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#include <linux/linkage.h>
11#include <asm/assembler.h>
12                .text
13
14/*
15 * Purpose  : Find a 'zero' bit
16 * Prototype: int find_first_zero_bit(void *addr, int maxbit);
17 */
18ENTRY(find_first_zero_bit)
19		mov	r2, #0
20.bytelp:	ldrb	r3, [r0, r2, lsr #3]
21		eors	r3, r3, #0xff		@ invert bits
22		bne	.found			@ any now set - found zero bit
23		add	r2, r2, #8		@ next bit pointer
24		cmp	r2, r1			@ any more?
25		bcc	.bytelp
26		add	r0, r1, #1		@ no free bits
27		RETINSTR(mov,pc,lr)
28
29/*
30 * Purpose  : Find next 'zero' bit
31 * Prototype: int find_next_zero_bit(void *addr, int maxbit, int offset)
32 */
33ENTRY(find_next_zero_bit)
34		ands	ip, r2, #7
35		beq	.bytelp			@ If new byte, goto old routine
36		ldrb	r3, [r0, r2, lsr#3]
37		eor	r3, r3, #0xff		@ now looking for a 1 bit
38		movs	r3, r3, lsr ip		@ shift off unused bits
39		orreq	r2, r2, #7		@ if zero, then no bits here
40		addeq	r2, r2, #1		@ align bit pointer
41		beq	.bytelp			@ loop for next bit
42
43/*
44 * One or more bits in the LSB of r3 are assumed to be set.
45 */
46.found:		tst	r3, #0x0f
47		addeq	r2, r2, #4
48		movne	r3, r3, lsl #4
49		tst	r3, #0x30
50		addeq	r2, r2, #2
51		movne	r3, r3, lsl #2
52		tst	r3, #0x40
53		addeq	r2, r2, #1
54		mov	r0, r2
55		RETINSTR(mov,pc,lr)
56
57