Intel Extensible Firmware Interface, Specification

Page: 182 / 494

Extensible Firmware Interface Specification
164 12/12/00 Version 1.02
7.5.3 SIMPLE_TEXT_OUTPUT.TestString()
Summary
Verifies that all characters in a Unicode string can be output to the target device.
Prototype
EFI_STATUS
(EFIAPI *EFI_TEXT_TEST_STRING) (
IN SIMPLE_TEXT_OUTPUT_INTERFACE *This,
IN CHAR16 *String
);
Parameters
This
A pointer to the
SIMPLE_TEXT_OUTPUT_INTERFACE
instance.
Type
SIMPLE_TEXT_OUTPUT_INTERFACE
is defined in Section 7.5.
String
The Null-terminated Unicode string to be examined for the output
device(s).
Description
The
TestString()
function verifies that all characters in a Unicode string can be output to the
target device.
This function provides a way to know if the desired character set is present for rendering on the
output device(s). This allows the installation procedure (or EFI image) to at least select a letter set
that the output devices are capable of displaying. Since the output device(s) may be changed
between boots, if the loader cannot adapt to such changes it is recommended that the loader call
OutputString()
with the text it has and ignore any “unsupported” error codes. The devices(s)
that are capable of displaying the Unicode letter set will do so.
Status Codes Returned
EFI_SUCCESS The device(s) are capable of rendering the output string.
EFI_UNSUPPORTED Some of the characters in the Unicode string cannot be rendered
by one or more of the output devices mapped by the EFI handle.