151 lines
3.3 KiB
C
151 lines
3.3 KiB
C
#include <linux/types.h>
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#include <linux/module.h>
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#include <asm/byteorder.h>
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#include <asm/bitops.h>
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/**
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* find_next_bit - find the next set bit in a memory region
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* @addr: The address to base the search on
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* @offset: The bitnumber to start searching at
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* @size: The maximum size to search
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*/
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unsigned long find_next_bit(const unsigned long *addr, unsigned long size,
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unsigned long offset)
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{
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const unsigned long *p = addr + BITOP_WORD(offset);
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unsigned long result = offset & ~(BITS_PER_LONG-1);
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unsigned long tmp;
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if (offset >= size)
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return size;
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size -= result;
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offset %= BITS_PER_LONG;
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if (offset) {
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tmp = *(p++);
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tmp &= (~0UL << offset);
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if (size < BITS_PER_LONG)
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goto found_first;
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if (tmp)
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goto found_middle;
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size -= BITS_PER_LONG;
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result += BITS_PER_LONG;
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}
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while (size & ~(BITS_PER_LONG-1)) {
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if ((tmp = *(p++)))
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goto found_middle;
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result += BITS_PER_LONG;
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size -= BITS_PER_LONG;
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}
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if (!size)
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return result;
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tmp = *p;
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found_first:
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tmp &= (~0UL >> (BITS_PER_LONG - size));
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if (tmp == 0UL) /* Are any bits set? */
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return result + size; /* Nope. */
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found_middle:
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return result + __ffs(tmp);
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}
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EXPORT_SYMBOL(find_next_bit);
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/*
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* This implementation of find_{first,next}_zero_bit was stolen from
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* Linus' asm-alpha/bitops.h.
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*/
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unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size,
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unsigned long offset)
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{
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const unsigned long *p = addr + BITOP_WORD(offset);
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unsigned long result = offset & ~(BITS_PER_LONG-1);
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unsigned long tmp;
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if (offset >= size)
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return size;
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size -= result;
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offset %= BITS_PER_LONG;
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if (offset) {
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tmp = *(p++);
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tmp |= ~0UL >> (BITS_PER_LONG - offset);
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if (size < BITS_PER_LONG)
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goto found_first;
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if (~tmp)
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goto found_middle;
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size -= BITS_PER_LONG;
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result += BITS_PER_LONG;
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}
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while (size & ~(BITS_PER_LONG-1)) {
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if (~(tmp = *(p++)))
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goto found_middle;
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result += BITS_PER_LONG;
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size -= BITS_PER_LONG;
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}
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if (!size)
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return result;
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tmp = *p;
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found_first:
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tmp |= ~0UL << size;
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if (tmp == ~0UL) /* Are any bits zero? */
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return result + size; /* Nope. */
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found_middle:
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return result + ffz(tmp);
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}
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EXPORT_SYMBOL(find_next_zero_bit);
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static inline unsigned int ext2_ilog2(unsigned int x)
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{
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int lz;
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asm("cntlzw %0,%1": "=r"(lz):"r"(x));
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return 31 - lz;
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}
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static inline unsigned int ext2_ffz(unsigned int x)
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{
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u32 rc;
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if ((x = ~x) == 0)
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return 32;
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rc = ext2_ilog2(x & -x);
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return rc;
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}
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unsigned long find_next_zero_le_bit(const unsigned long *addr,
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unsigned long size, unsigned long offset)
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{
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const unsigned int *p = ((const unsigned int *)addr) + (offset >> 5);
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unsigned int result = offset & ~31;
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unsigned int tmp;
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if (offset >= size)
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return size;
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size -= result;
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offset &= 31;
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if (offset) {
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tmp = cpu_to_le32p(p++);
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tmp |= ~0U >> (32 - offset); /* bug or feature ? */
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if (size < 32)
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goto found_first;
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if (tmp != ~0)
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goto found_middle;
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size -= 32;
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result += 32;
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}
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while (size >= 32) {
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if ((tmp = cpu_to_le32p(p++)) != ~0)
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goto found_middle;
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result += 32;
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size -= 32;
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}
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if (!size)
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return result;
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tmp = cpu_to_le32p(p);
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found_first:
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tmp |= ~0 << size;
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if (tmp == ~0) /* Are any bits zero? */
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return result + size; /* Nope. */
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found_middle:
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return result + ext2_ffz(tmp);
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}
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EXPORT_SYMBOL(find_next_zero_le_bit);
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