find.c
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/*
* MSB0 numbered special bitops handling.
*
* On s390x the bits are numbered:
* |0..............63|64............127|128...........191|192...........255|
* and on s390:
* |0.....31|31....63|64....95|96...127|128..159|160..191|192..223|224..255|
*
* The reason for this bit numbering is the fact that the hardware sets bits
* in a bitmap starting at bit 0 (MSB) and we don't want to scan the bitmap
* from the 'wrong end'.
*/
#include <linux/compiler.h>
#include <linux/bitops.h>
#include <linux/export.h>
unsigned long find_first_bit_inv(const unsigned long *addr, unsigned long size)
{
const unsigned long *p = addr;
unsigned long result = 0;
unsigned long tmp;
while (size & ~(BITS_PER_LONG - 1)) {
if ((tmp = *(p++)))
goto found;
result += BITS_PER_LONG;
size -= BITS_PER_LONG;
}
if (!size)
return result;
tmp = (*p) & (~0UL << (BITS_PER_LONG - size));
if (!tmp) /* Are any bits set? */
return result + size; /* Nope. */
found:
return result + (__fls(tmp) ^ (BITS_PER_LONG - 1));
}
EXPORT_SYMBOL(find_first_bit_inv);
unsigned long find_next_bit_inv(const unsigned long *addr, unsigned long size,
unsigned long offset)
{
const unsigned long *p = addr + (offset / BITS_PER_LONG);
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 >> 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;
found_first:
tmp &= (~0UL << (BITS_PER_LONG - size));
if (!tmp) /* Are any bits set? */
return result + size; /* Nope. */
found_middle:
return result + (__fls(tmp) ^ (BITS_PER_LONG - 1));
}
EXPORT_SYMBOL(find_next_bit_inv);