linux 2.6.16.38 w/ vs2.0.3-rc1

[linux-2.6.git] / lib / find_next_bit.c

diff --git a/lib/find_next_bit.c b/lib/find_next_bit.c
index bda0d71..c05b4b1 100644 (file)
--- a/lib/find_next_bit.c
+++ b/lib/find_next_bit.c
@@ -11,171 +11,48 @@
 
 #include <linux/bitops.h>
 #include <linux/module.h>
-#include <asm/types.h>
-#include <asm/byteorder.h>
 
-#define BITOP_WORD(nr)         ((nr) / BITS_PER_LONG)
-
-/**
- * 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 maximum size to search
- */
-unsigned long find_next_bit(const unsigned long *addr, unsigned long size,
-               unsigned long offset)
+int find_next_bit(const unsigned long *addr, int size, int offset)
 {
-       const unsigned long *p = addr + BITOP_WORD(offset);
-       unsigned long result = offset & ~(BITS_PER_LONG-1);
+       const unsigned long *base;
+       const int NBITS = sizeof(*addr) * 8;
        unsigned long tmp;
 
-       if (offset >= size)
-               return size;
-       size -= result;
-       offset %= BITS_PER_LONG;
+       base = addr;
        if (offset) {
-               tmp = *(p++);
-               tmp &= (~0UL << 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;
-               result += BITS_PER_LONG;
-               size -= BITS_PER_LONG;
-       }
-       if (!size)
-               return result;
-       tmp = *p;
+               int suboffset;
 
-found_first:
-       tmp &= (~0UL >> (BITS_PER_LONG - size));
-       if (tmp == 0UL)         /* Are any bits set? */
-               return result + size;   /* Nope. */
-found_middle:
-       return result + __ffs(tmp);
-}
+               addr += offset / NBITS;
 
-EXPORT_SYMBOL(find_next_bit);
+               suboffset = offset % NBITS;
+               if (suboffset) {
+                       tmp = *addr;
+                       tmp >>= suboffset;
+                       if (tmp)
+                               goto finish;
+               }
 
-/*
- * This implementation of find_{first,next}_zero_bit was stolen from
- * Linus' asm-alpha/bitops.h.
- */
-unsigned long find_next_zero_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;
-       if (offset) {
-               tmp = *(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;
-               result += BITS_PER_LONG;
-               size -= BITS_PER_LONG;
+               addr++;
        }
-       if (!size)
-               return result;
-       tmp = *p;
-
-found_first:
-       tmp |= ~0UL << size;
-       if (tmp == ~0UL)        /* Are any bits zero? */
-               return result + size;   /* Nope. */
-found_middle:
-       return result + ffz(tmp);
-}
-
-EXPORT_SYMBOL(find_next_zero_bit);
 
-#ifdef __BIG_ENDIAN
+       while ((tmp = *addr) == 0)
+               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
-}
+       offset = (addr - base) * NBITS;
 
-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;
+ finish:
+       /* count the remaining bits without using __ffs() since that takes a 32-bit arg */
+       while (!(tmp & 0xff)) {
+               offset += 8;
+               tmp >>= 8;
        }
 
-       while (size & ~(BITS_PER_LONG - 1)) {
-               if (~(tmp = *(p++)))
-                       goto found_middle_swap;
-               result += BITS_PER_LONG;
-               size -= BITS_PER_LONG;
+       while (!(tmp & 1)) {
+               offset++;
+               tmp >>= 1;
        }
-       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));
+       return offset;
 }
 
-EXPORT_SYMBOL(generic_find_next_zero_le_bit);
-
-#endif /* __BIG_ENDIAN */
+EXPORT_SYMBOL(find_next_bit);