linux / linux / kernel / git / viro / vfs / 5a1efc6e68a095917277459091fafba6a6baef17 / . / arch / arm / lib / findbit.S

/* | |

* 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 <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> | |

.text | |

/* | |

* Purpose : Find a 'zero' bit | |

* Prototype: int find_first_zero_bit(void *addr, unsigned int maxbit); | |

*/ | |

ENTRY(_find_first_zero_bit_le) | |

teq r1, #0 | |

beq 3f | |

mov r2, #0 | |

1: | |

ARM( ldrb r3, [r0, r2, lsr #3] ) | |

THUMB( lsr r3, r2, #3 ) | |

THUMB( ldrb r3, [r0, r3] ) | |

eors r3, r3, #0xff @ invert bits | |

bne .L_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 | |

mov pc, lr | |

ENDPROC(_find_first_zero_bit_le) | |

/* | |

* Purpose : Find next 'zero' bit | |

* Prototype: int find_next_zero_bit(void *addr, unsigned int maxbit, int offset) | |

*/ | |

ENTRY(_find_next_zero_bit_le) | |

teq r1, #0 | |

beq 3b | |

ands ip, r2, #7 | |

beq 1b @ If new byte, goto old routine | |

ARM( ldrb r3, [r0, r2, lsr #3] ) | |

THUMB( lsr r3, r2, #3 ) | |

THUMB( ldrb r3, [r0, r3] ) | |

eor r3, r3, #0xff @ now looking for a 1 bit | |

movs r3, r3, lsr ip @ shift off unused bits | |

bne .L_found | |

orr r2, r2, #7 @ if zero, then no bits here | |

add r2, r2, #1 @ align bit pointer | |

b 2b @ loop for next bit | |

ENDPROC(_find_next_zero_bit_le) | |

/* | |

* Purpose : Find a 'one' bit | |

* Prototype: int find_first_bit(const unsigned long *addr, unsigned int maxbit); | |

*/ | |

ENTRY(_find_first_bit_le) | |

teq r1, #0 | |

beq 3f | |

mov r2, #0 | |

1: | |

ARM( ldrb r3, [r0, r2, lsr #3] ) | |

THUMB( lsr r3, r2, #3 ) | |

THUMB( ldrb r3, [r0, r3] ) | |

movs r3, r3 | |

bne .L_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 | |

mov pc, lr | |

ENDPROC(_find_first_bit_le) | |

/* | |

* Purpose : Find next 'one' bit | |

* Prototype: int find_next_zero_bit(void *addr, unsigned int maxbit, int offset) | |

*/ | |

ENTRY(_find_next_bit_le) | |

teq r1, #0 | |

beq 3b | |

ands ip, r2, #7 | |

beq 1b @ If new byte, goto old routine | |

ARM( ldrb r3, [r0, r2, lsr #3] ) | |

THUMB( lsr r3, r2, #3 ) | |

THUMB( ldrb r3, [r0, r3] ) | |

movs r3, r3, lsr ip @ shift off unused bits | |

bne .L_found | |

orr r2, r2, #7 @ if zero, then no bits here | |

add r2, r2, #1 @ align bit pointer | |

b 2b @ loop for next bit | |

ENDPROC(_find_next_bit_le) | |

#ifdef __ARMEB__ | |

ENTRY(_find_first_zero_bit_be) | |

teq r1, #0 | |

beq 3f | |

mov r2, #0 | |

1: eor r3, r2, #0x18 @ big endian byte ordering | |

ARM( ldrb r3, [r0, r3, lsr #3] ) | |

THUMB( lsr r3, #3 ) | |

THUMB( ldrb r3, [r0, r3] ) | |

eors r3, r3, #0xff @ invert bits | |

bne .L_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 | |

mov pc, lr | |

ENDPROC(_find_first_zero_bit_be) | |

ENTRY(_find_next_zero_bit_be) | |

teq r1, #0 | |

beq 3b | |

ands ip, r2, #7 | |

beq 1b @ If new byte, goto old routine | |

eor r3, r2, #0x18 @ big endian byte ordering | |

ARM( ldrb r3, [r0, r3, lsr #3] ) | |

THUMB( lsr r3, #3 ) | |

THUMB( ldrb r3, [r0, r3] ) | |

eor r3, r3, #0xff @ now looking for a 1 bit | |

movs r3, r3, lsr ip @ shift off unused bits | |

bne .L_found | |

orr r2, r2, #7 @ if zero, then no bits here | |

add r2, r2, #1 @ align bit pointer | |

b 2b @ loop for next bit | |

ENDPROC(_find_next_zero_bit_be) | |

ENTRY(_find_first_bit_be) | |

teq r1, #0 | |

beq 3f | |

mov r2, #0 | |

1: eor r3, r2, #0x18 @ big endian byte ordering | |

ARM( ldrb r3, [r0, r3, lsr #3] ) | |

THUMB( lsr r3, #3 ) | |

THUMB( ldrb r3, [r0, r3] ) | |

movs r3, r3 | |

bne .L_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 | |

mov pc, lr | |

ENDPROC(_find_first_bit_be) | |

ENTRY(_find_next_bit_be) | |

teq r1, #0 | |

beq 3b | |

ands ip, r2, #7 | |

beq 1b @ If new byte, goto old routine | |

eor r3, r2, #0x18 @ big endian byte ordering | |

ARM( ldrb r3, [r0, r3, lsr #3] ) | |

THUMB( lsr r3, #3 ) | |

THUMB( ldrb r3, [r0, r3] ) | |

movs r3, r3, lsr ip @ shift off unused bits | |

bne .L_found | |

orr r2, r2, #7 @ if zero, then no bits here | |

add r2, r2, #1 @ align bit pointer | |

b 2b @ loop for next bit | |

ENDPROC(_find_next_bit_be) | |

#endif | |

/* | |

* One or more bits in the LSB of r3 are assumed to be set. | |

*/ | |

.L_found: | |

#if __LINUX_ARM_ARCH__ >= 5 | |

rsb r0, r3, #0 | |

and r3, r3, r0 | |

clz r3, r3 | |

rsb r3, r3, #31 | |

add r0, r2, r3 | |

#else | |

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 | |

#endif | |

cmp r1, r0 @ Clamp to maxbit | |

movlo r0, r1 | |

mov pc, lr | |