As a humorous comment: Seems like using a DSP instead of a well-tried boost controller turns out as reinventing the square wheel?
Actually, digital SMPS controllers are possible and also used by major manufacturers, e. g. TI with upward tendency. Clearly the control loop gain must have the correct sign, I think it should reduce ton for Vout>Vset. As said, most analog PWM controllers are realizing a PI or PID charateristics. With integrator, properties as wind-up stop may be important, it is achieved in analog circuits by appropriate design of amplifier voltage ranges.