Xinu7/man/man4/ether.doc

ETHER(4)            Xinu Programmer's Manual             ETHER(4)



NAME
     ether - standard 10Mbps Ethernet network interface device
     driver (type eth)

SYNOPSIS
     #include <deqna.h>
     #include <ether.h>

     read(device buffer, length)
     write(device, buffer, length)
     init(device)

DESCRIPTION
     The _e_t_h device driver provides input and output for a 10
     Mbps Ethernet local area network.  The standard Xinu device
     name for Ethernet devices is _E_T_H_E_R.

     Implemented on a Digital Equipment Corporation DEQNA (Digi-
     tal Equipment Q-Bus Network Adapter), the _e_t_h driver handles
     DMA input and output at the physical network level,
     transmitting complete frames between user processes and the
     device.

     The driver honors the following operations:

     read(device buffer, length)
          Reads one frame into _b_u_f_f_e_r, copying no more than
          _l_e_n_g_t_h characters.  It returns the length of the frame
          read; the count includes the 14-octet header.

     write(device, buffer, length)
          Writes a frame of _l_e_n_g_t_h characters found in _b_u_f_f_e_r.
          It returns _O_K if the frame was acceptable, _S_Y_S_E_R_R oth-
          erwise.  It it important to note that _b_u_f_f_e_r must
          specify the address of a valid buffer allocated from
          GETBUF(2), and that the driver does not copy the con-
          tents of the buffer.  The call to _w_r_i_t_e will return
          once output has been started, but the buffer will be in
          use until the device finishes.  The driver calls
          FREEBUF(2) to dispose of the buffer once the device
          finishes using it.

     init(device)
          Initializes the device and driver, including DEQNA
          setup packet processing.  The driver sets the device to
          accept only those packets addressed directly to the
          devices' physical address and broadcast packets (all
          1's address).

NOTES
     Although the DEQNA supports chaining back-to-back operations
     on both input and output, the driver forces a context switch



Version 6b               Printed 1/12/87                        1






ETHER(4)            Xinu Programmer's Manual             ETHER(4)



     and a new call from READ(2) or WRITE(2) to restart I/O, and
     depends on the hardware to buffer packets from the Ethernet.





















































Version 6b               Printed 1/12/87                        2