aboutsummaryrefslogtreecommitdiff
path: root/arch/sparc/lib/memscan.S
blob: 28e78ff090acbcb5abd0d0ca318a6c3291e6575b (plain)
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
/* $Id: memscan.S,v 1.4 1996/09/08 02:01:20 davem Exp $
 * memscan.S: Optimized memscan for the Sparc.
 *
 * Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu)
 */

/* In essence, this is just a fancy strlen. */

#define LO_MAGIC 0x01010101
#define HI_MAGIC 0x80808080

	.text
	.align	4
	.globl	__memscan_zero, __memscan_generic
	.globl	memscan
__memscan_zero:
	/* %o0 = addr, %o1 = size */
	cmp	%o1, 0
	bne,a	1f
	 andcc	%o0, 3, %g0

	retl
	 nop

1:
	be	mzero_scan_word
	 sethi	%hi(HI_MAGIC), %g2

	ldsb	[%o0], %g3
mzero_still_not_word_aligned:
	cmp	%g3, 0
	bne	1f
	 add	%o0, 1, %o0

	retl
	 sub	%o0, 1, %o0

1:
	subcc	%o1, 1, %o1
	bne,a	1f
	 andcc	%o0, 3, %g0

	retl
	 nop

1:
	bne,a	mzero_still_not_word_aligned
	 ldsb	[%o0], %g3

	sethi	%hi(HI_MAGIC), %g2
mzero_scan_word:
	or	%g2, %lo(HI_MAGIC), %o3
	sethi	%hi(LO_MAGIC), %g3
	or	%g3, %lo(LO_MAGIC), %o2
mzero_next_word:
	ld	[%o0], %g2
mzero_next_word_preloaded:
	sub	%g2, %o2, %g2
mzero_next_word_preloaded_next:
	andcc	%g2, %o3, %g0
	bne	mzero_byte_zero
	 add	%o0, 4, %o0

mzero_check_out_of_fuel:
	subcc	%o1, 4, %o1
	bg,a	1f
	 ld	[%o0], %g2

	retl
	 nop

1:
	b	mzero_next_word_preloaded_next
	 sub	%g2, %o2, %g2

	/* Check every byte. */
mzero_byte_zero:
	ldsb	[%o0 - 4], %g2
	cmp	%g2, 0
	bne	mzero_byte_one
	 sub	%o0, 4, %g3

	retl
	 mov	%g3, %o0

mzero_byte_one:
	ldsb	[%o0 - 3], %g2
	cmp	%g2, 0
	bne,a	mzero_byte_two_and_three
	 ldsb	[%o0 - 2], %g2

	retl
	 sub	%o0, 3, %o0

mzero_byte_two_and_three:
	cmp	%g2, 0
	bne,a	1f
	 ldsb	[%o0 - 1], %g2

	retl
	 sub	%o0, 2, %o0

1:
	cmp	%g2, 0
	bne,a	mzero_next_word_preloaded
	 ld	[%o0], %g2

	retl
	 sub	%o0, 1, %o0

mzero_found_it:
	retl
	 sub	%o0, 2, %o0

memscan:
__memscan_generic:
	/* %o0 = addr, %o1 = c, %o2 = size */
	cmp	%o2, 0
	bne,a	0f
	 ldub	[%o0], %g2

	b,a	2f
1:
	ldub	[%o0], %g2
0:
	cmp	%g2, %o1
	be	2f
	 addcc	%o2, -1, %o2
	bne	1b
	 add	%o0, 1, %o0
2:
	retl
	 nop