_kbhit() equivalent (peek UART buffer before getchar() or scanf()) on Xilinx Zynq Baremetal.

example.c

// return true if there is character in uart recv buffer, false otherwise.
int peek(){
	#include <xuartps_hw.h>
	#include <xparameters.h>
	return XUartPs_IsReceiveData(XPAR_PS7_UART_0_BASEADDR);
}

// it is recommended to use inbyte() to read a byte after peek() returned true.