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-rw-r--r--include/linux/bitops.h77
1 files changed, 77 insertions, 0 deletions
diff --git a/include/linux/bitops.h b/include/linux/bitops.h
index 40d54731de7e..3865f2c93bd8 100644
--- a/include/linux/bitops.h
+++ b/include/linux/bitops.h
@@ -112,4 +112,81 @@ static inline unsigned fls_long(unsigned long l)
return fls64(l);
}
+#ifdef __KERNEL__
+#ifdef CONFIG_GENERIC_FIND_NEXT_BIT
+extern unsigned long __find_next_bit(const unsigned long *addr,
+ unsigned long size, unsigned long offset);
+
+/**
+ * find_next_bit - find the next set bit in a memory region
+ * @addr: The address to base the search on
+ * @offset: The bitnumber to start searching at
+ * @size: The bitmap size in bits
+ */
+static __always_inline unsigned long
+find_next_bit(const unsigned long *addr, unsigned long size,
+ unsigned long offset)
+{
+ unsigned long value;
+
+ /* Avoid a function call if the bitmap size is a constant */
+ /* and not bigger than BITS_PER_LONG. */
+
+ /* insert a sentinel so that __ffs returns size if there */
+ /* are no set bits in the bitmap */
+ if (__builtin_constant_p(size) && (size < BITS_PER_LONG)) {
+ value = (*addr) & ((~0ul) << offset);
+ value |= (1ul << size);
+ return __ffs(value);
+ }
+
+ /* the result of __ffs(0) is undefined, so it needs to be */
+ /* handled separately */
+ if (__builtin_constant_p(size) && (size == BITS_PER_LONG)) {
+ value = (*addr) & ((~0ul) << offset);
+ return (value == 0) ? BITS_PER_LONG : __ffs(value);
+ }
+
+ /* size is not constant or too big */
+ return __find_next_bit(addr, size, offset);
+}
+
+extern unsigned long __find_next_zero_bit(const unsigned long *addr,
+ unsigned long size, unsigned long offset);
+
+/**
+ * find_next_zero_bit - find the next cleared bit in a memory region
+ * @addr: The address to base the search on
+ * @offset: The bitnumber to start searching at
+ * @size: The bitmap size in bits
+ */
+static __always_inline unsigned long
+find_next_zero_bit(const unsigned long *addr, unsigned long size,
+ unsigned long offset)
+{
+ unsigned long value;
+
+ /* Avoid a function call if the bitmap size is a constant */
+ /* and not bigger than BITS_PER_LONG. */
+
+ /* insert a sentinel so that __ffs returns size if there */
+ /* are no set bits in the bitmap */
+ if (__builtin_constant_p(size) && (size < BITS_PER_LONG)) {
+ value = (~(*addr)) & ((~0ul) << offset);
+ value |= (1ul << size);
+ return __ffs(value);
+ }
+
+ /* the result of __ffs(0) is undefined, so it needs to be */
+ /* handled separately */
+ if (__builtin_constant_p(size) && (size == BITS_PER_LONG)) {
+ value = (~(*addr)) & ((~0ul) << offset);
+ return (value == 0) ? BITS_PER_LONG : __ffs(value);
+ }
+
+ /* size is not constant or too big */
+ return __find_next_zero_bit(addr, size, offset);
+}
+#endif /* CONFIG_GENERIC_FIND_NEXT_BIT */
+#endif /* __KERNEL__ */
#endif