Changed packet drivers from services to plain processes.

Now tcpip_output() is a function pointer that is supposed to be set via the macro tcpip_set_outputfunc(). Packet drivers do so on process startup.

Thus if there are several packet drivers in a Contiki system the one started last is the one actually used. This behaviour is especially useful for the 'IP forwarding' "meta" packet driver.
This commit is contained in:
oliverschmidt 2007-05-21 22:29:13 +00:00
parent 3f4ec3cf44
commit 080ecc5488
6 changed files with 139 additions and 365 deletions

138
doc/example-packet-drv.c Normal file
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/*
* This is an example of how to write a network device driver ("packet
* driver") for Contiki. A packet driver is a regular Contiki process
* that does two things:
* # Checks for incoming packets and delivers those to the TCP/IP stack
* # Provides an output function that transmits packets
*
* The output function is registered with the Contiki TCP/IP stack,
* whereas incoming packets must be checked inside a Contiki process.
* We use the same process for checking for incoming packets and for
* registering the output function.
*/
/*
* We include the "contiki-net.h" file to get all the network functions.
*/
#include "contiki-net.h"
/*---------------------------------------------------------------------------*/
/*
* We declare the process that we use to register with the TCP/IP stack,
* and to check for incoming packets.
*/
PROCESS(example_packet_driver_process, "Example packet driver process");
/*---------------------------------------------------------------------------*/
/*
* Next, we define the function that transmits packets. This function
* is called from the TCP/IP stack when a packet is to be transmitted.
* The packet is located in the uip_buf[] buffer, and the length of the
* packet is in the uip_len variable.
*/
u8_t
example_packet_driver_output(void)
{
let_the_hardware_send_the_packet(uip_buf, uip_len);
}
/*---------------------------------------------------------------------------*/
/*
* This is the poll handler function in the process below. This poll
* handler function checks for incoming packets and delivers them to
* the TCP/IP stack.
*/
static void
pollhandler(void)
{
/*
* We assume that we have some hardware device that notifies us when
* a new packet has arrived. We also assume that we have a function
* that pulls out the new packet (here called
* check_and_copy_packet()) and puts it in the uip_buf[] buffer. The
* function returns the length of the incoming packet, and we store
* it in the global uip_len variable. If the packet is longer than
* zero bytes, we hand it over to the TCP/IP stack.
*/
uip_len = check_and_copy_packet();
/*
* The function tcpip_input() delivers the packet in the uip_buf[]
* buffer to the TCP/IP stack.
*/
if(uip_len > 0) {
tcpip_input();
}
/*
* Now we'll make sure that the poll handler is executed repeatedly.
* We do this by calling process_poll() with this process as its
* argument.
*
* In many cases, the hardware will cause an interrupt to be executed
* when a new packet arrives. For such hardware devices, the interrupt
* handler calls process_poll() (which is safe to use in an interrupt
* context) instead.
*/
process_poll(&example_packet_driver_process);
}
/*---------------------------------------------------------------------------*/
/*
* Here we shutdown the hardware in case the process exits.
*/
static void
exithandler(void)
{
shutdown_the_hardware();
}
/*---------------------------------------------------------------------------*/
/*
* Finally, we define the process that does the work.
*/
PROCESS_THREAD(example_packet_driver_process, ev, data)
{
/*
* This process has a poll handler, so we declare it here. Note that
* the PROCESS_POLLHANDLER() macro must come before the PROCESS_BEGIN()
* macro.
*/
PROCESS_POLLHANDLER(pollhandler());
/*
* This process has an exit handler, so we declare it here. Note that
* the PROCESS_EXITHANDLER() macro must come before the PROCESS_BEGIN()
* macro.
*/
PROCESS_EXITHANDLER(exithandler());
/*
* The process begins here.
*/
PROCESS_BEGIN();
/*
* We start with initializing the hardware.
*/
initialize_the_hardware();
/*
* Register the driver. This will cause any previously registered driver
* to be ignored by the TCP/IP stack.
*/
tcpip_set_outputfunc(example_packet_driver_output);
/*
* Now we'll make sure that the poll handler is executed initially. We do
* this by calling process_poll() with this process as its argument.
*/
process_poll(&example_packet_driver_process);
/*
* And we wait for the process to exit.
*/
PROCESS_WAIT_EVENT_UNTIL(ev == PROCESS_EVENT_EXIT);
/*
* Here ends the process.
*/
PROCESS_END();
}
/*---------------------------------------------------------------------------*/

