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1da177e4 LT |
1 | /* |
2 | * linux/arch/arm/lib/findbit.S | |
3 | * | |
4 | * Copyright (C) 1995-2000 Russell King | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License version 2 as | |
8 | * published by the Free Software Foundation. | |
9 | * | |
10 | * 16th March 2001 - John Ripley <jripley@sonicblue.com> | |
11 | * Fixed so that "size" is an exclusive not an inclusive quantity. | |
12 | * All users of these functions expect exclusive sizes, and may | |
13 | * also call with zero size. | |
14 | * Reworked by rmk. | |
15 | */ | |
16 | #include <linux/linkage.h> | |
17 | #include <asm/assembler.h> | |
18 | .text | |
19 | ||
20 | /* | |
21 | * Purpose : Find a 'zero' bit | |
22 | * Prototype: int find_first_zero_bit(void *addr, unsigned int maxbit); | |
23 | */ | |
24 | ENTRY(_find_first_zero_bit_le) | |
25 | teq r1, #0 | |
26 | beq 3f | |
27 | mov r2, #0 | |
28 | 1: ldrb r3, [r0, r2, lsr #3] | |
29 | eors r3, r3, #0xff @ invert bits | |
8adbb371 | 30 | bne .L_found @ any now set - found zero bit |
1da177e4 LT |
31 | add r2, r2, #8 @ next bit pointer |
32 | 2: cmp r2, r1 @ any more? | |
33 | blo 1b | |
34 | 3: mov r0, r1 @ no free bits | |
35 | RETINSTR(mov,pc,lr) | |
36 | ||
37 | /* | |
38 | * Purpose : Find next 'zero' bit | |
39 | * Prototype: int find_next_zero_bit(void *addr, unsigned int maxbit, int offset) | |
40 | */ | |
41 | ENTRY(_find_next_zero_bit_le) | |
42 | teq r1, #0 | |
43 | beq 3b | |
44 | ands ip, r2, #7 | |
45 | beq 1b @ If new byte, goto old routine | |
46 | ldrb r3, [r0, r2, lsr #3] | |
47 | eor r3, r3, #0xff @ now looking for a 1 bit | |
48 | movs r3, r3, lsr ip @ shift off unused bits | |
8adbb371 | 49 | bne .L_found |
1da177e4 LT |
50 | orr r2, r2, #7 @ if zero, then no bits here |
51 | add r2, r2, #1 @ align bit pointer | |
52 | b 2b @ loop for next bit | |
53 | ||
54 | /* | |
55 | * Purpose : Find a 'one' bit | |
56 | * Prototype: int find_first_bit(const unsigned long *addr, unsigned int maxbit); | |
57 | */ | |
58 | ENTRY(_find_first_bit_le) | |
59 | teq r1, #0 | |
60 | beq 3f | |
61 | mov r2, #0 | |
62 | 1: ldrb r3, [r0, r2, lsr #3] | |
63 | movs r3, r3 | |
8adbb371 | 64 | bne .L_found @ any now set - found zero bit |
1da177e4 LT |
65 | add r2, r2, #8 @ next bit pointer |
66 | 2: cmp r2, r1 @ any more? | |
67 | blo 1b | |
68 | 3: mov r0, r1 @ no free bits | |
69 | RETINSTR(mov,pc,lr) | |
70 | ||
71 | /* | |
72 | * Purpose : Find next 'one' bit | |
73 | * Prototype: int find_next_zero_bit(void *addr, unsigned int maxbit, int offset) | |
74 | */ | |
75 | ENTRY(_find_next_bit_le) | |
76 | teq r1, #0 | |
77 | beq 3b | |
78 | ands ip, r2, #7 | |
79 | beq 1b @ If new byte, goto old routine | |
80 | ldrb r3, [r0, r2, lsr #3] | |
81 | movs r3, r3, lsr ip @ shift off unused bits | |
