[PATCH 10/12] generic ext2_{set,clear,test,find_first_zero,find_next_zero}_bit()

Akinobu Mita
2006-01-26T03:38:06Z

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);

HAVE_ARCH_EXT2_NON_ATOMIC_BITOPS is defined when the architecture has
its own
version of these functions.

unsinged long ext2_find_next_zero_bit(const unsigned long *addr,
unsigned long size);

This code largely copied from:
include/asm-powerpc/bitops.h
include/asm-parisc/bitops.h

Index: 2.6-git/include/asm-generic/bitops.h
=================================--- 2.6-git.orig/include/asm-generic/bitops.h 2006-01-25 19:14:11.000000000 +0900
+++ 2.6-git/include/asm-generic/bitops.h 2006-01-25 19:14:11.000000000 +0900
@@ -5,6 +5,7 @@

#define BITOP_MASK(nr) (1UL << ((nr) % BITS_PER_LONG))
#define BITOP_WORD(nr) ((nr) / BITS_PER_LONG)
+#define BITOP_LE_SWIZZLE ((BITS_PER_LONG-1) & ~0x7)

#ifndef HAVE_ARCH_ATOMIC_BITOPS

@@ -510,6 +511,140 @@

#endif /* HAVE_ARCH_HWEIGHT64_BITOPS */

+#ifndef HAVE_ARCH_EXT2_NON_ATOMIC_BITOPS
+
+#include <asm/byteorder.h>
+
+#if defined(__LITTLE_ENDIAN)
+
+static __inline__ int generic_test_le_bit(unsigned long nr,
+ __const__ unsigned long *addr)
+{
+ __const__ unsigned char *tmp = (__const__ unsigned char *) addr;
+ return (tmp[nr >> 3] >> (nr & 7)) & 1;
+}
+
+#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)
+
+static __inline__ int generic_test_le_bit(unsigned long nr,
+ __const__ unsigned long *addr)
+{
+ __const__ unsigned char *tmp = (__const__ unsigned char *) addr;
+ return (tmp[nr >> 3] >> (nr & 7)) & 1;
+}
+
+#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))
+
+/* 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
+}
+
+static __inline__ 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));
+}
+#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)
+
+#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 /* HAVE_ARCH_EXT2_NON_ATOMIC_BITOPS */
+
#endif /* __KERNEL__ */

#endif /* _ASM_GENERIC_BITOPS_H */