89 lines
1.8 KiB
C
89 lines
1.8 KiB
C
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#include <linux/compiler.h>
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#include <linux/types.h>
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#include <asm/intrinsics.h>
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#include <linux/module.h>
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#include <linux/bitops.h>
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/*
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* Find next zero bit in a bitmap reasonably efficiently..
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*/
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int __find_next_zero_bit (const void *addr, unsigned long size, unsigned long offset)
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{
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unsigned long *p = ((unsigned long *) addr) + (offset >> 6);
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unsigned long result = offset & ~63UL;
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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 &= 63UL;
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if (offset) {
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tmp = *(p++);
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tmp |= ~0UL >> (64-offset);
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if (size < 64)
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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 -= 64;
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result += 64;
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}
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while (size & ~63UL) {
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if (~(tmp = *(p++)))
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goto found_middle;
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result += 64;
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size -= 64;
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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) /* 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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/*
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* Find next bit in a bitmap reasonably efficiently..
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*/
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int __find_next_bit(const void *addr, unsigned long size, unsigned long offset)
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{
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unsigned long *p = ((unsigned long *) addr) + (offset >> 6);
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unsigned long result = offset & ~63UL;
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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 &= 63UL;
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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 < 64)
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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 -= 64;
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result += 64;
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}
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while (size & ~63UL) {
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if ((tmp = *(p++)))
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goto found_middle;
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result += 64;
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size -= 64;
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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 >> (64-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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