The SLIP protocol is a very simple way to transmit IP packets over a serial line.

It does not provide any framing or error control, and is therefore not very widely used today.

This SLIP implementation requires two functions for accessing the serial device: slipdev_char_poll() and slipdev_char_put(). These must be implemented specifically for the system on which the SLIP protocol is to be run.

Files
file	slipdev.c
	SLIP protocol implementation.

file	slipdev.h
	SLIP header file.

Macros
#define	SLIP_END 0300

#define	SLIP_ESC 0333

#define	SLIP_ESC_END 0334

#define	SLIP_ESC_ESC 0335

Functions
uint8_t	slipdev_char_poll (uint8_t *c)
	Poll the serial device for a character. More...

void	slipdev_char_put (uint8_t c)
	Put a character on the serial device. More...

void	slipdev_init (void)
	Initialize the SLIP module. More...

uint16_t	slipdev_poll (void)
	Poll the SLIP device for an available packet. More...

uint8_t	slipdev_send (void)
	Send the packet in the uip_buf and uip_appdata buffers using the SLIP protocol. More...

Variables
static uint8_t	lastc

static uint16_t	len

static uint8_t	slip_buf [UIP_BUFSIZE]

static uint16_t	tmplen

#define SLIP_END 0300

Referenced by slipdev_poll(), and slipdev_send().

#define SLIP_ESC 0333

Referenced by slipdev_poll(), and slipdev_send().

#define SLIP_ESC_END 0334

Referenced by slipdev_poll(), and slipdev_send().

#define SLIP_ESC_ESC 0335

Referenced by slipdev_poll(), and slipdev_send().

uint8_t slipdev_char_poll ( uint8_t * c )

Poll the serial device for a character.

This function is used by the SLIP implementation to poll the serial device for a character. It must be implemented specifically for the system on which the SLIP implementation is to be run.

The function should return immediately regardless if a character is available or not. If a character is available it should be placed at the memory location pointed to by the pointer supplied by the argument c.

Parameters

c	A pointer to a byte that is filled in by the function with the received character, if available.

Return values

0	If no character is available.
Non-zero	If a character is available.

Referenced by slipdev_poll().

void slipdev_char_put ( uint8_t c )

Put a character on the serial device.

This function is used by the SLIP implementation to put a character on the serial device. It must be implemented specifically for the system on which the SLIP implementation is to be run.

Parameters

c	The character to be put on the serial device.

Referenced by slipdev_send().

void slipdev_init ( void )

Initialize the SLIP module.

This function does not initialize the underlying RS232 device, but only the SLIP part.

References lastc, and len.

uint16_t slipdev_poll ( void )

Poll the SLIP device for an available packet.

This function will poll the SLIP device to see if a packet is available. It uses a buffer in which all avaliable bytes from the RS232 interface are read into. When a full packet has been read into the buffer, the packet is copied into the uip_buf buffer and the length of the packet is returned.

Returns: The length of the packet placed in the uip_buf buffer, or zero if no packet is available.

References c, lastc, len, slip_buf, SLIP_END, SLIP_ESC, SLIP_ESC_END, SLIP_ESC_ESC, slipdev_char_poll(), tmplen, uip_buf, UIP_BUFSIZE, and UIP_LLH_LEN.

uint8_t slipdev_send ( void )

Send the packet in the uip_buf and uip_appdata buffers using the SLIP protocol.

The first 40 bytes of the packet (the IP and TCP headers) are read from the uip_buf buffer, and the following bytes (the application data) are read from the uip_appdata buffer.