source: Documentation/Tutorials/XPS_Intro/code/UserIO_Demo_v2.c

#include "warp_v4_userio.h"
#include "xparameters.h"

int main(void)
{
    unsigned char ledDisp = 0;
    
    // Set the hex displays to number mode (see FPGA Board v2.2 User Guide)
    WarpV4_UserIO_NumberMode_All(XPAR_WARP_V4_USERIO_ALL_BASEADDR);

    while(1)
    {
        xil_printf("Displaying: %x\r\n", ledDisp);

        // Show the number on the three hex displays and on the LEDs
        WarpV4_UserIO_WriteNumber_LeftHex(XPAR_WARP_V4_USERIO_ALL_BASEADDR, ledDisp, 0);
        WarpV4_UserIO_WriteNumber_MiddleHex(XPAR_WARP_V4_USERIO_ALL_BASEADDR, ledDisp, 0);
        WarpV4_UserIO_WriteNumber_RightHex(XPAR_WARP_V4_USERIO_ALL_BASEADDR, ledDisp, 0);
        WarpV4_UserIO_Leds(XPAR_WARP_V4_USERIO_ALL_BASEADDR, ledDisp);

        usleep(600000);

        //Cycle the displays through [0x0,0xF]
        if(ledDisp == 15)
            ledDisp = 0;
        else
            ledDisp++;
    }
    
    return 0;

}