NAME
__BITMAP_CLR,
__BITMAP_ISSET,
__BITMAP_SET, __BITMAP_SIZE,
__BITMAP_TYPE, __BITMAP_ZERO
— bitmap manipulation
macros
LIBRARY
library “libc”
SYNOPSIS
#include
<sys/bitops.h>
__BITMAP_CLR(int
bit, type
*bitmap);
__BITMAP_ISSET(int
bit, type
*bitmap);
__BITMAP_SET(int
bit, type
*bitmap);
__BITMAP_SIZE(type,
int nbits);
__BITMAP_TYPE(name,
type,
int nbits);
__BITMAP_ZERO(type
*bitmap);
DESCRIPTION
The supplied macros are similar to the select(2)FD_SET()
family, to the setbit(9), macros and the
bitstring(3) library. They are different from
FD_SET() because they are designed to handle multiple
sized bitmaps at the same time, and they can be of any integral type. They are
different from setbit(9) because they can operate on different integral types,
not just on bytes. They are different from
bitstring(3) because they are just macros, they don't allocate memory
or use code, and they can be used in both kernel and userland.
The following macros are provided for manipulating creating and manipulating bitmaps:
__BITMAP_CLR(bit,
bitmap) removes the given bit
from the bitmap.
__BITMAP_ISSET(bit,
bitmap) is non-zero if bit is a
member of bitmap, zero otherwise.
__BITMAP_SET(bit,
bitmap) Sets the given bit in
the bitmap.
__BITMAP_SIZE(type,
nbits) Returns the number of elements would be
required of the given type to hold
nbits.
__BITMAP_TYPE(name,
type, nbits) Declares the
properly sized bitmap structure of the given type that
holds nbits and is named
name.
__BITMAP_ZERO(bitmap)
initializes a descriptor set pointed to by bitmap to
the null set.
The behavior of these macros is undefined for negative bit values or ones greater than the number of bits the bitmap can hold.
EXAMPLES
#include <sys/bitops.h>
int
main(int argc, char **argv)
{
__BITMAP_TYPE(, uint32_t, 5000) bitmap;
/* Initialize the read set to null */
__BITMAP_ZERO(&bitmap);
/* Set bit 1 */
__BITMAP_SET(1, &bitmap);
for (size_t i = 0; i < 5000; i++) {
if (__BITMAP_ISSET(i, &bitmap)) {
/* Should just print 1 */
printf("Bit %zu is set\n", i);
__BITMAP_CLR(i, &bitmap);
}
break;
}
return 0;
}
SEE ALSO
HISTORY
The __BITMAP_*() macros appeared in
NetBSD 7.0.