diff options
| author | Linus Torvalds <[email protected]> | 2015-04-17 09:04:38 -0400 | 
|---|---|---|
| committer | Linus Torvalds <[email protected]> | 2015-04-17 09:04:38 -0400 | 
| commit | 54e514b91b95d6441c12a7955addfb9f9d2afc65 (patch) | |
| tree | 8b73d901bd2a6ec5a31f34a8954e5ea92216dd6c /lib/find_bit.c | |
| parent | 4fc8adcfec3da639da76e8314c9ccefe5bf9a045 (diff) | |
| parent | 6c8c90319c0bb1c9e0b68e721359b89ae4f28465 (diff) | |
Merge branch 'akpm' (patches from Andrew)
Merge third patchbomb from Andrew Morton:
 - various misc things
 - a couple of lib/ optimisations
 - provide DIV_ROUND_CLOSEST_ULL()
 - checkpatch updates
 - rtc tree
 - befs, nilfs2, hfs, hfsplus, fatfs, adfs, affs, bfs
 - ptrace fixes
 - fork() fixes
 - seccomp cleanups
 - more mmap_sem hold time reductions from Davidlohr
* emailed patches from Andrew Morton <[email protected]>: (138 commits)
  proc: show locks in /proc/pid/fdinfo/X
  docs: add missing and new /proc/PID/status file entries, fix typos
  drivers/rtc/rtc-at91rm9200.c: make IO endian agnostic
  Documentation/spi/spidev_test.c: fix warning
  drivers/rtc/rtc-s5m.c: allow usage on device type different than main MFD type
  .gitignore: ignore *.tar
  MAINTAINERS: add Mediatek SoC mailing list
  tomoyo: reduce mmap_sem hold for mm->exe_file
  powerpc/oprofile: reduce mmap_sem hold for exe_file
  oprofile: reduce mmap_sem hold for mm->exe_file
  mips: ip32: add platform data hooks to use DS1685 driver
  lib/Kconfig: fix up HAVE_ARCH_BITREVERSE help text
  x86: switch to using asm-generic for seccomp.h
  sparc: switch to using asm-generic for seccomp.h
  powerpc: switch to using asm-generic for seccomp.h
  parisc: switch to using asm-generic for seccomp.h
  mips: switch to using asm-generic for seccomp.h
  microblaze: use asm-generic for seccomp.h
  arm: use asm-generic for seccomp.h
  seccomp: allow COMPAT sigreturn overrides
  ...
Diffstat (limited to 'lib/find_bit.c')
| -rw-r--r-- | lib/find_bit.c | 193 | 
1 files changed, 193 insertions, 0 deletions
diff --git a/lib/find_bit.c b/lib/find_bit.c new file mode 100644 index 000000000000..18072ea9c20e --- /dev/null +++ b/lib/find_bit.c @@ -0,0 +1,193 @@ +/* bit search implementation + * + * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved. + * Written by David Howells ([email protected]) + * + * Copyright (C) 2008 IBM Corporation + * 'find_last_bit' is written by Rusty Russell <[email protected]> + * (Inspired by David Howell's find_next_bit implementation) + * + * Rewritten by Yury Norov <[email protected]> to decrease + * size and improve performance, 2015. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ + +#include <linux/bitops.h> +#include <linux/bitmap.h> +#include <linux/export.h> +#include <linux/kernel.h> + +#if !defined(find_next_bit) || !defined(find_next_zero_bit) + +/* + * This is a common helper function for find_next_bit and + * find_next_zero_bit.  