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lib: add weak clz/ctz functions

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Some architectures need __c[lt]z[sd]i2() for __builtin_c[lt]z[ll] and
that causes a build failure.  They can be implemented using the
fls()/__ffs() and overridden by linking arch-specific versions may not
be implemented yet.

This is required by "lib: add lz4 compressor module".

Reference: https://lkml.org/lkml/2013/4/18/603

Signed-off-by: Chanho Min <chanho.min@lge.com>
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: "Darrick J. Wong" <djwong@us.ibm.com>
Cc: Bob Pearson <rpearson@systemfabricworks.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Herbert Xu <herbert@gondor.hengli.com.au>
Cc: Yann Collet <yann.collet.73@gmail.com>
Cc: Kyungsik Lee <kyungsik.lee@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Chanho Min 2013-07-08 16:01:43 -07:00 committed by Linus Torvalds
parent 1b3a5d02ee
commit 4df87bb7b6
2 changed files with 59 additions and 1 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

2
lib/Makefile
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@ -23,7 +23,7 @@ lib-y += kobject.o klist.o
obj-y += bcd.o div64.o sort.o parser.o halfmd4.o debug_locks.o random32.o \
bust_spinlocks.o hexdump.o kasprintf.o bitmap.o scatterlist.o \
gcd.o lcm.o list_sort.o uuid.o flex_array.o iovec.o \
gcd.o lcm.o list_sort.o uuid.o flex_array.o iovec.o clz_ctz.o \
bsearch.o find_last_bit.o find_next_bit.o llist.o memweight.o kfifo.o
obj-y += string_helpers.o
obj-$(CONFIG_TEST_STRING_HELPERS) += test-string_helpers.o

58
lib/clz_ctz.c Normal file
View file

@ -0,0 +1,58 @@
/*
* lib/clz_ctz.c
*
* Copyright (C) 2013 Chanho Min <chanho.min@lge.com>
*
* 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.
*
* __c[lt]z[sd]i2 can be overridden by linking arch-specific versions.
*/
#include <linux/export.h>
#include <linux/kernel.h>
int __weak __ctzsi2(int val)
{
return __ffs(val);
}
EXPORT_SYMBOL(__ctzsi2);
int __weak __clzsi2(int val)
{
return 32 - fls(val);
}
EXPORT_SYMBOL(__clzsi2);
#if BITS_PER_LONG == 32
int __weak __clzdi2(long val)
{
return 32 - fls((int)val);
}
EXPORT_SYMBOL(__clzdi2);
int __weak __ctzdi2(long val)
{
return __ffs((u32)val);
}
EXPORT_SYMBOL(__ctzdi2);
#elif BITS_PER_LONG == 64
int __weak __clzdi2(long val)
{
return 64 - fls64((u64)val);
}
EXPORT_SYMBOL(__clzdi2);
int __weak __ctzdi2(long val)
{
return __ffs64((u64)val);
}
EXPORT_SYMBOL(__ctzdi2);
#else
#error BITS_PER_LONG not 32 or 64
#endif