cregit-Linux how code gets into the kernel

Release 4.13 lib/find_bit.c

Directory: lib
/* bit search implementation
 *
 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * Copyright (C) 2008 IBM Corporation
 * 'find_last_bit' is written by Rusty Russell <rusty@rustcorp.com.au>
 * (Inspired by David Howell's find_next_bit implementation)
 *
 * Rewritten by Yury Norov <yury.norov@gmail.com> 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 (unlikely(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); }

Contributors

PersonTokensPropCommitsCommitProp
Yury Norov5447.79%125.00%
Akinobu Mita2925.66%125.00%
David Howells2723.89%125.00%
Matthew Wilcox32.65%125.00%
Total113100.00%4100.00%

#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); }

Contributors

PersonTokensPropCommitsCommitProp
Yury Norov3093.75%150.00%
Akinobu Mita26.25%150.00%
Total32100.00%2100.00%

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); }

Contributors

PersonTokensPropCommitsCommitProp
Akinobu Mita1854.55%133.33%
Yury Norov1442.42%133.33%
Thomas Gleixner13.03%133.33%
Total33100.00%3100.00%

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; }

Contributors

PersonTokensPropCommitsCommitProp
Yury Norov3858.46%133.33%
Akinobu Mita2335.38%133.33%
David Howells46.15%133.33%
Total65100.00%3100.00%

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; }

Contributors

PersonTokensPropCommitsCommitProp
Yury Norov3551.47%150.00%
Alexander van Heukelum3348.53%150.00%
Total68100.00%2100.00%

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; }

Contributors

PersonTokensPropCommitsCommitProp
Yury Norov81100.00%1100.00%
Total81100.00%1100.00%

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 }

Contributors

PersonTokensPropCommitsCommitProp
Akinobu Mita2951.79%133.33%
Yury Norov1628.57%133.33%
Alexander van Heukelum1119.64%133.33%
Total56100.00%3100.00%

#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 (unlikely(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); }

Contributors

PersonTokensPropCommitsCommitProp
Yury Norov6050.42%133.33%
Akinobu Mita5647.06%133.33%
Matthew Wilcox32.52%133.33%
Total119100.00%3100.00%

#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); }

Contributors

PersonTokensPropCommitsCommitProp
Yury Norov3093.75%150.00%
Akinobu Mita26.25%150.00%
Total32100.00%2100.00%

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); }

Contributors

PersonTokensPropCommitsCommitProp
Aneesh Kumar K.V2374.19%125.00%
Yury Norov516.13%125.00%
Akinobu Mita39.68%250.00%
Total31100.00%4100.00%

EXPORT_SYMBOL(find_next_bit_le); #endif #endif /* __BIG_ENDIAN */

Overall Contributors

PersonTokensPropCommitsCommitProp
Yury Norov42856.76%214.29%
Akinobu Mita20026.53%535.71%
Alexander van Heukelum506.63%17.14%
David Howells405.31%214.29%
Aneesh Kumar K.V273.58%17.14%
Matthew Wilcox60.80%17.14%
Thomas Gleixner20.27%17.14%
Paul Gortmaker10.13%17.14%
Total754100.00%14100.00%
Directory: lib
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