4.4BSD/usr/share/man/cat3f/tskipf.0

F>=1  .if 3F<=8 .    if 3F>1 .if 3F<6 .ds an-extra3 "BSD Program-



TOPEN(3F)              BSD Reference Manual             TOPEN(3F)

mer's Manual
NNAAMMEE
       topen, tclose, tread, twrite, trewin, tskipf, tstate - f77
       tape I/O

SSYYNNOOPPSSIISS
       iinntteeggeerr ffuunnccttiioonn ttooppeenn (tlu, devnam, label)
       iinntteeggeerr tlu
       cchhaarraacctteerr**((**)) devnam
       llooggiiccaall label

       iinntteeggeerr ffuunnccttiioonn ttcclloossee (tlu)
       iinntteeggeerr tlu

       iinntteeggeerr ffuunnccttiioonn ttrreeaadd (tlu, buffer)
       iinntteeggeerr tlu
       cchhaarraacctteerr**((**)) buffer

       iinntteeggeerr ffuunnccttiioonn ttwwrriittee (tlu, buffer)
       iinntteeggeerr tlu
       cchhaarraacctteerr**((**)) buffer

       iinntteeggeerr ffuunnccttiioonn ttrreewwiinn (tlu)
       iinntteeggeerr tlu

       iinntteeggeerr ffuunnccttiioonn ttsskkiippff (tlu, nfiles, nrecs)
       iinntteeggeerr tlu, nfiles, nrecs

       iinntteeggeerr  ffuunnccttiioonn  ttssttaattee (tlu, fileno, recno, errf, eoff,
       eotf, tcsr)
       iinntteeggeerr tlu, fileno, recno, tcsr
       llooggiiccaall errf, eoff, eotf

DDEESSCCRRIIPPTTIIOONN
       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  nor-
       mal  returned value is 0.  If the value of the function is
       negative,  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
       association with _t_l_u.  The normal returned value is 0.   A



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TOPEN(3F)              BSD Reference Manual             TOPEN(3F)


       negative value indicates an error.

       _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 mmuusstt be of type  cchhaarraacctteerr.   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 indi-
       cates 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
       mmuusstt  be  of  type cchhaarraacctteerr.  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 begin-
       ning 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 nega-
       tive 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  cur-
       rent  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
       control  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 dou-
       ble 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  control  status register.  See _h_t(4) for
       details.

FFIILLEESS
       /usr/lib/libU77.a

SSEEEE AALLSSOO
       ht(4), perror(3F), rewind(1)







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