The difference is the "invert" argument, which + * is XORed with each fetched word before searching it for one bits. + */ +static unsigned long _find_next_bit(const unsigned long *addr, +		unsigned long nbits, unsigned long start, unsigned long invert) +{ +	unsigned long tmp; + +	if (!nbits || start >= nbits) +		return nbits; + +	tmp = addr[start / BITS_PER_LONG] ^ invert; + +	/* Handle 1st word. */ +	tmp &= BITMAP_FIRST_WORD_MASK(start); +	start = round_down(start, BITS_PER_LONG); + +	while (!tmp) { +		start += BITS_PER_LONG; +		if (start >= nbits) +			return nbits; + +		tmp = addr[start / BITS_PER_LONG] ^ invert; +	} + +	return min(start + __ffs(tmp), nbits); +} +#endif + +#ifndef find_next_bit +/* + * Find the next set bit in a memory region. + */ +unsigned long find_next_bit(const unsigned long *addr, unsigned long size, +			    unsigned long offset) +{ +	return _find_next_bit(addr, size, offset, 0UL); +} +EXPORT_SYMBOL(find_next_bit); +#endif + +#ifndef find_next_zero_bit +unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size, +				 unsigned long offset) +{ +	return _find_next_bit(addr, size, offset, ~0UL); +} +EXPORT_SYMBOL(find_next_zero_bit); +#endif + +#ifndef find_first_bit +/* + * Find the first set bit in a memory region. + */ +unsigned long find_first_bit(const unsigned long *addr, unsigned long size) +{ +	unsigned long idx; + +	for (idx = 0; idx * BITS_PER_LONG < size; idx++) { +		if (addr[idx]) +			return min(idx * BITS_PER_LONG + __ffs(addr[idx]), size); +	} + +	return size; +} +EXPORT_SYMBOL(find_first_bit); +#endif + +#ifndef find_first_zero_bit +/* + * Find the first cleared bit in a memory region. + */ +unsigned long find_first_zero_bit(const unsigned long *addr, unsigned long size) +{ +	unsigned long idx; + +	for (idx = 0; idx * BITS_PER_LONG < size; idx++) { +		if (addr[idx] != ~0UL) +			return min(idx * BITS_PER_LONG + ffz(addr[idx]), size); +	} + +	return size; +} +EXPORT_SYMBOL(find_first_zero_bit); +#endif + +#ifndef find_last_bit +unsigned long find_last_bit(const unsigned long *addr, unsigned long size) +{ +	if (size) { +		unsigned long val = BITMAP_LAST_WORD_MASK(size); +		unsigned long idx = (size-1) / BITS_PER_LONG; + +		do { +			val &= addr[idx]; +			if (val) +				return idx * BITS_PER_LONG + __fls(val); + +			val = ~0ul; +		} while (idx--); +	} +	return size; +} +EXPORT_SYMBOL(find_last_bit); +#endif + +#ifdef __BIG_ENDIAN + +/* include/linux/byteorder does not support "unsigned long" type */ +static inline unsigned long ext2_swab(const unsigned long y) +{ +#if BITS_PER_LONG == 64 +	return (unsigned long) __swab64((u64) y); +#elif BITS_PER_LONG == 32 +	return (unsigned long) __swab32((u32) y); +#else +#error BITS_PER_LONG not defined +#endif +} + +#if !defined(find_next_bit_le) || !defined(find_next_zero_bit_le) +static unsigned long _find_next_bit_le(const unsigned long *addr, +		unsigned long nbits, unsigned long start, unsigned long invert) +{ +	unsigned long tmp; + +	if (!nbits || start >= nbits) +		return nbits; + +	tmp = addr[start / BITS_PER_LONG] ^ invert; + +	/* Handle 1st word. */ +	tmp &= ext2_swab(BITMAP_FIRST_WORD_MASK(start)); +	start = round_down(start, BITS_PER_LONG); + +	while (!tmp) { +		start += BITS_PER_LONG; +		if (start >= nbits) +			return nbits; + +		tmp = addr[start / BITS_PER_LONG] ^ invert; +	} + +	return min(start + __ffs(ext2_swab(tmp)), nbits); +} +#endif + +#ifndef find_next_zero_bit_le +unsigned long find_next_zero_bit_le(const void *addr, unsigned +		long size, unsigned long offset) +{ +	return _find_next_bit_le(addr, size, offset, ~0UL); +} +EXPORT_SYMBOL(find_next_zero_bit_le); +#endif + +#ifndef find_next_bit_le +unsigned long find_next_bit_le(const void *addr, unsigned +		long size, unsigned long offset) +{ +	return _find_next_bit_le(addr, size, offset, 0UL); +} +EXPORT_SYMBOL(find_next_bit_le); +#endif + +#endif /* __BIG_ENDIAN */  |