| blob | 64f6bc1a91326c79800bbb9205645a7d0e7e5e0c |
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
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:
29 ARM( ldrb r3, [r0, r2, lsr #3] )
30 THUMB( lsr r3, r2, #3 )
31 THUMB( ldrb r3, [r0, r3] )
32 eors r3, r3, #0xff @ invert bits
33 bne .L_found @ any now set - found zero bit
34 add r2, r2, #8 @ next bit pointer
35 2: cmp r2, r1 @ any more?
36 blo 1b
37 3: mov r0, r1 @ no free bits
38 mov pc, lr
39 ENDPROC(_find_first_zero_bit_le)
41 /*
42 * Purpose : Find next 'zero' bit
43 * Prototype: int find_next_zero_bit(void *addr, unsigned int maxbit, int offset)
44 */
45 ENTRY(_find_next_zero_bit_le)
46 teq r1, #0
47 beq 3b
48 ands ip, r2, #7
49 beq 1b @ If new byte, goto old routine
50 ARM( ldrb r3, [r0, r2, lsr #3] )
51 THUMB( lsr r3, r2, #3 )
52 THUMB( ldrb r3, [r0, r3] )
53 eor r3, r3, #0xff @ now looking for a 1 bit
54 movs r3, r3, lsr ip @ shift off unused bits
55 bne .L_found
56 orr r2, r2, #7 @ if zero, then no bits here
57 add r2, r2, #1 @ align bit pointer
58 b 2b @ loop for next bit
59 ENDPROC(_find_next_zero_bit_le)
61 /*
62 * Purpose : Find a 'one' bit
63 * Prototype: int find_first_bit(const unsigned long *addr, unsigned int maxbit);
64 */
65 ENTRY(_find_first_bit_le)
66 teq r1, #0
67 beq 3f
68 mov r2, #0
69 1:
70 ARM( ldrb r3, [r0, r2, lsr #3] )
71 THUMB( lsr r3, r2, #3 )
72 THUMB( ldrb r3, [r0, r3] )
73 movs r3, r3
74 bne .L_found @ any now set - found zero bit
75 add r2, r2, #8 @ next bit pointer
76 2: cmp r2, r1 @ any more?
77 blo 1b
78 3: mov r0, r1 @ no free bits
79 mov pc, lr
80 ENDPROC(_find_first_bit_le)
82 /*
83 * Purpose : Find next 'one' bit
84 * Prototype: int find_next_zero_bit(void *addr, unsigned int maxbit, int offset)
85 */
86 ENTRY(_find_next_bit_le)
87 teq r1, #0
88 beq 3b
89 ands ip, r2, #7
90 beq 1b @ If new byte, goto old routine
91 ARM( ldrb r3, [r0, r2, lsr #3] )
92 THUMB( lsr r3, r2, #3 )
93 THUMB( ldrb r3, [r0, r3] )
94 movs r3, r3, lsr ip @ shift off unused bits
95 bne .L_found
96 orr r2, r2, #7 @ if zero, then no bits here
97 add r2, r2, #1 @ align bit pointer
98 b 2b @ loop for next bit
99 ENDPROC(_find_next_bit_le)
101 #ifdef __ARMEB__
103 ENTRY(_find_first_zero_bit_be)
104 teq r1, #0
105 beq 3f
106 mov r2, #0
107 1: eor r3, r2, #0x18 @ big endian byte ordering
108 ARM( ldrb r3, [r0, r3, lsr #3] )
109 THUMB( lsr r3, #3 )
110 THUMB( ldrb r3, [r0, r3] )
111 eors r3, r3, #0xff @ invert bits
112 bne .L_found @ any now set - found zero bit
113 add r2, r2, #8 @ next bit pointer
114 2: cmp r2, r1 @ any more?
115 blo 1b
116 3: mov r0, r1 @ no free bits
117 mov pc, lr
118 ENDPROC(_find_first_zero_bit_be)
120 ENTRY(_find_next_zero_bit_be)
121 teq r1, #0
122 beq 3b
123 ands ip, r2, #7
124 beq 1b @ If new byte, goto old routine
125 eor r3, r2, #0x18 @ big endian byte ordering
126 ARM( ldrb r3, [r0, r3, lsr #3] )
127 THUMB( lsr r3, #3 )
128 THUMB( ldrb r3, [r0, r3] )
129 eor r3, r3, #0xff @ now looking for a 1 bit
130 movs r3, r3, lsr ip @ shift off unused bits
131 bne .L_found
132 orr r2, r2, #7 @ if zero, then no bits here
133 add r2, r2, #1 @ align bit pointer
134 b 2b @ loop for next bit
135 ENDPROC(_find_next_zero_bit_be)
137 ENTRY(_find_first_bit_be)
138 teq r1, #0
139 beq 3f
140 mov r2, #0
141 1: eor r3, r2, #0x18 @ big endian byte ordering
142 ARM( ldrb r3, [r0, r3, lsr #3] )
143 THUMB( lsr r3, #3 )
144 THUMB( ldrb r3, [r0, r3] )
145 movs r3, r3
146 bne .L_found @ any now set - found zero bit
147 add r2, r2, #8 @ next bit pointer
148 2: cmp r2, r1 @ any more?
149 blo 1b
150 3: mov r0, r1 @ no free bits
151 mov pc, lr
152 ENDPROC(_find_first_bit_be)
154 ENTRY(_find_next_bit_be)
155 teq r1, #0
156 beq 3b
157 ands ip, r2, #7
158 beq 1b @ If new byte, goto old routine
159 eor r3, r2, #0x18 @ big endian byte ordering
160 ARM( ldrb r3, [r0, r3, lsr #3] )
161 THUMB( lsr r3, #3 )
162 THUMB( ldrb r3, [r0, r3] )
163 movs r3, r3, lsr ip @ shift off unused bits
164 bne .L_found
165 orr r2, r2, #7 @ if zero, then no bits here
166 add r2, r2, #1 @ align bit pointer
167 b 2b @ loop for next bit
168 ENDPROC(_find_next_bit_be)
170 #endif
172 /*
173 * One or more bits in the LSB of r3 are assumed to be set.
174 */
175 .L_found:
176 #if __LINUX_ARM_ARCH__ >= 5
177 rsb r0, r3, #0
178 and r3, r3, r0
179 clz r3, r3
180 rsb r3, r3, #31
181 add r0, r2, r3
182 #else
183 tst r3, #0x0f
184 addeq r2, r2, #4
185 movne r3, r3, lsl #4
186 tst r3, #0x30
187 addeq r2, r2, #2
188 movne r3, r3, lsl #2
189 tst r3, #0x40
190 addeq r2, r2, #1
191 mov r0, r2
192 #endif
193 cmp r1, r0 @ Clamp to maxbit
194 movlo r0, r1
195 mov pc, lr