Step to UEFI (51) ----- EFI_Graphics_Output_Protocol获得基本信息

学习了一下如何获得 Shell 下当前的显示信息。通过 GraphicsOutputProtocol 来完成这个功能。这个 Protocol 在【参考1】 中有描述。

Capture

头定义在 \MdePkg\Include\Protocol\GraphicsOutput.h

typedef struct _EFI_GRAPHICS_OUTPUT_PROTOCOL EFI_GRAPHICS_OUTPUT_PROTOCOL;

///
/// Provides a basic abstraction to set video modes and copy pixels to and from 
/// the graphics controller's frame buffer. The linear address of the hardware 
/// frame buffer is also exposed so software can write directly to the video hardware.
///
struct _EFI_GRAPHICS_OUTPUT_PROTOCOL {
  EFI_GRAPHICS_OUTPUT_PROTOCOL_QUERY_MODE  QueryMode;
  EFI_GRAPHICS_OUTPUT_PROTOCOL_SET_MODE    SetMode;
  EFI_GRAPHICS_OUTPUT_PROTOCOL_BLT         Blt;
  ///
  /// Pointer to EFI_GRAPHICS_OUTPUT_PROTOCOL_MODE data.
  ///
  EFI_GRAPHICS_OUTPUT_PROTOCOL_MODE        *Mode;
};

 

从名称上来看,这个 Protocol 能够实现的功能是:查询/设置当前显示模式,将屏幕内容和内存互copy等。

这次实验的是查询功能。

查询的结果输出是 EFI_GRAPHICS_OUTPUT_PROTOCOL_MODE 结构体

typedef struct {
  ///
  /// The number of modes supported by QueryMode() and SetMode().
  ///
  UINT32                                 MaxMode;
  ///
  /// Current Mode of the graphics device. Valid mode numbers are 0 to MaxMode -1.
  ///
  UINT32                                 Mode;
  ///
  /// Pointer to read-only EFI_GRAPHICS_OUTPUT_MODE_INFORMATION data.
  ///
  EFI_GRAPHICS_OUTPUT_MODE_INFORMATION   *Info;
  ///
  /// Size of Info structure in bytes.
  ///
  UINTN                                  SizeOfInfo;
  ///
  /// Base address of graphics linear frame buffer.
  /// Offset zero in FrameBufferBase represents the upper left pixel of the display.
  ///
  EFI_PHYSICAL_ADDRESS                   FrameBufferBase;
  ///
  /// Amount of frame buffer needed to support the active mode as defined by 
  /// PixelsPerScanLine xVerticalResolution x PixelElementSize.
  ///
  UINTN                                  FrameBufferSize;
} EFI_GRAPHICS_OUTPUT_PROTOCOL_MODE;

 

可以看到能够获得当前显示模式,屏幕分辨率和格式信息等。根据上面的信息,编写程序如下

#include  <Uefi.h>
#include  <Library/UefiLib.h>
#include  <Library/ShellCEntryLib.h>

#include  <stdio.h>
#include  <stdlib.h>
#include  <wchar.h>
#include  <time.h>
#include <Protocol/EfiShell.h>
#include <Library/ShellLib.h>

#include <Protocol/SimpleFileSystem.h>
#include <Protocol/BlockIo.h>
#include <Library/DevicePathLib.h>
#include <Library/HandleParsingLib.h>
#include <Library/SortLib.h>
#include <Library/MemoryAllocationLib.h>
#include <Library/BaseMemoryLib.h>

#include <Protocol/LoadedImage.h>



extern EFI_BOOT_SERVICES         *gBS;
extern EFI_SYSTEM_TABLE			 *gST;
extern EFI_RUNTIME_SERVICES 	 *gRT;

extern EFI_SHELL_ENVIRONMENT2    *mEfiShellEnvironment2;
extern EFI_HANDLE				 gImageHandle;

static EFI_GUID GraphicsOutputProtocolGuid = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
static EFI_GRAPHICS_OUTPUT_PROTOCOL *GraphicsOutput = NULL;

int
EFIAPI
main (                                         
  IN int Argc,
  IN char **Argv
  )
{
    EFI_STATUS Status;

    Status = gBS->LocateProtocol(&GraphicsOutputProtocolGuid, NULL, (VOID **) &GraphicsOutput);
    if (EFI_ERROR(Status)) {
        GraphicsOutput = NULL;
		Print(L"Loading Graphics_Output_Protocol error!\n");
		return EFI_SUCCESS;
	}	

	Print(L"Max mode     =[%d] \n",GraphicsOutput->Mode->MaxMode);
	Print(L"Current mode =[%d] \n",GraphicsOutput->Mode->Mode);
	Print(L"Version      =[%d] \n",GraphicsOutput->Mode->Info->Version);
	Print(L"Screen Width =[%d] \n",GraphicsOutput->Mode->Info->HorizontalResolution);
	Print(L"Screen height=[%d] \n",GraphicsOutput->Mode->Info->VerticalResolution);
	Print(L"Format       =[%d] \n",GraphicsOutput->Mode->Info->PixelFormat);
	Print(L"Num of pixel =[%d] \n",GraphicsOutput->Mode->Info->PixelsPerScanLine);
		
  return EFI_SUCCESS;
  
}

 

运行结果(还是NT32模拟器中)

gopinfo

完整代码下载:

GFXTest

参考:

1.UEFI Spec 2.4 P488 11.9 Graphics Output Protocol

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