FMSEEK
FMSEK8
PURPOSE: Position File
To position a file prior to sequential access.
SYNOPSIS
CALL FMSEEK (LOGUNT, LOCUNT)
CALL FMSEK8 (LOGUNT, LOCUNT)
INPUT PARAMETERS:
- LOGUNT = Integer.
The FMS file number, which is stored by
FMS in the file attribute list.
- LOCUNT = Integer. (FMSEEK only)
LOCUNT = REAL*8. (FMSEK8 only)
The file address (in words) where you want to position the
file. Valid addresses begin at 1 (the start of the
file).
= 0, erase file contents and set LOCUNT to 1.
For FMSEEK, this is an integer.
For FMSEK8, this is a REAL*8 Floating Point Number. FMSEK8 allows the addressing of files greater than 2 Gbytes on systems supporting only 32-bit integers.
OUTPUT PARAMETERS:
None.
DESCRIPTION:
This subroutine positions a file prior to sequential access
by
FMSSWR and
FMSSRD.
When a file is first opened, it is positioned at the
beginning. You may use subroutine FMSSWR to write the file
sequentially the first time without calling this subroutine.
If you want to read the file sequentially, you should call
this subroutine with the starting file address prior to
calling FMSSRD.
If you want to rewrite the file and don't care about the
previous file data, you should call this subroutine with
LOCUNT = 0. This is a special case which resets the file
pointers to the beginning of the file and erases the file
contents.
If you must alternate read and write operations to the file,
you should use the direct access subroutines
FMSRED and
FMSWRT.
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