while(__HAL_UART_GET_FLAG(&huart4,UART_FLAG_TC)!=SET);

This code snippet is incomplete and cannot be answered accurately without more context.

However, based on the partial code provided, it appears to be a part of a while loop that checks for a specific flag in the UART (Universal Asynchronous Receiver/Transmitter) status register.

The "__HAL_UART_GET_FLAG" function is a HAL (Hardware Abstraction Layer) library function that reads the status register of the UART and returns the value of the specified flag. The flag being checked is not specified in the given code snippet.

The while loop will continue to run as long as the specified flag is set in the UART status register. Once the flag is cleared, the loop will exit. The purpose of this loop could be to wait for a specific event or condition to occur before continuing with the program execution.