These take a pointer to a bit field. Bt: Bit Test Bts: Bit Test and Set to one Btr: Bit Test and Rst to zero Btc: Bit Test and Compliment (toggle) BEqu: Set bit to value. Bit operations are "atomic", no interrupt between the reading and writing the bit, important when multitasking. For multicore use "locked" forms. These don't take a pointer, but the actual field. Bsf: Bit Scan Fwd (Pos of first low one bit or -1) Bsr: Bit Scan Rev (Pos of first high one bit or -1) BCnt: Bit Cnt (Cnt of set bits)