This patch adds __find_next_bit() -- static-inline variant of find_next_bit()
optimized for small constant size arrays, because find_next_bit() is too heavy
for searching in an array with one/two long elements.
And unlike to find_next_bit() it does not mask tail bits.
Signed-off-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxx>
---
include/asm-generic/bitops/find.h | 36 ++++++++++++++++++++++++++++++++++++
1 files changed, 36 insertions(+), 0 deletions(-)
diff --git a/include/asm-generic/bitops/find.h b/include/asm-generic/bitops/find.h
index 71c7780..1dd2495 100644
--- a/include/asm-generic/bitops/find.h
+++ b/include/asm-generic/bitops/find.h
@@ -12,6 +12,42 @@ extern unsigned long find_next_bit(const unsigned long *addr, unsigned long
size, unsigned long offset);
#endif
+#ifndef __find_next_bit
+/**
+ * __find_next_bit - find the next set bit in a memory region
+ * @addr: The address to base the search on
+ * @size: The bitmap size in bits
+ * @offset: The bitnumber to start searching at
+ *
+ * Unrollable variant of find_next_bit() for constant size arrays.
+ * Tail bits starting from size to roundup(size, BITS_PER_LONG) must be zero.
+ * Returns next bit offset, or size if nothing found.
+ */
+static inline unsigned long __find_next_bit(const unsigned long *addr,
+ unsigned long size, unsigned long offset)
+{
+ if (!__builtin_constant_p(size))
+ return find_next_bit(addr, size, offset);
+
+ if (offset < size) {
+ unsigned long tmp;
+
+ addr += offset / BITS_PER_LONG;
+ tmp = *addr >> (offset % BITS_PER_LONG);
+ if (tmp)
+ return __ffs(tmp) + offset;
+ offset = (offset + BITS_PER_LONG) & ~(BITS_PER_LONG - 1);
+ while (offset < size) {
+ tmp = *++addr;
+ if (tmp)
+ return __ffs(tmp) + offset;
+ offset += BITS_PER_LONG;
+ }
+ }
+ return size;
+}
+#endif
+
#ifndef find_next_zero_bit
/**
* find_next_zero_bit - find the next cleared bit in a memory region
--
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