I was trying to understand the CV/CC charging of the Battery using a Buck converter. I came across this website, where it described the addition of sensor resistors to measure current and get the reading in voltage using op amp and send it as feedback.
https://www.ti.com/lit/an/snva829/snva829.pdf

I have a couple of questions regarding its implementation 
1. I have closed-loop DC to DC voltage regulator working, can I use voltage obtained from measuring current in the load as feedback and control the DC to DC converter ?
2. If I use current sensor feedback voltage, how does the buck converter will be controlled to keep constant current at the output with varying voltage in constant current mode?

I couldn't find good material explaining the control block diagram of the whole system, so didn't understand it. Could someone please help me with that?