Table 4: File System Intrinsics

Table 4: File System Intrinsics

Some Basic File

System Intrinsics Description

FOPEN This intrinsic is found on all models of the HP 3000, including the older 16-bit MPE/V models and the newer 32-bit PA-RISC machines based on MPE/iX. Its purpose is to open files. This intrinsic originated on the older 16-bit systems, and supports all the functionality of the MPE/V file system. The MPE/iX file system is a superset of the MPE/V file system. Therefore, if an application program uses FOPEN to open files on an MPE/iX machine, it may not be able to use the full functionality of the MPE/iX file system.

When a file is opened using FOPEN, the application program calling FOPEN must specify whether the file is being opened for INPUT or for OUTPUT.

If the intrinsic executes successfully, it returns a unique file number to the calling program. This number is used in subsequent calls to other file system intrinsics, such as FREAD and FWRITE.

HPFOPEN This intrinsic is implemented in MPE/iX on all PA-RISC models of the HP 3000. Like FOPEN, it is used to open files. Unlike FOPEN, it supports the full functionality of the MPE/iX file system. HPFOPEN can be thought of as the "native mode" intrinsic for opening files on an MPE/iX system. The older FOPEN intrinsic is there primarily to provide compatibility for applications from older MPE/V systems. (If an MPE/iX application program calls the older FOPEN intrinsic on an MPE/iX system, FOPEN will do little more than invoke HPFOPEN, which is what actually opens the file.)

When a file is opened using HPFOPEN, the application program calling HPFOPEN must specify whether the file is being opened for INPUT or for OUTPUT.

If the intrinsic executes successfully, it returns a unique file number to the calling program. This number is used in subsequent calls to other file system intrinsics, such as FREAD and FWRITE.

FREAD This intrinsic reads the next record in sequential order from an input file that has been opened using FOPEN or HPFOPEN. FREAD is typically used for sequential access.

FWRITE This intrinsic writes the next record in sequential order to an output file that has been opened using FOPEN or HPFOPEN. FWRITE is typically used for sequential access.

FREADDIR This intrinsic reads a specific record from an input file that has been opened using FOPEN or HPFOPEN. FREADDIR is used for direct access. For example, FREADDIR could be used to read the 100th record from a file without first having to read the 99 records that precede it.

FWRITEDIR This intrinsic can be used to write a specific record to an output file that has been opened using FOPEN or HPFOPEN. Like FREADDIR, the FWRITEDIR intrinsic is typically used for direct access to records in an output file. For example, FWRITEDIR could be used to update the 100th record in a file without first having to access the 99 records that precede it

FCLOSE This intrinsic closes files that have previously been opened using FOPEN or HPFOPEN.

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Some Basic File
System Intrinsics	Description
FOPEN	This intrinsic is found on all models of the HP 3000, including the older 16-bit MPE/V models and the newer 32-bit PA-RISC machines based on MPE/iX. Its purpose is to open files. This intrinsic originated on the older 16-bit systems, and supports all the functionality of the MPE/V file system. The MPE/iX file system is a superset of the MPE/V file system. Therefore, if an application program uses FOPEN to open files on an MPE/iX machine, it may not be able to use the full functionality of the MPE/iX file system.
	When a file is opened using FOPEN, the application program calling FOPEN must specify whether the file is being opened for INPUT or for OUTPUT.
	If the intrinsic executes successfully, it returns a unique file number to the calling program. This number is used in subsequent calls to other file system intrinsics, such as FREAD and FWRITE.


HPFOPEN	This intrinsic is implemented in MPE/iX on all PA-RISC models of the HP 3000. Like FOPEN, it is used to open files. Unlike FOPEN, it supports the full functionality of the MPE/iX file system. HPFOPEN can be thought of as the "native mode" intrinsic for opening files on an MPE/iX system. The older FOPEN intrinsic is there primarily to provide compatibility for applications from older MPE/V systems. (If an MPE/iX application program calls the older FOPEN intrinsic on an MPE/iX system, FOPEN will do little more than invoke HPFOPEN, which is what actually opens the file.)
	When a file is opened using HPFOPEN, the application program calling HPFOPEN must specify whether the file is being opened for INPUT or for OUTPUT.
	If the intrinsic executes successfully, it returns a unique file number to the calling program. This number is used in subsequent calls to other file system intrinsics, such as FREAD and FWRITE.




FREAD	This intrinsic reads the next record in sequential order from an input file that has been opened using FOPEN or HPFOPEN. FREAD is typically used for sequential access.
FWRITE	This intrinsic writes the next record in sequential order to an output file that has been opened using FOPEN or HPFOPEN. FWRITE is typically used for sequential access.
FREADDIR	This intrinsic reads a specific record from an input file that has been opened using FOPEN or HPFOPEN. FREADDIR is used for direct access. For example, FREADDIR could be used to read the 100th record from a file without first having to read the 99 records that precede it.
FWRITEDIR	This intrinsic can be used to write a specific record to an output file that has been opened using FOPEN or HPFOPEN. Like FREADDIR, the FWRITEDIR intrinsic is typically used for direct access to records in an output file. For example, FWRITEDIR could be used to update the 100th record in a file without first having to access the 99 records that precede it
FCLOSE	This intrinsic closes files that have previously been opened using FOPEN or HPFOPEN.