def _not16(ins):
    ''' Negates top (Logical NOT) of the stack (16 bits in HL)
    '''
    output = _16bit_oper(ins.quad[2])
    output.append('ld a, h')
    output.append('or l')
    output.append('sub 1')
    output.append('sbc a, a')
    output.append('push af')
    return output
Negates top (Logical NOT) of the stack (16 bits in HL)