Legacy Document

Inside Macintosh: Networking /

Chapter 11 - Ethernet, Token Ring, and Fiber Distributed Data Interface / Ethernet, Token Ring, and FDDI Reference

Routines / Obtaining Information About the Ethernet Driver and Switching Its Mode

ESetGeneral

The ESetGeneral function switches the .ENET driver from limited-transmission mode to general-transmission mode, allowing it to transmit a larger data packet.

FUNCTION ESetGeneral (thePBptr: EParamBlkPtr; 
                     async: Boolean): OSErr;

thePBptr

A pointer to a parameter block of type EParamBlock.

async

A Boolean value that specifies whether the function should be
executed asynchronously or synchronously. Specify TRUE for asynchronous execution.

-->	ioCompletion	ProcPtr	A pointer to completion routine.
<--	ioResult	OSErr	The result code.
-->	ioRefNum	Integer	The driver reference number.
-->	csCode	Integer	Always ENetSetGeneral for this function.

DESCRIPTION

The ESetGeneral function switches the .ENET driver from limited-transmission mode to general-transmission mode, which enables the .ENET driver to transmit an Ethernet data packet of up to 1514 bytes. In limited-transmission mode, the .ENET driver allocates a write-data buffer of 768 bytes. This buffer size is more than sufficient to hold an Ethernet data packet, which can be no larger than 621 bytes. However, if you want to send a packet that is larger than the Ethernet data packet, you must use the general-transmission mode.

SPECIAL CONSIDERATIONS

There is no command to switch the .ENET driver from general-transmission mode to limited-transmission mode. To switch back to limited-transmission mode, you have
to reset the driver by restarting the computer.

TOKEN RING AND FDDI CONSIDERATIONS

This function does not apply to token ring and FDDI. However, if an application calls this function for token ring or FDDI, the driver will return a value of noErr in register D0.

ASSEMBLY-LANGUAGE INFORMATION

To execute the ESetGeneral function from assembly language, call the _Control
trap macro with a value of ENetSetGeneral in the csCode field of the parameter block. To execute the _Control trap asynchronously, include the value ,ASYNC in the operand field.

RESULT CODES

noErr	0	No error
memFullErr	-108	Insufficient memory in heap