Chapter 12. Foreign File Conversion

Table of Contents
12.1. Conversion Overview
12.2. Transferring Data
12.3. Data Item Conversion
12.4. Foreign Conversion Techniques
12.5. Implicit Numeric Conversions (Cray PVP systems Only)

This chapter contains information about data conversion, a discussion about moving data between machines, and information about the working of implicit and explicit data conversion. It also explains the support provided for reading and writing files in foreign formats, including the record blocking and numeric and character conversion.

These routines convert data (primarily floating-point data, but also integer and character, as well as Fortran complex and logical data) from your system's native representation to a foreign representation, and vice versa. Most of the routines discussed in this chapter are not yet available on Cray MPP systems or on IRIX systems. For complete implementation details, see the individual man pages or the INTRO_CONVERSION man page.

12.1. Conversion Overview

Data can be transferred between IRIX/UNICOS systems and other computer systems in several ways. These methods include the use of stations supplied by Cray Research and online tapes and utilities built on TCP/IP (such as ftp).

Cray Research supports foreign data conversion to and from IBM, VAX/VMS, CDC NOS/VE, CYBER 205, and the Institute of Electrical and Electronics Engineers (IEEE) format. For each foreign file type, several supported file and record formats exist or explicit or implicit data conversion can also be used.

When processing foreign data on IRIX or UNICOS systems, you must consider the interactions between the data formats and the chosen method of data transfer. This section describes, in broad terms, the techniques available to do these data conversions.

Explicit data conversion is the process by which the user performs calls to subroutines that convert the native data to and from the foreign data formats. These routines are provided for many data formats. This is discussed in more detail in Section 12.3.1.

Implicit data conversion is the process by which users declare that a particular file contains foreign data and/or record blocking and then request that the run-time library perform appropriate transformations on the data to make it useful to the program at I/O time. This method of record and/or data format conversion requires changes in command scripts. This is discussed in more detail in Section 12.3.2.