How does a G1000 equipped with a GDC 74 calculate IAS from dynamic pressure? How exactly does a G1000 system equipped with a GDC 74 air data computer calculate the indicated airspeed that is displayed on the PFD from difference between the total and static pressure (i.e. dynamic pressure) measured from the pitot-static system?

The reason I ask is because I want to reverse the calculation and convert KIAS back to dynamic pressure, i.e. $ q $ as defined below:

$$ q = \frac{\rho u^2}{2} $$

My objective is to calculate dynamic pressure from the KIAS value that is logged to the data logs written to the top SD card by the MFD. The problem is that there are multiple ways to perform this calculation -- i.e. does the G1000 display an indicated airspeed that is uncorrected for instrument and position error (IAS, in the traditional sense) or corrected for instrument and position error (CAS)?
I'm not sure if it is the same for all G1000 installations, but according to this Integrated Flight Deck Pilot's Guide the flight data logging feature records both IAS in knots and TAS in knots.

Do you have the Pilot's Guide for your aircraft? It would likely indicate the values saved in there as well.