efi-demo-apps/EfiClock/UefiMain.c

#include <Uefi.h>
#include <Protocol/GraphicsOutput.h>
#include <Library/UefiLib.h>
#include <Library/TimerLib.h>
#include <Library/UefiBootServicesTableLib.h>
#include <Library/UefiRuntimeServicesTableLib.h>

EFI_GUID gop_guid = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID; 
EFI_GRAPHICS_OUTPUT_PROTOCOL *Gop = NULL;
UINT64 Gop_FrameBufferBase = 0;
UINT32 Gop_PixelsPerScanLine = 0;

static inline void drawPixel(UINT32 x, UINT32 y, UINT32 pixel)
{
  *((UINT32*)(Gop_FrameBufferBase + 4 * Gop_PixelsPerScanLine * y + 4 * x)) = pixel;
}

static inline void drawRectangle(UINT32 x, UINT32 y, UINT32 w, UINT32 h, UINT32 pixel)
{
  for(int ix = 0; ix < w; ++ix)
  {
    for(int iy = 0; iy < w; ++iy)
    {
      drawPixel(x+ix, y+iy, pixel);
    }
  }
}

EFI_STATUS EFIAPI UefiEntry(IN EFI_HANDLE imgHandle, IN EFI_SYSTEM_TABLE* sysTable)
{
  gST = sysTable;
  gBS = sysTable->BootServices;
  gImageHandle = imgHandle;

  gBS->SetWatchdogTimer(0, 0, 0, NULL);

  EFI_STATUS status = 0;

  /**
   * GOP Setup
   */

  status = gBS->LocateProtocol(&gop_guid, NULL, (VOID **)&Gop);
  if (EFI_ERROR(status)) {
    Print(u"\r\nERROR: %x; Cannot locate GOP protocol. Return.\r\n", status);
    return status;
  }

  Gop_FrameBufferBase   = Gop->Mode->FrameBufferBase;
  Gop_PixelsPerScanLine = Gop->Mode->Info->PixelsPerScanLine;
  UINT32 W = Gop->Mode->Info->HorizontalResolution;
  UINT32 H = Gop->Mode->Info->VerticalResolution;
  
  /**
   * Fills framebuffer
   */
   
  drawRectangle(0,0,W,H,0x000000);

  UINT32 sq_sid  = W * 50 / 1000;
  UINT32 sq_gap  = W * 17 / 1000;

  /**
   * Computes squares coordinates
   */

  UINT32 col0 = W/2 - 7*sq_gap/2 - 4*sq_sid;
  UINT32 col1 = W/2 - 5*sq_gap/2 - 3*sq_sid;
  UINT32 col2 = W/2 -   sq_gap/2 -   sq_sid;
  UINT32 col3 = W/2 +   sq_gap/2           ;
  UINT32 col4 = W/2 + 5*sq_gap/2 + 2*sq_sid;
  UINT32 col5 = W/2 + 7*sq_gap/2 + 3*sq_sid;

  UINT32 row0 = H/2 - 3*sq_sid/2 -   sq_gap;
  UINT32 row1 = H/2 -   sq_sid/2           ;
  UINT32 row2 = H/2 +   sq_sid/2 +   sq_gap;

  /**
   * Loops drawing the clockface
   */
   
  EFI_TIME Time;
  UINT16 second, minute, hour;
  const UINT32 accentColor = 0xFFAB3F, idleColor = 0x555555;
  
  while(1)
  {
    gRT->GetTime(&Time, NULL);      
    second = Time.Second;
    minute = Time.Minute;
    hour   = Time.Hour;
    
    second & 0b000001 ? drawRectangle(col5,row2,sq_sid,sq_sid,accentColor) : drawRectangle(col5,row2,sq_sid,sq_sid,idleColor);
    second & 0b000010 ? drawRectangle(col5,row1,sq_sid,sq_sid,accentColor) : drawRectangle(col5,row1,sq_sid,sq_sid,idleColor);
    second & 0b000100 ? drawRectangle(col5,row0,sq_sid,sq_sid,accentColor) : drawRectangle(col5,row0,sq_sid,sq_sid,idleColor);
    second & 0b001000 ? drawRectangle(col4,row2,sq_sid,sq_sid,accentColor) : drawRectangle(col4,row2,sq_sid,sq_sid,idleColor);
    second & 0b010000 ? drawRectangle(col4,row1,sq_sid,sq_sid,accentColor) : drawRectangle(col4,row1,sq_sid,sq_sid,idleColor);
    second & 0b100000 ? drawRectangle(col4,row0,sq_sid,sq_sid,accentColor) : drawRectangle(col4,row0,sq_sid,sq_sid,idleColor);

    minute & 0b000001 ? drawRectangle(col3,row2,sq_sid,sq_sid,accentColor) : drawRectangle(col3,row2,sq_sid,sq_sid,idleColor);
    minute & 0b000010 ? drawRectangle(col3,row1,sq_sid,sq_sid,accentColor) : drawRectangle(col3,row1,sq_sid,sq_sid,idleColor);
    minute & 0b000100 ? drawRectangle(col3,row0,sq_sid,sq_sid,accentColor) : drawRectangle(col3,row0,sq_sid,sq_sid,idleColor);
    minute & 0b001000 ? drawRectangle(col2,row2,sq_sid,sq_sid,accentColor) : drawRectangle(col2,row2,sq_sid,sq_sid,idleColor);
    minute & 0b010000 ? drawRectangle(col2,row1,sq_sid,sq_sid,accentColor) : drawRectangle(col2,row1,sq_sid,sq_sid,idleColor);
    minute & 0b100000 ? drawRectangle(col2,row0,sq_sid,sq_sid,accentColor) : drawRectangle(col2,row0,sq_sid,sq_sid,idleColor);

    hour   & 0b00001  ? drawRectangle(col1,row2,sq_sid,sq_sid,accentColor) : drawRectangle(col1,row2,sq_sid,sq_sid,idleColor);
    hour   & 0b00010  ? drawRectangle(col1,row1,sq_sid,sq_sid,accentColor) : drawRectangle(col1,row1,sq_sid,sq_sid,idleColor);
    hour   & 0b00100  ? drawRectangle(col1,row0,sq_sid,sq_sid,accentColor) : drawRectangle(col1,row0,sq_sid,sq_sid,idleColor);
    hour   & 0b01000  ? drawRectangle(col0,row2,sq_sid,sq_sid,accentColor) : drawRectangle(col0,row2,sq_sid,sq_sid,idleColor);
    hour   & 0b10000  ? drawRectangle(col0,row1,sq_sid,sq_sid,accentColor) : drawRectangle(col0,row1,sq_sid,sq_sid,idleColor);
    
    MicroSecondDelay(1e6);
  }
  
  return EFI_SUCCESS;   
}