summary refs log tree commit diff
path: root/sysdeps/powerpc/powerpc32/strcmp.S
blob: 91d60c905380134fb096014c4a06df04ec84b962 (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
/* Optimized strcmp implementation for PowerPC.
   Copyright (C) 1997-2013 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>

/* See strlen.s for comments on how the end-of-string testing works.  */

/* int [r3] strcmp (const char *s1 [r3], const char *s2 [r4])  */

EALIGN (strcmp, 4, 0)

#define rTMP2	r0
#define rRTN	r3
#define rSTR1	r3	/* first string arg */
#define rSTR2	r4	/* second string arg */
#define rWORD1	r5	/* current word in s1 */
#define rWORD2	r6	/* current word in s2 */
#define rFEFE	r7	/* constant 0xfefefeff (-0x01010101) */
#define r7F7F	r8	/* constant 0x7f7f7f7f */
#define rNEG	r9	/* ~(word in s1 | 0x7f7f7f7f) */
#define rBITDIF	r10	/* bits that differ in s1 & s2 words */
#define rTMP	r11


	or	rTMP, rSTR2, rSTR1
	clrlwi.	rTMP, rTMP, 30
	lis	rFEFE, -0x101
	bne	L(unaligned)

	lwz	rWORD1, 0(rSTR1)
	lwz	rWORD2, 0(rSTR2)
	lis	r7F7F, 0x7f7f
	addi	rFEFE, rFEFE, -0x101
	addi	r7F7F, r7F7F, 0x7f7f
	b	L(g1)

L(g0):	lwzu	rWORD1, 4(rSTR1)
	bne	cr1, L(different)
	lwzu	rWORD2, 4(rSTR2)
L(g1):	add	rTMP, rFEFE, rWORD1
	nor	rNEG, r7F7F, rWORD1
	and.	rTMP, rTMP, rNEG
	cmpw	cr1, rWORD1, rWORD2
	beq+	L(g0)

/* OK. We've hit the end of the string. We need to be careful that
   we don't compare two strings as different because of gunk beyond
   the end of the strings...  */
#ifdef __LITTLE_ENDIAN__
L(endstring):
	addi    rTMP2, rTMP, -1
	andc    rTMP2, rTMP2, rTMP
	rlwimi	rTMP2, rTMP2, 1, 0, 30
	and	rWORD2, rWORD2, rTMP2		/* Mask off gunk.  */
	and	rWORD1, rWORD1, rTMP2
	rlwinm	rTMP2, rWORD2, 8, 0xffffffff	/* Byte reverse word.  */
	rlwinm	rTMP, rWORD1, 8, 0xffffffff
	rlwimi	rTMP2, rWORD2, 24, 0, 7
	rlwimi	rTMP, rWORD1, 24, 0, 7
	rlwimi	rTMP2, rWORD2, 24, 16, 23
	rlwimi	rTMP, rWORD1, 24, 16, 23
	xor.	rBITDIF, rTMP, rTMP2
	sub	rRTN, rTMP, rTMP2
	bgelr+
	ori	rRTN, rTMP2, 1
	blr

L(different):
	lwz	rWORD1, -4(rSTR1)
	rlwinm	rTMP2, rWORD2, 8, 0xffffffff	/* Byte reverse word.  */
	rlwinm	rTMP, rWORD1, 8, 0xffffffff
	rlwimi	rTMP2, rWORD2, 24, 0, 7
	rlwimi	rTMP, rWORD1, 24, 0, 7
	rlwimi	rTMP2, rWORD2, 24, 16, 23
	rlwimi	rTMP, rWORD1, 24, 16, 23
	xor.	rBITDIF, rTMP, rTMP2
	sub	rRTN, rTMP, rTMP2
	bgelr+
	ori	rRTN, rTMP2, 1
	blr

#else
L(endstring):
	and	rTMP, r7F7F, rWORD1
	beq	cr1, L(equal)
	add	rTMP, rTMP, r7F7F
	xor.	rBITDIF, rWORD1, rWORD2
	andc	rNEG, rNEG, rTMP
	blt-	L(highbit)
	cntlzw	rBITDIF, rBITDIF
	cntlzw	rNEG, rNEG
	addi	rNEG, rNEG, 7
	cmpw	cr1, rNEG, rBITDIF
	sub	rRTN, rWORD1, rWORD2
	bgelr+	cr1
L(equal):
	li	rRTN, 0
	blr

L(different):
	lwz	rWORD1, -4(rSTR1)
	xor.	rBITDIF, rWORD1, rWORD2
	sub	rRTN, rWORD1, rWORD2
	bgelr+
L(highbit):
	ori	rRTN, rWORD2, 1
	blr
#endif

/* Oh well.  In this case, we just do a byte-by-byte comparison.  */
	.align 4
L(unaligned):
	lbz	rWORD1, 0(rSTR1)
	lbz	rWORD2, 0(rSTR2)
	b	L(u1)

L(u0):	lbzu	rWORD1, 1(rSTR1)
	bne-	L(u4)
	lbzu	rWORD2, 1(rSTR2)
L(u1):	cmpwi	cr1, rWORD1, 0
	beq-	cr1, L(u3)
	cmpw	rWORD1, rWORD2
	bne-	L(u3)
	lbzu	rWORD1, 1(rSTR1)
	lbzu	rWORD2, 1(rSTR2)
	cmpwi	cr1, rWORD1, 0
	cmpw	rWORD1, rWORD2
	bne+	cr1, L(u0)
L(u3):	sub	rRTN, rWORD1, rWORD2
	blr
L(u4):	lbz	rWORD1, -1(rSTR1)
	sub	rRTN, rWORD1, rWORD2
	blr
END (strcmp)
libc_hidden_builtin_def (strcmp)