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Ambroz Bizjak 8ba7363d11 Optimize passing contiguous nocopy buffers to tcp_write
While TCP_OVERSIZE works only when tcp_write() is used with
TCP_WRITE_FLAG_COPY, this new code achieves
similar benefits for the use case that the caller manages their own
send buffers and passes successive chunks of those to tcp_write()
without TCP_WRITE_FLAG_COPY.

In particular, if a buffer is passed to
tcp_write() that is adjacent in memory to the previously passed
buffer, it will be combined into the previous ROM pbuf reference
whenever possible, thus extending that ROM pbuf rather than allocating
a new ROM pbuf.

For the aforementioned use case, the advantages of this code are
twofold:
1) fewer ROM pbufs need to be allocated to send the same data, and,
2) the MAC layer gets outgoing TCP packets with shorter pbuf chains.

Original patch by Ambroz Bizjak <ambrop7@gmail.com>
Edited by David van Moolenbroek <david@minix3.org>
Signed-off-by: goldsimon <goldsimon@gmx.de>
2016-11-24 11:27:34 +01:00
doc PPP, documentation: Fix example code 2016-10-23 10:00:54 +02:00
src Optimize passing contiguous nocopy buffers to tcp_write 2016-11-24 11:27:34 +01:00
test/unit Update email address 2016-11-10 11:19:51 +01:00
.gitattributes Added .gitattributes to normalize CRLF 2014-02-07 09:36:03 +01:00
.gitignore Add redirection page for HTML doxygen output so one does not have to search for index.html in the huge output/html directory 2016-08-03 12:34:17 +02:00
CHANGELOG Optimize passing contiguous nocopy buffers to tcp_write 2016-11-24 11:27:34 +01:00
COPYING Re-added without vendor tag. 2002-10-20 15:13:14 +00:00
FILES update some FILES list files 2016-08-03 20:21:54 +02:00
README Update README applications sections 2016-08-14 15:39:58 +02:00
UPGRADING Add note about UDP multicast behavior fix to UPGRADING document 2016-11-23 13:10:16 +01:00

INTRODUCTION

lwIP is a small independent implementation of the TCP/IP protocol
suite that has been developed by Adam Dunkels at the Computer and
Networks Architectures (CNA) lab at the Swedish Institute of Computer
Science (SICS).

The focus of the lwIP TCP/IP implementation is to reduce the RAM usage
while still having a full scale TCP. This making lwIP suitable for use
in embedded systems with tens of kilobytes of free RAM and room for
around 40 kilobytes of code ROM.


FEATURES

  * IP (Internet Protocol, IPv4 and IPv6) including packet forwarding over
    multiple network interfaces
  * ICMP (Internet Control Message Protocol) for network maintenance and debugging
  * IGMP (Internet Group Management Protocol) for multicast traffic management
  * MLD (Multicast listener discovery for IPv6). Aims to be compliant with 
    RFC 2710. No support for MLDv2
  * ND (Neighbor discovery and stateless address autoconfiguration for IPv6).
    Aims to be compliant with RFC 4861 (Neighbor discovery) and RFC 4862
    (Address autoconfiguration)
  * UDP (User Datagram Protocol) including experimental UDP-lite extensions
  * TCP (Transmission Control Protocol) with congestion control, RTT estimation
    and fast recovery/fast retransmit
  * raw/native API for enhanced performance
  * Optional Berkeley-like socket API
  * DNS (Domain names resolver)


APPLICATIONS

  * HTTP server with SSI and CGI
  * SNMPv2c agent with MIB compiler (Simple Network Management Protocol)
  * SNTP (Simple network time protocol)
  * NetBIOS name service responder
  * MDNS (Multicast DNS) responder
  * iPerf server implementation


LICENSE

lwIP is freely available under a BSD license.


DEVELOPMENT

lwIP has grown into an excellent TCP/IP stack for embedded devices,
and developers using the stack often submit bug fixes, improvements,
and additions to the stack to further increase its usefulness.

Development of lwIP is hosted on Savannah, a central point for
software development, maintenance and distribution. Everyone can
help improve lwIP by use of Savannah's interface, Git and the
mailing list. A core team of developers will commit changes to the
Git source tree.

The lwIP TCP/IP stack is maintained in the 'lwip' Git module and
contributions (such as platform ports) are in the 'contrib' Git module.

See doc/savannah.txt for details on Git server access for users and
developers.

The current Git trees are web-browsable:
  http://git.savannah.gnu.org/cgit/lwip.git
  http://git.savannah.gnu.org/cgit/lwip/lwip-contrib.git

Submit patches and bugs via the lwIP project page:
  http://savannah.nongnu.org/projects/lwip/

Continuous integration builds (GCC, clang):
  https://travis-ci.org/yarrick/lwip-merged


DOCUMENTATION

Self documentation of the source code is regularly extracted from the current
Git sources and is available from this web page:
  http://www.nongnu.org/lwip/

There is now a constantly growing wiki about lwIP at
  http://lwip.wikia.com/wiki/LwIP_Wiki

Also, there are mailing lists you can subscribe at
  http://savannah.nongnu.org/mail/?group=lwip
plus searchable archives:
  http://lists.nongnu.org/archive/html/lwip-users/
  http://lists.nongnu.org/archive/html/lwip-devel/

lwIP was originally written by Adam Dunkels:
  http://dunkels.com/adam/

Reading Adam's papers, the files in docs/, browsing the source code
documentation and browsing the mailing list archives is a good way to
become familiar with the design of lwIP.

Adam Dunkels <adam@sics.se>
Leon Woestenberg <leon.woestenberg@gmx.net>