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authorSimon Kagstrom <simon.kagstrom@netinsight.net>2009-08-24 09:10:12 +0200
committerWolfgang Denk <wd@denx.de>2009-09-15 22:34:32 +0200
commit52d61227b66d4099b39c8309ab37cb67ee09a405 (patch)
tree0c5562920f48672d38baf05dd744118a4a8f2e69 /include/linux/bitops.h
parent4b15de08fe4d2c9d12a3764394731018a763216b (diff)
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Define ffs/fls for all architectures
UBIFS requires fls(), which is not defined for arm (and some other architectures) and this patch adds it. The implementation is taken from Linux and is generic. ffs() is also defined for those that miss it. Signed-off-by: Simon Kagstrom <simon.kagstrom@netinsight.net>
Diffstat (limited to 'include/linux/bitops.h')
-rw-r--r--include/linux/bitops.h45
1 files changed, 45 insertions, 0 deletions
diff --git a/include/linux/bitops.h b/include/linux/bitops.h
index 387a818..e14e6c7 100644
--- a/include/linux/bitops.h
+++ b/include/linux/bitops.h
@@ -38,6 +38,43 @@ static inline int generic_ffs(int x)
return r;
}
+/**
+ * fls - find last (most-significant) bit set
+ * @x: the word to search
+ *
+ * This is defined the same way as ffs.
+ * Note fls(0) = 0, fls(1) = 1, fls(0x80000000) = 32.
+ */
+static inline int generic_fls(int x)
+{
+ int r = 32;
+
+ if (!x)
+ return 0;
+ if (!(x & 0xffff0000u)) {
+ x <<= 16;
+ r -= 16;
+ }
+ if (!(x & 0xff000000u)) {
+ x <<= 8;
+ r -= 8;
+ }
+ if (!(x & 0xf0000000u)) {
+ x <<= 4;
+ r -= 4;
+ }
+ if (!(x & 0xc0000000u)) {
+ x <<= 2;
+ r -= 2;
+ }
+ if (!(x & 0x80000000u)) {
+ x <<= 1;
+ r -= 1;
+ }
+ return r;
+}
+
+
/*
* hweightN: returns the hamming weight (i.e. the number
* of bits set) of a N-bit word
@@ -82,6 +119,14 @@ static inline unsigned int generic_hweight8(unsigned int w)
# define __clear_bit generic_clear_bit
#endif
+#ifndef ffs
+# define ffs generic_ffs
+#endif
+
+#ifndef fls
+# define fls generic_fls
+#endif
+
/**
* __set_bit - Set a bit in memory
* @nr: the bit to set