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/* SPDX-License-Identifier: GPL-2.0-only */
/*
* linux/arch/arm/lib/findbit.S
*
* Copyright (C) 1995-2000 Russell King
*
* 16th March 2001 - John Ripley <jripley@sonicblue.com>
* 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>
#include <asm/unwind.h>
.text
#ifdef __ARMEB__
#define SWAB_ENDIAN le
#else
#define SWAB_ENDIAN be
#endif
.macro find_first, endian, set, name
ENTRY(_find_first_\name\()bit_\endian)
UNWIND( .fnstart)
teq r1, #0
beq 3f
mov r2, #0
1: ldr r3, [r0], #4
.ifeq \set
mvns r3, r3 @ invert/test bits
.else
movs r3, r3 @ test bits
.endif
.ifc \endian, SWAB_ENDIAN
bne .L_found_swab
.else
bne .L_found @ found the bit?
.endif
add r2, r2, #32 @ next index
2: cmp r2, r1 @ any more?
blo 1b
3: mov r0, r1 @ no more bits
ret lr
UNWIND( .fnend)
ENDPROC(_find_first_\name\()bit_\endian)
.endm
.macro find_next, endian, set, name
ENTRY(_find_next_\name\()bit_\endian)
UNWIND( .fnstart)
cmp r2, r1
bhs 3b
mov ip, r2, lsr #5 @ word index
add r0, r0, ip, lsl #2
ands ip, r2, #31 @ bit position
beq 1b
ldr r3, [r0], #4
.ifeq \set
mvn r3, r3 @ invert bits
.endif
.ifc \endian, SWAB_ENDIAN
rev_l r3, ip
.if .Lrev_l_uses_tmp
@ we need to recompute ip because rev_l will have overwritten
@ it.
and ip, r2, #31 @ bit position
.endif
.endif
movs r3, r3, lsr ip @ shift off unused bits
bne .L_found
orr r2, r2, #31 @ no zero bits
add r2, r2, #1 @ align bit pointer
b 2b @ loop for next bit
UNWIND( .fnend)
ENDPROC(_find_next_\name\()bit_\endian)
.endm
.macro find_bit, endian, set, name
find_first \endian, \set, \name
find_next \endian, \set, \name
.endm
/* _find_first_zero_bit_le and _find_next_zero_bit_le */
find_bit le, 0, zero_
/* _find_first_bit_le and _find_next_bit_le */
find_bit le, 1
#ifdef __ARMEB__
/* _find_first_zero_bit_be and _find_next_zero_bit_be */
find_bit be, 0, zero_
/* _find_first_bit_be and _find_next_bit_be */
find_bit be, 1
#endif
/*
* One or more bits in the LSB of r3 are assumed to be set.
*/
.L_found_swab:
UNWIND( .fnstart)
rev_l r3, ip
.L_found:
#if __LINUX_ARM_ARCH__ >= 7
rbit r3, r3 @ reverse bits
clz r3, r3 @ count high zero bits
add r0, r2, r3 @ add offset of first set bit
#elif __LINUX_ARM_ARCH__ >= 5
rsb r0, r3, #0
and r3, r3, r0 @ mask out lowest bit set
clz r3, r3 @ count high zero bits
rsb r3, r3, #31 @ offset of first set bit
add r0, r2, r3 @ add offset of first set bit
#else
mov ip, #~0
tst r3, ip, lsr #16 @ test bits 0-15
addeq r2, r2, #16
moveq r3, r3, lsr #16
tst r3, #0x00ff
addeq r2, r2, #8
moveq r3, r3, lsr #8
tst r3, #0x000f
addeq r2, r2, #4
moveq r3, r3, lsr #4
tst r3, #0x0003
addeq r2, r2, #2
moveq r3, r3, lsr #2
tst r3, #0x0001
addeq r2, r2, #1
mov r0, r2
#endif
cmp r1, r0 @ Clamp to maxbit
movlo r0, r1
ret lr
UNWIND( .fnend)
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