
	cmpb	%cl, %al
	jne	L(set)
	cmpl	%ecx, %eax
	jne	L(set)
	popl	%esi
	cfi_adjust_cfa_offset (-4)
	cfi_restore (esi)
	xorl	%eax, %eax
	RETURN

	cfi_adjust_cfa_offset (8)
	cfi_rel_offset (esi, 0)
	cfi_rel_offset (ebx, 4)
L(31bytes):
	movl	-31(%esi), %eax
	movl	-31(%edx), %ecx
	cmpl	%ecx, %eax
	jne	L(find_diff)
L(27bytes):
	movl	-27(%esi), %eax
	movl	-27(%edx), %ecx
	cmpl	%ecx, %eax
	jne	L(find_diff)
L(23bytes):
	movl	-23(%esi), %eax
	movl	-23(%edx), %ecx
	cmpl	%ecx, %eax
	jne	L(find_diff)
L(19bytes):
	movl	-19(%esi), %eax
	movl	-19(%edx), %ecx
	cmpl	%ecx, %eax
	jne	L(find_diff)
L(15bytes):
	movl	-15(%esi), %eax
	movl	-15(%edx), %ecx
	cmpl	%ecx, %eax
	jne	L(find_diff)
L(11bytes):
	movl	-11(%esi), %eax
	movl	-11(%edx), %ecx
	cmpl	%ecx, %eax
	jne	L(find_diff)
L(7bytes):
	movl	-7(%esi), %eax
	movl	-7(%edx), %ecx
	cmpl	%ecx, %eax
	jne	L(find_diff)
L(3bytes):
	movzwl	-3(%esi), %eax
	movzwl	-3(%edx), %ecx
	cmpb	%cl, %al
	jne	L(set)
	cmpl	%ecx, %eax
	jne	L(set)
	movzbl	-1(%esi), %eax
	cmpb	-1(%edx), %al
	jne	L(set)
	popl	%esi
	cfi_adjust_cfa_offset (-4)
	cfi_restore (esi)
	xorl	%eax, %eax
	RETURN

	cfi_adjust_cfa_offset (8)
	cfi_rel_offset (esi, 0)
	cfi_rel_offset (ebx, 4)
	ALIGN (4)
/* ECX >= 32.  */
L(32bytesormore):
	subl	$32, %ecx

	movl	(%esi), %eax
	cmpl	(%edx), %eax
	jne	L(load_ecx)

	movl	4(%esi), %eax
	cmpl	4(%edx), %eax
	jne	L(load_ecx_4)

	movl	8(%esi), %eax
	cmpl	8(%edx), %eax
	jne	L(load_ecx_8)

	movl	12(%esi), %eax
	cmpl	12(%edx), %eax
	jne	L(load_ecx_12)

	movl	16(%esi), %eax
	cmpl	16(%edx), %eax
	jne	L(load_ecx_16)

	movl	20(%esi), %eax
	cmpl	20(%edx), %eax
	jne	L(load_ecx_20)

	movl	24(%esi), %eax
	cmpl	24(%edx), %eax
	jne	L(load_ecx_24)

	movl	28(%esi), %eax
	cmpl	28(%edx), %eax
	jne	L(load_ecx_28)

	addl	$32, %esi
	addl	$32, %edx
	cmpl	$32, %ecx
	jge	L(32bytesormore)

	LOAD_JUMP_TABLE_ENTRY (L(table_32bytes), %ecx)
	addl	%ecx, %edx
	addl	%ecx, %esi
	jmp	*%ebx

L(load_ecx_28):
	addl	$0x4, %edx
L(load_ecx_24):
	addl	$0x4, %edx
L(load_ecx_20):
	addl	$0x4, %edx
L(load_ecx_16):
	addl	$0x4, %edx
L(load_ecx_12):
	addl	$0x4, %edx
L(load_ecx_8):
	addl	$0x4, %edx
L(load_ecx_4):
	addl	$0x4, %edx
L(load_ecx):
	movl	(%edx), %ecx

L(find_diff):
	cmpb	%cl, %al
	jne	L(set)
	cmpb	%ch, %ah
	jne	L(set)
	shrl	$16,%eax
	shrl	$16,%ecx
	cmpb	%cl, %al
	jne	L(set)
	/* We get there only if we already know there is a
	   difference.  */
	cmpl	%ecx, %eax
L(set):
	sbbl	%eax, %eax
	sbbl	$-1, %eax
	popl	%esi
	cfi_adjust_cfa_offset (-4)
	cfi_restore (esi)
	RETURN
END (BP_SYM (memcmp))

	.section	.rodata
	ALIGN (2)
L(table_32bytes) :
	.long	L(0bytes) - L(table_32bytes)
	.long	L(1bytes) - L(table_32bytes)
	.long	L(2bytes) - L(table_32bytes)
	.long	L(3bytes) - L(table_32bytes)
	.long	L(4bytes) - L(table_32bytes)
	.long	L(5bytes) - L(table_32bytes)
	.long	L(6bytes) - L(table_32bytes)
	.long	L(7bytes) - L(table_32bytes)
	.long	L(8bytes) - L(table_32bytes)
	.long	L(9bytes) - L(table_32bytes)
	.long	L(10bytes) - L(table_32bytes)
	.long	L(11bytes) - L(table_32bytes)
	.long	L(12bytes) - L(table_32bytes)
	.long	L(13bytes) - L(table_32bytes)
	.long	L(14bytes) - L(table_32bytes)
	.long	L(15bytes) - L(table_32bytes)
	.long	L(16bytes) - L(table_32bytes)
	.long	L(17bytes) - L(table_32bytes)
	.long	L(18bytes) - L(table_32bytes)
	.long	L(19bytes) - L(table_32bytes)
	.long	L(20bytes) - L(table_32bytes)
	.long	L(21bytes) - L(table_32bytes)
	.long	L(22bytes) - L(table_32bytes)
	.long	L(23bytes) - L(table_32bytes)
	.long	L(24bytes) - L(table_32bytes)
	.long	L(25bytes) - L(table_32bytes)
	.long	L(26bytes) - L(table_32bytes)
	.long	L(27bytes) - L(table_32bytes)
	.long	L(28bytes) - L(table_32bytes)
	.long	L(29bytes) - L(table_32bytes)
	.long	L(30bytes) - L(table_32bytes)
	.long	L(31bytes) - L(table_32bytes)


#undef bcmp
weak_alias (BP_SYM (memcmp), BP_SYM (bcmp))
libc_hidden_builtin_def (BP_SYM (memcmp))