nedk_bridge.c

很多仪器都输出同步时钟

// | File: nedk_bridge.c
// |
// |
// | A simple ethernet-ethernet bridge, echoes all packets
// | from one side to the other.
// |
//
// ex:set tabstop=4:


// +------------------------------
// | Includes
// |

#include "excalibur.h"
#include "plugs.h"

// | Design-specific definition for which ethernet peripheral
// | to use...

#include "plugs_example_designs.h"


// +------------------------------
// | Globals State
// |

#define k_port_count 2

typedef struct
	{
	int plug_handle[k_port_count];
	} globals;

// +------------------------------
// | Prototypes
// |

static int bridge_proc
		(
		int plug_handle,
		void *context,
		ns_plugs_packet *p,
		void *payload,
		int payload_length
		);
	

// +------------------------
// | The Tofu
// |

int main(void)
	{
	int result;
	globals g;   // How polite we are, the globals aren't really global!
	int i;

	// |
	// | Initialize the first card
	// |

	result = nr_plugs_initialize(0,0,
			__adapter__,
			__adapter_irq__,
			__adapter_struct_addr__);

	if(result)
		goto go_home;

	// |
	// | Initialize the second card
	// | Note the flag to nr_plugs_initialize which says,
	// | we're just adding an adapter, not clearing everything.
	// |

	result = nr_plugs_initialize(ne_plugs_flag_add_adapter,0,
			__adapter2__,
			__adapter2_irq__,
			__adapter_struct_addr__);

	if(result)
		goto go_home;

	// |
	// | Now, create all the plugs. They all share the same handler proc.
	// |

	for(i = 0; i < k_port_count; i++)
		{
		result = nr_plugs_create
			(
			&g.plug_handle[i],
			ne_plugs_ethernet,
			0,	// port number, does not matter here
			bridge_proc,
			&g,
			ne_plugs_flag_ethernet_all  // aka promiscuous
			   + i                      // adapter index
			);
		if(result)
			goto go_home;
		}
	
	// |
	// | Lastly, idle the plugs library forever
	// |

	printf("Forwarding packets between all ports now.\n\n");
	printf("Press Q to quit.\n\n");

	while(1)
		{
		int c;
	
		nr_plugs_idle();

		if((c = nr_uart_rxchar(0)) > 0)
			{
			printf("%c.",c);
			if(c == 'q' || c == 'Q')
				{
				printf("\n\nQuitting.\n\n");
				goto go_home;
				}
			}
		}

go_home:
	printf("nedk_bridge: exiting with %d\n",result);
	return result;
	}

// +--------------------------------
// | bridge_proc
// |
// | This is the packet handler for all adapters, and
// | all it does is resend a received packet on
// | every other port.
// |
// | It also prints a numeral for which adapter has
// | received a packet. If you put the NEDK bridge
// | between your computer and your LAN, for
// | example (with a crossover cable, of course)
// | then you get a nice "The Matrix" screen of
// | 1's and 0's. You cannot, however, realistically
// | ascertain hair color from this visualization,
// | even with practice. -- dvb
// |

static int bridge_proc
		(
		int plug_handle,
		void *context,
		ns_plugs_packet *p,
		void *payload,
		int payload_length
		)
	{
	globals *g = context;
	int result_z;
	int result = 0;
	int i;

	for(i = 0; i < k_port_count; i++)
		{
		// |
		// | Only rebroadcast the packet
		// | onto *other* ports, not the
		// | one it arrived on.
		// |

		if(g->plug_handle[i] != plug_handle)
			{
			result_z = nr_plugs_send
				(
				g->plug_handle[i],
				payload,
				payload_length,
				0
				);
			if(result_z && !result)
				result = result_z;
			}
		else
			nr_uart_txchar(i + '0',0);
		}

go_home:
	return result;
	}