Changes
CRTC
,/* VCC (C4) overflow */
=== VCC (C4) overflow ===
On all CRTCs, during the vertical display period (ie. when VCC <= R4), if Vertical Total (R4) is updated with a value less than VCC:
* if this update was done when VCC < R4, then VCC overflows and will continue to count up to its maximum value (127) before looping back
* if this update was done when VCC = R4, the decision was already made to switch to vertical adjust mode and no update to R4 will make the CRTC change its mind for the current frame
