lwip/doc/doxygen/main_page.h
2017-10-16 23:27:00 +02:00

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/**
* @defgroup lwip lwIP
*
* @defgroup infrastructure Infrastructure
*
* @defgroup callbackstyle_api Callback-style APIs
* Non thread-safe APIs, callback style for maximum performance and minimum
* memory footprint.
* Program execution is driven by callbacks functions, which are then
* invoked by the lwIP core when activity related to that application
* occurs. A particular application may register to be notified via a
* callback function for events such as incoming data available, outgoing
* data sent, error notifications, poll timer expiration, connection
* closed, etc. An application can provide a callback function to perform
* processing for any or all of these events. Each callback is an ordinary
* C function that is called from within the TCP/IP code. Every callback
* function is passed the current TCP or UDP connection state as an
* argument. Also, in order to be able to keep program specific state,
* the callback functions are called with a program specified argument
* that is independent of the TCP/IP state.
*
* @defgroup sequential_api Sequential-style APIs
* Sequential-style APIs, blocking functions. More overhead, but can be called
* from any thread except TCPIP thread.
*
* @defgroup netifs NETIFs
*
* @defgroup apps Applications
*/
/**
* @mainpage Overview
* @verbinclude "README"
*/
/**
* @page upgrading Upgrading
* @verbinclude "UPGRADING"
*/
/**
* @page changelog Changelog
* @verbinclude "CHANGELOG"
*/
/**
* @page contrib How to contribute to lwIP
* @verbinclude "contrib.txt"
*/
/**
* @page pitfalls Common pitfalls
*
* Multiple Execution Contexts in lwIP code
* ========================================
*
* The most common source of lwIP problems is to have multiple execution contexts
* inside the lwIP code.
*
* lwIP can be used in two basic modes: @ref lwip_nosys (no OS/RTOS
* running on target system) or @ref lwip_os (there is an OS running
* on the target system).
*
* Mainloop Mode
* -------------
* In mainloop mode, only @ref callbackstyle_api can be used.
* The user has two possibilities to ensure there is only one
* exection context at a time in lwIP:
*
* 1) Deliver RX ethernet packets directly in interrupt context to lwIP
* by calling netif->input directly in interrupt. This implies all lwIP
* callback functions are called in IRQ context, which may cause further
* problems in application code: IRQ is blocked for a long time, multiple
* execution contexts in application code etc. When the application wants
* to call lwIP, it only needs to disable interrupts during the call.
* If timers are involved, even more locking code is needed to lock out
* timer IRQ and ethernet IRQ from each other, assuming these may be nested.
*
* 2) Run lwIP in a mainloop. There is example code here: @ref lwip_nosys.
* lwIP is _ONLY_ called from mainloop callstacks here. The ethernet IRQ
* has to put received telegrams into a queue which is polled in the
* mainloop. Ensure lwIP is _NEVER_ called from an interrupt, e.g.
* some SPI IRQ wants to forward data to udp_send() or tcp_write()!
*
* OS Mode
* -------
* In OS mode, @ref callbackstyle_api AND @ref sequential_api can be used.
* @ref sequential_api are designed to be called from threads other than
* the TCPIP thread, so there is nothing to consider here.
* But @ref callbackstyle_api functions must _ONLY_ be called from
* TCPIP thread. It is a common error to call these from other threads
* or from IRQ contexts. Ethernet RX needs to deliver incoming packets
* in the correct way by sending a message to TCPIP thread, this is
* implemented in tcpip_input().
* Again, ensure lwIP is _NEVER_ called from an interrupt, e.g.
* some SPI IRQ wants to forward data to udp_send() or tcp_write()!
*
* 1) tcpip_callback() can be used get called back from TCPIP thread,
* it is safe to call any @ref callbackstyle_api from there.
*
* 2) Use @ref LWIP_TCPIP_CORE_LOCKING. All @ref callbackstyle_api
* functions can be called when lwIP core lock is aquired, see
* @ref LOCK_TCPIP_CORE() and @ref UNLOCK_TCPIP_CORE().
* These macros cannot be used in an interrupt context!
* Note the OS must correctly handle priority inversion for this.
*/
/**
* @page bugs Reporting bugs
* Please report bugs in the lwIP bug tracker at savannah.\n
* BEFORE submitting, please check if the bug has already been reported!\n
* https://savannah.nongnu.org/bugs/?group=lwip
*/
/**
* @page zerocopyrx Zero-copy RX
* The following code is an example for zero-copy RX ethernet driver:
* @include ZeroCopyRx.c
*/
/**
* @defgroup lwip_nosys Mainloop mode ("NO_SYS")
* @ingroup lwip
* Use this mode if you do not run an OS on your system. \#define NO_SYS to 1.
* Feed incoming packets to netif->input(pbuf, netif) function from mainloop,
* *not* *from* *interrupt* *context*. You can allocate a @ref pbuf in interrupt
* context and put them into a queue which is processed from mainloop.\n
* Call sys_check_timeouts() periodically in the mainloop.\n
* Porting: implement all functions in @ref sys_time, @ref sys_prot and
* @ref compiler_abstraction.\n
* You can only use @ref callbackstyle_api in this mode.\n
* Sample code:\n
* @include NO_SYS_SampleCode.c
*/
/**
* @defgroup lwip_os OS mode (TCPIP thread)
* @ingroup lwip
* Use this mode if you run an OS on your system. It is recommended to
* use an RTOS that correctly handles priority inversion and
* to use @ref LWIP_TCPIP_CORE_LOCKING.\n
* Porting: implement all functions in @ref sys_layer.\n
* You can use @ref callbackstyle_api together with @ref tcpip_callback,
* and all @ref sequential_api.
*/
/**
* @page raw_api lwIP API
* @verbinclude "rawapi.txt"
*/