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@ -1,148 +0,0 @@
/*
* This is an example of how to write a network device driver ("packet
* service") for Contiki. A packet service is a regular Contiki
* service that does two things:
* # Checks for incoming packets and delivers those to the TCP/IP stack
* # Provides an output function that transmits packets
*
* The output function is registered with the Contiki service
* mechanism, whereas incoming packets must be checked inside a
* Contiki process. We use the same process for checking for incoming
* packets and for registering the service.
*
* NOTE: This example does not work with the uip-fw module (packet
* forwarding with multiple interfaces). It only works with a single
* interface.
*/
/*
* We include the "contiki-net.h" file to get all the network
* functions.
*/
#include "contiki-net.h"
/*---------------------------------------------------------------------------*/
/*
* We declare the process that we use to register the service, and to
* check for incoming packets.
*/
PROCESS(example_packet_service_process, "Example packet service process");
/*---------------------------------------------------------------------------*/
/*
* This is the poll handler function in the process below. This poll
* handler function checks for incoming packets and delivers them to
* the TCP/IP stack.
*/
static void
pollhandler(void)
{
/*
* We assume that we have some hardware device that notifies us when
* a new packet has arrived. We also assume that we have a function
* that pulls out the new packet (here called
* check_and_copy_packet()) and puts it in the uip_buf[] buffer. The
* function returns the length of the incoming packet, and we store
* it in the global uip_len variable. If the packet is longer than
* zero bytes, we hand it over to the TCP/IP stack.
*/
uip_len = check_and_copy_packet();
/*
* The function tcpip_input() delivers the packet in the uip_buf[]
* buffer to the TCP/IP stack.
*/
if(uip_len > 0) {
tcpip_input();
}
/*
* Now we'll make sure that the poll handler is executed
* repeatedly. We do this by calling process_poll() with this
* process as its argument.
*
* In many cases, the hardware will cause an interrupt to be
* executed when a new packet arrives. For such hardware devices,
* the interrupt handler calls process_poll() (which is safe to use
* in an interrupt context) instead.
*/
process_poll(&example_packet_service_process);
}
/*---------------------------------------------------------------------------*/
/*
* Next, we define the function that transmits packets. This function
* is called from the TCP/IP stack when a packet is to be
* transmitted. The packet is located in the uip_buf[] buffer, and the
* length of the packet is in the uip_len variable.
*/
static void
send_packet(void)
{
let_the_hardware_send_the_packet(uip_buf, uip_len);
}
/*---------------------------------------------------------------------------*/
/*
* Now we declare the service. We call the service
* example_packet_service because of the name of this file. The
* service should be an instance of the "packet service" service, so
* we give packet_service as the second argument. Finally we give our
* send_packet() function as the last argument, because of how the
* packet_service interface is defined.
*
* We'll register this service with the Contiki system in the process
* defined below.
*/
SERVICE(example_packet_service, packet_service, { send_packet });
/*---------------------------------------------------------------------------*/
/*
* Finally, we define the process that does the work.
*/
PROCESS_THREAD(example_packet_service_process, ev, data)
{
/*
* This process has a poll handler, so we declare it here. Note that
* the PROCESS_POLLHANDLER() macro must come before the
* PROCESS_BEGIN() macro.
*/
PROCESS_POLLHANDLER(pollhandler());
/*
* The process begins here.
*/
PROCESS_BEGIN();
/*
* We start with initializing the hardware.
*/
initialize_the_hardware();
/*
* Register the service. This will cause any other instances of the
* same service to be removed.
*/
SERVICE_REGISTER(example_packet_service);
/*
* Now we'll make sure that the poll handler is executed
* initially. We do this by calling process_poll() with this
* process as its argument.
*/
process_poll(&example_packet_service_process);
/*
* And we wait for either the process to exit, or for the service to
* be removed (by someone else).
*/
PROCESS_WAIT_EVENT_UNTIL(ev == PROCESS_EVENT_EXIT ||
ev == PROCESS_EVENT_SERVICE_REMOVED);
/*
* And we always end with explicitly removing the service.
*/
SERVICE_REMOVE(example_packet_service);
/*
* Here endeth the process.
*/
PROCESS_END();
}
/*---------------------------------------------------------------------------*/

