#include <atk_libc.h>
EFI_STATUS
InitializeHelloLibCApplication (
    IN EFI_HANDLE           ImageHandle,
    IN EFI_SYSTEM_TABLE     *SystemTable
    )
{
       InitializeLib(ImageHandle, SystemTable);
       printf("Hello LibC application started\n\n\n");
       printf("Hit C/R to exit this image\n");
       return( getchar() );
}  

Example 3: Using C without any firmware-specific calls.