EngDebugPrint function (winddi.h)

Article
02/22/2024

The EngDebugPrint function prints the specified debug message to the kernel debugger.

Syntax

ENGAPI VOID EngDebugPrint(
  [in] PCHAR   StandardPrefix,
  [in] PCHAR   DebugMessage,
  [in] va_list ap
);

Parameters

[in] StandardPrefix

Pointer to a string that is prepended to DebugMessage.

[in] DebugMessage

Pointer to a string containing the debug message to be printed.

[in] ap

Specifies the variable argument list.

Return value

None

Remarks

EngDebugPrint is useful for debugging drivers that are under development. It prints StandardPrefix, followed by DebugMessage, to the kernel debugger.

The StandardPrefix parameter acts as a unique identifier of the driver executing the debug statement; therefore, the same string should be used for all calls to EngDebugPrint by a single driver.

The DebugMessage parameter is a variable argument ASCII C string; that is, it can contain both ordinary characters and C-style conversion specifications. The argument list contained in ap can have any number of arguments of any type in it.

An example use of EngDebugPrint follows:

#define STANDARD_DEBUG_PREFIX     "Permedia: "
LONG bank;
LONG width;
...
VOID MyDebugPrint(PCHAR DebugMessage, ...)
{
    va_list ap;

    va_start(ap, DebugMessage);
    EngDebugPrint(STANDARD_DEBUG_PREFIX, DebugMessage, ap);
    va_end(ap);
}
...
MyDebugPrint("Bank: %lx; Width: %ld", bank, width);

Note The Microsoft Windows Driver Kit (WDK) does not contain the Permedia (3dlabs.htm and Perm3.htm) and FrameBuffer (Framebuf.htm) sample display drivers. You can get these sample drivers from the Windows Server 2003 SP1 Driver Development Kit (DDK), which you can download from the DDK - Windows Driver Development Kit page of the WDHC website.

Requirements

Requirement	Value
Minimum supported client	Available in Windows 2000 and later versions of the Windows operating systems.
Target Platform	Universal
Header	winddi.h (include Winddi.h)
Library	Win32k.lib
DLL	Win32k.sys