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/*
* This file is an example of how to implement a service in
* Contiki. The header file example-service.h defines a service called
* "example_service", which we implement in this file.
*
* This example shows how to define an instance of a service, and how
* to write the service's controlling process.
*
* See the file example-use-service.c for an example of how to call a
* service.
*/
#include <stdio.h>
#include "example-service.h"
#include "contiki.h"
/*---------------------------------------------------------------------------*/
/*
* We start by implementing all the functions that the service
* offers. In this case, there is only a single function (called
* example_function()) and we implement it here. We give it the name
* example() and declare it with the "static" keyword to keep the
* scope local to this file.
*/
static void
example(void) {
printf("Example service called\n");
}
/*---------------------------------------------------------------------------*/
/*
* This is the instantiation of the service called
* "example_service". The service interface is defined in the header
* file example-service.h.
*
* This statement defines the name of this implementation of the
* service - example_service_implementation - and defines the
* functions that actually implement the functions offered by the
* service. In this example, the service consists of a single function
* called "example_function()". We implement this function in the
* function called "example()" defined above.
*
*/
SERVICE(example_service_implementation, /* The name of this instance
of the service - used with
SERVICE_REGISTER(). */
example_service, /* The name of the serivce
that is instantiated. */
{ example }); /* The list of functions
required by the
service. In this case, we
only have one function. */
/*
* All services needs a controlling process. The controlling process
* registers the service with the system when it starts, and is also
* notified if the service is removed or replaced.
*
* We simply call the process "example_service_process" and gives it a
* similar textual name.
*/
PROCESS(example_service_process, "Example service process");
/*
* For this example, we use a timer to remove the service after a
* certain time. We declare the timer here.
*/
static struct etimer timer;
/*
* Finally, we implement the controlling process.
*/
PROCESS_THREAD(example_service_process, ev, data)
{
/*
* A process thread starts with PROCESS_BEGIN() and ends with
* PROCESS_END().
*/
PROCESS_EXITHANDLER(goto exit);
PROCESS_BEGIN();
/*
* We register the service instance with a SERVICE_REGISTER()
* statement.
*/
printf("Registering example service\n");
SERVICE_REGISTER(example_service_implementation);
/*
* We set a timer for four seconds and wait for it to expire - or
* for the process to receive an event which requests it to exit.
*
* The only purpose for the timer is to demonstrate how a service is
* removed - it is not something that is commonly done.
*/
etimer_set(&timer, 4 * CLOCK_SECOND);
PROCESS_YIELD_UNTIL(ev == PROCESS_EVENT_SERVICE_REMOVED ||
etimer_expired(&timer));
/*
* And we remove the service before the process ends. This is a
* *very* important step - if the process exits and is unloaded
* without first removing its services, the system may crash!
*/
printf("Removing example service\n");
/*
* And finally the process ends.
*/
exit:
SERVICE_REMOVE(example_service_implementation);
PROCESS_END();
}
/*---------------------------------------------------------------------------*/

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/*
* This file is an example of how to define a service in Contiki. The
* example shows how to define a service interface, and how to give
* the service a name.
*/
#ifndef __EXAMPLE_SERVICE_H__
#define __EXAMPLE_SERVICE_H__
#include "sys/service.h"
/*
* This is how we define the service interface, and give the service a
* name. The name of this particular service is "example_service" and
* the interface consists of a single function, called
* example_function().
*/
SERVICE_INTERFACE(example_service,
{
void (* example_function)(void);
/* More functions can be added here, line by line. */
});
/*
* We must also give the service a textual name. We do this by using a
* special #define statment - we define a macro with the same name as
* the service, but postfixed with "_name".
*
* The textual name is used when looking up services. The name must be
* unique within the system.
*/
#define example_service_name "Example service"
#endif /* __EXAMPLE_SERVICE_H__ */

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/*
* This file contains an example of how to call a service.
*
* This program implements a process that calls the service defined in
* example-service.h every second.
*/
#include <stdio.h>
#include "contiki.h"
/*
* We must include the header file for the service.
*/
#include "example-service.h"
/*
* All Contiki programs must have a process, and we declare it here.
*/
PROCESS(example_use_service_process, "Use example");
/*
* The program is to call the service once every second, so we use an
* event timer in order to run every second.
*/
static struct etimer timer;
/*---------------------------------------------------------------------------*/
/*
* Here we implement the process.
*/
PROCESS_THREAD(example_use_service_process, ev, data)
{
/*
* A process thread starts with PROCESS_BEGIN() and ends with
* PROCESS_END().
*/
PROCESS_BEGIN();
/*
* We loop for ever, calling the service once every second.
*/
while(1) {
/*
* We set a timer that wakes us up once every second.
*/
etimer_set(&timer, CLOCK_SECOND);
PROCESS_YIELD_UNTIL(etimer_expired(&timer));
/*
* We call the service. If the service is not registered, the
* SERVICE_CALL() statement does nothing. If we need to know if
* the service exists, we can use the SERVICE_FIND() function.
*/
printf("use example: calling example\n");
SERVICE_CALL(example_service, example_function());
}
/*
* And finally the process ends.
*/
PROCESS_END();
}
/*---------------------------------------------------------------------------*/

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/** \example example-program.c */ /** \example example-program.c */
/** \example example-service.c */
/** \example example-service.h */
/** \example example-use-service.c */
/** \example example-pollhandler.c */ /** \example example-pollhandler.c */
/** \example example-list.c */ /** \example example-list.c */
/** \example example-packet-service.c */ /** \example example-packet-drv.c */
/** \example example-psock-server.c */ /** \example example-psock-server.c */
/** \example test-abc.c */ /** \example test-abc.c */