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DESCRIPTION

The BITSET_DEFINE() macro defines a bitset struct STRUCTNAME with room to represent SETSIZE bits.

The BITSET_T_INITIALIZER() macro allows one to initialize a bitset struct with a compile time literal value.

The BITSET_FSET() macro generates a compile time literal, usable by BITSET_T_INITIALIZER(), representing a full bitset (all bits set). For examples of BITSET_T_INITIALIZER() and BITSET_FSET() usage, see the BITSET_T_INITIALIZER EXAMPLE section. The N_WORDS parameter to BITSET_FSET() should be:

__bitset_words(SETSIZE)

The BIT_CLR() macro clears bit bit in the bitset pointed to by bitset. The BIT_CLR_ATOMIC() macro is identical, but the bit is cleared atomically.

The BIT_COPY() macro copies the contents of the bitset from to the bitset to. BIT_COPY_STORE_REL() is similar, but copies component machine words from from and writes them to to with atomic store with release semantics. (That is, if to is composed of multiple machine words, BIT_COPY_STORE_REL() performs multiple individually atomic operations.)

The BIT_SET() macro sets bit bit in the bitset pointed to by bitset. The BIT_SET_ATOMIC() macro is identical, but the bit is set atomically. The BIT_SET_ATOMIC_ACQ() macro sets the bit with acquire semantics.

The BIT_ZERO() macro clears all bits in bitset.

The BIT_FILL() macro sets all bits in bitset.

The BIT_SETOF() macro clears all bits in bitset before setting only bit bit.

The BIT_EMPTY() macro returns true if bitset is empty.

The BIT_ISFULLSET() macro returns true if bitset is full (all bits set).

The BIT_FFS() macro returns the 1-index of the first (lowest) set bit in bitset, or zero if bitset is empty. Like with ffs(3), to use the non-zero result of BIT_FFS() as a bit index parameter to any other bitset(9) macro, you must subtract one from the result.

The BIT_FLS() macro returns the 1-index of the last (highest) set bit in bitset, or zero if bitset is empty. Like with fls(3), to use the non-zero result of BIT_FLS() as a bit index parameter to any other bitset(9) macro, you must subtract one from the result.

The BIT_COUNT() macro returns the total number of set bits in bitset.

The BIT_SUBSET() macro returns true if needle is a subset of haystack.

The BIT_OVERLAP() macro returns true if bitset1 and bitset2 have any common bits. (That is, if bitset1 AND bitset2 is not the empty set.)

The BIT_CMP() macro returns true if bitset1 is NOT equal to bitset2.

The BIT_OR() macro sets bits present in src in dst. (It is the bitset(9) equivalent of the scalar: dst |= src.) BIT_OR_ATOMIC() is similar, but sets bits in the component machine words in dst atomically. (That is, if dst is composed of multiple machine words, BIT_OR_ATOMIC() performs multiple individually atomic operations.)

The BIT_OR2() macro computes src1 bitwise or src2 and assigns the result to dst. (It is the bitset(9) equivalent of the scalar: dst = src1 | src2.)

The BIT_AND() macro clears bits absent from src from dst. (It is the bitset(9) equivalent of the scalar: dst &= src.) BIT_AND_ATOMIC() is similar, with the same atomic semantics as BIT_OR_ATOMIC().

The BIT_AND2() macro computes src1 bitwise and src2 and assigns the result to dst. (It is the bitset(9) equivalent of the scalar: dst = src1 & src2.)

The BIT_NAND() macro clears bits set in src from dst. (It is the bitset(9) equivalent of the scalar: dst &= ~ src.)

The BIT_NAND2() macro computes src1 bitwise and not src2 and assigns the result to dst. (It is the bitset(9) equivalent of the scalar: dst = src1 & ~ src2.)

The BIT_XOR() macro toggles bits set in src in dst. (It is the bitset(9) equivalent of the scalar: dst ^= src.)

The BIT_XOR2() macro computes src1 bitwise exclusive or src2 and assigns the result to dst. (It is the bitset(9) equivalent of the scalar: dst = src1 ^ src2.)

BITSET_DEFINE(_myset, MYSETSIZE);

struct _myset myset;

/* Initialize myset to filled (all bits set) */
myset = BITSET_T_INITIALIZER(BITSET_FSET(__bitset_words(MYSETSIZE)));

/* Initialize myset to only the lowest bit set */
myset = BITSET_T_INITIALIZER(0x1);