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diff --git a/Lesson_10/README.md b/Lesson_10/README.md deleted file mode 100644 index cca1dc5..0000000 --- a/Lesson_10/README.md +++ /dev/null @@ -1,156 +0,0 @@ - -It is common in UEFI code to use construct like this: -``` -if (!EFI_ERROR(Status) { - ... -} else { - ... -} -``` - -For the internal implementation of EFI_STATUS functionality look at the files: -MdePkg/Include/Uefi/UefiBaseType.h -MdePkg/Include/Base.h - -``` -#define EFI_ERROR(A) RETURN_ERROR(A) - -... - -/** - Returns TRUE if a specified RETURN_STATUS code is an error code. - - This function returns TRUE if StatusCode has the high bit set. Otherwise, FALSE is returned. - - @param StatusCode The status code value to evaluate. - - @retval TRUE The high bit of StatusCode is set. - @retval FALSE The high bit of StatusCode is clear. - -**/ -#define RETURN_ERROR(StatusCode) (((INTN)(RETURN_STATUS)(StatusCode)) < 0) - -... - -// -// Status codes common to all execution phases -// -typedef UINTN RETURN_STATUS; -``` - -So the `EFI_ERROR` macro simply test if a passed value is negative which is the same fact for a signed integer that is has high bit set. - -Enumration of possible EFI_STATUS values is in the file MdePkg/Include/Uefi/UefiBaseType.h -``` -/// -/// Enumeration of EFI_STATUS. -///@{ -#define EFI_SUCCESS RETURN_SUCCESS -#define EFI_LOAD_ERROR RETURN_LOAD_ERROR -#define EFI_INVALID_PARAMETER RETURN_INVALID_PARAMETER -#define EFI_UNSUPPORTED RETURN_UNSUPPORTED -#define EFI_BAD_BUFFER_SIZE RETURN_BAD_BUFFER_SIZE -#define EFI_BUFFER_TOO_SMALL RETURN_BUFFER_TOO_SMALL -#define EFI_NOT_READY RETURN_NOT_READY -#define EFI_DEVICE_ERROR RETURN_DEVICE_ERROR -#define EFI_WRITE_PROTECTED RETURN_WRITE_PROTECTED -#define EFI_OUT_OF_RESOURCES RETURN_OUT_OF_RESOURCES -#define EFI_VOLUME_CORRUPTED RETURN_VOLUME_CORRUPTED -#define EFI_VOLUME_FULL RETURN_VOLUME_FULL -#define EFI_NO_MEDIA RETURN_NO_MEDIA -#define EFI_MEDIA_CHANGED RETURN_MEDIA_CHANGED -#define EFI_NOT_FOUND RETURN_NOT_FOUND -#define EFI_ACCESS_DENIED RETURN_ACCESS_DENIED -#define EFI_NO_RESPONSE RETURN_NO_RESPONSE -#define EFI_NO_MAPPING RETURN_NO_MAPPING -#define EFI_TIMEOUT RETURN_TIMEOUT -#define EFI_NOT_STARTED RETURN_NOT_STARTED -#define EFI_ALREADY_STARTED RETURN_ALREADY_STARTED -#define EFI_ABORTED RETURN_ABORTED -#define EFI_ICMP_ERROR RETURN_ICMP_ERROR -#define EFI_TFTP_ERROR RETURN_TFTP_ERROR -#define EFI_PROTOCOL_ERROR RETURN_PROTOCOL_ERROR -#define EFI_INCOMPATIBLE_VERSION RETURN_INCOMPATIBLE_VERSION -#define EFI_SECURITY_VIOLATION RETURN_SECURITY_VIOLATION -#define EFI_CRC_ERROR RETURN_CRC_ERROR -#define EFI_END_OF_MEDIA RETURN_END_OF_MEDIA -#define EFI_END_OF_FILE RETURN_END_OF_FILE -#define EFI_INVALID_LANGUAGE RETURN_INVALID_LANGUAGE -#define EFI_COMPROMISED_DATA RETURN_COMPROMISED_DATA -#define EFI_HTTP_ERROR RETURN_HTTP_ERROR - -#define EFI_WARN_UNKNOWN_GLYPH RETURN_WARN_UNKNOWN_GLYPH -#define EFI_WARN_DELETE_FAILURE RETURN_WARN_DELETE_FAILURE -#define EFI_WARN_WRITE_FAILURE RETURN_WARN_WRITE_FAILURE -#define EFI_WARN_BUFFER_TOO_SMALL RETURN_WARN_BUFFER_TOO_SMALL -#define EFI_WARN_STALE_DATA RETURN_WARN_STALE_DATA -#define EFI_WARN_FILE_SYSTEM RETURN_WARN_FILE_SYSTEM -``` - -If you want to see how they encoded look at the MdePkg\Include\Base.h : -``` -/// -/// The operation completed successfully. -/// -#define RETURN_SUCCESS 0 - -/// -/// The image failed to load. -/// -#define RETURN_LOAD_ERROR ENCODE_ERROR (1) - -/// -/// The parameter was incorrect. -/// -#define RETURN_INVALID_PARAMETER ENCODE_ERROR (2) - -<...> - -/** - Produces a RETURN_STATUS code with the highest bit set. - - @param StatusCode The status code value to convert into a warning code. - StatusCode must be in the range 0x00000000..0x7FFFFFFF. - - @return The value specified by StatusCode with the highest bit set. - -**/ -#define ENCODE_ERROR(StatusCode) ((RETURN_STATUS)(MAX_BIT | (StatusCode))) - -/** - Produces a RETURN_STATUS code with the highest bit clear. - - @param StatusCode The status code value to convert into a warning code. - StatusCode must be in the range 0x00000000..0x7FFFFFFF. - - @return The value specified by StatusCode with the highest bit clear. - -**/ -#define ENCODE_WARNING(StatusCode) ((RETURN_STATUS)(StatusCode)) -``` - -Let's use `EFI_ERROR` macro in our code and test error printing with the help of `%r` Print formatting option. - -We could test error display with a passing `NULL` pointer instead of ImageHandle: -``` -Print(L"________\n"); -EFI_GUID **ProtocolGuidArray; -UINTN ArrayCount; -EFI_STATUS Status = gBS->ProtocolsPerHandle(NULL, - &ProtocolGuidArray, - &ArrayCount); - -if (!EFI_ERROR(Status)) { - for (int i=0; i<ArrayCount; i++) { - Print(L"%g\n", ProtocolGuidArray[i]); - } - FreePool(ProtocolGuidArray); -} else { - Print(L"ProtocolsPerHandle error: %r\n", Status); -} -``` - -This would give us this message in OVMF: -``` -ProtocolsPerHandle error: Invalid Parameter -``` |