xref: /openbmc/linux/arch/arm/lib/findbit.S (revision 22d55f02) 
1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 *  linux/arch/arm/lib/findbit.S
4 *
5 *  Copyright (C) 1995-2000 Russell King
6 *
7 * 16th March 2001 - John Ripley <jripley@sonicblue.com>
8 *   Fixed so that "size" is an exclusive not an inclusive quantity.
9 *   All users of these functions expect exclusive sizes, and may
10 *   also call with zero size.
11 * Reworked by rmk.
12 */
13#include <linux/linkage.h>
14#include <asm/assembler.h>
15                .text
16
17/*
18 * Purpose  : Find a 'zero' bit
19 * Prototype: int find_first_zero_bit(void *addr, unsigned int maxbit);
20 */
21ENTRY(_find_first_zero_bit_le)
22		teq	r1, #0
23		beq	3f
24		mov	r2, #0
251:
26 ARM(		ldrb	r3, [r0, r2, lsr #3]	)
27 THUMB(		lsr	r3, r2, #3		)
28 THUMB(		ldrb	r3, [r0, r3]		)
29		eors	r3, r3, #0xff		@ invert bits
30		bne	.L_found		@ any now set - found zero bit
31		add	r2, r2, #8		@ next bit pointer
322:		cmp	r2, r1			@ any more?
33		blo	1b
343:		mov	r0, r1			@ no free bits
35		ret	lr
36ENDPROC(_find_first_zero_bit_le)
37
38/*
39 * Purpose  : Find next 'zero' bit
40 * Prototype: int find_next_zero_bit(void *addr, unsigned int maxbit, int offset)
41 */
42ENTRY(_find_next_zero_bit_le)
43		teq	r1, #0
44		beq	3b
45		ands	ip, r2, #7
46		beq	1b			@ If new byte, goto old routine
47 ARM(		ldrb	r3, [r0, r2, lsr #3]	)
48 THUMB(		lsr	r3, r2, #3		)
49 THUMB(		ldrb	r3, [r0, r3]		)
50		eor	r3, r3, #0xff		@ now looking for a 1 bit
51		movs	r3, r3, lsr ip		@ shift off unused bits
52		bne	.L_found
53		orr	r2, r2, #7		@ if zero, then no bits here
54		add	r2, r2, #1		@ align bit pointer
55		b	2b			@ loop for next bit
56ENDPROC(_find_next_zero_bit_le)
57
58/*
59 * Purpose  : Find a 'one' bit
60 * Prototype: int find_first_bit(const unsigned long *addr, unsigned int maxbit);
61 */
62ENTRY(_find_first_bit_le)
63		teq	r1, #0
64		beq	3f
65		mov	r2, #0
661:
67 ARM(		ldrb	r3, [r0, r2, lsr #3]	)
68 THUMB(		lsr	r3, r2, #3		)
69 THUMB(		ldrb	r3, [r0, r3]		)
70		movs	r3, r3
71		bne	.L_found		@ any now set - found zero bit
72		add	r2, r2, #8		@ next bit pointer
732:		cmp	r2, r1			@ any more?
74		blo	1b
753:		mov	r0, r1			@ no free bits
76		ret	lr
77ENDPROC(_find_first_bit_le)
78
79/*
80 * Purpose  : Find next 'one' bit
81 * Prototype: int find_next_zero_bit(void *addr, unsigned int maxbit, int offset)
82 */
83ENTRY(_find_next_bit_le)
84		teq	r1, #0
85		beq	3b
86		ands	ip, r2, #7
87		beq	1b			@ If new byte, goto old routine
88 ARM(		ldrb	r3, [r0, r2, lsr #3]	)
89 THUMB(		lsr	r3, r2, #3		)
90 THUMB(		ldrb	r3, [r0, r3]		)
91		movs	r3, r3, lsr ip		@ shift off unused bits
92		bne	.L_found
93		orr	r2, r2, #7		@ if zero, then no bits here
94		add	r2, r2, #1		@ align bit pointer
95		b	2b			@ loop for next bit
96ENDPROC(_find_next_bit_le)
97
98#ifdef __ARMEB__
99
100ENTRY(_find_first_zero_bit_be)
101		teq	r1, #0
102		beq	3f
103		mov	r2, #0
1041:		eor	r3, r2, #0x18		@ big endian byte ordering
105 ARM(		ldrb	r3, [r0, r3, lsr #3]	)
106 THUMB(		lsr	r3, #3			)
107 THUMB(		ldrb	r3, [r0, r3]		)
108		eors	r3, r3, #0xff		@ invert bits
109		bne	.L_found		@ any now set - found zero bit
110		add	r2, r2, #8		@ next bit pointer
1112:		cmp	r2, r1			@ any more?
