[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/include/asm-generic/bitops/ext2-non-atomic.h b/include/asm-generic/bitops/ext2-non-atomic.h
new file mode 100644 (file)
index 0000000..1697404
--- /dev/null
+++ b/include/asm-generic/bitops/ext2-non-atomic.h
@@ -0,0 +1,18 @@
+#ifndef _ASM_GENERIC_BITOPS_EXT2_NON_ATOMIC_H_
+#define _ASM_GENERIC_BITOPS_EXT2_NON_ATOMIC_H_
+
+#include <asm-generic/bitops/le.h>
+
+#define ext2_set_bit(nr,addr)  \
+       generic___test_and_set_le_bit((nr),(unsigned long *)(addr))
+#define ext2_clear_bit(nr,addr)        \
+       generic___test_and_clear_le_bit((nr),(unsigned long *)(addr))
+
+#define ext2_test_bit(nr,addr) \
+       generic_test_le_bit((nr),(unsigned long *)(addr))
+#define ext2_find_first_zero_bit(addr, size) \
+       generic_find_first_zero_le_bit((unsigned long *)(addr), (size))
+#define ext2_find_next_zero_bit(addr, size, off) \
+       generic_find_next_zero_le_bit((unsigned long *)(addr), (size), (off))
+
+#endif /* _ASM_GENERIC_BITOPS_EXT2_NON_ATOMIC_H_ */

diff --git a/include/asm-generic/bitops/le.h b/include/asm-generic/bitops/le.h
new file mode 100644 (file)
index 0000000..b9c7e5d
--- /dev/null
+++ b/include/asm-generic/bitops/le.h
@@ -0,0 +1,53 @@
+#ifndef _ASM_GENERIC_BITOPS_LE_H_
+#define _ASM_GENERIC_BITOPS_LE_H_
+
+#include <asm/types.h>
+#include <asm/byteorder.h>
+
+#define BITOP_WORD(nr)         ((nr) / BITS_PER_LONG)
+#define BITOP_LE_SWIZZLE       ((BITS_PER_LONG-1) & ~0x7)
+
+#if defined(__LITTLE_ENDIAN)
+
+#define generic_test_le_bit(nr, addr) test_bit(nr, addr)
+#define generic___set_le_bit(nr, addr) __set_bit(nr, addr)
+#define generic___clear_le_bit(nr, addr) __clear_bit(nr, addr)
+
+#define generic_test_and_set_le_bit(nr, addr) test_and_set_bit(nr, addr)
+#define generic_test_and_clear_le_bit(nr, addr) test_and_clear_bit(nr, addr)
+
+#define generic___test_and_set_le_bit(nr, addr) __test_and_set_bit(nr, addr)
+#define generic___test_and_clear_le_bit(nr, addr) __test_and_clear_bit(nr, addr)
+
+#define generic_find_next_zero_le_bit(addr, size, offset) find_next_zero_bit(addr, size, offset)
+
+#elif defined(__BIG_ENDIAN)
+
+#define generic_test_le_bit(nr, addr) \
+       test_bit((nr) ^ BITOP_LE_SWIZZLE, (addr))
+#define generic___set_le_bit(nr, addr) \
+       __set_bit((nr) ^ BITOP_LE_SWIZZLE, (addr))
+#define generic___clear_le_bit(nr, addr) \
+       __clear_bit((nr) ^ BITOP_LE_SWIZZLE, (addr))
+
+#define generic_test_and_set_le_bit(nr, addr) \
+       test_and_set_bit((nr) ^ BITOP_LE_SWIZZLE, (addr))
+#define generic_test_and_clear_le_bit(nr, addr) \
+       test_and_clear_bit((nr) ^ BITOP_LE_SWIZZLE, (addr))
+
+#define generic___test_and_set_le_bit(nr, addr) \
+       __test_and_set_bit((nr) ^ BITOP_LE_SWIZZLE, (addr))
+#define generic___test_and_clear_le_bit(nr, addr) \
+       __test_and_clear_bit((nr) ^ BITOP_LE_SWIZZLE, (addr))
+
+extern unsigned long generic_find_next_zero_le_bit(const unsigned long *addr,
+               unsigned long size, unsigned long offset);
+
+#else
+#error "Please fix <asm/byteorder.h>"
+#endif
+
+#define generic_find_first_zero_le_bit(addr, size) \
+        generic_find_next_zero_le_bit((addr), (size), 0)
+
+#endif /* _ASM_GENERIC_BITOPS_LE_H_ */

diff --git a/lib/find_next_bit.c b/lib/find_next_bit.c
index 9c90853..bda0d71 100644 (file)
--- 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 @@ found_middle:
 }
 
 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 */