Function 4410h Query IOCTL Handle

mov bx, Handle ;Device handle

mov ch, Category ;Category to check

mov cl, Function ;Function to check

mov ax, 4410h ;Query IOCTL Handle 4410h

int 21h

jnc supported ;carry clear means IOCTL supported

Query IOCTL Handle (Function 4410h) determines whether the specified IOCTL is supported by the given device driver.

Parameters

Handle

Identifies the device to check.

Category

Specifies an IOCTL category code. It can be one of the following:

Value

Meaning

01h	Serial device
03h	Console (screen)
05h	Parallel printer

Function

Specifies a Function 440Ch minor code. It can be one of the following:

Value

Meaning

45h	Set Iteration Count
65h	Get Iteration Count

Return Value

If IOCTL is supported, the carry flag is clear. Otherwise, the carry flag is set and AX contains an error value, which may be one of the following:

Value

Name

0001h	ERROR_INVALID_FUNCTION
0005h	ERROR_ACCESS_DENIED

Comments

Query IOCTL Handle returns 0001h (ERROR_INVALID_FUNCTION) if the device driver has no support for IOCTL functions. The function returns 0005h (ERROR_ACCESS_DENIED) if the device driver supports IOCTL functions but does not support the specified IOCTL.