Ethernet Loopback

Ethernet Loopback Device Driver. More...

Functions
devcall	ethloopClose (device *devptr)
devcall	ethloopControl (device *devptr, int func, long arg1, long arg2)
devcall	ethloopInit (device *devptr)
devcall	ethloopOpen (device *devptr)
devcall	ethloopRead (device *devptr, void *buf, uint len)
devcall	ethloopWrite (device *devptr, const void *buf, uint len)

Detailed Description

Ethernet Loopback Device Driver.

This is a driver for a device that presents itself as an Ethernet Driver but actually just writes packets into a buffer and reads them back from the same buffer.

Function Documentation

devcall ethloopClose

(

device *

devptr

)

Close a ethloop device.

Parameters

devptr

ethloop device table entry

Returns

OK if ethloop is closed properly, otherwise SYSERR

devcall ethloopControl	(	device *	devptr,
		int	func,
		long	arg1,
		long	arg2
	)

Control function for ethloop devices.

Parameters

devptr	ethloop device table entry
func	control function to execute
arg1	first argument for the control function
arg2	second argument for the control function

Returns

the result of the control function

devcall ethloopInit

(

device *

devptr

)

Initialize ethloop device

Parameters

devptr

Returns

OK on open

devcall ethloopOpen

(

device *

devptr

)

Open an ethloop device.

Parameters

devptr

ethloop device table entry

Returns

OK if ethloop is opened properly, otherwise SYSERR

devcall ethloopRead	(	device *	devptr,
		void *	buf,
		uint	len
	)

Read data from an Ethernet Loopback device. This will block until data has been made available by a call to ethloopWrite().

Parameters

devptr	Pointer to the device table entry for the ethloop.
buf	Buffer into which to place the read data.
len	Maximum length of the data to read, in bytes.

Returns

On success, returns the number of bytes read, which will be less than or equal to len. Otherwise returns SYSERR.

devcall ethloopWrite	(	device *	devptr,
		const void *	buf,
		uint	len
	)

Write data to an Ethernet Loopback device. On success, the data will be available to be read by a subsequent call to ethloopRead().

Parameters

devptr	Pointer to the device table entry for the ethloop.
buf	Buffer of data to write.
len	Length of data to write, in bytes.

Returns

On success, returns the number of bytes written, which will be exactly len. On failure, returns SYSERR.