about summary refs log tree commit diff
path: root/sysdeps/powerpc/powerpc64/strcmp.S
blob: d4fb5b364a68315480df0553554a5e12493e7772 (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
/* Optimized strcmp implementation for PowerPC64.
   Copyright (C) 1997-2016 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)
	CALL_MCOUNT 2

#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 0xfefefefefefefeff (-0x0101010101010101) */
#define r7F7F	r8	/* constant 0x7f7f7f7f7f7f7f7f */
#define rNEG	r9	/* ~(word in s1 | 0x7f7f7f7f7f7f7f7f) */
#define rBITDIF	r10	/* bits that differ in s1 & s2 words */
#define rTMP	r11

	dcbt	0,rSTR1
	or	rTMP, rSTR2, rSTR1
	dcbt	0,rSTR2
	clrldi.	rTMP, rTMP, 61
	lis	rFEFE, -0x101
	bne	L(unaligned)

	ld	rWORD1, 0(rSTR1)
	ld	rWORD2, 0(rSTR2)
	lis	r7F7F, 0x7f7f
	addi	rFEFE, rFEFE, -0x101
	addi	r7F7F, r7F7F, 0x7f7f
	sldi	rTMP, rFEFE, 32
	insrdi	r7F7F, r7F7F, 32, 0
	add	rFEFE, rFEFE, rTMP
	b	L(g1)

L(g0):	ldu	rWORD1, 8(rSTR1)
	bne	cr1, L(different)
	ldu	rWORD2, 8(rSTR2)
L(g1):	add	rTMP, rFEFE, rWORD1
	nor	rNEG, r7F7F, rWORD1
	and.	rTMP, rTMP, rNEG
	cmpd	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
	beq	cr1, L(equal)
	andc    rTMP2, rTMP2, rTMP
	rldimi	rTMP2, rTMP2, 1, 0
	and	rWORD2, rWORD2, rTMP2	/* Mask off gunk.  */
	and	rWORD1, rWORD1, rTMP2
	cmpd	cr1, rWORD1, rWORD2
	beq	cr1, L(equal)
	xor	rBITDIF, rWORD1, rWORD2	/* rBITDIF has bits that differ.  */
	neg	rNEG, rBITDIF
	and	rNEG, rNEG, rBITDIF	/* rNEG has LS bit that differs.  */
	cntlzd	rNEG, rNEG		/* bitcount of the bit.  */
	andi.	rNEG, rNEG, 56		/* bitcount to LS byte that differs. */
	sld	rWORD1, rWORD1, rNEG	/* shift left to clear MS bytes.  */
	sld	rWORD2, rWORD2, rNEG
	xor.	rBITDIF, rWORD1, rWORD2
	sub	rRTN, rWORD1, rWORD2
	blt-	L(highbit)
	sradi	rRTN, rRTN, 63		/* must return an int.  */
	ori	rRTN, rRTN, 1
	blr
L(equal):
	li	rRTN, 0
	blr

L(different):
	ld	rWORD1, -8(rSTR1)
	xor	rBITDIF, rWORD1, rWORD2	/* rBITDIF has bits that differ.  */
	neg	rNEG, rBITDIF
	and	rNEG, rNEG, rBITDIF	/* rNEG has LS bit that differs.  */
	cntlzd	rNEG, rNEG		/* bitcount of the bit.  */
	andi.	rNEG, rNEG, 56		/* bitcount to LS byte that differs. */
	sld	rWORD1, rWORD1, rNEG	/* shift left to clear MS bytes.  */
	sld	rWORD2, rWORD2, rNEG
	xor.	rBITDIF, rWORD1, rWORD2
	sub	rRTN, rWORD1, rWORD2
	blt-	L(highbit)
	sradi	rRTN, rRTN, 63
	ori	rRTN, rRTN, 1
	blr
L(highbit):
	sradi	rRTN, rWORD2, 63
	ori	rRTN, rRTN, 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)
	cntlzd	rBITDIF, rBITDIF
	cntlzd	rNEG, rNEG
	addi	rNEG, rNEG, 7
	cmpd	cr1, rNEG, rBITDIF
	sub	rRTN, rWORD1, rWORD2
	blt-	cr1, L(equal)
	sradi	rRTN, rRTN, 63		/* must return an int.  */
	ori	rRTN, rRTN, 1
	blr
L(equal):
	li	rRTN, 0
	blr

L(different):
	ld	rWORD1, -8(rSTR1)
	xor.	rBITDIF, rWORD1, rWORD2
	sub	rRTN, rWORD1, rWORD2
	blt-	L(highbit)
	sradi	rRTN, rRTN, 63
	ori	rRTN, rRTN, 1
	blr
L(highbit):
	sradi	rRTN, rWORD2, 63
	ori	rRTN, rRTN, 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)
	cmpd	rWORD1, rWORD2
	bne-	L(u3)
	lbzu	rWORD1, 1(rSTR1)
	lbzu	rWORD2, 1(rSTR2)
	cmpdi	cr1, rWORD1, 0
	cmpd	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)