Xinu7/man/man2/control.doc

CONTROL(2)          Xinu Programmer's Manual           CONTROL(2)



NAME
     control - device independent control routine

SYNOPSIS
     int control(dev, function, arg1, arg2)
     int dev;
     int function;
     int arg1, arg2;

DESCRIPTION
     _C_o_n_t_r_o_l is the mechanism used to send control information to
     devices and device drivers, or to interrogate their status.
     (Data normally flows through GETC(2), PUTC(2), READ(2), and
     WRITE(2).)

     _C_o_n_t_r_o_l returns SYSERR if _d_e_v is incorrect or if the func-
     tion cannot be performed.  The values returned otherwise are
     device dependent.  For example, there is a control function
     for "tty" devices that returns the number of characters
     waiting in the input queue.

SEE ALSO
     close(2), getc(2), open(2), putc(2), read(2), seek(2),
     write(2)































Version 6b               Printed 1/12/87                        1