Architecture specific uIP functions
[The uIP TCP/IP stack]

The functions in the architecture specific module implement the IP check sum and 32-bit additions. More...

Files
file	uip_arch.h
	Declarations of architecture specific functions.
Functions
void	uip_add32 (u8_t *op32, u16_t op16)
	Carry out a 32-bit addition.
u16_t	uip_chksum (u16_t *buf, u16_t len)
	Calculate the Internet checksum over a buffer.
u16_t	uip_ipchksum (void)
	Calculate the IP header checksum of the packet header in uip_buf.
u16_t	uip_tcpchksum (void)
	Calculate the TCP checksum of the packet in uip_buf and uip_appdata.
Variables
u8_t	uip_acc32 [4]
	4-byte array used for the 32-bit sequence number calculations.

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Detailed Description

The functions in the architecture specific module implement the IP check sum and 32-bit additions.

The IP checksum calculation is the most computationally expensive operation in the TCP/IP stack and it therefore pays off to implement this in efficient assembler. The purpose of the uip-arch module is to let the checksum functions to be implemented in architecture specific assembler.

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Function Documentation

void uip_add32	(	u8_t *	op32,
		u16_t	op16
	)

Carry out a 32-bit addition.

Because not all architectures for which uIP is intended has native 32-bit arithmetic, uIP uses an external C function for doing the required 32-bit additions in the TCP protocol processing. This function should add the two arguments and place the result in the global variable uip_acc32.

Note:

The 32-bit integer pointed to by the op32 parameter and the result in the uip_acc32 variable are in network byte order (big endian).

Parameters:

	op32	A pointer to a 4-byte array representing a 32-bit integer in network byte order (big endian).
	op16	A 16-bit integer in host byte order.

Definition at line 241 of file uip.c.

References uip_acc32.

Referenced by uip_process(), and uip_split_output().

u16_t uip_chksum	(	u16_t *	buf,
		u16_t	len
	)

Calculate the Internet checksum over a buffer.

The Internet checksum is the one's complement of the one's complement sum of all 16-bit words in the buffer.

See RFC1071.

Note:

This function is not called in the current version of uIP, but future versions might make use of it.

Parameters:

	buf	A pointer to the buffer over which the checksum is to be computed.
	len	The length of the buffer over which the checksum is to be computed.

Returns:

The Internet checksum of the buffer.

The Internet checksum is the one's complement of the one's complement sum of all 16-bit words in the buffer.

See RFC1071.

Parameters:

	buf	A pointer to the buffer over which the checksum is to be computed.
	len	The length of the buffer over which the checksum is to be computed.

Returns:

The Internet checksum of the buffer.

Definition at line 339 of file uip6.c.

References uip_htons().

u16_t uip_ipchksum

(

void

)

Calculate the IP header checksum of the packet header in uip_buf.

The IP header checksum is the Internet checksum of the 20 bytes of the IP header.

Returns:

The IP header checksum of the IP header in the uip_buf buffer.

Definition at line 346 of file uip6.c.

References uip_htons(), uip_ipchksum(), and UIP_LLH_LEN.

Referenced by hc_inflate(), uip_ipchksum(), and uip_split_output().

u16_t uip_tcpchksum

(

void

)

Calculate the TCP checksum of the packet in uip_buf and uip_appdata.

The TCP checksum is the Internet checksum of data contents of the TCP segment, and a pseudo-header as defined in RFC793.

Note:

The uip_appdata pointer that points to the packet data may point anywhere in memory, so it is not possible to simply calculate the Internet checksum of the contents of the uip_buf buffer.

Returns:

The TCP checksum of the TCP segment in uip_buf and pointed to by uip_appdata.

The TCP checksum is the Internet checksum of data contents of the TCP segment, and a pseudo-header as defined in RFC793.

Returns:

The TCP checksum of the TCP segment in uip_buf and pointed to by uip_appdata.

Definition at line 317 of file uip_arch.c.

References uip_appdata, UIP_LLH_LEN, and uip_tcpchksum().

Referenced by uip_process(), uip_split_output(), and uip_tcpchksum().