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    Subject[PATCH v4 2/3] lib: move find_last_bit to lib/find_next_bit.c
    Date
    Currently all 'find_*_bit' family is located in lib/find_next_bit.c,
    except 'find_last_bit', which is in lib/find_last_bit.c. It seems,
    there's no major benefit to have it separated.
    ---
    lib/Makefile | 2 +-
    lib/find_last_bit.c | 42 ------------------------------------------
    lib/find_next_bit.c | 27 ++++++++++++++++++++++++++-
    3 files changed, 27 insertions(+), 44 deletions(-)
    delete mode 100644 lib/find_last_bit.c

    diff --git a/lib/Makefile b/lib/Makefile
    index 87eb3bf..9dafcd5 100644
    --- a/lib/Makefile
    +++ b/lib/Makefile
    @@ -25,7 +25,7 @@ obj-y += lockref.o
    obj-y += bcd.o div64.o sort.o parser.o halfmd4.o debug_locks.o random32.o \
    bust_spinlocks.o kasprintf.o bitmap.o scatterlist.o \
    gcd.o lcm.o list_sort.o uuid.o flex_array.o clz_ctz.o \
    - bsearch.o find_last_bit.o find_next_bit.o llist.o memweight.o kfifo.o \
    + bsearch.o find_next_bit.o llist.o memweight.o kfifo.o \
    percpu-refcount.o percpu_ida.o rhashtable.o reciprocal_div.o
    obj-y += string_helpers.o
    obj-$(CONFIG_TEST_STRING_HELPERS) += test-string_helpers.o
    diff --git a/lib/find_last_bit.c b/lib/find_last_bit.c
    deleted file mode 100644
    index edbb281..0000000
    --- a/lib/find_last_bit.c
    +++ /dev/null
    @@ -1,42 +0,0 @@
    -/* find_last_bit.c: fallback find next bit implementation
    - *
    - * Copyright (C) 2008 IBM Corporation
    - * 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/export.h>
    -#include <linux/kernel.h>
    -
    -#define LOW_BITS_MASK(nr) (~0UL >> -(nr))
    -
    -#ifndef find_last_bit
    -
    -unsigned long find_last_bit(const unsigned long *addr, unsigned long size)
    -{
    - if (size) {
    - unsigned long val = LOW_BITS_MASK(size % BITS_PER_LONG);
    - 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
    diff --git a/lib/find_next_bit.c b/lib/find_next_bit.c
    index 1f5f108..627d0ec 100644
    --- a/lib/find_next_bit.c
    +++ b/lib/find_next_bit.c
    @@ -1,8 +1,12 @@
    -/* find_next_bit.c: fallback find next bit implementation
    +/* 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.
    *
    @@ -17,6 +21,7 @@
    #include <linux/kernel.h>

    #define HIGH_BITS_MASK(nr) (~0UL << (nr))
    +#define LOW_BITS_MASK(nr) (~0UL >> -(nr))

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

    @@ -108,6 +113,26 @@ unsigned long find_first_zero_bit(const unsigned long *addr, unsigned long 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 = LOW_BITS_MASK(size % BITS_PER_LONG);
    + 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 */
    --
    2.1.0


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