ieee1284_terminate(3) [debian man page]
IEEE1284_NEGOTIATION(3) Functions IEEE1284_NEGOTIATION(3) NAME
ieee1284_negotiate, ieee1284_terminate - IEEE 1284 negotiation SYNOPSIS
#include <ieee1284.h> int ieee1284_negotiate(struct parport *port, int mode); void ieee1284_terminate(struct parport *port); DESCRIPTION
These functions are for negotiating to and terminating from IEEE 1284 data transfer modes. The default mode is called compatibility mode, or in other words normal printer protocol. It is a host-to-peripheral mode only. There are special modes that allow peripheral-to-host transfer as well, which may be negotiated to using ieee1284_negotiate. IEEE 1284 negotiation is a process by which the host requests a transfer mode and the peripheral accepts or rejects it. An IEEE 1284-compliant device will require a successful negotiation to a particular mode before it is used for data transfer (but simpler devices may not if they only speak one transfer mode). To terminate the special mode and go back to compatilibity mode use ieee1284_terminate. These functions act on the parallel port associated with port, which must be claimed. With a device strictly complying to IEEE 1284 you will need to call ieee1284_terminate in between any two calls to ieee1284_negotiate for modes other than M1284_COMPAT. AVAILABLE MODES
Uni-directional modes o M1284_COMPAT: Compatibility mode. Normal printer protocol. This is not a negotiated mode, but is the default mode in absence of negotiation. ieee1284_negotiate(port, M1284_COMPAT) is equivalent to ieee1284_terminate(port). This host-to-peripheral mode is used for sending data to printers, and is historically the mode that has been used for that before IEEE 1284. o M1284_NIBBLE: Nibble mode. This peripheral-to-host mode uses the status lines to read data from the peripheral four bits at a time. o M1284_BYTE: Byte mode. This peripheral-to-host mode uses the data lines in reverse mode to read data from the peripheral a byte at a time. Bi-directional modes o M1284_ECP: ECP mode. On entry to ECP mode it is a host-to-peripheral (i.e. forward) mode, but it may be set to reverse mode using ieee1284_ecp_fwd_to_rev(3). It is common for PC hardware to provide assistance with this mode by the use of a FIFO which the host (or, in reverse mode, the peripheral) may fill, so that the hardware can do the handshaking itself. o M1284_EPP: EPP mode. In this bi-directional mode the direction of data transfer is signalled at each byte. Mode variations o M1284_FLAG_DEVICEID: Device ID retrieval. This flag may be combined with a nibble, byte, or ECP mode to notify the device that it should send its IEEE 1284 Device ID when asked for data. o M1284_BECP: Bounded ECP is a modification to ECP that makes it more robust at the point that the direction is changed. (Unfortunately it is not yet implemented in the Linux kernel driver.) o M1284_ECPRLE: ECP with run length encoding. In this mode, consecutive data bytes of the same value may be transferred in only a few cycles. RETURN VALUE
E1284_OK The negotiation was successful. E1284_NOTAVAIL Negotiation is not available with this port type. E1284_REJECTED Negotiation was rejected by the peripheral. E1284_NEGFAILED Negotiation failed for some reason. Perhaps the device is not IEEE 1284 compliant. E1284_SYS A system error occured during negotiation. E1284_INVALIDPORT The port parameter is invalid (for instance, perhaps the port is not claimed). AUTHOR
Tim Waugh <twaugh@redhat.com> Author. COPYRIGHT
Copyright (C) 2001-2003 Tim Waugh 09/18/2007 IEEE1284_NEGOTIATION(3)
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IEEE1284_TRANSFER(3) Functions IEEE1284_TRANSFER(3) NAME
ieee1284_nibble_read, ieee1284_compat_write, ieee1284_byte_read, ieee1284_epp_read_data, ieee1284_epp_write_data, ieee1284_epp_read_addr, ieee1284_epp_write_addr, ieee1284_ecp_read_data, ieee1284_ecp_write_data, ieee1284_ecp_read_addr, ieee1284_ecp_write_addr - data transfer functions SYNOPSIS