8adbb371 | 82 | bne .L_found |
1da177e4 LT |
83 | orr r2, r2, #7 @ if zero, then no bits here |
84 | add r2, r2, #1 @ align bit pointer | |
85 | b 2b @ loop for next bit | |
86 | ||
87 | #ifdef __ARMEB__ | |
88 | ||
89 | ENTRY(_find_first_zero_bit_be) | |
90 | teq r1, #0 | |
91 | beq 3f | |
92 | mov r2, #0 | |
93 | 1: eor r3, r2, #0x18 @ big endian byte ordering | |
94 | ldrb r3, [r0, r3, lsr #3] | |
95 | eors r3, r3, #0xff @ invert bits | |
8adbb371 | 96 | bne .L_found @ any now set - found zero bit |
1da177e4 LT |
97 | add r2, r2, #8 @ next bit pointer |
98 | 2: cmp r2, r1 @ any more? | |
99 | blo 1b | |
100 | 3: mov r0, r1 @ no free bits | |
101 | RETINSTR(mov,pc,lr) | |
102 | ||
103 | ENTRY(_find_next_zero_bit_be) | |
104 | teq r1, #0 | |
105 | beq 3b | |
106 | ands ip, r2, #7 | |
107 | beq 1b @ If new byte, goto old routine | |
108 | eor r3, r2, #0x18 @ big endian byte ordering | |
109 | ldrb r3, [r0, r3, lsr #3] | |
110 | eor r3, r3, #0xff @ now looking for a 1 bit | |
111 | movs r3, r3, lsr ip @ shift off unused bits | |
8adbb371 | 112 | bne .L_found |
1da177e4 LT |
113 | orr r2, r2, #7 @ if zero, then no bits here |
114 | add r2, r2, #1 @ align bit pointer | |
115 | b 2b @ loop for next bit | |
116 | ||
117 | ENTRY(_find_first_bit_be) | |
118 | teq r1, #0 | |
119 | beq 3f | |
120 | mov r2, #0 | |
121 | 1: eor r3, r2, #0x18 @ big endian byte ordering | |
122 | ldrb r3, [r0, r3, lsr #3] | |
123 | movs r3, r3 | |
8adbb371 | 124 | bne .L_found @ any now set - found zero bit |
1da177e4 LT |
125 | add r2, r2, #8 @ next bit pointer |
126 | 2: cmp r2, r1 @ any more? | |
127 | blo 1b | |
128 | 3: mov r0, r1 @ no free bits | |
129 | RETINSTR(mov,pc,lr) | |
130 | ||
131 | ENTRY(_find_next_bit_be) | |
132 | teq r1, #0 | |
133 | beq 3b | |
134 | ands ip, r2, #7 | |
135 | beq 1b @ If new byte, goto old routine | |
136 | eor r3, r2, #0x18 @ big endian byte ordering | |
137 | ldrb r3, [r0, r3, lsr #3] | |
138 | movs r3, r3, lsr ip @ shift off unused bits | |
8adbb371 | 139 | bne .L_found |
1da177e4 LT |
140 | orr r2, r2, #7 @ if zero, then no bits here |
141 | add r2, r2, #1 @ align bit pointer | |
142 | b 2b @ loop for next bit | |
143 | ||
144 | #endif | |
145 | ||
146 | /* | |
147 | * One or more bits in the LSB of r3 are assumed to be set. | |
148 | */ | |
8adbb371 | 149 | .L_found: |
1da177e4 LT |
150 | #if __LINUX_ARM_ARCH__ >= 5 |
151 | rsb r1, r3, #0 | |
152 | and r3, r3, r1 | |
153 | clz r3, r3 | |
154 | rsb r3, r3, #31 | |
155 | add r0, r2, r3 | |
156 | #else | |
157 | tst r3, #0x0f | |
158 | addeq r2, r2, #4 | |
159 | movne r3, r3, lsl #4 | |
160 | tst r3, #0x30 | |
161 | addeq r2, r2, #2 | |
162 | movne r3, r3, lsl #2 | |
163 | tst r3, #0x40 | |
164 | addeq r2, r2, #1 | |
165 | mov r0, r2 | |
166 | #endif | |
167 | RETINSTR(mov,pc,lr) | |
168 |