Cutting Circles

I feel really stupid asking this question.  I want to use G2 to cut a 1" diameter circle with a .125" end mill, with the center at (x,y).  There are tutorials on cutting arcs, on cutting rounded corners on squares.  There are lots of gCode generators that seem to produce nothing.  Can anyone tell me how tto write either G2 or G3 starting at (x, y) with diameter d feed rate 5?  IIf I have one working example, I will write a prograjm to produce the gCode for whatever size I need.  I am sure most of you can do this in your sleep.  I fear the stroke in 2014 took away too much analytic skill.

This is an idea, without G41/G42, but it compensates tooldiameter from tooltable entry. Just enter the machining diameter near top.
Straight X move, then one round, and straight back to center.
You can do a helix also, just start at Z0, enter in the line with G2 also Z depth and amount P of turns (Z-2 P10)
Maybe G2 G3 can be changed for opposite direction.
It is not tested, so try careful dry run
Edit:
It is tested in my sim, and half circle lead in / lead out added for smooth transition to circle