15 6a e2 7e    add. r23,r2,r13
    spec       add. RT,RA,RB (OE=0 Rc=1)
    opcode     0x7c000215
    mask       0xfc0007ff
    RT         0b10111 [6, 7, 8, 9, 10]
    RA         0b00010 [11, 12, 13, 14, 15]
    RB         0b01101 [16, 17, 18, 19, 20]
    OE         0b0 [21]
    Rc         0b1 [31]