Read

read input from parallel port

This command causes a stream of characters to be read from the parallel I/O register. The number of characters is specified in io_Length. The EOF and EOL modes are supported, but be warned that using these modes can result in a buffer overflow if the proper EOL or EOF character is not received in time. These modes should be used only when the sender and receiver have been designed to cooperate. A safety guard can be implemented to EOF by setting io_Length to a maximum allowed value. That cannot be done with EOL since the EOL mode is identified by io_Length=-1.

The parallel.device has no internal buffer; if no read request has been made, pending input (i.e. handshake request) is not acknowledged.

io_Message

mn_ReplyPort initialized

io_Device

set by OpenDevice

io_Unit

set by OpenDevice

io_Command

CMD_READ (02)

io_Flags

If IOF_QUICK is set, driver will attempt Quick IO

io_Length

number of characters to receive.

io_Data

pointer where to put the data.

io_Error

if the Read succeded, then io_Error will be null. If the Read failed, then io_Error will contain an error code.

parallel.device/PDCMD_SETPARAMS