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authorAlexander van Heukelum <heukelum@mailshack.com>2008-04-01 11:46:19 +0200
committerIngo Molnar <mingo@elte.hu>2008-04-26 19:21:16 +0200
commit77b9bd9c49442407804c37bcc82021a35277f83c (patch)
tree251900d95c6c9c5371542d5dda7d89cb31cd0801 /lib/find_next_bit.c
parentd57594c203b1e7b54373080a797f0cbfa4aade68 (diff)
downloadlinux-2.6.38-lt-ux500-77b9bd9c49442407804c37bcc82021a35277f83c.tar.gz
x86: generic versions of find_first_(zero_)bit, convert i386
Generic versions of __find_first_bit and __find_first_zero_bit are introduced as simplified versions of __find_next_bit and __find_next_zero_bit. Their compilation and use are guarded by a new config variable GENERIC_FIND_FIRST_BIT. The generic versions of find_first_bit and find_first_zero_bit are implemented in terms of the newly introduced __find_first_bit and __find_first_zero_bit. This patch does not remove the i386-specific implementation, but it does switch i386 to use the generic functions by setting GENERIC_FIND_FIRST_BIT=y for X86_32. Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'lib/find_next_bit.c')
-rw-r--r--lib/find_next_bit.c58
1 files changed, 58 insertions, 0 deletions
diff --git a/lib/find_next_bit.c b/lib/find_next_bit.c
index ce94c4c92d1..d3f5784807b 100644
--- a/lib/find_next_bit.c
+++ b/lib/find_next_bit.c
@@ -16,6 +16,7 @@
#define BITOP_WORD(nr) ((nr) / BITS_PER_LONG)
+#ifdef CONFIG_GENERIC_FIND_NEXT_BIT
/*
* Find the next set bit in a memory region.
*/
@@ -102,6 +103,63 @@ found_middle:
return result + ffz(tmp);
}
EXPORT_SYMBOL(__find_next_zero_bit);
+#endif /* CONFIG_GENERIC_FIND_NEXT_BIT */
+
+#ifdef CONFIG_GENERIC_FIND_FIRST_BIT
+/*
+ * Find the first set bit in a memory region.
+ */
+unsigned long __find_first_bit(const unsigned long *addr,
+ unsigned long size)
+{
+ const unsigned long *p = addr;
+ unsigned long result = 0;
+ unsigned long tmp;
+
+ while (size & ~(BITS_PER_LONG-1)) {
+ if ((tmp = *(p++)))
+ goto found;
+ result += BITS_PER_LONG;
+ size -= BITS_PER_LONG;
+ }
+ if (!size)
+ return result;
+
+ tmp = (*p) & (~0UL >> (BITS_PER_LONG - size));
+ if (tmp == 0UL) /* Are any bits set? */
+ return result + size; /* Nope. */
+found:
+ return result + __ffs(tmp);
+}
+EXPORT_SYMBOL(__find_first_bit);
+
+/*
+ * Find the first cleared bit in a memory region.
+ */
+unsigned long __find_first_zero_bit(const unsigned long *addr,
+ unsigned long size)
+{
+ const unsigned long *p = addr;
+ unsigned long result = 0;
+ unsigned long tmp;
+
+ while (size & ~(BITS_PER_LONG-1)) {
+ if (~(tmp = *(p++)))
+ goto found;
+ result += BITS_PER_LONG;
+ size -= BITS_PER_LONG;
+ }
+ if (!size)
+ return result;
+
+ tmp = (*p) | (~0UL << size);
+ if (tmp == ~0UL) /* Are any bits zero? */
+ return result + size; /* Nope. */
+found:
+ return result + ffz(tmp);
+}
+EXPORT_SYMBOL(__find_first_zero_bit);
+#endif /* CONFIG_GENERIC_FIND_FIRST_BIT */
#ifdef __BIG_ENDIAN