## bts - bit test and set

    CF = bit(dest, source)  ; extract & set bit numbered by source from dest
    bit(dest,source) = 1

The btc instruction uses the source value as the bit number of the destination to test and set. The destination can be a 64, 32 or 16 bit register or memory location. The source can be either an immediate value or a register of the same size as the destination.

When testing and setting based on a memory address using a register as source operand, the register can hold a larger integer which defines a doubleword in memory to test and a bit within the doubleword. So you can access an array of bits.

Probably the most likely use of bts is simply to set a particular bit. It just happens that testing can be done in the same instruction and you can ignore the CF.

Some examples of using bts:

            bts     rax, 15         ; test and set bit 15 of rax
            bts     eax, 10         ; test and set bit 10 of eax
            bts     dx, cx          ; cx contains bit number of dx to test & set
            bts     [x], rdx        ; rdx contains bit number of x to test & set

### flags: CF