| Author(s): J. Zoll | Library: KERNLIB, VAX and UNIX systems only |
| Submitter: | Submitted: 31.10.1991 |
| Language: Fortran + C | Revised: 01.04.1994 |
The routines of this package are an interface to the C library functions open, read, write, lseek, close, to permit a Fortran program to handle an unstructured Unix file as a string of bytes. Both sequential and direct-access READ / WRITE can be done.
New files are opened with the default permissions 644; one may set different permissions by calling CIPERM just before calling CIOPEN, which resets to the default after every call.
One parameter is common to almost all routines : LUNDES is the file-descriptor of C to identify the file; with CIOPEN this is an output parameter, for all other routines it is an input parameter.
Structure:
SUBROUTINE subprograms
User Entry Names:
CIOPEN, CIGET, CIGETW,
CIPUT, CIPUTW,
CISIZE, CITELL, CISEEK, CIREW,
CICLOS, CIPERM
Files Referenced: Parameter
Usage:
Note: the symbol * designates output parameters.
Open a file
CALL CIOPEN(LUNDES, CHMODE, CHNAME, ISTAT)
LUNDES* file-descriptor returned
CHMODE CHARACTER string selecting the IO mode :
= 'r' open for reading
'r+' open for read/write
'w' create or truncate for writing
'w+' open for write/read, create or truncate
'a' append
'a+' open for append/read
CHNAME name of the file, of type CHARACTER
ISTAT* status, =zero if success
For example, create a new file in the current directory :
CALL CIOPEN(LUNDES, 'w', 'concert.car', ISTAT)
IF(ISTAT .NE. 0) GO TO trouble
Read next string of bytes
CALL CIGET (LUNDES, CHBUF, NBDO, NBDONE, ISTAT)
CHBUF* text vector to be read into
NBDO maximum number of bytes to be read
NBDONE* number of bytes actually read
ISTAT* status, = zero if success,
= -1 if end-of-file
Read next string of full words
CALL CIGETW(LUNDES, MBUF, NWDO, NWDONE, ISTAT)
MBUF* vector to be read into
NWDO maximum number of words to be read
NWDONE* number of words actually read
ISTAT* status, = zero if success,
= -1 if end-of-file
A full word is normally 4 bytes; on the CRAY it is 8 bytes.
To simulate direct-access reading one has to call CISEEK first.
For example:
To read the next 2048 bytes:
<< starting at byte 8193 :
CALL CISEEK(LUNDES, 8192, ISTAT)
IF(ISTAT .NE. 0) GO TO trouble >>
CALL CIGET(LUNDES, CHBUF, 2048, NBDONE, ISTAT)
IF(ISTAT .EQ. -1) GO TO eof
IF(ISTAT .NE. 0) GO TO trouble
Write next string of bytes
CALL CIPUT(LUNDES, CHBUF, NBDO, ISTAT)
CHBUF text vector to be written, NBDO bytes
ISTAT* status, =zero if success
Write next string of full words
CALL CIPUTW(LUNDES, MBUF, NWDO, ISTAT)
MBUF vector to be written, NWDO words
ISTAT* status, =zero if success
Get the size of the file
CALL CISIZE(LUNDES, NBYTT, ISTAT)
NBYTT* number of bytes on the file
ISTAT* status, =zero if success
Careful : this will position the file to the end.
Get the current file position
CALL CITELL(LUNDES, NBYTC, ISTAT)
NBYTC* number of bytes before current
ISTAT* status, =zero if success
Set the current file position
CALL CISEEK(LUNDES, NBYTC, ISTAT)
NBYTC number of bytes before current
ISTAT* status, =zero if success
For example :
CALL CISEEK(LUNDES, 0, ISTAT) position to start-of-file
CALL CISEEK(LUNDES, 8, ISTAT) position to 9th byte
use CISIZE to position to end-of-file
Rewind the file
CALL CIREW(LUNDES)
Close the file
CALL CICLOS(LUNDES)
Set the permissions for the next open
CALL CIPERM(IPERM)
IPERM the permissions as a decimal integer,
as returned by STATF (Z265) for example
For example (using NCOCTI of M432) :
CALL CIPERM(NCOCTI('664'))
set read for everybody, and write for owner and group.
Note: formally the buffer for reading and writing should be of
type CHARACTER for CIGET and CIPUT,
and of type INTEGER for CIGETW and CIPUTW.
On most machines there is no difference, but on the
VAX this must be observed, because the parameter passing mechanisme
differs crucially for the two cases. Also, on the CRAY there would
be problems if one were using CIGETW to read
into a Character address other than a word boundary.
