db85eaeb52
Fix some numbers in the comments describing the layout of the bit maps. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
77 lines
1.9 KiB
C
77 lines
1.9 KiB
C
/*
|
|
* MSB0 numbered special bitops handling.
|
|
*
|
|
* On s390x the bits are numbered:
|
|
* |0..............63|64............127|128...........191|192...........255|
|
|
* and on s390:
|
|
* |0.....31|32....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);
|