#include <ieee1284.h> ssize_t ieee1284_nibble_read(struct parport *port, int flags, char *buffer, size_t len); ssize_t ieee1284_compat_write(struct parport *port, int flags, const char *buffer, size_t len); ssize_t ieee1284_byte_read(struct parport *port, int flags, char *buffer, size_t len); ssize_t ieee1284_epp_read_data(struct parport *port, int flags, char *buffer, size_t len); ssize_t ieee1284_epp_write_data(struct parport *port, int flags, const char *buffer, size_t len); ssize_t ieee1284_epp_read_addr(struct parport *port, int flags, char *buffer, size_t len); ssize_t ieee1284_epp_write_addr(struct parport *port, int flags, const char *buffer, size_t len); ssize_t ieee1284_ecp_read_data(struct parport *port, int flags, char *buffer, size_t len); ssize_t ieee1284_ecp_write_data(struct parport *port, int flags, const char *buffer, size_t len); ssize_t ieee1284_ecp_read_addr(struct parport *port, int flags, char *buffer, size_t len); ssize_t ieee1284_ecp_write_addr(struct parport *port, int flags, const char *buffer, size_t len); DESCRIPTION
This set of functions is for tranferring bytes in the relevant transfer mode. For ECP and EPP modes two types of transfer are possible: data and address (usually referred to as channel in ECP). The supplied port must be a claimed port. The supplied buffer must be at least len bytes long. When reading, the transferred data is stored in the buffer; when writing the data to be transferred is taken from the buffer. For reads (peripheral to host): if no data is available and F1284_NONBLOCK is not in effect, the inactivity timer is started. If data becomes available before the inactivity time-out elapses it is read; otherwise the return value will be E1284_TIMEDOUT. For writes (host to peripheral): if the peripheral is not willing to accept data and F1284_NONBLOCK is not in effect, the inactivity timer is started. If the peripheral indicates that it is willing to accept data before the inactivity time-out elapses it is sent; otherwise the return value will be E1284_TIMEDOUT The flags may alter the behaviour slightly: F1284_NONBLOCK For reads (peripheral to host): if no data is available, return immediately (with E1284_TIMEDOUT). For writes (host to peripheral): if the peripheral is not willing to accept data, return immediately (with E1284_TIMEDOUT). F1284_SWE Don't use hardware assistance for the transfer, but instead set the parallel port pins according to the wire protocol. F1284_RLE (for ECP only) Use run length encoding. If the peripheral is in ECP mode with RLE, calls to ieee1284_ecp_read_data must set this flag in order for the RLE from the peripheral to be interpreted correctly, and calls to ieee1284_ecp_write_data may set this flag in order to take advantage of RLE. F1284_FASTEPP (for EPP only) Use multi-byte transfers. Several bytes at a time are transferred using hardware assistance, if supporting hardware is present. The price of this increased speed is that the return value will be less reliable when this flag is used. For ECP mode, a given direction is in force at any particular time, and it is up to the application to ensure that it is only writing when in forward mode, and reading when in reverse mode. RETURN VALUE
The return value is the number of bytes successfully transferred or, if negative, one of: E1284_NOTIMPL This transfer mode and flags combination is not yet implemented in libieee1284. E1284_TIMEDOUT Timed out waiting for peripheral to handshake. E1284_NOMEM Not enough memory is available. E1284_SYS There was a problem at the operating system level. The global variable errno has been set appropriately. E1284_INVALIDPORT The port parameter is invalid (for instance, perhaps the port is not claimed). If any bytes are successfully transferred, that number is returned. An error is returned only if no bytes are transferred. For host-to-peripheral transfers, all data is at the peripheral by the time the call returns. SEE ALSO
ieee1284_ecp_fwd_to_rev(3) AUTHOR
Tim Waugh <twaugh@redhat.com> Author. COPYRIGHT
Copyright (C) 2001-2003 Tim Waugh 09/18/2007 IEEE1284_TRANSFER(3)