4.3BSD-UWisc/man/cat3/topen.3f
TOPEN(3F) UNIX Programmer's Manual TOPEN(3F)
NAME
topen, tclose, tread, twrite, trewin, tskipf, tstate - f77
tape I/O
SYNOPSIS
integer function topen (tlu, devnam, label)
integer tlu
character*(*) devnam
logical label
integer function tclose (tlu)
integer tlu
integer function tread (tlu, buffer)
integer tlu
character*(*) buffer
integer function twrite (tlu, buffer)
integer tlu
character*(*) buffer
integer function trewin (tlu)
integer tlu
integer function tskipf (tlu, nfiles, nrecs)
integer tlu, nfiles, nrecs
integer function tstate (tlu, fileno, recno, errf, eoff,
eotf, tcsr)
integer tlu, fileno, recno, tcsr
logical errf, eoff, eotf
DESCRIPTION
These functions provide a simple interface between f77 and
magnetic tape devices. A ``tape logical unit'', _t_l_u, is
``topen''ed in much the same way as a normal f77 logical
unit is ``open''ed. All other operations are performed via
the _t_l_u. The _t_l_u has no relationship at all to any normal
f77 logical unit.
_T_o_p_e_n associates a device name with a _t_l_u. _T_l_u must be in
the range 0 to 3. The logical argument _l_a_b_e_l should indi-
cate whether the tape includes a tape label. This is used
by _t_r_e_w_i_n below. _T_o_p_e_n does not move the tape. The normal
returned value is 0. If the value of the function is nega-
tive, an error has occured. See _p_e_r_r_o_r(3F) for details.
_T_c_l_o_s_e closes the tape device channel and removes its asso-
ciation with _t_l_u. The normal returned value is 0. A nega-
tive value indicates an error.
Printed 12/27/86 May 15, 1985 1
TOPEN(3F) UNIX Programmer's Manual TOPEN(3F)
_T_r_e_a_d reads the next physical record from tape to _b_u_f_f_e_r.
_B_u_f_f_e_r must be of type character. The size of _b_u_f_f_e_r should
be large enough to hold the largest physical record to be
read. The actual number of bytes read will be returned as
the value of the function. If the value is 0, the end-of-
file has been detected. A negative value indicates an
error.
_T_w_r_i_t_e writes a physical record to tape from _b_u_f_f_e_r. The
physical record length will be the size of _b_u_f_f_e_r. _B_u_f_f_e_r
must be of type character. The number of bytes written will
be returned. A value of 0 or negative indicates an error.
_T_r_e_w_i_n rewinds the tape associated with _t_l_u to the beginning
of the first data file. If the tape is a labelled tape (see
_t_o_p_e_n above) then the label is skipped over after rewinding.
The normal returned value is 0. A negative value indicates
an error.
_T_s_k_i_p_f allows the user to skip over files and/or records.
First, _n_f_i_l_e_s end-of-file marks are skipped. If the current
file is at EOF, this counts as 1 file to skip. (Note: This
is the way to reset the EOF status for a _t_l_u.) Next, _n_r_e_c_s
physical records are skipped over. The normal returned
value is 0. A negative value indicates an error.
Finally, _t_s_t_a_t_e allows the user to determine the logical
state of the tape I/O channel and to see the tape drive con-
trol status register. The values of _f_i_l_e_n_o and _r_e_c_n_o will
be returned and indicate the current file and record number.
The logical values _e_r_r_f, _e_o_f_f, and _e_o_t_f indicate an error
has occurred, the current file is at EOF, or the tape has
reached logical end-of-tape. End-of-tape (EOT) is indicated
by an empty file, often referred to as a double EOF mark.
It is not allowed to read past EOT although it is allowed to
write. The value of _t_c_s_r will reflect the tape drive con-
trol status register. See _h_t(4) for details.
FILES
/usr/lib/libU77.a
SEE ALSO
ht(4), perror(3F), rewind(1)
Printed 12/27/86 May 15, 1985 2