cregit-Linux how code gets into the kernel

Release 4.18 tools/lib/find_bit.c

Directory: tools/lib
/* bit search implementation
 *
 * Copied from lib/find_bit.c to tools/lib/find_bit.c
 *
 * 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/kernel.h>

#if !defined(find_next_bit) || !defined(find_next_zero_bit) || \
		!defined(find_next_and_bit)

/*
 * This is a common helper function for find_next_bit, find_next_zero_bit, and
 * find_next_and_bit. The differences are:
 *  - The "invert" argument, which is XORed with each fetched word before
 *    searching it for one bits.
 *  - The optional "addr2", which is anded with "addr1" if present.
 */

static inline unsigned long _find_next_bit(const unsigned long *addr1, const unsigned long *addr2, unsigned long nbits, unsigned long start, unsigned long invert) { unsigned long tmp; if (unlikely(start >= nbits)) return nbits; tmp = addr1[start / BITS_PER_LONG]; if (addr2) tmp &= addr2[start / BITS_PER_LONG]; tmp ^= 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 = addr1[start / BITS_PER_LONG]; if (addr2) tmp &= addr2[start / BITS_PER_LONG]; tmp ^= invert; } return min(start + __ffs(tmp), nbits); }

Contributors

PersonTokensPropCommitsCommitProp
Arnaldo Carvalho de Melo10570.00%250.00%
Clement Courbet4228.00%125.00%
Matthew Wilcox32.00%125.00%
Total150100.00%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, NULL, size, offset, 0UL); }

Contributors

PersonTokensPropCommitsCommitProp
Arnaldo Carvalho de Melo3294.12%266.67%
Clement Courbet25.88%133.33%
Total34100.00%3100.00%

#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
Arnaldo Carvalho de Melo65100.00%2100.00%
Total65100.00%2100.00%

#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
Jiri Olsa68100.00%1100.00%
Total68100.00%1100.00%

#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, NULL, size, offset, ~0UL); }

Contributors

PersonTokensPropCommitsCommitProp
Jiri Olsa3394.29%150.00%
Clement Courbet25.71%150.00%
Total35100.00%2100.00%

#endif #ifndef find_next_and_bit
unsigned long find_next_and_bit(const unsigned long *addr1, const unsigned long *addr2, unsigned long size, unsigned long offset) { return _find_next_bit(addr1, addr2, size, offset, 0UL); }

Contributors

PersonTokensPropCommitsCommitProp
Clement Courbet40100.00%1100.00%
Total40100.00%1100.00%

#endif

Overall Contributors

PersonTokensPropCommitsCommitProp
Arnaldo Carvalho de Melo23351.43%240.00%
Jiri Olsa11224.72%120.00%
Clement Courbet10523.18%120.00%
Matthew Wilcox30.66%120.00%
Total453100.00%5100.00%
Directory: tools/lib
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