Coverd Call

Take ABC as example:
I bought ABC at $20 as Mid-long term investment. It appears not a good buy. Now, after ER it's at $18. I have two choices.
1: I sell it at 10% loss.
2: I reduce the cost of buy and keep it.
Especially ABC already report ER and the worst is behind, ( at least short term) and surprisingly ABC next month $20 calls worth $1.70 still. So I choose 2, to reduce my cost.

Say I have 1000 shares of ABC, so I can sell 10 call contracts at 1.70/share.
That will reduce my cost to 20- 1.70 =18.30
The call will expire next month on the 22nd, 20 some days from now.
Next month on the 22nd, if ABC price higher than $20, my covered call be assigned, my ABC shares be sold at $20 each, and I will make 20+ 1.70 - 20 = 1.70 less commission . That is 8% gain. Not too bad in 20 days.
If ABC price is lower than $20 at OE day, my covered call expired worthless, and I can keep my ABC shares with the cost down to $18.30.