112		blo	1b
1133:		mov	r0, r1			@ no free bits
114		ret	lr
115ENDPROC(_find_first_zero_bit_be)
116
117ENTRY(_find_next_zero_bit_be)
118		teq	r1, #0
119		beq	3b
120		ands	ip, r2, #7
121		beq	1b			@ If new byte, goto old routine
122		eor	r3, r2, #0x18		@ big endian byte ordering
123 ARM(		ldrb	r3, [r0, r3, lsr #3]	)
124 THUMB(		lsr	r3, #3			)
125 THUMB(		ldrb	r3, [r0, r3]		)
126		eor	r3, r3, #0xff		@ now looking for a 1 bit
127		movs	r3, r3, lsr ip		@ shift off unused bits
128		bne	.L_found
129		orr	r2, r2, #7		@ if zero, then no bits here
130		add	r2, r2, #1		@ align bit pointer
131		b	2b			@ loop for next bit
132ENDPROC(_find_next_zero_bit_be)
133
134ENTRY(_find_first_bit_be)
135		teq	r1, #0
136		beq	3f
137		mov	r2, #0
1381:		eor	r3, r2, #0x18		@ big endian byte ordering
139 ARM(		ldrb	r3, [r0, r3, lsr #3]	)
140 THUMB(		lsr	r3, #3			)
141 THUMB(		ldrb	r3, [r0, r3]		)
142		movs	r3, r3
143		bne	.L_found		@ any now set - found zero bit
144		add	r2, r2, #8		@ next bit pointer
1452:		cmp	r2, r1			@ any more?
146		blo	1b
1473:		mov	r0, r1			@ no free bits
148		ret	lr
149ENDPROC(_find_first_bit_be)
150
151ENTRY(_find_next_bit_be)
152		teq	r1, #0
153		beq	3b
154		ands	ip, r2, #7
155		beq	1b			@ If new byte, goto old routine
156		eor	r3, r2, #0x18		@ big endian byte ordering
157 ARM(		ldrb	r3, [r0, r3, lsr #3]	)
158 THUMB(		lsr	r3, #3			)
159 THUMB(		ldrb	r3, [r0, r3]		)
160		movs	r3, r3, lsr ip		@ shift off unused bits
161		bne	.L_found
162		orr	r2, r2, #7		@ if zero, then no bits here
163		add	r2, r2, #1		@ align bit pointer
164		b	2b			@ loop for next bit
165ENDPROC(_find_next_bit_be)
166
167#endif
168
169/*
170 * One or more bits in the LSB of r3 are assumed to be set.
171 */
172.L_found:
173#if __LINUX_ARM_ARCH__ >= 5
174		rsb	r0, r3, #0
175		and	r3, r3, r0
176		clz	r3, r3
177		rsb	r3, r3, #31
178		add	r0, r2, r3
179#else
180		tst	r3, #0x0f
181		addeq	r2, r2, #4
182		movne	r3, r3, lsl #4
183		tst	r3, #0x30
184		addeq	r2, r2, #2
185		movne	r3, r3, lsl #2
186		tst	r3, #0x40
187		addeq	r2, r2, #1
188		mov	r0, r2
189#endif
190		cmp	r1, r0			@ Clamp to maxbit
191		movlo	r0, r1
192		ret	lr
193
194