blob: 26f67cccc37c3c4dd31164ba3499572ffa937d49 [file] [log] [blame]
* linux/arch/arm/lib/findbit.S
* Copyright (C) 1995-2000 Russell King
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
* 16th March 2001 - John Ripley <>
* Fixed so that "size" is an exclusive not an inclusive quantity.
* All users of these functions expect exclusive sizes, and may
* also call with zero size.
* Reworked by rmk.
#include <linux/linkage.h>
#include <asm/assembler.h>
* Purpose : Find a 'zero' bit
* Prototype: int find_first_zero_bit(void *addr, unsigned int maxbit);
teq r1, #0
beq 3f
mov r2, #0
1: ldrb r3, [r0, r2, lsr #3]
eors r3, r3, #0xff @ invert bits
bne .found @ any now set - found zero bit
add r2, r2, #8 @ next bit pointer
2: cmp r2, r1 @ any more?
blo 1b
3: mov r0, r1 @ no free bits
* Purpose : Find next 'zero' bit
* Prototype: int find_next_zero_bit(void *addr, unsigned int maxbit, int offset)
teq r1, #0
beq 2b
ands ip, r2, #7
beq 1b @ If new byte, goto old routine
ldrb r3, [r0, r2, lsr #3]
eor r3, r3, #0xff @ now looking for a 1 bit
movs r3, r3, lsr ip @ shift off unused bits
bne .found
orr r2, r2, #7 @ if zero, then no bits here
add r2, r2, #1 @ align bit pointer
b 2b @ loop for next bit
* One or more bits in the LSB of r3 are assumed to be set.
.found: tst r3, #0x0f
addeq r2, r2, #4
movne r3, r3, lsl #4
tst r3, #0x30
addeq r2, r2, #2
movne r3, r3, lsl #2
tst r3, #0x40
addeq r2, r2, #1
mov r0, r2