the "speed" is determined by the loop iteration rate in your image…
And the direction is determined by the 90 degree phase shift.
By the way, XOR(x, TRUE) is exactly the same as NOT just more code
Are you trying to simulate a Stepper Motor driven by a pair of phase-shifted pulse trains? Generally, each pulse moves the stepper one "step" (defined by the motor), and the phase difference of the two pulse trains determines the direction of the movement. The frequency of the pulse train essentially gives the velocity of the movement, as it is in "steps/(pulse period)" = "steps * pulse frequency". To get Position, you need to define a known position (or have an encoder that reports the position) and simply count the steps (knowing whether you are moving in the positive or negative direction).
It sounds like you are trying to decode the signal from a Quadrature Encoder. I suggest you use that term as a search phrase in the forums (and possibly Google). There have been many posts on this topic.