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 */
24ENTRY(_find_first_zero_bit_le)
25		teq	r1, #0
26		beq	3f
27		mov	r2, #0
281:		ldrb	r3, [r0, r2, lsr #3]
29		eors	r3, r3, #0xff		@ invert bits
30		bne	.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		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 */
41ENTRY(_find_next_zero_bit_le)
42		teq	r1, #0
43		beq	2b
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
49		bne	.found
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 * One or more bits in the LSB of r3 are assumed to be set.
56 */
57.found:		tst	r3, #0x0f
58		addeq	r2, r2, #4
59		movne	r3, r3, lsl #4
60		tst	r3, #0x30
61		addeq	r2, r2, #2
62		movne	r3, r3, lsl #2
63		tst	r3, #0x40
64		addeq	r2, r2, #1
65		mov	r0, r2
66		RETINSTR(mov,pc,lr)
67