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Command: __BITMAP_ISSET | Section: 3 | Source: NetBSD | File: __BITMAP_ISSET.3
BITMAP(3) FreeBSD Library Functions Manual BITMAP(3)
NAME
__BITMAP_CLR, __BITMAP_ISSET, __BITMAP_SET, __BITMAP_SIZE, __BITMAP_TYPE,
__BITMAP_ZERO - bitmap manipulation macros
LIBRARY
Standard C Library (libc, -lc)
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
select(2), bitops(3), bitstring(3), setbit(9)
HISTORY
The __BITMAP_*() macros appeared in NetBSD 7.0.
FreeBSD 14.1-RELEASE-p8 March 8, 2018 FreeBSD 14.1-RELEASE-p8