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SAR$–Symbolic Access Routines
16.1. File Information Packet
The file information packet (FIP) is used to pass information to the Symbolic Access
Routines (SAR$) for input and output to SDF files, SDF elements, and alternate symbiont
files. The SAR$ calling program must supply the D-bank storage space for the FIP.
The file information packet is not required for reading from or writing to the standard
symbiont (READ$ and PRINT$) files.
All required information is placed in the FIP, and the address of the FIP is placed in the
SAR$ READ or WRITE packets.
16.1.1. PLUS Interface
The type definition for the FIP is contained in the PLUS definition element
SAR$FILEPKTD in the SYSLIB file SYS$LIB$*SYSLIB and may be obtained with the
PLUS COPY statement “COPY ('SAR$FILEPKTD');”. The identifier of the FIP data
structure type is SAR_FILE_INFO_PACKET. The length of the FIP is equal to the
constant SAR_FILE_INFO_PACKET_WORD_LENGTH defined in the element
SAR$FILEPKTD (current length is nine words). SAR_FILE_INFO_PACKET is defined as
LOCATABLE.
16.1.1.1. FIP Field Descriptions
The following fields of the FIP are set by the calling program:
PACKET_VERSION
PLUS Attribute: 6-bit integer
The FIP data structure version. The current version is equal to the constant
SAR_FILE_INFO_PACKET_CURRENT_VERSION defined in the element
SAR$FILEPKTD.
ACCESS_TYPE
PLUS Attribute: 6-bit status
The type of input being accessed
S'SDF_file' Input is from an SDF file.
S'SDF_element' Input is from an SDF element.
S'PROC' Input is from a PLUS, FORTRAN, or COBOL PROC.
S'Alternate_symbiont' Input is from an alternate READ file.
This field is set for input only; it is omitted for output. If input is from the runstream
(READ$ file), the FIP address in the READ packet is set to NULL.
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