[PATCH] bitops: generic ext2_{set,clear,test,find_first_zero,find_next_zero}_bit()
This patch introduces the C-language equivalents of the functions below:
int ext2_set_bit(int nr, volatile unsigned long *addr);
int ext2_clear_bit(int nr, volatile unsigned long *addr);
int ext2_test_bit(int nr, const volatile unsigned long *addr);
unsigned long ext2_find_first_zero_bit(const unsigned long *addr,
unsigned long size);
unsinged long ext2_find_next_zero_bit(const unsigned long *addr,
unsigned long size);
In include/asm-generic/bitops/ext2-non-atomic.h
This code largely copied from:
include/asm-powerpc/bitops.h
include/asm-parisc/bitops.h
Signed-off-by: Akinobu Mita <mita@miraclelinux.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/lib/find_next_bit.c b/lib/find_next_bit.c
index 9c90853..bda0d71 100644
--- a/lib/find_next_bit.c
+++ b/lib/find_next_bit.c
@@ -12,6 +12,7 @@
#include <linux/bitops.h>
#include <linux/module.h>
#include <asm/types.h>
+#include <asm/byteorder.h>
#define BITOP_WORD(nr) ((nr) / BITS_PER_LONG)
@@ -106,3 +107,75 @@
}
EXPORT_SYMBOL(find_next_zero_bit);
+
+#ifdef __BIG_ENDIAN
+
+/* include/linux/byteorder does not support "unsigned long" type */
+static inline unsigned long ext2_swabp(const unsigned long * x)
+{
+#if BITS_PER_LONG == 64
+ return (unsigned long) __swab64p((u64 *) x);
+#elif BITS_PER_LONG == 32
+ return (unsigned long) __swab32p((u32 *) x);
+#else
+#error BITS_PER_LONG not defined
+#endif
+}
+
+/* include/linux/byteorder doesn't support "unsigned long" type */
+static inline unsigned long ext2_swab(const unsigned long y)
+{
+#if BITS_PER_LONG == 64
+ return (unsigned long) __swab64((u64) y);
+#elif BITS_PER_LONG == 32
+ return (unsigned long) __swab32((u32) y);
+#else
+#error BITS_PER_LONG not defined
+#endif
+}
+
+unsigned long generic_find_next_zero_le_bit(const unsigned long *addr, unsigned
+ long size, unsigned long offset)
+{
+ const unsigned long *p = addr + BITOP_WORD(offset);
+ unsigned long result = offset & ~(BITS_PER_LONG - 1);
+ unsigned long tmp;
+
+ if (offset >= size)
+ return size;
+ size -= result;
+ offset &= (BITS_PER_LONG - 1UL);
+ if (offset) {
+ tmp = ext2_swabp(p++);
+ tmp |= (~0UL >> (BITS_PER_LONG - offset));
+ if (size < BITS_PER_LONG)
+ goto found_first;
+ if (~tmp)
+ goto found_middle;
+ size -= BITS_PER_LONG;
+ result += BITS_PER_LONG;
+ }
+
+ while (size & ~(BITS_PER_LONG - 1)) {
+ if (~(tmp = *(p++)))
+ goto found_middle_swap;
+ result += BITS_PER_LONG;
+ size -= BITS_PER_LONG;
+ }
+ if (!size)
+ return result;
+ tmp = ext2_swabp(p);
+found_first:
+ tmp |= ~0UL << size;
+ if (tmp == ~0UL) /* Are any bits zero? */
+ return result + size; /* Nope. Skip ffz */
+found_middle:
+ return result + ffz(tmp);
+
+found_middle_swap:
+ return result + ffz(ext2_swab(tmp));
+}
+
+EXPORT_SYMBOL(generic_find_next_zero_le_bit);
+
+#endif /* __BIG_ENDIAN */